is mental time travel possible

Mental time travel is a great decision-making tool — this is how to use it

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When the future seems largely unpredictable, is there anything you can do to prepare for it?

“Yes!” says futurist and game designer Jane McGonigal . All you need to do is to tap into your imagination and envision all your potential futures — using what she calls “futures thinking.” 

“Futures thinking isn’t a superpower, and you don’t have to fix everything or save everyone,” McGonigal writes in her new book called Imaginable . “But futures thinking is an incredibly useful, practical tool to prepare your mind to adapt faster to new challenges, build hope and resilience, reduce anxiety and depression, and inspire you to take actions today that set yourself up for future happiness and success.”

Her book draws on the latest research in psychology and neuroscience to show you how to train your mind to think the unthinkable. In this excerpt, you’ll get a taste of how you can start thinking like a futurist — and create a better future for yourself. 

For the next 30 seconds, I want you to imagine yourself waking up tomorrow morning. Try to picture it in your mind or describe it to yourself as clearly as possible. 

These questions may help make your imagined scene clearer. What room or space are you in? What wakes you up — an alarm, the sunlight, someone nudging you or calling you? Is it light out or still dark? Is there anyone with you? What are you wearing? What kind of mood are you in? And what’s the very first thing you do now that you’re awake?

Keep imagining your tomorrow morning until you have a clear answer to all of these questions.

This quick mental time trip you just took is an example of a highly imaginable future — it was likely quite easy for you to envision, with plenty of vivid details.

Now let’s try something more challenging. For the next 30 seconds, I want you to imagine yourself waking up one year from today. 

Again, try to envision this as clearly as possible. Feel free to change as many or as few details as you want from the first scene you imagined. Are you somewhere different? Are you physically changed? What’s your mood? Do you have a different morning habit? What might that new habit be?

Keep imagining your morning one year from now until you have answers to all of these questions — even the harder ones. Notice how easily and automatically ideas came to you, or how hard you had to work to come up with details.

If you’re having difficulty imagining life 10 years from now, write down a description of what you imagine. It can be easier to think about the future with words rather than with mental images.

Now let’s try one more act of imagination. This time, I want you to imagine yourself waking up 10 years from today.

Take as long as you need to come up with a vivid and plausible image — of yourself, of the space that you’re in, and who might be with you. Where are you? What’s around you? What do you see, hear, smell, and feel? What’s the first thing on your mind when you wake up? What do you have planned for the day? How are you physically different?

Try not to make this future scene a total fantasy; stay grounded in what you feel is genuinely realistic and possible for you. If you’re having difficulty, write down a description of what you imagine. Sometimes, it’s easier to think about the future with words rather than with mental images.

You’ll probably find that 10 years is a trickier challenge compared with one year. Why? You’ve never been 10 years older than you are now, so your brain doesn’t know what to expect. Plus, there’s so much opportunity for things to change in a decade — your body, relationships, life circumstances, physical environment.

Your brain intuitively grasps this unknowability, so instead of confidently projecting one possibility, it opens up a blank space for you to consider multiple possibilities. You have to start making intentional choices about what you want to imagine in your future — you have to fill in the blanks.

“Episodic future thinking” or EFT is often described as “mental time travel” — your brain is working to help you see and feel the future as clearly and vividly as if you were already there.

Filling in the blanks takes considerable effort. But that’s precisely why this kind of imagination is so powerful. Instead of simply remembering what it knows, your brain has to invent a new possibility. It draws on past experiences, current hopes and fears, and your intuitions about what might possibly change in 10 years.

Then, after you’ve made this new memory, something amazing happens: What was previously unimaginable to your brain is now imaginable. You can revisit this new memory whenever you want and examine how it makes you feel. Does it spark positive or negative emotions? These pre-feelings can help you decide: Should you change what you’re doing today to make this future more or less likely? And because you invented this memory, you can change it whenever you want.

Scientists call this form of imagination “episodic future thinking,” or EFT. EFT is often described as a kind of “mental time travel” because your brain is working to help you see and feel the future as clearly and vividly as if you were already there.

EFT isn’t an escape from reality. It’s a way of playing with reality, to discover risks and opportunities you might not have considered. EFT is not a daydream in which you fantasize about waking up in a world where your problems are magically solved. It is a way of connecting who you are today with what you might really feel and do in the future.

An important element of imagination training is to fill your brain with what I call “clues to the future,” concrete examples of new ideas that might shape how your future turns out.

Because EFT allows us to pre-feel different possible futures, it’s a powerful decision-making, planning and motivational tool. It helps us decide: Is this a world I want to wake up in? What do I need to do to be ready for it? Should I change what I’m doing today to make this future more or less likely?

According to fMRI studies, EFT involves heightened activity and increased connectivity between 11 distinct brain regions. Compare this to remembering a past event, which activates 6 of the 11 regions of the brain.

There are three major kinds of sense making that happen when you engage in mental time travel to your future. First, your brain has to do what cognitive scientists call “scene construction” — mentally building the future world. Think of this as crafting the stage set, cast and props for a theatrical play.

During EFT, your brain goes on a hunt for realistic details and plausible ideas. To do this, it activates the hippocampus , the seat of memory and learning, and digs through your memories, plus any other facts and ideas you’ve stored away. Depending on what kind of future you’re imagining, the hippocampus identifies the most relevant stuff and retrieves and recombines it into a new scene.

Whatever you see in your future will always come from information your brain has already perceived and processed. Ideally, as you get better at imagining the unimaginable, you’ll incorporate not just obvious ideas and events but also surprising things that could be important in your future.

Another important part of imagination training is to try out new behaviors that could prove useful in the future. I call these micro-actions — taking no more than five minutes to do something today you’ve never done before.

That’s why an important element of imagination training is to fill your brain with what I call “clues to the future,” concrete examples of new ideas that might shape how your future turns out. When you have a hippocampus full of clues, your brain will have better data to draw on, and the scenes you construct will be way more interesting.

After scene construction, your brain starts to do what cognitive scientists call “opportunity detection.” Here, you look for ways to fulfill your needs and achieve your goals. For example: If you predict you will be hungry when you wake up in 10 years, what will future you eat? If you imagine yourself lonely when you wake up, who will future you try to connect with? Opportunity detection is like an actor showing up for rehearsal and asking, “What’s my motivation?” In other words: What do you want in this scene?

To figure this out, your brain fires up the ventromedial prefrontal cortex (vmPFC), a region that’s heavily used whenever you set goals and track your progress. Like the hippocampus, the vmPFC can suggest any goals you’ve had or previously considered. One of the most interesting things about EFT is that the motivations that pop into your mind first are likely to be closely linked to your deepest values and most essential needs, like always learning something new, helping others, pushing yourself to do brave things, taking care of your family, being creative, or  putting new ideas or art into the world.

But you still have to figure out the best way for future you to achieve these future goals. So then the putamen , also part of the motivation and reward system, kicks in. The putamen helps keep track of which specific actions and behaviors typically lead to positive results for you. It’s the part of your brain that knows things like “I feel better when I get some fresh air”; “I make my mom happy when I text her back right away”; “If I’m having a bad day, cooking helps”; or “If I don’t stand up for myself in the moment, I’ll beat myself up about it later.”

There are real benefits to intentionally and carefully imagining futures that frighten you. This can help you do the important work of getting ready for anything — even things you’d rather not experience.

The putamen is like a reality check on your future imagination. Since the putamen is trained on real experiences, the future actions it suggests will be heavily influenced by strategies that worked for you in the past. That’s why another important part of imagination training is to try out new behaviors that could prove useful in the future. I call these micro-actions — taking no more than five minutes to do something today you’ve never done before. When you experiment with micro-actions, you expand what your putamen considers realistic behavior.

Finally, as your brain works to transport you to the future, feelings will kick in. The insula and amygdala , emotion centers in the brain, fire up to give you a preview of how you might feel in the future — excited, disappointed, hopeful, afraid, proud, jealous, joyful, sad, curious, bored, embarrassed, relieved, loved, lonely, awed, confused, stressed out, free or more. These emotions give you important information and help you decide: Is this a future I want to wake up in? Should I take actions today to make this future more or less likely?

Crucially, these are real feelings. Studies show that the emotions you experience during EFT can be just as psychologically powerful as emotions experienced in the present. This is one reason why many of us prefer to imagine best-case-scenario futures and avoid imagining the futures that scare us.

But there are real benefits to intentionally and carefully imagining futures that frighten you. This can help you do the important work of getting ready for anything — even things you’d rather not think about, let alone actually experience, someday.

Excerpted from the new book Imaginable: How to See the Future Coming and Feel Ready for Anything Even Things That Seem Impossible Today by Jane McGonigal. Copyright © 2022 by Jane McGonigal. Used by permission of Spiegel & Grau LLC, New York. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.

Watch her TED Talk here:

About the author

Jane McGonigal is a future forecaster and world-renowned designer of alternate reality games designed to improve real lives and solve real problems. She is the Director of Games Research & Development at the Institute for the Future and currently teaches the course “How to Think Like a Futurist” at Stanford University, as well as serving as the lead instructor for the Institute for the Future’s series on the Coursera platform. She is The New York Times bestselling author of the books "Reality Is Broken" and "SuperBetter" and the new book "Unimaginable." Her innovative games and ideas have been recognized by the World Economic Forum, Harvard Business Review, Fast Company, MIT Technology Review, O Magazine and the New York Times, among others.

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Is Mental Time Travel Good For Us?

Forget the “be here now” concept, which stresses focus on the present. allowing your mind to wander freely has its own benefits..

In our fast-paced modern lives, we are increasingly encouraged to stop and focus on the present. And there are tangible advantages.

Studies on the effects of mindfulness and meditation — practices that gear people’s cognitive capacities towards the present moment — have pointed to reduced stress, increased focus and less emotional reactivity.

As a result, mindfulness has become a billion-dollar industry that promises to alleviate all manner of psychological ills.

However, Anna-Lisa Cohen, a psychology professor at Yeshiva University in New York, says that while there is concrete evidence pointing to the positive changes that mindfulness can bring about, we shouldn’t overlook other tools.

“While there is scientific evidence that mindfulness and meditation do lead to positive changes in our brains and biology, especially for stress reduction,” Cohen says, “I think it is also important to carve out space in the public forum to acknowledge the new science on the benefits of doing the opposite.”

What Is Mental Time Travel?

Cohen points to recent research on “self-projection,” better known as “mental time travel.” In short, this is our unique ability to reflect on past experiences and project ourselves into the future.

“Our ability to disengage from the present and immerse ourselves in imaginary worlds is one of our most extraordinary gifts as humans and underlies some of our greatest accomplishments,” she says.

Being present at pivotal moments obviously has its values: Keeping the mind from wandering could be the difference between disaster and a job well-done, especially for a brain surgeon or air-traffic controller.

But researchers are becoming increasingly aware that our default cognitive state — what we know as daydreaming — consists largely of being detached from the present moment. And given the frequency with which some of us wander in our thoughts, it’s likely that this mode of thinking serves an important role in our day-to-day lives. 

When we allow this to happen and separate from the present, Cohen says, we unlock a form of cognitive flexibility that’s otherwise unavailable.

“Now the imagination is involved. Psychological barriers are lowered. Suddenly, ideas, concepts and possibilities that we might not have considered have a better chance of coming to mind. There is a fluidity to our thinking,” she says.

Read More: Is There a Particle That Can Travel Back in Time?

The Evolution of the Wandering Mind

A 2017 study in Psychological Science found that we spend an astonishing 30 to 50 percent of our waking hours detached from the present moment.

In another study , published in 2015, researchers attempted to figure out the general contents of mind wandering episodes. Their results show that when people were mind wandering, thoughts were most often oriented toward the future and were goal-related.

Research psychologists generally agree that the degree to which humans can separate from the present moment and contemplate things beyond our immediate senses is a unique feature of our species.

Evolutionary psychologists Thomas Suddendorf and Micheal Corballis, for example, have argued that the cognitive development of mental time travel was a crucial step in the evolutionary success of our species.

With it, we can imagine mutually exclusive possible futures. We can make plans and contingencies in case they go awry. Just ask the insurance industry.

Read More: A Major Time Travel Perk May Be Technically Impossible

When Is Mind Wandering Too Much?

“No other nonhuman animals look further back into the past, or further into the future,” says Cohen.

But while this ability has underlined some of humanity’s greatest accomplishments, it can also bring about a host of unwieldy emotions — some of which, like regret, anxiety and embarrassment, we might want to avoid.

Because we can imagine what should have been done otherwise, or all the ways in which something can go wrong, it's inevitable: If we are too focused on the past or the future, this could be destructive to our well-being.

And here, it comes full circle back to mindfulness and being present.

For the overly active mind wanderer, the overthinker, a little bit of mindfulness might be the right way to balance the psychological systems that have set us up for evolutionary success.

After all, if you are forever somewhere else, you might miss the nuances of the moment — and the things that make planning for a future worthwhile.

Read More: What Is the Grandfather Paradox of Time Travel?

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How to do mental time travel

Feeling overwhelmed by the present moment find a connection to the longer view and a wiser perspective on what matters.

by Richard Fisher   + BIO

is the author of The Long View: Why We Need to Transform How the World Sees Time (2023), an honorary professor at University College London, and a senior journalist at the BBC. He writes a newsletter called The Long View: A Field Guide .

Edited by Christian Jarrett

Need to know

You have a remarkable talent – the ability to step outside the present, and imagine the past and future in your mind’s eye. Known as ‘mental time-travel’, some psychologists propose it’s a trait that allowed our species to thrive.

If I ask you to imagine what you did yesterday, or what you’re planning for tomorrow, you can conjure up rich scenes in the theatre of your mind. Not only that, you can turn back the clock to picture past eras – Shakespeare’s London, ancient Greece, the dinosaurs, the Big Bang – before spinning the dial to imagine deep futures, from our grandchildren’s lives in the next century all the way to the day the Sun becomes a red giant, billions of years from now.

Yet many people don’t make as much of this talent as they could. In the accelerating, information-rich, target-driven culture of the early 21st century, the present often dominates thoughts and priorities instead.

Obviously, there’s much going on in the current day that deserves our attention: not just urgent global problems that lead the news, but precious moments of individual joy, fulfilment and happiness too. We need to be present-minded sometimes. However, too much focus on the ‘now’ can also lead to the kind of harmful short-termism that infuses business, politics and media – a near-term perspective that worsens many of the long-term challenges we face this century, such as the climate crisis.

Short-termism is, to an extent, culturally driven, from the near-term incentives of modern capitalism to the relentless barrage of 24-hour media. But it’s also compounded by a host of unhelpful human habits and biases too, such as our ‘present bias’, whereby we tend to prioritise short-term rewards over long-term benefits (the classic example is the marshmallow test , in which some children can’t resist eating a single treat now, rejecting the chance to chomp two later on). We also have a ‘near-far’ temporal bias caused by the fact that our brains tend to equate time with space. As a consequence, the present appears close, obvious, salient, concrete; the past or future, by contrast, is roughly drawn, abstract, unimportant.

Crucially, these biases and cultural influences are not insurmountable. I’ve learnt that there can be multiple benefits to consciously cultivating a longer view – and not just because it banishes harmful short-termism. I think of mentally time-travelling out of the present as a form of exercise. If practised regularly, it can lead to greater perspective in these tumultuous times, as well as being a source of hope and meaning. A longer view provides a deeper, richer awareness of how we fit into the human story – and the planet’s – and reveals just how fortunate you are to be here, right now. The geologist Marcia Bjornerud calls this perspective ‘timefulness’.

This is not escapism: on the contrary, the long view can reveal what truly matters in the present – what to be mindful of, and what to ignore. The upshot is greater clarity about one’s choices and priorities amid the cacophony and distractions of life in the mid-2020s.

So what can you do to expand your temporal perspective as you navigate work, school, family and all the other demands and desires of daily life? In this Guide, I’ll share practical tips and exercises that can help you escape the unwanted, short-termist distractions of the present, and discover the upsides of a longer time perspective.

Discover which ‘time perspective’ you hold

Before you begin taking steps to develop a longer-term view, it can help to get a sense of your current time perspective. Some people are more inclined to be present-minded while others are more past- or future-minded; and these perspectives also come in positive or negative varieties.

For a flavour of your own time perspective, reflect on the following statements, and for each one ask yourself: ‘How characteristic or true is this of me?’ Make a note of whether it is very untrue , untrue , neutral , true , or very true :

• I think about the bad things that have happened to me in the past.
• Painful past experiences keep being replayed in my mind.
• It’s hard for me to forget unpleasant images of my youth.
• Familiar childhood sights, sounds, smells often bring back a flood of wonderful memories.
• Happy memories of good times spring readily to mind.
• I enjoy stories about how things used to be in the ‘good old times’.
• Life today is too complicated; I would prefer the simpler life of the past.
• Since whatever will be will be, it doesn’t really matter what I do.
• Often, luck pays off better than hard work.
• I make decisions on the spur of the moment.
• Taking risks keeps my life from becoming boring.
• It is important to put excitement in my life.
• When I want to achieve something, I set goals and consider specific means for reaching those goals.
• Meeting tomorrow’s deadlines and doing other necessary work comes before tonight’s play.
• I complete projects on time by making steady progress.

This is a short version of a test called the Zimbardo Time Perspective Inventory (if you prefer, you can complete the full version online) that was developed by the tech researcher John Boyd and the psychologist Philip Zimbardo (who you may know for staging the Stanford prison experiment). People’s answers reveal how they view time through five different psychological lenses.

Most people’s answers indicate a mix of all five, but some perspectives can be more dominant than others – and each has upsides and downsides. To get a sense of your dominant perspective(s), look to see which statements you agreed with most strongly:

Past-negative (if you agreed most strongly with 1, 2, 3) : your worldview is coloured by the trauma, difficulties and regret you’ve experienced. Past-positive (if you agreed most strongly with 4, 5, 6): you are grounded in your history and traditions, warmly and nostalgically. Present-fatalistic (if you agreed most strongly with 7, 8, 9): you’re pessimistic, perhaps even doomist, about current events. Present-hedonistic (if you agreed most strongly with 10, 11, 12) : the time is now , and you’re going to enjoy it. Future (if you agreed most strongly with 13, 14, 15) : you’re a forward-planner and gratification-delayer.

Your score can reveal your own personal starting point as you seek to cultivate a longer-term view. For example, if you scored high on present-hedonistic , you’re currently more likely to focus on the moment, taking risks and seeking adventure. People high on this category are pleasure-seeking, intense and playful. The downside is that they are poor forward-planners, and their ‘devil may care’ attitude makes them more likely to fall prey to addictions. Delaying gratification is difficult when there are salient pleasures to be won and immediate pains to be avoided.

The people who score high on present-fatalistic , by contrast, are the Eeyores of the world, defined by feelings of helplessness towards the future, which they see as predestined. On the positive side, they are more likely to believe that luck or fate can change circumstances, but their doomist inclinations lead to lower mental wellbeing.

The ideal mix, according to Zimbardo and Boyd, is to score low on the measures with negative rumination, and moderate-to-high on the others. Or more specifically, you want to avoid being too past-negative and present-fatalistic , and embrace a healthy mix of past-positive , present-hedonistic and future . This allows an individual to learn from their roots, live in the moment and plan for tomorrow.

The good news is that people are not fixed in their categories. One group of psychologists who gave people mindfulness training, for instance, found that it fostered a more balanced time perspective with less rumination. Others found that certain interventions can boost the future perspective: for example, asking people to write down what they would want said about themselves in their funeral eulogy, or to imagine being 90 years old, sitting in a rocking chair and remembering their life. As you’ll discover, the rest of this section is about using these types of interventions to boost your own long-term perspective – fostering a clearer, healthier view of both the past and future.

Have a conversation with your future self

The psychologist Hal Hershfield – author of Your Future Self (2023) – argues that we tend to think of our future selves as different people, with the same kind of psychological distance as if we were considering the needs of a stranger.

That makes it hard to set ourselves long-term goals – from eating healthier to reducing smartphone time – even when we know they could bring benefits. It helps explain why I’ve broken too many new year’s resolutions to remember.

However, Hershfield has found that it’s possible to bring the future self closer, and make better choices in the present. For example, in one study , he found that showing people their faces edited to look older encouraged them to set aside more money for retirement.

Recently, I asked Hershfield to translate his findings into a simple exercise for people to try: an imagined conversation with their future self. In a BBC article we worked on together, he explored the question If you could meet ‘future you’, what would you ask them?

You might be tempted to pose a simple, closed question, such as ‘Are you happy?’ However, Hershfield suggests it’s more fruitful to imagine open questions, such as these:

• What have you been most proud of and why?
• In what ways – both positive and negative – have you changed over time?
• What’s something that you miss most from earlier in your life?
• What actions have you regretted?
• What actions did you not take that you regret?
• What’s a time period you’d most want to repeat?
• What things should I be paying more attention to now?
• Which things should I stress about a little less?

‘Imagine if you were to put these eight questions to your future self,’ he wrote. ‘What might you find out that would modify how you live now? It’d probably be the most important conversation of your life.’

Another way to bridge the gap between your present self and your future self could be to add events to a long-term diary : personal milestones that you hope to experience one day. For example, I’ll be celebrating my daughter’s 21st birthday in February 2034, retiring in 2046 and, if I’m lucky, marking my 50th wedding anniversary in 2058. This exercise risks being a little morbid; it can make you realise how little time you actually have left on Earth, but I find that the act of marking an actual date for the milestones in my life makes them feel more tangible. And crucially, I find myself more inclined to make changes today that will ensure they happen, such as eating more healthily or exercising regularly. (For even more ways to connect with your future self, check out this previous Psyche Guide .)

Take the perspectives of people in the past and future

If ‘future you’ is a stranger, then that’s even more so when you consider ‘future others’. Many of the world’s biggest problems, such as the climate crisis, might be tackled more easily if we could collectively extend greater empathy towards future generations.

Sometimes, the case for passing on a better world to our descendants is made using statistics: statements such as ‘By 2100, the world faces 1-2°C warming above pre-industrial levels,’ and so on. These claims are well intentioned, but the trouble is, if you don’t expect to live that long, it’s difficult to feel as much concern as if it were today or tomorrow. There’s a different approach that’s more effective. Research suggests that empathy for the people of 2100 comes more easily if you can step into their shoes.

In one study , researchers asked people to consider the impacts of future climate change in different ways. They gave one group data about climate impacts, on a global scale. They handed a second group the same information, but also showed them the story of one woman living in a degraded environment in 2105, burnt by the sun, with an itchy rash caused by swimming in a polluted sea. Afterwards, the researchers observed that, on leaving the experiment, this second group were more likely to pick up brochures about environmental harms. In other words, a single future person’s perspective seemed to trigger the participants’ concern more than a barrage of statistics.

You could try using this approach to cultivate your own long-term perspective. Rather than imagining the distant future in vague or statistical terms, picture vividly what it might be for a specific young person you know (or their children).

A related, but more positive, technique in this vein is known as ‘backcasting’, which involves imagining a hoped-for future. Similar to Hershfield’s ‘future self’ conversation, this involves picturing a future person looking backward to you in the present.

One example is a set of exercises from the Long Time Project, founded by Ella Saltmarshe and Beatrice Pembroke. They suggest picturing a child you know and care about today as an old man or woman, looking back at the legacy you left for them:

There’s a framed picture of you on the table. That person you care about who is celebrating their 90th birthday taps their glass and asks for everyone’s attention. They raise their glass and toast you. They thank you for something you did that helped shape their world for the better. What are they toasting you for?

Other groups have encouraged people to time-travel in the opposite direction: to step into the shoes of their ancestors, and consider the sacrifices they made, such as fighting in wars, or achievements such as making medical discoveries. Ask yourself: What did your grandparents’ generation do that enables your current way of life? Doing this, the researchers suggest, can encourage people to feel greater benevolence towards their own descendants.

In sum, past and future people become less like strangers if you make the effort to mentally time-travel to imagine the specific details of their lives.

Seek ‘temporal windows’ to deep time

If you want to take your mental time-travel abilities to the extreme, then why not take a step into deep time ? Projecting the mind thousands or millions of years away from the present might seem like taking things too far. You might wonder how it could possibly be relevant to your needs today. But I find that when I reflect on how my life fits into the longer story of our planet, I feel more in touch with nature and the wider world.

There’s no doubt it can be discombobulating to consider that, from Earth’s perspective, your own lifespan is equivalent to a flash of sunlight on the surface of a lake. However, I find that knowing I am one link within a vast chain of people and organisms, living within a Universe that traces back to the Big Bang, evokes a feeling of sublime awe . And awe, psychologists have found , brings myriad benefits: it decreases the likelihood of rumination, for instance, as well as promoting altruism, and making us feel more connected with one another.

When possible, I try to seek out deep time through what I call temporal windows . This involves spending just a short while every week transporting your mind into the very long term, by mindfully observing your surroundings. If you look around, these windows are often accessible – whether it’s the rocks beneath your feet or the ancient light from the stars above you.

Even in a busy city, such windows can be found. Near where I live in London, for example, there are ancient barrows in Richmond Park, some of which are more than 4,000 years old. Until a friend pointed them out, I had often walked past them without realising they were there. Even holes in the street can offer a temporal window: roadworks can reveal layers of tarmac and rock layers that speak of historical and geological timescales.

With a bit of imagination, you can also conjure up temporal windows to the future. There’s an elderly care home around the corner from my house, with a small sign outside: it explains that a time capsule for future generations was buried there when the structure was built. I don’t know what’s inside, but I like that someone thought to leave a message for the future in such an everyday place. (If you want to find one near you, the International Time Capsule Society keeps a registry of such capsules placed around the world.)

The academic David Farrier – author of the book Footprints (2020), about humanity’s legacies – once told me about another exercise in mental time-travel he practised when he visited Shanghai. As he gazed up at the buildings, he spent a moment imagining how all the skyscrapers there might change, evolve and decay over millions of years: what would survive and what would not? Which materials are truly long lasting, and which are transient on geological timescales?

So, when possible, try moving your mind into deep time, and asking yourself: what came before all this, and what could it become in the long term? I find that doing so often reminds me just how fortunate I am to be alive, right now, reflecting on my vantage point within a grander temporal arc.

Think of time in generations , not years or centuries

Look at your family tree, and you’ll see you are only a handful of generations from the time of Jane Austen or George Washington. If you were born in the 1980s like me, you are around seven generations from Charles Dickens, and approximately 17 from William Shakespeare. If your tree traces to the UK, it’s possible that one of your ancestors even watched an original performance of Hamlet : after all, you potentially have more than 100,000 great-grandparents who lived in the 1600s (without any overlaps in your family tree, such as from cousins marrying, your number of grandparents doubles every generation).

Framed this way, the future is also closer than you think. One of the ways I find it easier to step outside the present is to think about my daughter’s life in the coming decades. Born in 2013, she could potentially live to see the 22nd century. On New Year’s Eve 2099, as the fireworks explode and people sing ‘Auld Lang Syne’, she’ll be in her late 80s.

You might make a similar calculation for the young people in your own life: sons, daughters, nieces, nephews. In 2024, it’s estimated that 135 million people will be born worldwide – many of whom will become citizens of the next century. And, looking ahead, almost 11 billion more children will begin their lives before 2100. If they are lucky, some of the people born this century – including my daughter’s potential grandchildren – will live through to the 2200s.

Previous generations are only a branch or two away on your family tree, and the people of the next century and beyond are already here – or will be very soon.

Give a gift to the future

A few years ago, James Janson Young – who founded a YouTube channel about long-term thinking called Ours for the Making – was recovering from major surgery. During this time, he writes, his ‘sense of the future collapsed’. So, he decided to cultivate a practice called future-gifting .

‘In its simplest form,’ Young writes, ‘future-gifting is the straightforward, instinctive act of doing something in the present to support yourself (or those around you) in the future. It’s a practice of being generous to your future self in order to help them out a little and shape your future in the process.’ For example, you might write yourself a letter that you won’t open until 2030, or a scheduled email that won’t arrive for a year or even a decade.

While it starts with the self, what makes it powerful, Janson Young argues, is that it helps to build a habit that can spill over to acts of generosity and empathy for other people in the future too.

So, what would be your gift to future people? All of us leave behind both wanted and unwanted heirlooms. What will your legacy look like? It does not need to be a grand statue or presidential library but can be far more everyday. It could also be a personal possession, or a positive idea, tradition or norm: something you taught someone, or a way you inspired them.

I believe the greatest legacy I can aspire to leave behind is simply choice . Much of what we are collectively doing in the present threatens to close down the range of possibilities available to our descendants: whether it’s worsening climate change or causing species extinctions. It needn’t be so. I know I cannot solve the grand challenges of our time by myself, nor can I claim to know what the people of tomorrow will want or need. However, if I’m ever uncertain about my daily decisions or beliefs, I return to a core principle: I wish to pass on a world where tomorrow’s people have the ability to choose their own destinies. That, to me, is what it means to take the long view and be a good ancestor – and through that, I derive meaning and purpose in the present.

Seek alternative time perspectives and long-term communities

As we saw with the time perspective questionnaire, everyone has their own horizon of time. For some, it’s days or weeks, while for others it’s years or decades. It’s worth asking: who around you is pulling you towards the moment, and who is encouraging a longer horizon?

Throughout my life, I have come across many people whose targets, priorities and desires were heavily rooted in the present – I’m sure you have too. But I have also met many people who have a far longer perspective than my own: artists, philosophers, scientists and historians who spend their days extending their minds across thousands or even millions of years. Every conversation with them has opened my perspective to be a little closer to their lens on time. The more I immerse myself in their work, art or ideas, the easier I find it to escape the present.

Similarly, I’ve also come across other cultures around the world who think about time differently to my own Western-centric, scientifically trained, geological world view. For example, for the Yupno people who live in steep valleys in Papua New Guinea, time flows uphill . Yesterday is downslope and tomorrow is higher up the mountain. Other cultures see the past, present and future differently : the past is visible in front of them, and the future is unseen behind their heads (which is actually more accurate, if you think about it). Finally, Indigenous Australians have described time more like a body of water that surrounds you. When I realise time is a cultural construct , not an absolute object, I find it easier to think about how we might reframe our role and position within it.

In my research, I have also encountered various communities of people – some of which you can join – who come together to cultivate a longer view. They allow people to connect, listen to talks, share insights, and even go on field trips. Each long-minded group has a different flavour, but they are united in the belief that the long term matters.

Perhaps the most well-known community is the Long Now Foundation. Headquartered in San Francisco, it has become increasingly international, with offshoots in Boston, London and Europe that organise meetups and talks, run by volunteers. Each local group has developed its own approach: the Boston chapter is shaped by the culture of its nearby universities, Harvard and MIT, as well as the region’s biotechnology sector. London has a more British approach, meeting monthly in a pub and going on an annual field trip to maintain the White Horse of Uffington, a 3,000-year-old chalk geoglyph in Oxfordshire. If you’re nearby, why not tag along this summer?

Another example of a long-term community would be the effective altruists. This community is concerned with many areas, such as poverty reduction in the developing world or the threat of AI, but it’s also a hub for those interested in exploring the principles of ‘longtermism’: the ethical belief that ensuring the future goes well is a key moral priority of our time. It has attracted controversy in recent years, but one place to discover if their approach is for you or not is the podcast and website 80,000 Hours, or the book What We Owe the Future (2022) by the philosopher William MacAskill.

Finally, there are communities and places you can visit centred on long-term art, especially in Europe. Every year, you can attend a ceremony in a forest north of Oslo in Norway for the Future Library, a project where novelists like Margaret Atwood submit a manuscript that won’t be published until 2114 – it’s the literary version of ‘future-gifting’. Visit the Dutch city of Utrecht, and you will find a poem embedded in the cobblestones of the street that is intended to run for centuries. Every Saturday, a stonemason adds a new letter, sponsored by the public. And in Germany, a trip to the small town of Wemding will bring you to the Time Pyramid – a project that the local citizens are planning over 12 centuries. Once every decade, they meet for a ceremony to place a new block: so put September 2033 in your long-term diary because that’s the next one.

A longer view is out there to be found – and, if you can seek it out, your perspective on time and the world can begin to feel a little richer, more grounded and perhaps even more hopeful. You have an incredible mind: capable of taking you to the ancient past or the deep future; to meet your ancestors or to picture your descendants. A unique form of time-travel is within your grasp.

Key points – How to do mental time travel

• Cultivating a long-term view – taking in the distant past and future – brings many benefits. It will make you more aware of how you fit into the human story and bring clarity to what truly matters in the present.
• Discover which ‘time perspective’ you hold. Complete a version of the Zimbardo Time Perspective Inventory to reveal your own starting point as you seek to cultivate a longer-term view.
• Have a conversation with your future self. Imagine asking yourself open-ended questions, such as ‘What actions have you regretted?’, and it will help bridge the gap between your present self and your future self.
• Take the perspectives of people in the past and future. Rather than imagining the distant future in vague or statistical terms, picture vividly what it might be for a specific young person you know (or their children). Alternatively, try time-travelling in the opposite direction to step into the shoes of your ancestors.
• Seek ‘temporal windows’ to deep time. Spend a short while every week transporting your mind into the very long term, by mindfully observing your surroundings, whether it’s the rocks beneath your feet or the ancient light from the stars above you.
• Think of time in generations , not years or centuries. Previous generations are only a branch or two away on your family tree, and the people of the next century and beyond are already here – or will be very soon.
• Give a gift to the future. It does not need to be a grand statue or presidential library, but can be far more everyday. It could be a personal possession, or a positive idea, tradition or norm: something you taught someone, or a way you inspired them.
• Seek alternative time perspectives and long-term communities. From long-term art movements to the Long Now Foundation, there are various communities of people – some of which you can join – who come together to cultivate a longer view.

Identify the short-term targets in your work

In this Guide, I’ve talked about cultivating the long view in your life more generally, but what about where we spend much of our waking hours: the workplace?

Many of the behaviours that foster short-termism happen at work. Capitalism, in general, tends to foster a shorter view. The most notorious example in the business world is the ‘quarterly report’, which forces leaders to report performance and projections to the market every four months. Research shows it discourages investment and long-term planning.

When people are continually judged by short-termist metrics, such as hitting a looming sales target or reporting to shareholders every few months, then they will naturally focus more on the present.

In his book Moral Mazes (1988), the sociologist Robert Jackall describes a particularly problematic type of business-person, who satisfies short-term goals but neglects the longer view. They achieve this, he argues, by ‘milking a plant’. It goes like this. A manager would arrive at a plant or factory, and be handed a set of steep short-term targets by, say, the company board. They’d immediately crack the whip: asking more of their workers, and pushing the machinery harder than before. Productivity would rise. Months later, the targets would be hit and the board would be happy. Promotion or a new job soon followed, and the manager moved on. Left behind, however, was a mess. Workers were unhappy, the best talent had left for better conditions, and the machinery had been run into the ground, needing expensive replacements. The next manager had to pick up the pieces.

If this person sounds like someone you know, it’s because the fast-turnover career opportunities of present-day organisations do little to root out such behaviour. It’s possible for these short-termist managers to outrun their failures before long-term consequences become visible or accountable.

Setting long-term targets is, of course, hard. However, there are organisations offering guidance, such as the Boston-based Focusing Capital on the Long-term (FCLT), which conducts research, convenes business-leaders, and gathers their wisdom.

I’m no management consultant, but in my own working life I’ve learnt that it helps to distinguish the difference between tactics , strategy and mission . Tactics are what you’re aiming for day-to-day and month-to-month; strategy is the playbook for where you want to go over the next year or so; but mission is the bigger, longer-term goal. Plenty of organisations neglect this last one, but as research by FCLT shows, organisations with long-view metrics thrive in the long term.

Links & books

For me, embracing the long view means cultivating a ‘long’ media diet. If you digest only the daily news and social media, then the information that forms your perspective on the world is skewed – you know what’s happening now, but it’s the equivalent of shining a torchlight at your feet to navigate through a pitch-black forest. Daily news or social memes also cannot capture the slow changes that shape our world, both bad and good, from the creep of environmental change to the strides that science has made in tackling once-deadly disease.

For a longer perspective on global events, an excellent site is Our World in Data. Via long-term statistics and accessible writing, it makes for an insightful companion to your daily news diet, revealing long-term trends that might otherwise go unnoticed. The site covers both the bad and the good: creeping problems like climate change, but also positive developments like gradual medical victories over fatal diseases. Ultimately, you get a more rounded and accurate picture of how our world is changing.

The Long Time Project that I mentioned earlier in the Guide also produced a podcast series called the Long Time Academy. It comes with exercises to try, based on the ideas covered in each episode.

A fun immersive listening experience to try is Deep Time Walk, where, as you move, you journey through billions of years of Earth history.

For the BBC, I recently presented a trilogy of short films about a deep-time perspective. From Scotland’s million-year-old geology to forward-thinking art projects in Norway, my goal in these mini-documentaries was to explore what it takes to expand your view of time.

In terms of books, there’s my own , The Long View (2023), and I’ve already mentioned a few others in this Guide – but there are several more that offer complementary insights, including:

Timefulness (2018) by the geologist Marcia Bjornerud, a meditation on what you can learn by taking Earth’s deep-time perspective.

The Invention of Tomorrow (2022) by Thomas Suddendorf, Jonathan Redshaw and Adam Bulley. If psychology is your thing, then this book dives deeper into mental time-travel and why the evolution of foresight was so consequential for the success of our species.

Deep Time Reckoning (2020) by Vincent Ialenti. To derive his own long-term learnings , this social anthropologist spent a few years in Finland observing the planners of a nuclear waste repository – a 10,000-year view.

The Good Ancestor (2020) by the philosopher Roman Krznaric. What duties do we have to posterity? Krznaric explores the social and political steps we could take if we began to care more about future generations

The Ministry for the Future (2020) by Kim Stanley Robinson. If fiction is your preferred read, then this novel follows an organisation seeking to advocate for the rights of future generations.

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December 22, 2010 feature

Scientists find evidence for 'chronesthesia,' or mental time travel

by Lisa Zyga , Medical Xpress

(PhysOrg.com) -- The ability to remember the past and imagine the future can significantly affect a person's decisions in life. Scientists refer to the brain’s ability to think about the past, present, and future as "chronesthesia," or mental time travel, although little is known about which parts of the brain are responsible for these conscious experiences. In a new study, researchers have used functional magnetic resonance imaging (fMRI) to investigate the neural correlates of mental time travel and better understand the nature of the mental time in which the metaphorical "travel" occurs.

The researchers, Lars Nyberg from Umea University in Umea, Sweden; Reza Habib from Southern Illinois University in Carbondale, Illinois; and Alice S. N. Kim, Brian Levine, and Endel Tulving from the University of Toronto in Toronto, Ontario, have published their results in a recent issue of the Proceedings of the National Academy of Sciences .

"Mental time travel consists of two independent sets of processes: (1) those that determine the contents of any act of such ‘travel’: what happens, who are the 'actors,' where does the action occur; it is similar to the contents of watching a movie – everything that you see on the screen; and (2) those that determine the subjective moment of time in which the action takes place – past, present, or future," Tulving told PhysOrg.com .

"In cognitive neuroscience, we know quite a bit (relatively speaking) about perceived, remembered, known, and imagined space," he said. "We know essentially nothing about perceived, remembered, known, and imagined time. When you remember something that you did last night, you are consciously aware not only that the event happened and that you were ‘there,’ as an observer or participant ('episodic memory'), but also that it happened yesterday, that is, at a time that is no more. The question we are asking is, how do you know that it happened at a time other than 'now'?"

In their study, the researchers asked several well-trained subjects to repeatedly think about taking a short walk in a familiar environment in either the imagined past, the real past, the present, or the imagined future. By keeping the content the same and changing only the mental time in which it occurs, the researchers could identify which areas of the brain are correlated with thinking about the same event at different times.

The results showed that certain regions in the left lateral parietal cortex, left frontal cortex, and cerebellum, as well as the thalamus, were activated differently when the subjects thought about the past and future compared with the present. Notably, brain activity was very similar for thinking about all of the non-present times (the imagined past, real past, and imagined future).

Because mental time is a product of the human brain and differs from the external time that is measured by clocks and calendars, scientists also call this time “subjective time.” Chronesthesia, by definition, is a form of consciousness that allows people to think about this subjective time and to mentally travel in it.

Some previous research has questioned whether the concept of subjective time is actually necessary for understanding similarities in brain activity during past and future thinking compared with thinking about the present. A few past studies have suggested that the brain’s ability for scene construction, and not subjective time, can account for the ability to think about past and future events. However, since scene construction was held constant in this study, the new results suggest that the brain’s ability to conceive of a subjective time is in fact necessary to explain how we think about the past and future.

“Until now, the processes that determine contents and the processes that determine time have not been separated in functional neuroimaging studies of chronesthesia; especially, there have been no studies in which brain regions involved in time alone, rather than time together with action, have been identified,” Tulving said. “The concept of ‘chronesthesia’ is essentially brand new. (You find a few entries on it in Google, but not on Web of Science.) Therefore, I would say, the most important result of our study is the novel finding that there seem to exist brain regions that are more active in the (imagined) past and the (imagined) future than they are in the (imagined) present. That is, we found some evidence for chronesthesia. Before we undertook this study it was entirely possible to imagine that we find nothing!”

He added that, at this stage of the game, it is too early to talk about potential implications or applications of understanding how the brain thinks about the past, present, and future.

“Our study, we hope, is the first swallow of the spring, and others will follow,” he said. “Our findings, as I alluded to above, are promising, but they have to be replicated, checked for validity and reliability, and, above all, extended to other conditions and situations, before we can start thinking about their implications and applications (of which it is easy to think of many).”

Copyright 2010 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

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Mental Time Travel

How does the brain zip back and forth in time.

Posted December 23, 2010

Remembering the past and envisioning the future: These are the closest we can get to "time travel," and a new study has investigated how this process works in the human brain.

Results of the study -- performed by Lars Nyberg of Sweden's Umea University, Reza Habib of Southern Illinois University, and Alice S. N. Kim, Brian Levine, and Endel Tulving of the University of Toronto -- appear in a recent issue of the Proceedings of the National Academy of Sciences.

Chronesthesia is the technical term for the brain's ability to maintain simultaneous awareness of past, present and future and to "travel" back and forth between them.

Interviewed by a reporter from PhysOrg.com , Tulving said:

"Mental time travel consists of two independent sets of processes: (1) those that determine the contents of any act of such ‘travel': what happens, who are the 'actors,' where does the action occur; it is similar to the contents of watching a movie - everything that you see on the screen; and (2) those that determine the subjective moment of time in which the action takes place -- past, present, or future.

"In cognitive neuroscience , we know quite a bit (relatively speaking) about perceived, remembered, known, and imagined space," he said. "We know essentially nothing about perceived, remembered, known, and imagined time. When you remember something that you did last night, you are consciously aware not only that the event happened and that you were ‘there,' as an observer or participant ('episodic memory '), but also that it happened yesterday, that is, at a time that is no more. The question we are asking is, how do you know that it happened at a time other than 'now'?"

The study is titled " Consciousness of subjective time in the brain."

The researchers asked participants to repeatedly think about "taking a short walk in a familiar environment in either the imagined past, the real past, the present, or the imagined future." This helped them identify which areas of the brain are linked with thinking about the same event at different times. These are certain regions in the left lateral parietal cortex, left frontal cortex, cerebellum, and thalamus.

Tulving told PhysOrg.com:

"Until now, the processes that determine contents and the processes that determine time have not been separated in functional neuroimaging studies of chronesthesia; especially, there have been no studies in which brain regions involved in time alone, rather than time together with action, have been identified," Tulving said. "The concept of chronesthesia is essentially brand new. ... Therefore, I would say, the most important result of our study is the novel finding that there seem to exist brain regions that are more active in the (imagined) past and the (imagined) future than they are in the (imagined) present. That is, we found some evidence for chronesthesia."

S. Rufus is the author, under the byline Anneli Rufus, of books including Party of One and Stuck.

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• v.364(1521); 2009 May 12

Mental time travel and the shaping of the human mind

Thomas suddendorf.

1 Department of Psychology, University of Queensland, St Lucia, Queensland 4072, Australia

Donna Rose Addis

2 Department of Psychology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand

Michael C. Corballis

Episodic memory, enabling conscious recollection of past episodes, can be distinguished from semantic memory, which stores enduring facts about the world. Episodic memory shares a core neural network with the simulation of future episodes, enabling mental time travel into both the past and the future. The notion that there might be something distinctly human about mental time travel has provoked ingenious attempts to demonstrate episodic memory or future simulation in non-human animals, but we argue that they have not yet established a capacity comparable to the human faculty. The evolution of the capacity to simulate possible future events, based on episodic memory, enhanced fitness by enabling action in preparation of different possible scenarios that increased present or future survival and reproduction chances. Human language may have evolved in the first instance for the sharing of past and planned future events, and, indeed, fictional ones, further enhancing fitness in social settings.

1. Introduction

Clive Wearing is an English musician. As an acknowledged expert on early music, he had built up a musical career with the BBC when he was infected at the age of 46 with the herpes simplex virus. This effectively destroyed his hippocampus and left him profoundly amnesic. The nature of his amnesia illustrates the distinction between semantic memory, which is memory for enduring facts about the world, and episodic memory, which is a personal record of the past ( Tulving 1983 ). Wearing's semantic memory is largely intact, as is his procedural memory. He retains a normal vocabulary, recognizes his wife and family, and can still play the piano and conduct a choir. His episodic memory, though, is profoundly impaired. He has sufficient short-term memory to be able to converse but quickly forgets about topics he spoke about or experienced just moments earlier. He is continually under the impression that he has just woken up, or recovered from being dead. His conscious experience is entirely of the present, and is well captured in the book, Forever today , written by his wife Deborah ( Wearing 2005 ).

Neuropsychological evidence reveals that deficits in episodic and semantic memory are doubly dissociated, implying distinct mechanisms. As with Clive Wearing, most cases of amnesia, especially those resulting from damage to the hippocampus, are characterized by severe deficits in episodic memory, while semantic memory remains largely intact ( Scoville & Milner 1957 ; Tulving et al . 1988 ; VarghaKhadem et al . 1997 ; Aggleton & Brown 1999 ). Indeed, the very term ‘memory’ is usually taken to mean episodic memory, as when William James wrote ‘Memory requires more than the mere dating of an event in the past. It must be dated in my past’ ( James 1890 , p. 650). Yet in a degenerative condition known as semantic dementia, semantic memory is grossly impaired, leaving episodic memory surprisingly unaffected ( Hodges & Graham 2001 ).

Retrieval of episodic memories involves the conscious reliving of past events, a sort of mental journey into the past ( Tulving 1983 ). In recent years, evidence has accumulated that the episodic memory system is also involved in mental travel into the future, suggesting a general concept of mental time travel (Suddendorf & Corballis 1997 , 2007 ). Conceiving of future events, of course, involves a process of active construction of events that have not yet occurred, but the more general process of mental time travel highlights the evidence that episodic memory, too, is better conceived as a conscious act of construction, rather than a faithful re-enactment of the past. Indeed, if the only function of episodic memory was to record the past, it might be expected to function in a reproductive manner, similar to a video recorder ( Suddendorf & Corballis 1997 ). However, the slew of errors and distortions that episodic memory is vulnerable to shows us this is not the case ( Schacter 1999 ; Schacter & Addis 2007 ). The primary role of episodic memory, then, may be to provide information from the past for the simulation of the future. Indeed, natural selection can only work on what memory can offer for present and future fitness rather than on the accuracy of the past record per se ( Suddendorf & Corballis 1997 ; Suddendorf & Busby 2005 ).

In spite of the dissociation between semantic and episodic memory, there must be some links between them. The encoding of episodic memories must to some extent depend on semantic memories that are already in place ( Tulving 2002 ); a remembered visit to a restaurant, for example, must depend in part on one's knowledge of what a restaurant is and what happens there. Indeed, descriptions of episodic memories and future simulations comprise both episodic and semantic details that are woven together into a narrative of the experience (e.g. Levine et al . 2002 ; Addis et al . 2008 ). Individual episodes, having drawn on semantic elements, are then related to the self in subjectively sensed time. This allows the experience of an event to be stored separately from the semantic system, and retrieved in what Tulving called ‘episodic retrieval mode’ ( Tulving 2002 ). Just as they are during encoding, retrieved episodic memories are interwoven with elements of semantic memory. The episodic details of an event are not retrieved in isolation of the context that semantic information can provide ( Levine et al . 2002 ). This would apply, we suggest, not only to the reconstruction of past events, but also to the construction of future ones, and even to story-telling—the construction of fictional episodes that permeate folklore, literature, stage drama, film and television ( Hassabis et al . 2007 b ; Suddendorf & Corballis 2007 ).

In this paper, we review neuroscientific evidence for the continuity of mental time travel into the past and future, and consider what, if anything, might be uniquely human about mental time travel. We go on to suggest that human language may have evolved primarily for the communication of episodes, whether from the past or the imagined future, or indeed in the form of fiction. We conclude with some speculation as to when and why mental time travel evolved in hominin evolution.

2. Neuropsychological and neuroimaging evidence

The title of Deborah Wearing's book, Forever today , also captures the fact that Clive Wearing is as unable to imagine future events as he is incapable of remembering past ones. It is becoming clear that this is true of other profoundly amnesic patients as well ( Tulving 1985 ; Klein et al . 2002 ; Rosenbaum et al . 2005 ; Hassabis et al . 2007 b ). In one study, for example, patients with bilateral hippocampal damage and intact premorbid semantic memory were given cue words and short descriptions of scenarios, and asked to generate new experiences from them. Their scores for the detail and coherence of the imagined scenarios fell well below those of a control group ( Hassabis et al . 2007 b ). Interestingly, this study suggests that the hippocampus may play a critical role, not only in terms of retrieving details from episodic memory to be used for an imagined scenario, but also the integration of such details into a coherent event. Moreover, it seems that such processes are not unique to imagining future events per se , but apply more generally to the construction of any fictitious scenario ( Rosenbaum et al . 2005 ; Hassabis et al . 2007 b ).

Consistent with neuropsychological data, functional brain imaging also reveals a strong overlap in brain activity between backward and forward mental time travel. In one study, positron emission tomography revealed activity in the frontal poles and medial temporal lobes, including hippocampal and parahippocampal regions, to tasks involving both the remembered past and the imagined future episodes ( Okuda et al . 2003 ). Although most areas showed equivalent activation to both the past and the future tasks, areas in the anteromedial pole showed greater activation to future than to past tasks, and greater activation to both tasks, the more distant the episode in time. A more recent study showed that hippocampal activity, too, was greatly increased for future events that were more distant from the present ( Addis & Schacter 2008 ). These effects may reflect the degree of construction required, with higher levels of construction for more distant events.

Based on this, and on another work using functional magnetic resonance imaging ( Addis et al . 2007 ; Szpunar et al . 2007 ), Schacter et al . (2007) identify a ‘core network’ that is used not just for remembering the past, but that functions adaptively and is even more actively recruited when integrating information from past experiences to construct mental simulations about possible future events. The prominent components of this network include regions of the medial prefrontal cortex, the lateral and medial parietal cortex (including precuneus and retrosplenial cortex), and the lateral and medial temporal lobes, including notably the hippocampus. Activity is intercorrelated across these regions and with activity in the hippocampal formation. While some recent studies challenge this finding, reporting more activity for past than future events ( Hassabis et al . 2007 a ; Botzung et al . 2008 ; D'Argembeau et al . 2008 ), it is important to note that, in these studies, future events are not being imagined during the scan. Rather, they are constructed outside of the scanner and then recalled during the scan. Memories of imagined events are typically less detailed than memories of real experiences, and thus recruit fewer hippocampal resources during retrieval. This further supports the core network being more actively recruited when one must use episodic memory to construct and imagine a new event online.

Moreover, these findings challenge the traditional view that the role of the hippocampus is to hold episodic memories for a limited period of time until they are consolidated in other neocortical areas ( Squire 1992 ; Squire et al . 2004 ). The alternative view, more consistent with these and other recent results, is that the hippocampus is always necessary for the retrieval of detailed episodic experiences, including remote ones ( Moscovitch et al . 2005 ). By this account, the extent of hippocampal involvement probably depends on the vividness of the internal representation, whether of past episodes or imagined future ones ( Hassabis et al . 2007 b ). Confirming this, Addis & Schacter (2008) also found more detailed representations to be associated with increased posterior hippocampal activity. This probably reflects the retrieval of information, necessary when remembering as well as imagining events. By contrast, future event detail was associated with greater activity in the anterior hippocampus, possibly reflecting the recombination of details into a coherent event.

The reported phenomenological richness of imagined events ( D'Argembeau & Van der Linden 2004 ), as well as the number of imagined events reported ( Spreng & Levine 2006 ), decreases with temporal distance into both the past and the future. There are further parallels in the development of mental time travel into past and future across the lifespan, both in terms of initial emergence ( Busby & Suddendorf 2005 ) and eventual decline ( Addis et al . 2008 ). The neural and cognitive evidence linking episodic memory to imagining the future is increasingly recognized (e.g. Hassabis & Maguire 2009 ; Schacter & Addis 2009 ).

3. Uniquely human?

In a detailed account of the nature of episodic memory, Tulving (1983) proposed that it was uniquely human. It was later proposed more generally that mental time travel was unique to our species and that the main adaptive advantage must lie with foresight (Suddendorf & Corballis 1997 , 2007 ). This does not mean that non-human animals do not behave in a manner oriented to the future. The futures of animals and their offspring often depend on instinctive behaviours, such as food caching, migrations and nest building, as well as on learned behaviours and semantic memory ( Suddendorf & Corballis 2007 ). Semantic knowledge can be important for prospection, but must be distinguished from episodic future thinking. For example, knowledge of where Paris is located, what language is spoken there and how to get there will clearly enhance the prospects of making a trip to that city. Episodic memories of experiences in Paris, though, allow conscious construction of imagined future events there, including, perhaps, friends that one might meet there, places one might revisit, specific restaurants and, perhaps, specific dishes, and so forth. More generally, episodic memory provides a vocabulary from which to construct possible scenarios, and compare them off-line in order to optimize future behaviour. This ability to act with specific, individually anticipated future events in mind may account for why human behaviour is so immensely flexible and, as we shall argue further below, why humans have evolved open-ended communication systems.

The claim that only humans are capable of episodic memory and episodic foresight has posed a challenge to animal researchers. One of the difficulties has been to demonstrate memory that is truly episodic, and not merely semantic or procedural. For example, does the dog that returns to where a bone is buried remember actually burying it, or does it simply know where it is buried? One suggestion is that episodic memory in non-human animals might be defined in terms of what happened, where it happened and when it happened—the so-called www criteria. It has been proposed that scrub jays ( Aphelcoma coerulescens ) meet these criteria, because of experimental evidence that they can select the locations of food they have previously cached not only according to the type of food that is stored there, but also according to how long it has been stored, implying that they remember when it was stored. For example, they will recover recently cached worms in preference to nuts, since fresh worms are more palatable, but if the worms have been cached for too long they will retrieve nuts, because the worms will have decayed and become unpalatable ( Clayton & Dickinson 1998 ). Furthermore, if another jay observes them caching food, they will later re-cache it, presumably to prevent the observer stealing the food. They will only do this, however, if they have themselves stolen food in the past ( Emery & Clayton 2001 ). Clayton and colleagues ( Clayton et al . 2003 ) concluded that scrub jays can not only remember the what, where and when of past events, but also anticipate the future by taking steps to avoid future theft.

A recent study suggests that meadow voles ( Microtus pennsylvanicus ), too, have a similar capacity ( Ferkin et al . 2008 ). Male voles were first allowed to explore two chambers, one containing a pregnant female 24 hours pre-partum, and the other containing a female that was neither lactating nor pregnant. Twenty-four hours later, they were again given access to the chambers, now empty and clean, and spent more time exploring the chamber that had contained the previously pregnant female than the one that had housed the other female. This suggests that they had remembered the pregnant female and her location, and understood that she would now be in post-partum oestrus, a state of heightened sexual receptivity. In another condition, they first explored a chamber containing a female in post-partum oestrus and another containing a female that was neither lactating nor pregnant, and was not in oestrus. Twenty-four hours later, they were again allowed to explore the now-empty cages, and showed no preference for the chamber that had housed the female in oestrus. This suggests that they realized the female would no longer be in a state of heightened receptivity.

Several other recent experiments have documented that various species of mammals and birds may pass the www criteria (for reviews, see Dere et al . 2005 ; Zentall 2006 ; Suddendorf & Corballis 2007 ). If this entails that these species can travel mentally in time, then we are in need of a fundamental reconsideration of animal welfare and ethics ( Lea 2001 ; Suddendorf & Corballis 2007 ). The extent to which animals live in the present has a major impact on their capacity for suffering—if they can mentally revisit a past traumatic event or anticipate future pain, as humans do, then considerations for their welfare would need to take this into account when attempting to minimize their suffering (see Mendl & Paul 2008 for a detailed discussion).

It remains possible, though, that these ingenious studies do not prove that the animals actually remember or anticipate episodes. For example, associative memory might be sufficient to link an object with a location, and a time tag or ‘use-by’ date might then be attached to the representation of the object to update information about it ( Suddendorf & Corballis 2007 ). Moreover, ‘how long ago’ can be empirically distinguished from ‘when’, so the ability of scrub jays to recover food depending on how long ago it was cached need not actually imply that they remember when it was cached. As evidence for this, a recent study suggests that rats can learn to retrieve food in a radial maze on the basis of how long ago it was stored, but not on when it was stored, suggesting that ‘episodic-like memory in rats is qualitatively different from episodic memory in humans’ ( Roberts et al . 2008 ).

More generally, the www criteria may not be sufficient to demonstrate true episodic memory. Most of us know where we were born, when we were born and, indeed, what was born, but this is semantic memory, not episodic memory ( Suddendorf & Busby 2003 ). Conversely, one can imagine past and future events and be factually wrong about what, where and when details (in fact, we are often mistaken). This double dissociation, then, strongly suggests that we should not equate mental time travel with www memory.

Non-human animals and very young children may be limited in their foresight in a number of different ways ( Suddendorf & Corballis 2007 ). One variant on the claim to human uniqueness is the so-called Bischof-Köhler hypothesis, which states that only humans can flexibly anticipate their own future mental states of need and act in the present to secure them ( Bischof 1978 ; Bischof-Köhler 1985 ; Suddendorf & Corballis 1997 ). Again, an experiment with scrub jays has been claimed as a counterexample. The birds were prefed with one type of food for three hours and then allowed to cache the prefed and an alternative food. They were subsequently prefed with the alternative food before being allowed to recover what they had cached. On the second and third trials, the birds cached more of the food on which they were satiated, on the apparent understanding that they would be hungry for this food at later recovery, thus challenging the Bischof-Köhler hypothesis ( Correia et al . 2007 ). Closer analysis of the data, however, suggests that this interpretation is misleading. Although the birds cached a greater proportion of food for which they would later be hungry, the absolute number of items stored did not change in any meaningful way. The six birds in the critical condition cached an average of 0.7 items of the prefed food on the first trial, and 1.2 items and 0.8 items on the second and third trials, respectively. Thus, they did not increasingly store the food that was more desirable in the future ( Suddendorf & Corballis 2008 ).

The most promising challenge to the Bischof-Köhler hypothesis so far comes from the great apes. In one study, orang-utans ( Pongo abelii ) and bonobos ( Pan paniscus ) learned to use a tool to extract grapes from an apparatus in a test room. They were later given a choice of tools, some appropriate and others inappropriate for extracting grapes, and significantly chose appropriate ones for later access to the test room ( Mulcahy & Call 2006 ). In a similar experiment, two chimpanzees ( Pan troglodytes ) and an orang-utan were shown, on a single trial, how to use a plastic hose as a straw to obtain juice from an apparatus, and on subsequent trials, prior to access to the test room an hour later, chose this tool in preference to others. In one critical condition, the animals were offered grapes, their favourite food, along with the other tools, and chose the hose more often than the grapes, suggesting that obtaining a large amount of fruit juice in the future may have been valued more than a small instant grape reward ( Osvath & Osvath 2008 ). In both the studies, the experimenters took pains to rule out alternative explanations, such as simple association between tool and later reward, but there continue to be some methodological concerns (see Suddendorf 2006 and Suddendorf et al . in press for critical analyses).

So far, examples of putative mental time travel in non-human species appear limited to situations with a strong instinctive component. They do suggest ways in which animals might adapt their behaviour to maximize future reward, but, so far, they have little of the flexibility and generality of mental time travel in humans. Humans can simulate virtually any event and evaluate it in terms of likelihood and desirability. It has been argued that this human faculty may be likened to a theatre production in that we employ mental analogues to a stage, a playwright, actors, a set, a director, an executive producer and a broadcaster ( Suddendorf & Corballis 2007 ). These sophisticated mental roles may be employed to simulate future events, just as readily as to imagine the minds of others (theory of mind) and entirely fictional stories ( Suddendorf & Corballis 1997 ; Buckner & Carroll 2007 ; Hassabis et al . 2007 b ). Animals may be restricted in their capacity to travel mentally in time by limits in any of these domains. For example, just as a playwright is responsible for creating new stories, mental simulations of novel future events require open-ended generativity—our ability to combine and recombine a limited set of items into virtually unlimited ways (something not evident in any of the animal studies). Our memories for episodes are made up of combinations of people, actions, objects and places, along with qualities such as time of day, season, emotional states, and so forth. Imagined future events are similarly constructed, and we may, in fact, compose different scenarios depending on various contingencies, such as the weather, or who is likely to show up. Indeed, it may be the generative component that most clearly distinguishes mental time travel in humans from future-directed capacities in other species. This generativity is also characteristic of other human faculties such as navigation, number, theory of mind and language ( Corballis 2003 ). Language is often regarded as the most distinct of human faculties (e.g. Hauser et al . 2002 ), and much of what humans talk about (or broadcast) are the mental simulations of past events and future possibilities ( Szagun 1978 ).

4. Language

Testing for episodic memory in humans is normally reliant on language, which is why it is difficult to devise ways of testing for it in non-human animals. This raises the possibility that the evolution of language itself is intimately connected with the evolution of mental time travel. Language is exquisitely designed to express ‘who did what to whom, what is true of what, where, when and why’, as Pinker (2003) put it—a combination of w 's that goes well beyond the www criteria—and these are precisely the qualities needed to recount episodic memories. The same applies to the expression of future events—who will do what to whom, or what will happen to what, where, when and why, and what are we going to do about it. When considering the future, the conditional may also be important—if it rains, then X will happen; if it does not we may enjoy Y. To a large extent, then, the stuff of mental time travel is also the stuff of language ( Corballis & Suddendorf 2007 ).

Language allows personal episodes and plans to be shared, enhancing the ability to plan and construct viable futures. To do so, though, requires ways of representing the elements of episodes: people; objects; actions; qualities; times of occurrence; and so forth. Language may well have begun as pantomime, with the use of bodily gestures to mimic events ( Donald 1991 ), with gestures becoming conventionalized, and thus more arbitrary and less representational, in the interests of greater economy and efficiency. According to this scenario, vocal gestures gradually replaced manual ones as the dominant mode ( Corballis 2003 ; Rizzolatti & Sinigalglia 2007 ), although most people still gesture manually as they speak.

The recounting of mental time travel places a considerable and, perhaps, uniquely human burden on communication, since there must be ways of referring to different points in time—past, present and future—and to locations other than that of the present. Different cultures have solved these problems in different ways. Many languages use tense as a way of modifying verbs to indicate the time of an episode, and to make other temporal distinctions, such as that between continuous action and completed action. Some languages, such as Chinese, have no tenses, but indicate time through other means, such as adverbs or aspect markers ( Lin 2005 ). The language spoken by the Pirahã, a tribe of some 200 people in Brazil, has only a very primitive way of talking about relative time, in the form of two tense-like morphemes, which seem to indicate simply whether an event is in the present or not, and Pirahã are said to live largely in the present ( Everett 2005 ).

Reference to space may have a basis in hippocampal function; as noted earlier, current theories suggest that the hippocampus provides the mechanism for the retrieval of memories based on spatial cues. It has also been suggested that, in humans, the hippocampus may encompass temporal coding, perhaps through analogy with space; thus, most prepositions referring to time are borrowed from those referring to space. In English, for example, words such as at , about , around , between , among , along , across , opposite , against , from , to and through are fundamentally spatial, but are also employed to refer to time, although a few, such as since or until , apply only to the time dimension ( O'Keefe 1996 ). It has been suggested that the hippocampus may have undergone modification in human evolution, such that the right hippocampus is responsible for the retrieval of spatial information, and the left for temporal (episodic or autobiographical) information ( Burgess et al . 2002 ). It remains unclear whether the left hippocampal specialization is a consequence of left hemispheric specialization for language, or of the incorporation of time into human consciousness of past and future, but either way it reinforces the link between language and mental time travel.

The most striking parallel between language and mental time travel has to do with generativity. We generate episodes from basic vocabularies of events, just as we generate sentences to describe them. It is the properties of generativity and recursiveness that, perhaps, most clearly single out language as a uniquely human capacity ( Hauser et al . 2002 ). The rules governing the generation of sentences about episodes must depend partly on the way in which the episodes themselves are constructed, but added rules are required by the constraints of the communication medium itself. Speech, for example, requires that the account of an event that is structured in space–time be linearized, or reduced to a temporal sequence of events. Sign languages allow more freedom to incorporate spatial as well as temporal structure, but still require conventions. For example, in American sign language, the time at which an event occurred is indicated spatially, with the continuum of past to future running from behind the body to the front of the body.

Of course, language is not wholly dependent on mental time travel. We can talk freely about semantic knowledge without reference to events in time, as typically required by the education industry—and, indeed, this very paper. However, it is mental time travel that forced communication to incorporate the time dimension, and to deal with reference to elements of the world, and combinations of those elements, that are not immediately available to the senses. It is these factors, we suggest, that were in large part responsible for the development of grammars. Given the variety of ways in which grammars are constructed, such as the different ways in which time is marked in different languages, we suspect that grammar is not so much a product of some innately determined universal grammar ( Chomsky 1988 ; O'Keefe 1996 ) as it is a product of culture and human ingenuity, constrained by brain structure ( Christiansen & Chater 2008 ). Through language, then, we see not just language itself, but also the structure of human thought, and how it is composed of basic elements including ‘events, states, things, substances, places and goals’ ( Pinker 2007 )—and times. Moreover, the generativity of language reflects the generativity of the underlying thought processes themselves.

5. Evolutionary considerations

Instinct, learning and memory are adaptations that enhance the fitness of animals, and shape their futures. Episodic memory is a form of memory, possibly unique to humans, that further allows the fine-tuning of behaviour, based on specific episodes in the past. It allows us to imagine future episodes, make specific plans and compare different scenarios. Language, we suspect, coevolved with mental time travel to allow the sharing of episodic information, sometimes to the point that we confuse events that have actually happened in our lives with those told to us by others, or even with those gleaned from fictional accounts.

Mental time travel and grammatical language probably evolved during the Pleistocene (Suddendorf & Corballis 1997 , 2007 ; Corballis 2003 ). Survival pressures brought about by changes in climate and the replacement of a forested environment by the more exposed savannah necessitated greater social cohesion, more detailed future planning and more effective communication. Brain size increased dramatically in the genus Homo during the Pleistocene, reaching a peak with the large-brained Neanderthals and precursors to modern humans perhaps 500 000 years ago. It has been suggested that the emergence of the genus Homo was also accompanied by a prolongation of the period of development from infancy to adulthood, and that an extra stage, known as childhood, was inserted into the sequence of developmental stages ( Locke & Bogin 2006 ). Childhood lasts from age 2.5 to approximately age 7, roughly the period during which both mental time travel and grammatical language develop.

There can be little doubt that flexible foresight became a key human survival strategy ( Suddendorf 2006 ) and that humans have taken the quest for securing future survival to a new level. Consider, for example, Norway's construction of a ‘doomsday’ seed bank designed to withstand global catastrophes to protect all known varieties of the world's crop. Yet, in spite of our strong reliance on foresight, humans are notoriously fallible with our predictions. For example, we display systematic errors in predicting the affective consequences of future action. Gilbert & Wilson (2007) recently reviewed these biases and concluded that several characteristics of mental simulation are the main contributors to these pervasive errors. Simulations tend to be unrepresentative, since they are often based on the most recent or most salient aspects of episodic memory, rather than on the most representative sampling. They often tend to reflect the gist of an event but fail to represent many details, and they often fail to take into account different future contexts in which events occur. The systematic biases in misapprehending how we will feel when a future event becomes the here and now is an essential problem for anyone in pursuit of happiness, and Gilbert (2006) offered the following simple solution to the dilemma: ask someone else who is or has been where we project ourselves as going. Their advice, on average, will be a far better guide to what it will be like than one's own biased simulations. This resonates with our proposal that one adaptive function of language may be to allow us to improve our mental time travel by drawing on the descriptions others can offer of what the future may hold. Undoubtedly, language allows us to learn from other individuals' experiences as no other animal can.

Whether this also leads to greater happiness remains debatable. Unlike, perhaps, psychologists, evolution does not care for our happiness and errors in affective forecasting are only errors if they negatively affect survival and reproduction. As with reconstruction of past events, it is not accuracy per se but the fitness consequences of foresight that matter. Systematic biases and errors may thus, in fact, serve adaptive purposes. For example, humans generally tend to expect more positive events than is rational to expect, and this optimism bias has specific neural correlates ( Sharot et al . 2007 ). Although we may often be wrong with our optimism, this positive mental stance may have profound selective advantages over a more realistic (and possibly bleak) perspective. Foresight, fallible and biased as it often may be, must have made a net positive contribution to fitness. Indeed, it is arguably our most formidable weapon. The price we might have had to pay for this are unique psychological stresses and disorders (e.g. Brune 2006 makes the case for obsessive–compulsive disorder).

In this review, we proposed that human language evolved in the first instance for the sharing of mental time travel. After reviewing the growing neuroscientific evidence linking episodic memory and episodic foresight, we discussed data from non-human animals. On current evidence, mental time travel, as with language, appears to reflect something uniquely human. This is not to say, however, that language and mental time travel are drawing on the same neurocognitive machinery. Language and mental time travel are clearly dissociable in modern humans. The total collapse of our faculty for mental time travel leaves a linguistically sophisticated person such as Clive Wearing trapped in the present and unable to conduct his life without the extensive support of others who can look ahead.

Acknowledgments

The writing of this manuscript was supported in part by an Australian Research Council Discovery Grant (DP0770113) to T.S.

One contribution of 18 to a Theme Issue ‘Predictions in the brain: using our past to prepare for the future’.

• Addis D.R., Schacter D.L. Effects of detail and temporal distance of past and future events on the engagement of a common neural network. Hippocampus. 2008; 18 :227–237. doi:10.1002/hipo.20405 [ PubMed ] [ Google Scholar ]
• Addis D.R., Wong A.T., Schacter D.L. Remembering the past and imagining the future: common and distinct neural substrates during event construction and elaboration. Neuropsychologia. 2007; 45 :1363–1377. doi:10.1016/j.neuropsychologia.2006.10.016 [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Addis D.R., Wong A.T., Schacter D.L. Age-related changes in the episodic simulation of future events. Psychol. Sci. 2008; 19 :33–41. doi:10.1111/j.1467-9280.2008.02043.x [ PubMed ] [ Google Scholar ]
• Aggleton J.P., Brown M.W. Episodic memory, amnesia and the hippocampal–anterior thalamic axis. Behav. Brain Sci. 1999; 22 :425–444. doi:10.1017/S0140525X99002034 [ PubMed ] [ Google Scholar ]
• Bischof N. On the phylogeny of human morality. In: Stent G.S., editor. Morality as biological phenomenon. Dahlem Konferenzen; Berlin, Germany: 1978. pp. 53–74. [ Google Scholar ]
• Bischof-Köhler D. Zur Phylogenese menschlicher Motivation [On the phylogeny of human motivation] In: Eckensberger L.H., Lantermann E.D., editors. Emotion und Reflexivität. Urban & Schwarzenberg. [In German.]; Vienna, Austria: 1985. pp. 3–47. [ Google Scholar ]
• Botzung A., Denkova E., Manning L. Experiencing past and future personal events: functional neuroimaging evidence on the neural bases of mental time travel. Brain Cogn. 2008; 66 :202–212. doi:10.1016/j.bandc.2007.07.011 [ PubMed ] [ Google Scholar ]
• Brune M. The evolutionary psychology of obsessive-compulsive disorder: the role of cognitive metarepresentation. Perspect. Biol. Med. 2006; 49 :317–329. doi:10.1353/pbm.2006.0037 [ PubMed ] [ Google Scholar ]
• Buckner R.L., Carroll D.C. Self-projection and the brain. Trends Cogn. Sci. 2007; 11 :49–57. doi:10.1016/j.tics.2006.11.004 [ PubMed ] [ Google Scholar ]
• Burgess N., Maguire E.A., O'Keefe J. The human hippocampus and spatial and episodic memory. Neuron. 2002; 35 :625–641. doi:10.1016/S0896-6273(02)00830-9 [ PubMed ] [ Google Scholar ]
• Busby J., Suddendorf T. Recalling yesterday and predicting tomorrow. Cogn. Dev. 2005; 20 :362–372. doi:10.1016/j.cogdev.2005.05.002 [ Google Scholar ]
• Chomsky N. MIT Press; Cambridge, MA: 1988. Language and problems of knowledge: the Managua lectures. [ Google Scholar ]
• Christiansen M., Chater N. Brains, genes, and language evolution: a new synthesis. Behav. Brain Sci. 2008; 31 :537–558. doi:10.1017/S0140525X08005281 [ Google Scholar ]
• Clayton N.S., Dickinson A. Episodic-like memory during cache recovery by scrub jays. Nature. 1998; 395 :272–278. doi:10.1038/26216 [ PubMed ] [ Google Scholar ]
• Clayton N.S., Bussey T.J., Dickinson A. Can animals recall the past and plan for the future? Nat. Rev. Neurosci. 2003; 4 :685–691. doi:10.1038/nrn1180 [ PubMed ] [ Google Scholar ]
• Corballis M.C. Princeton University Press; New York, NY: 2003. From hand to mouth: the origins of language. [ Google Scholar ]
• Corballis M.C., Suddendorf T. Memory, time and language. In: Pasternak C., editor. What makes us human? Oneworld; Oxford, UK: 2007. pp. 17–36. [ Google Scholar ]
• Correia S.P.C., Dickinson A., Clayton N.S. Western scrub-jays anticipate future needs independently of their current motivational state. Curr. Biol. 2007; 17 :856–861. doi:10.1016/j.cub.2007.03.063 [ PubMed ] [ Google Scholar ]
• D'Argembeau A., Van der Linden M. Phenomenal characteristics associated with projecting oneself back into the past and forward into the future: influence of valence and temporal distance. Conscious. Cogn. 2004; 13 :844–858. doi:10.1016/j.concog.2004.07.007 [ PubMed ] [ Google Scholar ]
• D'Argembeau A., Xue G., Lu Z.L., Van der Linden M., Bechara A. Neural correlates of envisioning emotional events in the near and far future. NeuroImage. 2008; 40 :398–407. doi:10.1016/j.neuroimage.2007.11.025 [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Dere E., Huston J.P., Silva M.A.S. Episodic-like memory in mice: simultaneous assessment of object, place and temporal order memory. Brain Res. Protoc. 2005; 16 :10–19. doi:10.1016/j.brainresprot.2005.08.001 [ PubMed ] [ Google Scholar ]
• Donald M. Harvard University Press; Cambridge, MA: 1991. Origins of the human mind: three stages in the evolution of culture and cognition. [ Google Scholar ]
• Emery N.J., Clayton N.S. Effects of experience and social context on prospective caching strategies by scrub jays. Nature. 2001; 414 :443–446. doi:10.1038/35106560 [ PubMed ] [ Google Scholar ]
• Everett D.L. Cultural constraints on grammar and cognition in Pirahã—another look at the design features of human language. Curr. Anthropol. 2005; 46 :621–646. doi:10.1086/431525 [ Google Scholar ]
• Ferkin M.H., Combs A., delBarco-Trillo J., Pierce A.A., Franklin S. Meadow voles, Microtus pennsylvanicus , have the capacity to recall the “what”, “where”, and “when” of a single past event. Anim. Cogn. 2008; 11 :147–159. doi:10.1007/s10071-007-0101-8 [ PubMed ] [ Google Scholar ]
• Gilbert D.T. A. A. Knopf; New York, NY: 2006. Stumbling on happiness. [ Google Scholar ]
• Gilbert D.T., Wilson T.D. Prospection: experiencing the future. Science. 2007; 317 :1351–1354. doi:10.1126/science.1144161 [ PubMed ] [ Google Scholar ]
• Hassabis D., Maguire E.A. The construction system of the brain. Phil. Trans. R. Soc. B. 2009; 364 :1263–1271. doi:10.1098/rstb.2008.0296 [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Hassabis D., Kumaran D., Maguire E.A. Using imagination to understand the neural basis of episodic memory. J. Neurosci. 2007a; 27 :14 365–14 374. doi:10.1523/JNEUROSCI.4549-07.2007 [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Hassabis D., Kumaran D., Vann S.D., Maguire E.A. Patients with hippocampal amnesia cannot imagine new experiences. Proc. Natl Acad. Sci. USA. 2007b; 104 :1726–1731. doi:10.1073/pnas.0610561104 [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Hauser M.D., Chomsky N., Fitch W.T. The faculty of language: what is it, who has it, and how did it evolve? Science. 2002; 298 :1569–1579. doi:10.1126/science.298.5598.1569 [ PubMed ] [ Google Scholar ]
• Hodges J.R., Graham K.S. Episodic memory: insights from semantic dementia. Phil. Trans. R. Soc. B. 2001; 356 :1423–1434. doi:10.1098/rstb.2001.0943 [ PMC free article ] [ PubMed ] [ Google Scholar ]
• James W. Macmillan; London, UK: 1890. The principles of psychology. [ Google Scholar ]
• Klein S.B., Loftus J., Kihlstrom J.F. Memory and temporal experience: the effects of episodic memory loss on an amnesic patient's ability to remember the past and imagine the future. Social Cogn. 2002; 20 :353–379. doi:10.1521/soco.20.5.353.21125 [ Google Scholar ]
• Lea S.E.G. Anticipation and memory as criteria for special welfare consideration. Anim. Welf. 2001; 10 :S195–S208. [ Google Scholar ]
• Levine B., Svoboda E., Hay J.F., Winocur G. Aging and autobiographical memory: dissociating episodic from semantic retrieval. Psychol. Aging. 2002; 17 :677–689. doi:10.1037/0882-7974.17.4.677 [ PubMed ] [ Google Scholar ]
• Lin J.W. Time in a language without tense: the case of Chinese. J. Semant. 2005; 23 :1–53. doi:10.1093/jos/ffh033 [ Google Scholar ]
• Locke J.L., Bogin B. Language and life history: a new perspective on the development and evolution of human language. Behav. Brain Sci. 2006; 29 :259–280. doi:10.1017/S0140525X0600906X [ PubMed ] [ Google Scholar ]
• Mendl M., Paul E.S. Do animals live in the present? Current evidence and implications for welfare. Appl. Anim. Behav. Sci. 2008; 113 :357–382. doi:10.1016/j.applanim.2008.01.013 [ Google Scholar ]
• Moscovitch M., et al. Functional neuroanatomy of remote episodic, semantic and spatial memory: a unified account based on multiple trace theory. J. Anat. 2005; 207 :35. doi:10.1111/j.1469-7580.2005.00421.x [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Mulcahy N.J., Call J. Apes save tools for future use. Science. 2006; 312 :1038–1040. doi:10.1126/science.1125456 [ PubMed ] [ Google Scholar ]
• O'Keefe J. The spatial prepositions in English, vector grammar, and the cognitive map theory. In: Bloom P., editor. Language and space. MIT Press; Cambridge, MA: 1996. pp. 277–316. [ Google Scholar ]
• Okuda J., et al. Thinking of the future and past: the roles of the frontal pole and the medial temporal lobes. Neuroimage. 2003; 19 :1369–1380. doi:10.1016/S1053-8119(03)00179-4 [ PubMed ] [ Google Scholar ]
• Osvath M., Osvath H. Chimpanzee ( Pan troglodytes ) and orangutan ( Pongo abelii ) forethought: self-control and pre-experience in the face of future tool use. Anim. Cogn. 2008; 11 :661–674. doi:10.1007/s10071-008-0157-0 [ PubMed ] [ Google Scholar ]
• Pinker S. Language as an adaptation to the cognitive niche. In: Christiansen M.H., Kirby S., editors. Language evolution. Oxford University Press; Oxford, UK: 2003. pp. 16–37. [ Google Scholar ]
• Pinker S. Viking; New York, NY: 2007. The stuff of thought. [ Google Scholar ]
• Rizzolatti G., Sinigalglia C. Oxford University Press; Oxford, UK: 2007. Mirrors in the brain. [ Google Scholar ]
• Roberts W.A., Feeney M.C., MacPherson K., Petter M., McMillan N., Musolino E. Episodic-like memory in rats: is it based on when or how long ago? Science. 2008; 320 :113–115. doi:10.1126/science.1152709 [ PubMed ] [ Google Scholar ]
• Rosenbaum R.S., Kohler S., Schacter D.L., Moscovitch M., Westmacott R., Black S.E., Gao F.Q., Tulving E. The case of KC: contributions of a memory-impaired person to memory theory. Neuropsychologia. 2005; 43 :989–1021. doi:10.1016/j.neuropsychologia.2004.10.007 [ PubMed ] [ Google Scholar ]
• Schacter D.L. The seven sins of memory: insights from psychology and cognitive neuroscience. Am. Psychol. 1999; 54 :182–203. doi:10.1037/0003-066X.54.3.182 [ PubMed ] [ Google Scholar ]
• Schacter D.L., Addis D.R. The ghosts of past and future. Nature. 2007; 445 :27. doi:10.1038/445027a [ PubMed ] [ Google Scholar ]
• Schacter D.L., Addis D.R. On the nature of medial temporal lobe contributions to the constructive simulation of future events. Phil. Trans. R. Soc. B. 2009; 364 :1245–1253. doi:10.1098/rstb.2008.0308 [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Schacter D.L., Addis D.R., Buckner R.L. Remembering the past to imagine the future: the prospective brain. Nat. Rev. Neurosci. 2007; 8 :657–661. doi:10.1038/nrn2213 [ PubMed ] [ Google Scholar ]
• Scoville W.B., Milner B. Loss of recent memory after bilateral hippocampal lesion. J. Neurol. Neurosurg. Psychiatry. 1957; 20 :11–21. doi:10.1136/jnnp.20.1.11 [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Sharot T., Riccardi A.M., Raio C.M., Phelps E.A. Neural mechanisms mediating optimism bias. Nature. 2007; 450 :102–106. doi:10.1038/nature06280 [ PubMed ] [ Google Scholar ]
• Spreng R.N., Levine B. The temporal distribution of past and future autobiographical events across the lifespan. Mem. Cogn. 2006; 34 :1644–1651. [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Squire L.R. Memory and the hippocampus: a synthesis from findings with rats, monkeys and humans. Psychol. Rev. 1992; 99 :195–231. doi:10.1037/0033-295X.99.2.195 [ PubMed ] [ Google Scholar ]
• Squire L.R., Starck C.E., Clark R.E. The medial temporal lobe. Annu. Rev. Neurosci. 2004; 27 :279–306. doi:10.1146/annurev.neuro.27.070203.144130 [ PubMed ] [ Google Scholar ]
• Suddendorf T. Foresight and evolution of the human mind. Science. 2006; 312 :1006–1007. doi:10.1126/science.1129217 [ PubMed ] [ Google Scholar ]
• Suddendorf T., Busby J. Mental time travel in animals? Trends Cogn. Sci. 2003; 7 :391–396. doi:10.1016/S1364-6613(03)00187-6 [ PubMed ] [ Google Scholar ]
• Suddendorf T., Busby J. Making decisions with the future in mind: developmental and comparative identification of mental time travel. Learn. Motivat. 2005; 36 :110–125. doi:10.1016/j.lmot.2005.02.010 [ Google Scholar ]
• Suddendorf T., Corballis M.C. Mental time travel and the evolution of the human mind. Genet. Soc. Gen. Psychol. Monogr. 1997; 123 :133–167. [ PubMed ] [ Google Scholar ]
• Suddendorf T., Corballis M.C. The evolution of foresight: what is mental time travel and is it unique to humans? Behav. Brain Sci. 2007; 30 :299–313. doi:10.1017/S0140525X07001975 [ PubMed ] [ Google Scholar ]
• Suddendorf T., Corballis M.C. New evidence for animal foresight? Anim. Behav. 2008; 75 :e1–e3. doi:10.1016/j.anbehav.2008.01.006 [ Google Scholar ]
• Suddendorf, T., Corballis, M. C. & Collier-Baker, E. In press. How great is great ape foresight. Anim. Cogn [ PubMed ]
• Szagun G. On the frequency of use of tenses in English and German children's spontaneous speech. Child Dev. 1978; 49 :898–901. doi:10.2307/1128267 [ Google Scholar ]
• Szpunar K.K., Watson J.M., McDermott K.B. Neural substrates of envisioning the future. Proc. Natl Acad. Sci. USA. 2007; 104 :642–647. doi:10.1073/pnas.0610082104 [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Tulving E. Clarendon Press; Oxford, UK: 1983. Elements of episodic memory. [ Google Scholar ]
• Tulving E. Memory and consciousness. Can. Psychol. 1985; 26 :1–12. doi:10.1037/h0080017 [ Google Scholar ]
• Tulving E. Episodic memory: from mind to brain. Annu. Rev. Psychol. 2002; 53 :1–25. doi:10.1146/annurev.psych.53.100901.135114 [ PubMed ] [ Google Scholar ]
• Tulving E., Schacter D.L., McLachlan D.R., Moscovitch M. Priming of semantic autobiographical knowledge: a case study of retrograde-amnesia. Brain Cogn. 1988; 8 :3–20. doi:10.1016/0278-2626(88)90035-8 [ PubMed ] [ Google Scholar ]
• VarghaKhadem F., Gadian D.G., Watkins K.E., Connelly A., VanPaesschen W., Mishkin M. Differential effects of early hippocampal pathology on episodic and semantic memory. Science. 1997; 277 :376–380. doi:10.1126/science.277.5324.376 [ PubMed ] [ Google Scholar ]
• Wearing D. Doubleday; New York, NY: 2005. Forever today. [ Google Scholar ]
• Zentall T.R. Mental time travel in animals: a challenging question. Behav. Process. 2006; 72 :173–183. doi:10.1016/j.beproc.2006.01.009 [ PubMed ] [ Google Scholar ]

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Shayla Love

Collective Mental Time Travel Can Influence the Future

We’re often told to “be here now.” Yet the mind is rarely tethered in place. We take mental trips to our past, revisiting what happened yesterday or when we were children, or we project into an imagined future: tomorrow’s dinner date, the trajectory of our career at age 50.

Rather than a diversion from the norm of mindful presence, this tendency to internally visit other time lines, called “mental time travel,” is common; young adults, for example, think about their future an average of 59 times a day. Psychologists have suggested that this ability to time travel from the confines of our own heads is a fundamental aspect of what it means to be human.

The past and future are not locations that remain the same regardless of who is visiting and when. The way we envision our past or future is ever-changing, and the construction of these scenarios has an impact on what we do and how we think in the present. Until recently, the study of mental time travel largely focused on individuals and their personal histories. But this doesn’t reflect the social nature of our lives. Identities are comprised of groups that nestle into one another. We are part of our families and friend circles, occupational networks, countries and nations, and ethnic groups. The study of mental time travel is starting to reflect this: When we travel through time, we don’t always go alone.

Research on “collective mental time travel” shows that the way we imagine the collective future or past also impacts the present. It can sway attitudes toward policy decisions and laws, as well as how aligned people feel with their country or existing systems. It can affect a person’s willingness to engage in prosocial behaviors, like voting, donating, or activism. Because of this, collective mental time travel is more than just a neat cognitive trick—it provides an opportunity to be more intentional about how we represent the collective past and future. 

In the 1980s, psychologist Endel Tulving proposed that humans have the ability to relive their past and pre-experience the future, theorizing that the same memory mechanisms were used for both. This was supported by case studies with amnesiacs: One man, “K.C.,” had brain lesions that affected his ability to retain personal memories, like a visit he’d taken to a family lake house. This patient couldn’t imagine going there in the future, despite knowing that his family owned the house.

More recent brain imaging has supported Tulving’s theory by showing that similar networks are activated when remembering the personal past and personal future, said Karl Szpunar, an associate professor of psychology and director of the Memory Lab at Toronto Metropolitan University. Based on this evidence, some scientists think that we imagine the future by recombining past experiences—this is called the “constructed episodic simulation hypothesis.”

For the collective past and future, the story may be more complex. Is our collective future simply made up of fragments of the collective past? Intriguingly, when people with damage to their hippocampus, a brain region involved in personal memory, are asked about collective future events, like “What environmental concerns will the world face over the coming decade?” they are able to come up with answers. Even though their ability to mentally time travel into their personal futures was compromised, the ability to imagine events affecting a group’s future was intact. More work on this is needed, but as Spzunar and his colleague wrote, “The capacity to engage in collective future thought appears to rely on cognitive processes distinct from those involved in individual or personal future thinking.”

By Matt Kamen

By Mark Harris

By Angela Watercutter

By Adrienne So

The collective past likely has an influence on the collective future, but only to a point, says Meymune Topcu, a visiting scholar at The New School. She’s coauthor of a recent review chapter on collective mental time travel, in which she examined numerous cases of people collectively “visiting” the past and future and looked at whether they felt positively or negatively about their mental representations and how specific the content of their time travel was.

She found that past events can influence what people imagine to happen in the collective future, but there isn’t necessarily a complete overlap. Imagined collective futures can also be less specific than memories of the collective past, Topcu said. Additionally, when we think about our own futures, we tend to have an optimism bias, but when people are asked to think about the future of their countries, they often focus more on potentially worrisome , rather than potentially exciting, possibilities. (These findings have not been found to be culturally universal: Some newer research with Chinese participants has shown that such positive and negative biases are not present in those study groups.)

On an individual level, thinking about the future is correlated with specific actions or attitudes. Studies from Hal Hershfield, a psychologist at UCLA who studies the effects of time perception, and his colleagues, have found that people who relate more to their future selves make more future-oriented decisions, like saving money for later, and have higher levels of well-being over a 10-year period. Hershfield has also asked people about their conception of how long the present is. The longer they thought “ right now ” lasted, the fewer emotions they felt about the future. People who said that the present ended sooner were more likely to make future-oriented decisions. Having a future time perspective can also predict pro-environmental attitudes, like favoring and participating in more sustainable behaviors.

If how you think about the future or present can be a guiding influence, it’s a short leap to envisioning how collective pasts and futures might be manipulated for various means. Jeremy Yamashiro, an assistant professor of psychology at UC Santa Cruz, said that rather than creating hard and fast rules for the best way to represent the past and the future, he’s become more sensitive to the ways people use representations in strategic ways . “It’s much more, ‘How are people using that in order to convince you of what they’re trying to convince you of?’” He said. The collective future probably isn’t based only on the building blocks of the past, but also cultural narratives , Yamashiro said.

Those narratives can have immediate and practical policy ramifications. In 2014 , social and cultural psychologist Contance de Saint-Laurent analyzed the parliamentary debates on immigration in France and found two dominant narratives for how left-wing and right-wing politicians thought about the country’s past.

The left saw the past as “a constant struggle between humanists and their adversaries,” while the right saw the central tenet of French history as the “social contract that enables co-existence in society.” Because of the way these groups viewed the past, de Saint-Laurent wrote, people on the left were more willing to see the future as an opportunity to address colonial crimes, while the others would only accept immigrants who adhered to the social contract of the country.

A person’s current reality also affects how much they focus on the future. Johanna Peetz, a social psychologist at Carleton University, has found a link between future thinking and the economic index of countries and their general quality of life. If a country’s economic index was stable or decreasing, and quality of life was declining, people did not want to look toward the future.

We could, however, think of some manipulations being wielded for good. Topcu thinks that collective future thinking could play a role in addressing intergroup conflicts. In one study , people who lived in the European Union were given different descriptions of the EU. One was an excerpt that mentioned the common heritage of European societies, the other was a narrative focusing on how the EU was a project for the future. Then the people played a game in which they had to choose to cooperate with other participants. When people saw the EU as a future-oriented project, rather than one based in the past, they were more likely to play nice.

“I’m just speculating, but if we ask people to imagine a future in a different way, or simply imagining a future where there’s more peace and cooperation between these two groups, it could have an effect on whether they would be more willing to change the present situation,” Topcu said.

This approach could be applied at a more global scale. In 2018, researchers asked people to write about their vision of the best possible overall society. People who imagined utopia-like futures ended up being less satisfied with the status quo and were less likely to justify current systems. People asked to engage in utopian thinking also reported being more willing to participate in individual and collective action to attain that future.

But the type of utopia mattered. In a follow-up study , participants were asked to imagine either a “green utopia” composed of an “ecologically friendly society that champions sustainable efficiency” or a “sci-fi utopia,” where technological advancement and material efficiency dominated. Both utopias were seen as positive, but those who imagined the green utopia were more willing to participate in social change or report that they would donate to a nonprofit. The authors speculated that it had to do with agency—those who invested in a sci-fi future envisioned technology solving every problem and may have felt less able to bring about that positive future.

This suggests that proposing a future on Mars, for example, might unintentionally lead to less action in the present than collectively imagining a different kind of future would. “When we think about techno-fixes, it’s couched in a narrative of progress,” said Piotr Szpunar, a professor in the Communication Department at the University at Albany: “a narrative that technology continuously gets better, and at the same time, that society continuously gets better, or more equitable.” This can happen within nations too, as with the story of American exceptionalism. “There’s this idea that regardless of what happens, we’re still progressing,” he said. William Hirst, professor and cochair of psychology at The New School for Social Research, described the often rigid relationship between memory and history as “mnemonic inertia,” when certain stories become sticky and have outsized weight in terms of how we think about the present and future.

The future can also modify how we view the past, a concept that psychologist Ignacio Brescó de Luna called “prolepsis,” or when “imagined futures are brought into the present by means of particular ways of reconstructing the past.” In 2018, transdisciplinary scholar Séamus A. Power interviewed people engaged in water protests in Ireland. He argued that a driving reason for their collective action was imagining a dystopic future in which water was privatized, an imagined future based on remembering past cases of privatization in Ireland.

“There is a continuous looping from the past to the future and back again, always converging on the focal point of the present,” Power wrote. There’s room for flexibility—the most important lesson currently from collective mental time travel might be how dynamic an interaction there is between our notions of future, present, and past.

No matter how we use it, collective mental time travel ultimately challenges the objective reality of our past and present. The English philosopher C.D. Broad proposed the “growing block theory of time,” which says that only the past and present are real, and the future is not. As the future becomes the present, it is added on to the “growing block of reality.” Collective mental time travel reminds us that all remembrances of the past are reconstructions to some extent, and our present is continuously being informed by the way we imagine the future and conceive of the past.

“When you can change the narrative of the past, it’s going to change the way you conceive of the future too,” Hirst said. We won’t ever be able to escape this relationship, but we can seek a better understanding of how our perceptions are influenced by mental time travel, and how the collective past and future can be tools for building a better present.

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Mental Time Travel? A Neurocognitive Model of Event Simulation

• Published: 30 April 2020
• Volume 11 , pages 233–259, ( 2020 )

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• Donna Rose Addis 1 , 2 , 3  

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Mental time travel (MTT) is defined as projecting the self into the past and the future. Despite growing evidence of the similarities of remembering past and imagining future events, dominant theories conceive of these as distinct capacities. I propose that memory and imagination are fundamentally the same process – constructive episodic simulation – and demonstrate that the ‘simulation system’ meets the three criteria of a neurocognitive system. Irrespective of whether one is remembering or imagining, the simulation system: (1) acts on the same information, drawing on elements of experience ranging from fine-grained perceptual details to coarser-grained conceptual information and schemas about the world; (2) is governed by the same rules of operation, including associative processes that facilitate construction of a schematic scaffold, the event representation itself, and the dynamic interplay between the two (cf. predictive coding); and (3) is subserved by the same brain system. I also propose that by forming associations between schemas, the simulation system constructs multi-dimensional cognitive spaces, within which any given simulation is mapped by the hippocampus. Finally, I suggest that simulation is a general capacity that underpins other domains of cognition, such as the perception of ongoing experience. This proposal has some important implications for the construct of ‘MTT’, suggesting that ‘time’ and ‘travel’ may not be defining, or even essential, features. Rather, it is the ‘mental’ rendering of experience that is the most fundamental function of this domain-general simulation system enabling humans to re-experience the past, pre-experience the future, and also comprehend the complexities of the present.

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Episodic memory, simulated future planning, and their evolution.

Addis, D.R. 2018. Are episodic memories special? On the sameness of remembered and imagined event simulation. Journal of the Royal Society of New Zealand 48 (2–3): 64–88. https://doi.org/10.1080/03036758.2018.1439071 .

Article   Google Scholar  

Addis, D.R., T. Cheng, R.P. Roberts, and D.L. Schacter. 2011. Hippocampal contributions to the episodic simulation of specific and general future events. Hippocampus 21: 1045–1052. https://doi.org/10.1002/hipo.20870 .

Addis, D.R., S. Hach, and L.J. Tippett. 2016. Do strategic processes contribute to the specificity of future simulation in depression? The British Journal of Clinical Psychology 55: 167–186. https://doi.org/10.1111/bjc.12103 .

Addis, D.R., M. Moscovitch, A.P. Crawley, and M.P. McAndrews. 2004. Recollective qualities modulate hippocampal activation during autobiographical memory retrieval. Hippocampus 14: 752–762. https://doi.org/10.1002/hipo.10215 .

Addis, D.R., L. Pan, M.A. Vu, N. Laiser, and D.L. Schacter. 2009. Constructive episodic simulation of the future and the past: Distinct subsystems of a core brain network mediate imagining and remembering. Neuropsychologia 47: 2222–2238. https://doi.org/10.1016/j.neuropsychologia.2008.10.026 .

Addis, D.R., and D.L. Schacter. 2012. The Hippocampus and Imagining the Future: Where Do We Stand? Front Hum Neurosci 5 : 173. https://doi.org/10.3389/fnhum.2011.00173 .

Addis, D.R., A.T. Wong, and D.L. Schacter. 2007. Remembering the past and imagining the future: Common and distinct neural substrates during event construction and elaboration. Neuropsychologia 45: 1363–1377. https://doi.org/10.1016/j.neuropsychologia.2006.10.016 .

Addis, D.R., A.T. Wong, and D.L. Schacter. 2008. Age-related changes in the episodic simulation of future events. Psychological Science 19: 33. https://doi.org/10.1111/j.1467-9280.2008.02043.x .

Anderson, R.J., S.A. Dewhurst, and R.A. Nash. 2012. Shared cognitive processes underlying past and future thinking: the impact of imagery and concurrent task demands on event specificity. Journal of Experimental Psychology: Learning, Memory, & Cognition 38: 356–365. https://doi.org/10.1037/a0025451 .

Arzy, S., and D.L. Schacter. 2019. Self-agency and self-ownership in cognitive mapping. Trends in Cognitive Sciences 23: 476–487. https://doi.org/10.1016/j.tics.2019.04.003 .

Atance, C.M., and D.K. O'Neill. 2001. Episodic future thinking. Trends in Cognitive Sciences 5 (12): 533–539. https://doi.org/10.1016/S1364-6613(00)01804-0 .

Baddeley, A.D. 2000. The episodic buffer: A new component of working memory? Trends in Cognitive Sciences 4: 417–423. https://doi.org/10.1016/S1364-6613(00)01538-2 .

Baldassano, C., J. Chen, A. Zadbood, J.W. Pillow, U. Hasson, and K.A. Norman. 2017. Discovering event structure in continuous narrative perception and memory. Neuron 95: 709–721. https://doi.org/10.1016/j.neuron.2017.06.041 .

Bar, M. 2009. The proactive brain: Memory for predictions. Philosophical Transactions of the Royal Society B-Biological Sciences 364 (1521): 1235–1243. https://doi.org/10.1098/rstb.2008.0310 .

Bartlett, F.C. 1932. Remembering . Cambridge: Cambridge University Press.

Google Scholar  

Beaty, R.E., M. Benedek, S. Barry Kaufman, and P.J. Silvia. 2015. Default and executive network coupling supports creative idea production. Scientific Reports 5: 10964. https://doi.org/10.1038/srep10964 .

Behrens, T.E.J., T.H. Muller, J.C.R. Whittington, S. Mark, A.B. Baram, K.L. Stachenfeld, and Z. Kurth-Nelson. 2018. What is a cognitive map? Organizing knowledge for flexible behavior. Neuron 100: 490–509. https://doi.org/10.1016/j.neuron.2018.10.002 .

Binder, J.R., R.H. Desai, W.W. Graves, and L.L. Conant. 2009. Where is the semantic system? A critical review and meta-analysis of 120 functional neuroimaging studies. Cerebral Cortex 19: 2767–2796. https://doi.org/10.1093/cercor/bhp055 .

Brewin, C.R. 2014. Episodic memory, perceptual memory, and their interaction: Foundations for a theory of posttraumatic stress disorder. Psychological Bulletin 140: 69–97. https://doi.org/10.1037/a0033722 .

Buckner, R.L., and D.C. Carroll. 2007. Self-projection and the brain. Trends in Cognitive Sciences 11: 49–57. https://doi.org/10.1016/j.tics.2006.11.004 .

Burianova, H., and C.L. Grady. 2007. Common and unique neural activations in autobiographical, episodic, and semantic retrieval. Journal of Cognitive Neuroscience 19: 1520–1534. https://doi.org/10.1162/jocn.2007.19.9.1520 .

Cabeza, R., and M. Moscovitch. 2013. Memory systems, processing modes, and components: Functional neuroimaging evidence. Perspectives on Psychological Science 8: 49–55. https://doi.org/10.1177/1745691612469033 .

Cabral, J., M.L. Kringelbach, and G. Deco. 2014. Exploring the network dynamics underlying brain activity during rest. Progress in Neurobiology 114: 102–131. https://doi.org/10.1016/j.pneurobio.2013.12.005 .

Chen, J., C.J. Honey, E. Simony, M.J. Arcaro, K.A. Norman, and U. Hasson. 2016. Accessing real-life episodic information from minutes versus hours earlier modulates hippocampal and high-order cortical dynamics. Cerebral Cortex 26: 3428–3441. https://doi.org/10.1093/cercor/bhv155 .

Christoff, K., Z.C. Irving, K.C.R. Fox, R.N. Spreng, and J.R. Andrews-Hanna. 2016. Mind-wandering as spontaneous thought: A dynamic framework. Nature Reviews Neuroscience 17: 718–731. https://doi.org/10.1038/nrn.2016.113 .

Christoff, K., V. Prabhakaran, J. Dorfman, Z. Zhao, J.K. Kroger, K.J. Holyoak, and J.D. Gabrieli. 2001. Rostrolateral prefrontal cortex involvement in relational integration during reasoning. Neuroimage 14 (5): 1136–1149. https://doi.org/10.1006/nimg.2001.0922 .

Conway, M.A., and C.W. Pleydell-Pearce. 2000. The construction of autobiographical memories in the self-memory system. Psychological Review 107: 261–288. https://doi.org/10.1037/0033-295x.107.2.261 .

Craik, F.I.M. 2007. Encoding: A cognitive perspective. In Science of memory concepts , ed. H.L. Roediger, Y. Dudai, and S.M. Fitzpatrick, 129–136. New York: Oxford University Press. https://doi.org/10.1093/acprof:oso/9780195310443.003.0007 .

Chapter   Google Scholar  

Craik, F.I.M., and R.S. Lockhart. 1972. Levels of processing: A framework for memory research. Journal of Verbal Learning and Verbal Behavior 11: 671–684. https://doi.org/10.1016/S0022-5371(72)80001-X .

D'Argembeau, A., D. Stawarczyk, S. Majerus, F. Collette, M. Van der Linden, D. Feyers, et al. 2010. The neural basis of personal goal processing when envisioning future events. Journal of Cognitive Neuroscience 22: 1701–1713. https://doi.org/10.1162/jocn.2009.21314 .

D'Argembeau, A., and M. Van der Linden. 2004. Phenomenal characteristics associated with projecting oneself back into the past and forward into the future: Influence of valence and temporal distance. Consciousness & Cognition 13: 844–858.

D'Argembeau, A., and M. Van der Linden. 2006. Individuals differences in the phenomenology of mental time travel: The effects of vivid visual imagery and emotion regulation strategies. Consciousness and Cognition 15: 342–350. https://doi.org/10.1016/j.concog.2004.07.007 .

D'Argembeau, A., and M. Van der Linden. 2012. Predicting the phenomenology of episodic future thoughts. Consciousness and Cognition 21: 1198–1206. https://doi.org/10.1016/j.concog.2012.05.004 .

Dannenberg, H., A.S. Alexander, J.C. Robinson, and M.E. Hasselmo. 2018. The role of hierarchical dynamical functions in coding for episodic memory and cognition. Journal of Cognitive Neuroscience 31 (9): 1–19. https://doi.org/10.1162/jocn_a_01439 .

Dayan, P., G.E. Hinton, and R.M.T. Neal. 1995. The Helmholtz machine. Neural Computation 7: 889–904. https://doi.org/10.1162/neco.1995.7.5.889 .

De Brigard, F., D.R. Addis, J.H. Ford, D.L. Schacter, and K.S. Giovanello. 2013. Remembering what could have happened: Neural correlates of episodic counterfactual thinking. Neuropsychologia 51: 2401–2414. https://doi.org/10.1016/j.neuropsychologia.2013.01.015 .

de Vito, S., N. Gamboz, and M.A. Brandimonte. 2012a. What differentiates episodic future thinking from complex scene imagery? Consciousness and Cognition 21: 813–823. https://doi.org/10.1016/j.concog.2012.01.013 .

de Vito, S., N. Gamboz, A.M. Brandimonte, P. Barone, M. Amboni, and S. Della Sala. 2012b. Future thinking in Parkinson's disease: An executive function? Neuropsychologia 50: 1494–1501. https://doi.org/10.1016/j.neuropsychologia.2012.03.001 .

Devitt, A.L., E. Monk-Fromont, D.L. Schacter, and D.R. Addis. 2016. Factors that influence the generation of autobiographical memory conjunction errors. Memory 24: 204–222. https://doi.org/10.1080/09658211.2014.998680 .

Dixon, M.L., A. De La Vega, C. Mills, J.R. Andrews-Hanna, R.N. Spreng, M.W. Cole, and K. Christoff. 2018. Heterogeneity within the frontoparietal control network and its relationship to the default and dorsal attention networks. Proceedings of the National Academy of Sciences of the United States of America 115: E1598–E1607. https://doi.org/10.1073/pnas.1715766115 .

Ernst, A., A. Scoboria, and A. D’Argembeau. 2019. On the role of autobiographical knowledge in shaping belief in the future occurrence of imagined events. Quarterly Journal of Experimental Psychology 72: 2658–2671. https://doi.org/10.1177/1747021819855621 .

Frith, U., and C. Frith. 2003. Development and neurophysiology of mentalizing. Philosophical Transactions of the Royal Society of London. Series B . Biological Sciences 358: 459–473. https://doi.org/10.1098/rstb.2002.1218 .

Fuster, J.M. 1997. Network memory. Trends in Neurosciences 20: 451–459. https://doi.org/10.1016/S0166-2236(97)01128-4 .

Garry, M., C.G. Manning, E.F. Loftus, and S.J. Sherman. 1996. Imagination inflation: Imagining a childhood event inflates confidence that it occurred. Psychonomic Bulletin & Review 3 (2): 208–214. https://doi.org/10.3758/BF03212420 .

Gentner, D. 1983. Structure-mapping: A theoretical framework for analogy. Cognitive Science 7: 155–170. https://doi.org/10.1016/S0364-0213(83)80009-3 .

Ghosh, V.E., and A. Gilboa. 2014. What is a memory schema? A historical perspective on current neuroscience literature. Neuropsychologia 53: 104–114. https://doi.org/10.1016/j.neuropsychologia.2013.11.010 .

Gilboa, A., and H. Marlatte. 2017. Neurobiology of schemas and schema-mediated memory. Trends in Cognitive Sciences 21: 618–631. https://doi.org/10.1016/j.tics.2017.04.013 .

Gilboa, A., and M. Moscovitch. 2017. Ventromedial prefrontal cortex generates pre-stimulus theta coherence desynchronization: A schema instantiation hypothesis. Cortex 87: 16–30. https://doi.org/10.1016/j.cortex.2016.10.008 .

Graf, P., and D.L. Schacter. 1989. Unitization and grouping mediate dissociations in memory for new associations. Journal of Experimental Psychology: Learning, Memory, & Cognition 15: 930–940. https://doi.org/10.1037/0278-7393.15.5.930 .

Grysman, A., J. Prabhakar, S.M. Anglin, and J.A. Hudson. 2013. The time travelling self: Comparing self and other in narratives of past and future events. Consciousness & Cognition 22: 742–755. https://doi.org/10.1016/j.concog.2013.04.010 .

Hassabis, D., D. Kumaran, S.D. Vann, and E.A. Maguire. 2007. Patients with hippocampal amnesia cannot imagine new experiences. Proceedings of the National Academy of Sciences of the United States of America 104: 1726–1731. https://doi.org/10.1073/pnas.0610561104 .

Hassabis, D., and E.A. Maguire. 2007. Deconstructing episodic memory with construction. Trends in Cognitive Sciences 11: 299–306.

Hasson, U., J. Chen, and C.J. Honey. 2015. Hierarchical process memory: Memory as an integral component of information processing. Trends in Cognitive Sciences 19: 304–313. https://doi.org/10.1016/j.tics.2015.04.006 .

Hebb, D.O. 1949. The organization of behavior: A neuropsychological theory . Oxford: Wiley.

Holyoak, K.J. 2012. Analogy and relational reasoning. In The Oxford handbook of thinking and reasoning , ed. K.J. Holyoak and R.G. Morrison, 234–259. New York, N.Y: Oxford University Press. https://doi.org/10.1093/oxfordhb/9780199734689.013.0013 .

Horner, A.J., and N. Burgess. 2013. The associative structure of memory for multi-element events. Journal of Experimental Psychology: General 142: 1370–1383. https://doi.org/10.1037/a0033626 .

Hummel, J.E., and K.J. Holyoak. 2003. A symbolic-connectionist theory of relational inference and generalization. Psychological Review 110: 220–263. https://doi.org/10.1037/0033-295x.110.2.220 .

Irish, M., D.R. Addis, J. Hodges, and O. Piguet. 2012a. Considering the role of semantic memory in episodic future thinking: Evidence from semantic dementia. Brain 135: 2178–2191. https://doi.org/10.1093/brain/aws119 .

Irish, M., D.R. Addis, J. Hodges, and O. Piguet. 2012b. Exploring the content and quality of episodic future thinking simulations in semantic dementia. Neuropsychologia 50: 3488–3495. https://doi.org/10.1016/j.neuropsychologia.2012.09.012 .

Irish, M., and O. Piguet. 2013. The pivotal role of semantic memory in remembering the past and imagining the future. Frontiers in Behavioral Neuroscience 7: 27. https://doi.org/10.3389/fnbeh.2013.00027 .

Isomura, T., T. Parr, and K. Friston. 2019. Bayesian filtering with multiple internal models: Toward a theory of social intelligence. Neural Computation 31: 2390–2431. https://doi.org/10.1162/neco_a_01239 .

Johnson, M.K., S. Hashtroudi, and D.S. Lindsay. 1993. Source monitoring. Psychological Bulletin 114: 3–28. https://doi.org/10.1037/0033-2909.114.1.3 .

Johnson, M.K., and C.L. Raye. 1981. Reality monitoring. Psychological Review 88: 67–85. https://doi.org/10.1037/0033-295X.88.1.67 .

Kensinger, E.A., R.J. Garoff-Eaton, and D.L. Schacter. 2007. Effects of emotion on memory specificity: Memory trade-offs elicited by negative visually arousing stimuli. Journal of Memory and Language 56: 575–591. https://doi.org/10.1016/j.jml.2006.05.004 .

Levine, B., E. Svoboda, J.F. Hay, G. Winocur, and M. Moscovitch. 2002. Aging and autobiographical memory: Dissociating episodic from semantic retrieval. Psychology and Aging 17: 677–689. https://doi.org/10.1037/0882-7974.17.4.677 .

Mahr, J., and G. Csibra. 2018. Why do we remember? The communicative function of episodic memory. Behavioral and Brain Sciences 41: e1. https://doi.org/10.1017/S0140525X17000012 .

Mar, R.A. 2004. The neuropsychology of narrative: Story comprehension, story production and their interrelation. Neuropsychologia 42: 1414–1434. https://doi.org/10.1016/j.neuropsychologia.2003.12.016 .

McIntosh, A.R. 2007. Coding and representation: The importance of mesoscale dynamics. In Science of memory concepts , ed. H.L. Roediger, Y. Dudai, and S.M. Fitzpatrick, 65–68. New York, NY: Oxford University Press. https://doi.org/10.1093/acprof:oso/9780195310443.003.0004 .

Menon, V., and L.Q. Uddin. 2010. Saliency, switching, attention and control: A network model of insula function. Brain Structure & Function 214: 655–667. https://doi.org/10.1007/s00429-010-0262-0 .

Michaelian, K. 2011. Generative memory. Philosophical Psychology 24: 323–342. https://doi.org/10.1080/09515089.2011.559623 .

Michaelian, K. 2016a. Against discontinuism: Mental time travel and our knowledge of past and future events. In Seeing the future: Theoretical perspectives on future-oriented mental time travel , ed. K. Michaelian, S.B. Klein, and K.K. Szpunar, 62–92. Oxford: Oxford University Press. https://doi.org/10.1093/acprof:oso/9780190241537.003.0004 .

Michaelian, K. 2016b. Confabulating, misremembering, relearning: The simulation theory of memory and unsuccessful remembering. Frontiers in Psychology 7: 1857. https://doi.org/10.3389/fpsyg.2016.01857 .

Misra, P., A. Marconi, M. Peterson, and G. Kreiman. 2018. Minimal memory for details in real life events. Scientific Reports 8: 16701. https://doi.org/10.1038/s41598-018-33792-2 .

Neisser, U. 1976. Cognition and reality: Principles and implications of cognitive psychology . New York, NY: W H Freeman/Times Books/ Henry Holt & Co..

O'Keefe, J., and L. Nadel. 1978. The hippocampus as a cognitive map . Oxford: Clarendon Press.

Okuda, J., T. Fujii, H. Ohtake, T. Tsukiura, K. Tanji, K. Suzuki, R. Kawashima, H. Fukuda, M. Itoh, and A. Yamadori. 2003. Thinking of the future and the past: The roles of the frontal pole and the medial temporal lobes. Neuroimage 19: 1369–1380. https://doi.org/10.1016/S1053-8119(03)00179-4 .

Peer, M., Y. Ron, R. Monsa, and S. Arzy. 2019. Processing of different spatial scales in the human brain. eLife 8: e47492. https://doi.org/10.7554/eLife.47492 .

Perrin, D. 2016. Asymmetries in subjective time. In Seeing the future: Theoretical perspectives on future-oriented mental time travel , ed. K. Michaelian, S.B. Klein, and K.K. Szpunar, 39–61. New York, NY: Oxford University Press. https://doi.org/10.1093/acprof:oso/9780190241537.003.0003 .

Perrin, D., and K. Michaelian. 2017. Memory as mental time travel. In The Routledge handbook of philosophy of memory , ed. S. Bernecker and K. Michaelian, 228–240. London: Routledge.

Rasmussen, A.S., and D. Berntsen. 2013. The reality of the past versus the ideality of the future: Emotional valence and functional differences between past and future mental time travel. Memory & Cognition 41: 187–200. https://doi.org/10.3758/s13421-012-0260-y .

Richardson, A. 2012. Defaulting to fiction: Neuroscience rediscovers the romantic imagination. Poetics Today 32 (4): 663–692. https://doi.org/10.1215/03335372-1459845 .

Roberts, R.P., and D.R. Addis. 2018. A common mode of processing governing divergent thinking and future imagination. In The Cambridge handbook of the neuroscience of creativity , ed. R.E. Jung and O. Vartanian, 211–230. Cambridge: Cambridge University Press. https://doi.org/10.1017/9781316556238.013 .

Roberts, R.P., D.L. Schacter, and D.R. Addis. 2017a. Scene construction and relational processing: Separable constructs? Cerebral Cortex . https://doi.org/10.1093/cercor/bhx081 .

Roberts, R.P., K. Wiebels, R.L. Sumner, V. van Mulukom, C.L. Grady, D.L. Schacter, and D.R. Addis. 2017b. An fMRI investigation of the relationship between future imagination and cognitive flexibility. Neuropsychologia 95: 156–172. https://doi.org/10.1016/j.neuropsychologia.2016.11.019 .

Robins, S.K. 2016. Misremembering. Philosophical Psychology 29: 432–447. https://doi.org/10.1080/09515089.2015.1113245 .

Roediger, H.L., Y. Dudai, and S.M. Fitzpatrick, eds. 2007. Science of memory concepts . New York, NY: Oxford University Press. https://doi.org/10.1093/acprof:oso/9780195310443.001.0001 .

Book   Google Scholar  

Rubin, D.C., and S. Umanath. 2015. Event memory: A theory of memory for laboratory, autobiographical, and fictional events. Psychological Review 122: 1–23. https://doi.org/10.1037/a0037907 .

Rumelhart, D.E., and A. Ortony. 1977. The representation of knowledge in memory. In Schooling and the acquisition of knowledge , ed. R.C. Anderson, R.J. Spiro, and W.E. Montague, 99–135. Hillsdale, N.J: Erlbaum.

Schacter, D.L., and D.R. Addis. 2007. The cognitive neuroscience of constructive memory: Remembering the past and imagining the future. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 362: 773–786. https://doi.org/10.1098/rstb.2007.2087 .

Schacter, D.L., D.R. Addis, and R.L. Buckner. 2007. The prospective brain: Remembering the past to imagine the future. Nature Reviews Neuroscience 8: 657–661. https://doi.org/10.1038/nrn2213 .

Schacter, D.L., K.A. Norman, and W. Koutstaal. 1998. The cognitive neuroscience of constructive memory. Annual Review of Psychology 49: 289–318. https://doi.org/10.1146/annurev.psych.49.1.289 .

Schacter, D.L., and E. Tulving. 1994. What are the memory systems of 1994? In Memory systems , ed. D.L. Schacter and E. Tulving, 1–38. Cambridge, MA: MIT Press.

Schank, R.C., and R.P. Abelson. 1977. Scripts, plans, goals and understanding: An inquiry into human knowledge structures . Oxford: Lawrence Erlbaum.

Scoboria, A., D.L. Jackson, J. Talarico, M. Hanczakowski, L. Wysman, and G. Mazzoni. 2014. The role of belief in occurrence within autobiographical memory. Journal of Experimental Psychology: General 143: 1242–1258. https://doi.org/10.1037/a0034110 .

Sheldon, S., and B. Levine. 2016. The role of the hippocampus in memory and mental construction. Annals of the New York Academy of Sciences 1369: 76–92. https://doi.org/10.1111/nyas.13006 .

Sheldon, S., M.P. McAndrews, and M. Moscovitch. 2011. Episodic memory processes mediated by the medial temporal lobes contribute to open-ended problem solving. Neuropsychologia 49: 2439–2447. https://doi.org/10.1016/j.neuropsychologia.2011.04.021 .

Shine, J.M., P.G. Bissett, P.T. Bell, O. Koyejo, J.H. Balsters, K.J. Gorgolewski, C.A. Moodie, and R.A. Poldrack. 2016. The dynamics of functional brain networks: Integrated network states during cognitive task performance. Neuron 92: 544–554. https://doi.org/10.1016/j.neuron.2016.09.018 .

Spreng, R.N., W.D. Stevens, J.P. Chamberlain, A.W. Gilmore, and D.L. Schacter. 2010. Default network activity, coupled with the frontoparietal control network, supports goal-directed cognition. Neuroimage 53: 303–317 10.1016%2Fj.neuroimage.2010.06.016.

Squire, L.R., E.T. Rolls, M.K. Johnson, and R.L. Buckner. 2007. Memory systems. In Science of memory: Concepts , ed. H.L. Roediger, Y. Dudai, and S.M. Fitzpatrick, 338–364. New York: Oxford University Press. https://doi.org/10.1093/acprof:oso/9780195310443.003.0016 .

Squire, L.R., A.S. van der Horst, S.G.R. McDuff, J.C. Frascino, R.O. Hopkinse, and K.N. Mauldin. 2010. Role of the hippocampus in remembering the past and imagining the future. Proceedings of the National Academy of Sciences of the United States of America 107: 19044–19048. https://doi.org/10.1073/pnas.1014391107 .

Szpunar, K.K., J.C.K. Chan, and K.B. McDermott. 2009. Contextual processing in episodic future thought. Cerebral Cortex 19: 1539–1548. https://doi.org/10.1093/cercor/bhn191 .

Szpunar, K.K., J.M. Watson, and K.B. McDermott. 2007. Neural substrates of envisioning the future. Proceedings of the National Academy of Sciences of the United States of America 104 : 642–647. https://doi.org/10.1073/pnas.0610082104 .

Taylor, S.E., and S.K. Schneider. 1989. Coping and the simulation of events. Social Cognition 7: 174–194. https://doi.org/10.1521/soco.1989.7.2.174 .

Tolman, E.C. 1948. Cognitive maps in rats and men. Psychological Review 55: 189–208. https://doi.org/10.1037/h0061626 .

Tulving, E. 1972. Episodic and semantic memory. In Organization of Memory , ed. E. Tulving and W. Donaldson, 381–403. New York: Academic Press.

Tulving, E. 1985. Memory and consciousness. Canadian Psychologist 25: 1–12. https://doi.org/10.1037/h0080017 .

Urmson, J.O. 1967. Memory and imagination. Mind 76 (301): 83–91.

van Mulukom, V., D.L. Schacter, M.C. Corballis, and D.R. Addis. 2013. Re-imagining the future: Repetition decreases hippocampal involvement in future simulation. PLoS One 8: e69596. https://doi.org/10.1371/journal.pone.0069596 .

Verfaellie, M., A.A. Wank, A.G. Reid, E. Race, and M.M. Keane. 2019. Self-related processing and future thinking: Distinct contributions of ventromedial prefrontal cortex and the medial temporal lobes. Cortex 115: 159–171. https://doi.org/10.1016/j.cortex.2019.01.028 .

Webb, C.E., I.C. Turney, and N.A. Dennis. 2016. What's the gist? The influence of schemas on the neural correlates underlying true and false memories. Neuropsychologia 93: 61–75. https://doi.org/10.1016/j.neuropsychologia.2016.09.023 .

Weiler, J.A., B. Suchan, and I. Daum. 2010. Foreseeing the future: Occurrence probability of imagined future events modulates hippocampal activation. Hippocampus 20: 685–690. https://doi.org/10.1002/hipo.20695 .

Wiebels, K., D.R. Addis, D. Moreau, V. van Mulukom, K.E. Onderdijk, and R.P. Roberts. 2020. Relational processing demands and the role of spatial context in the construction of episodic future simulation. Journal of Experimental Psychology: Learning, Memory, and Cognition . Advance online publication. https://doi.org/10.1037/xlm0000831 .

Zacks, J.M., N.K. Speer, K.M. Swallow, T.S. Braver, and J.R. Reynolds. 2007. Event perception: A mind/brain perspective. Psychological Bulletin 133: 273–293. https://doi.org/10.1037/0033-2909.133.2.273 .

Zacks, J.M., and B. Tversky. 2001. Event structure in perception and conception. Psychological Bulletin 127: 3–21. https://doi.org/10.1037/0033-2909.127.1.3 .

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Acknowledgements

I gratefully acknowledge the editors of this Special Issue who also organized the Otago Mental Time Travel Symposium that served as inspiration for the paper, and the comments of anonymous reviewers. This work was supported thanks to funding from the Canada 150 Research Chairs Program.

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Addis, D.R. Mental Time Travel? A Neurocognitive Model of Event Simulation. Rev.Phil.Psych. 11 , 233–259 (2020). https://doi.org/10.1007/s13164-020-00470-0

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HYPOTHESIS AND THEORY article

The complex role of mental time travel in depressive and anxiety disorders: an ensemble perspective.

• Department of Psychology, Saint Louis University, St. Louis, MO, United States

The ensemble hypothesis proposes that uniquely human cognitive abilities depend on more than just language. Besides overt language, inner speech, and causal interpretations, executive attention, mental time travel, and theory of mind abilities are essential parts that combine additively and even multiplicatively. In this review, we consider the implications of the ensemble hypothesis for the psychopathologies of anxiety and depression. Generalized anxiety disorder (GAD) and major depressive disorder (MDD) are two of the most common mental disorders worldwide. The mechanisms that differentiate them are difficult to identify, however. Mental time travel has been implicated in models of depressive and anxiety disorders, but here we argue that at least two other ensemble components, namely, interpreter biases and executive attention, must also be considered. Depressive and anxiety disorders have both been found to show impairments in all three of these components, but the precise relationships seem to distinguish the two kinds of disorders. In reviewing the literature, we develop models for depression and anxiety that take into account an ensemble of mental components that are unique for each disorder. We specify how the relations among mental time travel, interpreter biases, and executive attentional control differ in depression and anxiety. We conclude by considering the implications of these models for treating and conceptualizing anxiety and depression.

Introduction

Depressive and anxiety disorders are two major categories of psychopathology, yet they have proven difficult to differentiate in some respects. As will be documented below, both are characterized by dysfunctional executive attention and pessimistic attributional styles, with a high degree of comorbidity. Here we build on the premise of Roepke and Seligman (2016) that the core problem in depression is a difficulty in mental time travel, specifically, an inability to envision positive events in the future. We consider the role of mental time travel in differentiating the two disorders and conclude that this component of human cognition is by itself insufficient. Mental time travel, we suggest, is moderated by problems with executive attention and an interpretive component responsible for causal attributions and inner speech.

In an important paper, Roepke and Seligman (2016) argued that prospection, or the mental representation of future events, plays a major role in depression. Human episodic memory enables mental time travel, that is to say, the ability both to recall past autobiographical events and to imagine possible future events ( Tulving, 2002 ). Roepke and Seligman suggested that the negative beliefs about the future and feelings of hopelessness that characterize depressive disorders ( Beck, 1974 ) can be directly linked to faulty prospection, an inability to envision possible futures and poor evaluation of possible futures. In their view, “.faulty prospection is the core causal process of much depression” (p. 24). A similar proposal was advanced by Miloyan et al. (2014) to account for depression; they also extended the analysis by suggesting that a different form of faulty prospection, centered on worry rather than pessimism and hopelessness, lay at the core of anxiety disorders.

We agree that problems with mental time travel are central to psychopathology, but we question whether this component can be isolated from other cognitive components to ascertain its relative contribution. Instead, we argue that other fundamental components of human cognition are concurrently at work in both depressive and anxiety disorders. In our view, it is important to consider how other components impair or even enhance the functioning of mental time travel. To develop this perspective, we draw on the ensemble hypothesis, which holds that human cognition depends on five core systems or components that interact in non-additive ways ( Kellogg, 2013 ; Kellogg and Evans, 2019 ). Mental time travel is necessary but not sufficient for explaining either the remarkable competencies of human cognition or its breakdowns in disorders such as anxiety and depression. An advanced executive form of working memory, a theory of mind augmenting social cognition, language, the ability to interpret information using inner speech, and causal inference are necessary, as well as an episodic memory capable of mental time travel. Kellogg (2013) introduced the ensemble hypothesis in the context of understanding the exceptional cognitive abilities in the evolution of our species, Homo sapiens . The book provides the reasons for considering the five components and their interactions in normally developing and functioning human beings. Kellogg and Evans (2019) offered further evidence in support of the hypothesis from behavioral studies, lesion studies, and studies involving neuro-atypical populations.

The key claim of the ensemble hypothesis is that two or more mental capacities can interact in a multiplicative fashion to yield competencies in a well-functioning human being that exceed their simple additive effects. For example, delay of gratification is a phenomenon that entails an ability both to prospectively consider the future and to exercise cognitive control using executive attention. In typically developing children, growth in the capacity of executive attention for self-regulation boosts the ability to delay rewards in anticipation of a larger future reward ( Mischel et al., 1989 ). Similarly, planning in problem solving requires future thinking and a normally functioning system of executive attention. Frontal lobe injuries that damage networks of executive attention often impair planning ( Kellogg and Evans, 2019 ). In normally functioning adults, retrospective memory for a list of words presented in a laboratory task requires an intact hippocampus and medial temporal lobe, but it is also boosted by maintenance and elaborative rehearsal strategies that depend on executive attention. Failing to deploy attentional resources to an encoding strategy impairs the recall of a list of words presented in a laboratory task in individuals with depression ( Hertel and Rude, 1991 ). As will be considered in detail later, the normal functioning of mental time travel can be altered by depression because of its effects, in part, on executive attention.

The purpose of the present paper is to consider the implications of the ensemble hypothesis for two broad categories of psychopathology: depression and anxiety. We suggest that much of the phenomenology and symptoms that underlie depressive and anxiety disorders can best be understood as an interaction of components of the hypothesized ensemble. We wish to extend the insights provided by Miloyan et al. (2014) and Roepke and Seligman (2016) by demonstrating how the interpreter and executive attention influence mental time travel. As will be seen, language is considered in the form of inner speech, but the broader concept of language as interpersonal communication falls outside the scope of the current paper. Similarly, as will be addressed in the limitation section of our paper, an extensive literature on theory of mind and social cognition in depression ultimately needs to be accounted for. Even so, our focus on the interpreter, executive attention, and mental time travel documents the importance of the interactions posited by the ensemble hypothesis.

To illustrate, consider the case of depression (see Figure 1 ), as exemplified by major depressive disorder (MDD). As will be discussed in detail later, the interpreter shown in Figure 1 refers to the inner voice and causal inference capacity of the left hemisphere of the human brain that enables attributions about the self and other people ( Gazzaniga, 2000 ; Kellogg, 2013 ). In depression, the interpreter is biased to assign blame to the self for negative experiences. This pessimistic and personally negative explanatory style ( Petersen and Seligman, 1984 ) causes the depressed individual to focus attention on negative past events and have difficulty envisioning anything positive about the future. Further, there is evidence that depression is associated with a concurrent deficit in executive attention ( Ólafsson et al., 2011 ), causing impaired cognitive control over mental time travel resulting in persistent negative rumination. Thus, the influence of both a bias in interpretation and a deficit in executive attention, we propose, could underlie faulty prospection in depressed individuals. The interactive model of Figure 1 differs from the position of Roepke and Seligman (2016) with respect to effective approaches to treatment for depression. They advocate for treatments targeting mental time travel, specifically, the core problem with prospection. Alternately, we contend that efforts to improve executive attention and to correct the pessimistic explanatory style of the interpreter ought not be neglected, because they can alter the functioning of mental time travel.

Figure 1. Model of major depressive disorder.

The plan of the paper is, first, to introduce several components of the ensemble hypothesis that are central to our analysis of depressive and anxiety disorders. Second, we consider evidence on the role of mental time travel in depressive and anxiety disorders. Third, we discuss literature regarding the pessimistic explanatory style in depression and suggest that anxious individuals are characterized by a related but distinct dysfunctional style of explaining events as threatening to the self. The emphasis on loss in depression and threats in anxiety can influence the functioning of mental time travel, we propose. Fourth, we document that both kinds of disorders are associated with impairments in executive attention that may compound problems with mental time travel. Fifth, we discuss how the symptoms of depression versus anxiety can best be understood by considering mental time travel, the interpreter, and executive attention as an integrated ensemble. We conclude by considering the implications of the ensemble perspective regarding effective therapies for depressive and anxiety disorders.

Mental Time Travel, the Interpreter, and Executive Attention

Mental time travel is the unusual form of human episodic memory that allows the mind to recollect the specific time and place of a past event in one’s personal history ( Tulving, 2002 ; Suddendorf and Corballis, 2007 ). It is conceived as mental time travel because the same neural systems are involved in imagining future events as well as recollecting past events. The brain systems involved in mental time travel include the hippocampus and medial temporal lobe structures as well as the default mode network activated in resting state conditions when no external task is presented ( Buckner et al., 2008 ). The ability to construct spatially coherent scenes in which an event takes place is essential in both recollecting the past and imagining the future. It has been suggested that scene construction is a core function of the hippocampus ( Clark and Maguire, 2016 ).

A uniquely human mental ability appears to be the interpretive capacity of the left hemisphere ( Gazzaniga, 2000 ). Over the course of human evolution, our oral language capacity became internalized as inner speech, mediated by language networks in the left hemisphere. Vygotsky (1962) emphasized that speech begins in early childhood as a means for communication, but as speech is internalized, it also becomes a means for planning and problem solving. Self-directed inner speech, then, has long been recognized as an important vehicle for thinking and appraising situations and events. The interpreter constructs a personal narrative that explains why we feel and behave as we do. Inner speech is combined with a specialization of the left hemisphere for a specific kind of thinking. The left hemisphere is not only specialized for the use of language, including self-directed language of inner speech, but it is also specialized for forming hypotheses ( Wolford et al., 2000 ) and making inferences about causal relationships ( Roser et al., 2005 ). Similarly, the ability to reason deductively is known to be impaired in patients with left frontal lesions but not right frontal lesions ( Reverberi et al., 2010 ).

In clinical psychology, the interpreter is important in understanding the role of inner speech and causal inference in how people respond to stressful life events. How an individual cognitively appraises stressors can either attenuate or exacerbate the strain that they cause. This role for causal attributions has long been recognized in understanding depressive and anxiety disorders. For example, Petersen and Seligman (1984) highlighted that depression is characterized by a personalized and pessimistic explanatory style. The individual attributes personal, pervasive, and permanent causes to negative personal experiences, committing what social psychologists call the fundamental attribution error. The role played by the interpreter in explaining why things happen and what significance events have for the self is central to both depression and anxiety, as will be detailed later in the paper.

The executive attention component of working memory enables the coordination and regulation of representations held in verbal, visual, and spatial stores of short-term memory. Working memory, planning, cognitive control, self-regulation, and response inhibition have all been referred to as executive functions that have traditionally been viewed as dependent on the frontal lobe ( Alvarez and Emory, 2006 ; Posner and Rothbart, 2007 ; Diamond, 2013 ; Ajilchi and Nejati, 2017 ). A more complex understanding has emerged in the literature with two distinct brain networks involved in executive attention; these include but are not limited to regions in the frontal lobe ( Posner and Peterson, 1990 ; Petersen and Posner, 2012 ).

By studying a battery of executive functioning tasks, Miyake et al. (2000) identified three correlated but distinctive processes underlying performance. Updating the contents of working memory, shifting goals as required in multitasking, and inhibiting irrelevant information are considered three essential and irreducible functions of executive attention. A widely used test of individual differences in working memory capacity, called the Operation Span (OSPAN) test, indicates that the ability to inhibit irrelevant information is especially important and shows a strong correlation with general fluid intelligence or the ability to solve novel problems ( Engle et al., 1999 ).

Mental time travel, the interpreter, and executive attention are three fundamental components of human cognition. Kellogg (2013) proposed that these components, together with theory of mind and language, comprise an ensemble that renders human cognition unique and qualitatively different from non-human cognition. Importantly, his hypothesis suggests that it is the interaction of these components that yields the unique properties of human cognition. If that is so, then it stands to reason that common forms of psychopathology should reveal such interactions, too. In persons experiencing anxiety or depression, a deficit in one component can cascade to degrade the functioning of another component, despite that the latter component is not necessarily dysfunctional.

Mental Time Travel Impairments

Roepke and Seligman (2016) reviewed a variety of evidence that faulty prospection lies at the heart of depression. First, persons experiencing depression can envision negative future scenarios more readily, compared to non-depressed persons ( MacLeod and Byrne, 1996 ). This characteristic is also shared with those experiencing anxiety, indicating it is not a unique dysfunction of mental time travel associated with depression. Miloyan et al. (2014) suggested that anxious as well as depressed individuals anticipate negative future events but that each disorder shows a unique profile of faulty prospection. Individuals with anxiety anticipate more negative experiences, but not fewer positive experiences, relative to control participants without a history of psychiatric diagnosis, according to some studies ( MacLeod and Byrne, 1996 ; MacLeod et al., 1997b ). Depression, on the other hand, is associated with a failure to anticipate positive future events ( Miranda and Mennin, 2006 ; Pomerantz and Rose, 2014 ). When depressed psychiatric outpatients were asked to describe a distressing personal problem and to imagine and rate the likelihood of both the worst and best possible outcomes, they rated the worst outcome as being more likely and the best outcome as being less likely, relative to generalized anxiety disorder (GAD) and control groups ( Beck et al., 2006 ).

Thus, it is possible that a faulty form of prospection found in depression results in a diminished ability to envision positive future events ( MacLeod and Salaminiou, 2001 ). However, both this finding and the finding that individuals with depression envision more negative future events than do controls can also be linked to a pessimistic explanatory style. MacLeod et al. (1997a) found that both depressed and anxious patients not only judged future negative events to be more likely, relative to controls; they also provided more supportive as opposed to contradictory reasons for their occurrence. As MacLeod et al. (p. 22) concluded, “…mood-disturbed subjects were pessimistic about what would happen to them in the future, and this was supported by their causal thinking about those events.” Thus, the pessimistic explanatory style of the interpreter rather than a malfunction in mental time travel per se could explain the findings. They could also be linked to the deficits in executive attention that are associated with depression ( Ólafsson et al., 2011 ). As will be argued in later sections of the paper, problems with mental time travel may arise because of the moderating influences of the interpreter and executive attention.

An important exception regarding memory impairment in depression is the tendency to focus and elaborate upon sad events ( Williams et al., 1997 ). A case can be made for mood congruent memory in depression ( Mineka and Nugent, 1995 ). For example, in a study by Derry and Kuiper (1981) , a list of depression-related adjectives (e.g., bleak, dismal, helpless) and non-depression-related adjectives (e.g., amiable, curious, loyal) were presented in an incidental learning task. The nature of the orienting task was manipulated, with one way being whether the adjective applied to the self. On a subsequent recall test, this self-reference orienting task resulted in a greater proportion of depressed-content words recalled (41%) than non-depressed content (16%) for depressed patients. Strikingly, this pattern was completely reversed for normal controls, who recalled more non-depressed content (43%) compared with depressed content (8%). Even a group of psychiatric controls showed a reversal with more non-depressed content (36%) relative to depressed content (18%). None of these effects were observed for structural (small letters?) and semantic (means the same?) orienting tasks, indicating that they are contingent on judging the word as relevant to the self.

Similarly, in another study, after being shown a list of words including pleasant, unpleasant, and neutral words, individuals with depression recalled more unpleasant words compared with pleasant words ( McDowall, 1984 ). A non-depressed control group as well as another control group made up of psychiatric patients with a diagnosis other than depression did not show this bias toward improved memory for unpleasant words. The depressed patients’ free recall of unpleasant words was at the same level as that for the two control groups, whereas they showed a memory impairment for pleasant words. This indicates that the mood congruent benefit of remembering unpleasant words can offset the usual memory impairment found in depression.

Clark and Teasdale (1982) found that autobiographical experiences also reveal mood congruency even within the same group of individuals with depression. The investigators compared the recall of personal memories at two different times of day to capitalize on diurnal variations in mood among psychiatric patients experiencing depression. The percentage of unhappy memories (52.3%) was reliably greater when the individual reported being more depressed compared with less depressed (36.7%). Happy memories (37.7 versus 51.1%) showed exactly the reverse pattern.

The above studies show that depression can bias retrospection in the direction of remembering sad events more readily than happy events. Would such findings also hold for prospection? MacLeod et al. (1997b) measured the recall of past experiences and the anticipation of future experiences in anxious, depressed, and control individuals. The study prompted the participants to remember or anticipate either positive experiences or negative experiences. This prompt variable allowed the comparison of the number of positive events versus negative events produced under conditions of both retrospection and prospection. Their findings showed no difference between the retrospection and prospection conditions for either disorder. Of importance, individuals with depression produced fewer events compared with controls—both positive and negative—both in recalling their past and in anticipating their future.

An analogous outcome has been found in laboratory studies of the retrospective recall of word lists versus prospective memory for future actions. Hertel and Rude (1991) found poorer free recall of a list of words presented earlier for currently depressed patients compared with recovered patients and control individuals with no history of depression in a retrospective task. Rude et al. (1999) similarly reported that depressed individuals perform poorly on a prospective memory task requiring the ability to self-initiate an action in the future. Their difficulties with “remembering to remember” to act in the future were parallel to impairments found in retrospective tasks, according to the authors. Of course, these tasks are different from the autobiographical reports examined by MacLeod et al., but the conclusions reached are consistent. MacLeod et al. (1997a) also found that anxious individuals did not differ from controls either in remembering or in anticipating positive events. However, they generated more negative events compared with controls regardless of whether they were engaged in retrospection or prospection. Their findings thus confirm that anxiety is primarily a disorder of worrying about negative outcomes ( Barlow, 1988 ). Whereas MacLeod et al.’s control participants both recalled and anticipated about 44% more positive life events than negative ones, the anxious participants only recalled 15% more positive events. Compared to participants with depression, the participants with anxiety recalled and anticipated about 67% more negative events.

Finally, MacLeod et al. expected that individuals with depression would show a mood congruent effect by remembering or anticipating more negative events compared with positive events. In contrast to prior studies reviewed earlier, this outcome did not occur. Rather, negative events were remembered by patients with depression at about the same rate as found in the controls. This rate was equivalent to the number of positive events remembered by those with depression, who were 75% less likely to remember positive events than were patients with anxiety and controls. This is reminiscent of the findings with the free recall of word lists reported by McDowall (1984) . Unpleasant words were remembered as well by patients with depression as by controls, but recall for pleasant words showed a marked impairment.

The above findings on memory could depend on the severity of the depressive disorder. It is important to note in that regard that MacLeod et al. (1997b) examined patients who met the diagnostic criteria for panic disorder and MDD. Similarly, the studies by Derry and Kuiper (1981) , Clark and Teasdale (1982) , McDowall (1984) , Hertel and Rude (1991) , and Rude et al. (1999) examined psychiatric inpatients or patients with depression in the community with screening done to insure they met the diagnostic criterion for depression. By contrast, in a non-clinical student population, neither trait anxiety nor trait depression was associated with difficulties in a measure of prospective memory ( Arnold et al., 2014 ). Thus, the severity of the disorder probably plays a role in the effects of depression and anxiety on mental time travel.

In contrast to the picture for clinical depression, the findings on retrospective memory for anxiety disorders are mixed. MacLeod and McLaughlin (1995) found that individuals currently receiving treatment for GAD performed worse than those in a control group on an explicit recognition test for words presented in a laboratory setting. By contrast, on explicit memory tests of cued recall ( Mathews et al., 1989 ) and free recall ( Becker et al., 1999 ), anxious individuals performed at the same level as control participants. For threatening words included among the lists presented in the laboratory, GAD patients showed no advantage in recall or recognition, but they did show superior performance on various implicit memory tests compared with controls ( Mathews et al., 1989 ; MacLeod and McLaughlin, 1995 ). A similar heightened explicit memory for threatening words was found by Becker et al. (1999) for individuals diagnosed with panic disorder but not with social phobia or GAD. In a review of the literature on memory and anxiety disorders, Mineka and Nugent (1995) concluded that the evidence for an explicit memory bias for threatening events is weak, difficult to replicate, and unconvincing, at least with respect to persons experiencing GAD.

We conclude from this sample of findings in the literature that while depression impairs mental time travel ability, it does not seem to be a selective difficulty with prospection. Judging from the findings of MacLeod et al. (1997a) , at least for positive events, anxious individuals do not appear to show any impairment in mental time travel, either in its prospective or in its retrospective form. In fact, they appear to recollect past negative events and envision future negative events more often than is found in both non-anxious controls and depressed patients. However, other studies indicate that such memory bias for threatening events is tenuous at best in anxiety. Patients with depression, on the other hand, forget positive events more readily than is found in non-depressed controls. A central question is what accounts for these differences in the functioning of the mental time travel component. We propose that considering the role played by the interpreter and executive attention helps to understand the pattern of results found for mental time travel.

Interpreter Biases

As noted earlier, the interpreter in individuals with depression employs a pessimistic explanatory style ( Petersen and Seligman, 1984 ). An inability to envision a positive future and a facility with envisioning a negative future could be understood as a dysfunction of the explanatory style found in individuals with depression rather than a fault with mental time travel per se ( MacLeod et al., 1997a ). A negative style of explaining why things happen as they do is a prime reason for feelings of hopelessness in depressed people ( Alloy et al., 1988 ). Individuals with depression tend to attribute the reasons for events in life to internalized causes about the self that are stable over time and that are global or pervasive in multiple situations. Another compounding factor is a negative attributional style that attributes negative events to uncontrollable causes ( Sanjuán and Magallares, 2009 ). As a consequence, persons with depression might be able to recollect or imagine an event that most people would regard as positive (e.g., getting a job promotion) but then interpret it as negative. Individuals with depression might appraise the promotion as full of pitfalls—more responsibility, longer working hours, and greater stress. Remembering or anticipating a job promotion may not be the problem but, rather, its pessimistic interpretation.

The interpreter, therefore, has a prominent, if not central, role in depression. Indeed, Beck (1974) designed cognitive behavioral therapy (CBT) to confront and modify a depressed person’s inner speech of hopelessness and self-deprecation. By altering the person’s cognitive appraisals of situations and causal explanations of events, mood improves as a result. Beck’s concept of the cognitive triad included a negative view of the self, negative interpretations of ongoing experiences, and a negative view of the future. Although the latter could be caused by faulty prospection, the first two stem from the distorted explanations of the interpreter.

Comparisons of the interpretative style of depressed versus anxious individuals have yielded conflicting results, however. For example, Heimberg et al. (1989) , by contrast, found that the attributional style found in the learned helplessness of individuals with depression was also characteristic of multiple anxiety disorders, such as social phobia, agoraphobia, and panic disorder. In their study, the two disorders differed only in that depression produced global and unstable attributions regarding the causes of positive events, whereas anxiety was associated with the same kind of attributions for negative events. Still other findings indicate that attributing internal, stable, and global causes to negative events is in fact found in currently depressed individuals, but especially in those with comorbid anxiety ( Fresco et al., 2006 ). Similarly, Luten et al. (1997) concluded that a pessimistic attributional style is not specific to depression but, rather, is correlated with high levels of negative affect as is also found in in persons with anxiety disorders. Ahrens and Haaga (1993) even reported that a negative event attributional style was only found with anxiety disorders rather than with depression.

Thus, it seems that pessimistic forms of causal inference about life’s events are a non-specific risk factor for anxiety and depression. This commonality with respect to the dysfunction of the interpreter is a likely reason why depressive and anxiety disorders share a high degree of comorbidity ( Gotlib, 1984 ; Kessler et al., 2007 ; Grisanzio et al., 2018 ).

Despite their similarities and high rates of comorbidity, there may be some unique aspects to the interpreter’s dysfunction in anxiety disorders, however. Riskind and Williams (2005) identified a looming cognitive style in which individuals overestimate the progression of a potential threat in terms of both spatial and temporal dimensions. Individuals with a high score on their looming cognitive scale misinterpret potential threats as catastrophic threats. A study by Reardon and Williams (2007) showed that this looming cognitive style is uniquely associated with anxiety disorders. A pessimistic cognitive style contributed to both anxiety disorders and depressive disorders, but individuals predisposed to anxiety disorders also were prone to a looming cognitive style that magnifies potential threats. Anxiety disorders also feature highly persistent negative self-talk. The excessive worry that characterizes anxiety is largely verbal in nature ( Borkovec et al., 1998 ). Instead of imagining a threat in a visual–spatial context, anxious individuals talk to themselves about it. Finally, it has long been recognized that the causal inferences made in depression are associated with personal failures and self-deprecation ( Beck, 1974 ). This contrasts with worries about uncertainties and potential dangers in the case of anxiety disorders ( Beck et al., 1987 ; Clark et al., 1990 ).

As shown in Figure 2 , the anxious interpreter views events as threatening to the self rather than as a negative reflection of the self as in depression ( Figure 1 ). Kendall and Ingram (1989) differentiated the two disorders precisely in terms of their characteristic attributions. The interpretations of the depressive person often are “self-referent, definitive, past-oriented cognitions of sadness, failure, degradation, and loss,” in contrast to the “future oriented ‘questioning’ cognitions” found in anxiety disorders ( Kendall and Ingram, 1989 ; p. 36).

Figure 2. Model of generalized anxiety disorder.

In our view, the interpreter biases play a role in the problems observed in mental time travel with depressed and anxious individuals ( Eysenck et al., 2006 ). For depression ( Figure 1 ), the pessimism of the interpreter causes individuals with depression to remember and ruminate about negative life experiences that reinforce feelings of loss and self-blame. Perhaps the difficulty with imagining a positive future is a direct consequence of depressed individuals focusing on negative past events. Roepke and Seligman (2016 , p. 27), in fact, suggest the possibility that persons experiencing depression “struggle to recall a good past,” with few positive memories ( Williams and Scott, 1988 ).

For GAD ( Figure 2 ), the interpreter is biased to detect threats to the self. This might cause one to recall, see, and foresee dangers rather than losses. Instead of mental time travel being impaired relative to control individuals who are neither depressed nor anxious, there is, if anything, an excessive prospection and retrospection of negative events. This outcome can be seen in the study by MacLeod et al. (1997b) , who reported that anxious individuals both retrospectively and prospectively generated more negative events than did controls and even individuals with depression. Similarly, when asked to recall recent life events, 77% of anxious participants remembered danger events compared to 44% of depressed participants ( Finlay-Jones and Brown, 1981 ). Loss events, on the other hand, were more frequently remembered by participants with depression (65%) compared with anxiety (15%). Comparable findings for autobiographical recall have been reported by Witheridge et al. (2010) .

Thus, in our view, the interpreter plays a key role in the functioning of the mental time travel component. The content of the events that are remembered in depression is more likely to deal with loss rather than danger. This, we suggest, occurs because of the bias of the interpreter on mental time travel. In anxiety disorders, retrospection is not impaired; if anything, there is excessive rather than impaired prospection and retrospection about threatening events. In addition to mental time travel being moderated by the interpreter, we further consider in the next section the possible influence of executive attention.

Executive Attention Deficits in Depression and Anxiety

A number of studies have shown that anxiety and depression are associated with impaired performance on a variety of neuropsychological tests that measure for executive control functions ( Reinholdt-Dunne et al., 2013 ; Devito et al., 2018 ). This supports the notion that both disorders are associated with impairments in executive attentional control. In this article, we refer to executive attention as executive attentional control and attentional control, interchangeably. In accordance with Stefanopoulou et al. (2014 , p. 330), attentional control can be defined as “the ability to sustain focus on tasks in the face of competing activities or to shift attention from one task to another.” However, depression and anxiety do not show the same pattern of executive attention deficits.

The Attentional Control Scale (ACS) is a self-reported attention control measure that is comprised of two components: focusing and shifting ( Reinholdt-Dunne et al., 2013 ). Ólafsson et al. (2011 , p.77) define attentional focusing as “the capacity to intentionally hold the attentional focus on desired channels and thereby resist unintentional shifting to irrelevant or distracting channels” and define attentional shifting as “the capacity to intentionally shift the attentional focus to desired channels, thereby avoiding unintentional focusing on particular channels.” Because it has been noted that those with anxiety show attentional impairment in relation to shifting and focusing ( Devito et al., 2018 ), the ACS has been used to compare the relationship between attentional focusing, attentional shifting, and levels of anxiety and depression in adults. Ólafsson et al. (2011) found that when controlled for depression, the focusing ACS subscale significantly predicted anxiety ratings, whereas when anxiety ratings were controlled for, the shifting subscale significantly predicted depression ratings. Reinholdt-Dunne et al. (2013) supported these findings when they found ACS focusing to be associated with lower anxiety and ACS shifting to be associated with fewer depression symptoms. These findings support the claim that anxiety is more associated with attentional focusing and depression is more associated with attentional shifting.

Shi et al. (2019) performed a meta-analysis to investigate the size and nature of attentional control deficits in participants with anxiety versus non-anxious participants. They found that anxiety-producing deficits were supported in processing efficiency, rather than effectiveness, on a variety of behavioral tasks. However, they also found that when looking at task switching studies alone, both efficiency and effectiveness produced anxiety-related deficits in attentional control. Their results also showed that studies requiring participants to operate under high cognitive load conditions showed greater anxiety-related attentional control deficits compared to studies where participants were under normal cognitive load conditions ( Shi et al., 2019 ).

Although attentional control deficits have been related to anxiety disorders, these deficits are prominently seen in individuals diagnosed with GAD, characterized by uncontrollable worry. This uncontrollable worry has been connected to deficits of the central executive function of working memory, which includes attentional control as a key component of working memory ( Stefanopoulou et al., 2014 ). Uncontrollable worrying can be attention-demanding and, consequently, consumes voluntary attentional resources required ( Eysenck et al., 2007 ). This links uncontrollable worry to impairments in attentional control.

Stefanopoulou et al. (2014) used the key-pressing task to assess the extent to which attentional resources were depleted by worry in individuals with GAD. Stefanopoulou et al. (2014) found that GAD individuals were less random on the key-pressing task while worrying compared to when thinking of a positive topic, indicating that fewer residual attentional control resources were available during the worrying process. However, the performance of the healthy participants did not differ between conditions. GAD participants also reported having more negative thoughts and anxiety during this task compared to healthy participants. This same study also used the N-back task, which “varies in difficulty and is sensitive to subtle difference in ability to handle increasing demands on attentional control” ( Stefanopoulou et al., 2014 , p. 330). During this task, GAD participants exhibited longer reaction times compared to healthy participants for the higher load conditions. These results together indicate a greater difficulty in sustaining focus in conditions requiring a higher degree of attentional control, suggesting that poor attentional control may partially explain the excessive worry seen in individuals with GAD.

Further, there appears to be a bidirectional relationship between attentional control and anxiety ( Devito et al., 2018 ). Impairments in attentional control may increase one’s risk for developing anxiety, and anxiety symptoms may prevent executive components of attention from being recruited. We indicate this bidirectional relationship between the interpreter and executive attention in Figure 2 . The pessimistic explanatory style and negative self-talk of the interpreter consume limited attentional resources. The resulting deficit in executive attention weakens the ability to inhibit the dysfunctional thinking of the interpreter in anxiety disorders.

Whether a similar bidirectional relationship occurs in depression is unclear. An argument against this takes into account the speech and inner speech of depressed versus anxious individuals based on the symptoms outlined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition ( DSM-V ). The hallmark of GAD is excessive worry in the form of inner speech. By contrast, in MDD, fatigue and tiredness occur on nearly a daily basis, and this can be accompanied by slowed speech, long pauses before responding, and a decrease in the amount and variety of speech content ( American Psychiatric Association, 2013 , p. 132). These suggest that inner speech in MDD is more likely to be inhibited or overly regulated rather than exaggerated, as is apparent in GAD. Moreover, in a review of the literature on inner speech, Alderson-Day and Fernyhough (2015) noted that the evidence for inner speech playing a central role in anxiety disorders is stronger and more specific than it is with depression. The verbalized worry of anxiety is, in their words (p. 948), “…repetitive thinking that is.negative, uncontrollable, and aimed at some ill-defined problem solving, such as a problem with a clear solution.” We propose that the bidirectional links between executive attention and the interpreter produce worry in GAD that is indeed out of control (see Figure 2 ). A positive feedback loop ensues in which worry depletes attention, which in turn worsens worry. In depression, the negative impact of depleting attention does not appear to feed back on the interpreter. Instead, we suggest, it feeds forward to impact mental time travel. Specifically, the deficit in executive attention found in depression results in a loss of control in mental time travel (see Figure 1 ). The arrows shown in Figures 1 , 2 are intended to reflect the major pathways of influence from one component to another. From the perspective of the ensemble hypothesis, all possible links among components are potentially relevant, including bidirectional relationships. In a normally developed and well-functioning adult human being, each of these components influences the others. Our aim in these figures is to take a minimalist approach by highlighting only strong interactions that differ from normal under a diagnosis of psychopathology. The purpose is to differentiate as clearly as possible how MDD and GAD differ from each other. For example, we intentionally omit an influence of executive attention on mental time travel in GAD. Although it is known that the availability of executive attention affects the functioning of mental time travel even in healthy individuals, we only indicate interactions that are unique to GAD or MDD.

Memory Impairment From an Ensemble Perspective

As shown in Figure 1 , we suggest that both retrospection and prospection will be impaired as a result of a deficit in executive attention ( Hertel and Rude, 1991 ; Rude et al., 1999 ). Evidence for a causal role played by attention comes from an intervention designed by Hertel and Rude (1991) to remediate the attentional deficits. Hertel and Rude studied three groups of individuals who were currently depressed, recovered from depression, or without a history of depression in an incidental learning and memory task. The participants’ ability to recall a list of target words that they had viewed in the first phase of the experiment was markedly impaired in the individuals with depression compared with recovered and healthy controls. But this outcome only occurred when their attention to the words during learning was unconstrained by the demands of the task. For half of the participants, the investigators required the participants to repeat the target words aloud on each trial, as a means of focusing their attention. Strikingly, this manipulation eliminated the memory impairment of the depressed patients entirely. This result suggests that retrospection per se is not necessarily deficient in depression, but a memory deficit can be observed as a result of the influence of executive attention not being appropriately allocated to the task at hand.

A comparable finding was reported by McDowall (1984) . On a free recall test, inpatients with depression performed markedly worse than did a control group consisting of non-depressed psychiatric inpatients in remembering pleasant words. However, when given an orienting task of rating each word for pleasantness as was shown during the study phase, patients with depression showed no difference in recall between pleasant and unpleasant words and performed no worse than did the psychiatric control group doing the same task. Their mean recall of 5.6 words out of 12 was only slightly less than was found for a non-psychiatric control group (6.8 words), again with no difference between pleasant versus unpleasant words. As with the word repetition technique used by Hertel and Rude (1991) , the orienting task directed attention to the words in a way that eliminated most, if not all, of the memory impairment for individuals with depression.

Ruminating on negative life experiences is part and parcel of the sense of loss, hopelessness, and self-deprecation frequently seen in persons experiencing depression. In our view, these phenomena are the direct result of the interpreter bias found in depression. It is the influence of the interpreter with mental time travel that contributes to the inability of individuals with depression to think about positive life experiences, whether they lie in the past, the present, or the future. Further, the persistence and intrusiveness of negative memories in depression could reflect an inability to inhibit them because of executive attention deficits (see Figure 1 ). Poor cognitive control may combine with the loss bias of the interpreter to produce the profile of memory problems found in depression.

As shown in Figure 2 , for GAD, the mental time travel system is biased to focus on the uncertainties and threats of life experiences. Instead of loss and self-blame, the content of memories predominately concerns threats to the self in anxiety disorders to the extent that they are biased at all. This can account for why negative events are, at times, better remembered or anticipated by anxious individuals (e.g., MacLeod et al., 1997b ). However, in contrast to the memory bias effects for losses observed in depression, similar effects for threatening events in anxiety disorders are harder to detect reliably ( Mineka and Nugent, 1995 ). They might be found in panic disorder but not GAD ( Becker et al., 1999 ). Or they can be observed with implicit memory tests but not explicit tests of recall or recognition ( Mathews et al., 1989 ; MacLeod and McLaughlin, 1995 ). They might also be observed when people are asked to recall autobiographical events of personal relevance ( Finlay-Jones and Brown, 1981 ; Witheridge et al., 2010 ) but not when they are asked to remember word lists that contain some threatening versus neutral words ( Levy and Mineka, 1998 ).

We suggest that the mixed picture for memory bias in anxiety disorders occurs because executive attention deficits do not generally disrupt mental time travel in persons experiencing GAD, which is not the case for MDD (see Figure 2 ). The deficit in executive attention causes a loss of control with the interpreter but not with mental time travel. Without both a loss of cognitive control and a threat bias from the interpreter, the mental time travel system functions relatively normally in GAD. That implicit tests of memory reveal bias effects for negative information implies that a threat bias from the interpreter is at work. But for the declarative memory system of episodic memory to show such effects, it requires both the threat bias and a loss of cognitive control over mental time travel. Perhaps only in severe cases of anxiety disorders, such as panic disorder, does the loss of cognitive control from deficits in executive attention spill over to affect mental time travel, much as it does in depression. This could account for the results of Becker et al. (1999) for panic disorder in contrast with other forms of anxiety disorder. It is worth noting that MacLeod et al. (1997b) studied anxious participants who all met the criteria for panic disorder. Thus, the characteristics of their sample might have explained why they observed a bias for negative events when so many other studies have been unable to do so, as they noted in their discussion section.

In summary, accounting for the consistent memory bias for losses or a lack of positive memories in MDD seems to depend on distorting inputs from both executive attention and the interpreter (see Figure 1 ). For persons experiencing GAD without panic disorder, the input from executive attention is weak or non-existent. Without this concomitant symptomatology, the bias of the interpreter for threatening events does not distort either retrospective or prospective memory, although it shows up on implicit, non-declarative forms of memory.

Limitations, Implications, and Future Directions

As noted previously, our explication of the complex role of mental time travel in explaining the phenomenology and research findings related to MDD and GAD has focused on interrelationships between three of the five components of the ensemble hypothesis. In focusing on these three constructs, we acknowledge the limited attention we have given to the importance of the two remaining ensemble components—overt use of language and social cognition—in accounting for differences and similarities in MDD and GAD. Reviewing the broader concept of language as interpersonal communication falls outside the scope of the current paper. Similarly, the extensive literature on theory of mind and social cognition in disorders such as MDD and GAD merits careful consideration that is not undertaken by our current analysis. Research indicates that theory of mind, a specialized aspect of social cognition ( Frith and Frith, 2007 ), plays a complex role in presentations of depression and anxiety where aspects of social cognition are prominent ( Bora and Berk, 2016 ; Washburn et al., 2016 ). Examples would include depression in the context of discordant relationships or bereavement, and social anxiety disorder. Exploring the interrelationships between social cognition and other components of the ensemble hypothesis is a fruitful direction for further theorizing and research.

Also, our paper is limited in scope, in that we focused on accounting for differences between disorders such as MDD and GAD, rather than examining similarities in their phenomenology and accounting for the high comorbidity of these conditions. We believe that further analysis of the interrelationships among the ensemble of mental components in MDD and GAD may help account for the comorbidity of these two disorders. For example, the high incidence of comorbidity might be accounted for by the reciprocal relations between the cognitive ensemble components and symptoms that constitute pathways that connect the disorders ( Borsboom and Cramer, 2013 ). It is worth noting the strong similarities of MDD and GAD as portrayed in Figures 1 , 2 . Both disorders involve several components of the ensemble hypothesis, including executive attention and the interpreter, in addition to mental time travel. The specific characteristics of memory functioning seem to depend on these interrelated cognitive components of the ensemble perspective. Thus, future theorizing and research should explore the interrelated components of the ensemble hypothesis as they relate to comorbid presentations of MDD and GAD.

Regarding one final limitation of our paper, we acknowledge that the ensemble component of “mental time travel” as it pertains to episodic foresight involves multiple constructs, each with substantive theoretical and empirical literatures that lie beyond the scope of our paper. Examples would include the role of mental time travel in future decision making involving delayed rewards ( Boyer, 2008 ) and the literature on “affective forecasting” ( Wilson and Gilbert, 2005 ) as it relates to the ensemble components in persons experiencing depression or anxiety. Once again, future theorizing and research should explore the interrelationships of such constructs with the ensemble components as they pertain to the etiology and phenomenology of MDD and GAD.

In review, we believe that similarities and differences between MDD and GAD are best conceptualized by considering an ensemble of mental components. Although mental time travel plays a role in both disorders, this component is influenced by the interpreter that assigns causal attributions to events and a dysfunction in executive attention.

If depression is primarily a problem with faulty prospection, then it is reasonable to target future thinking as perhaps the most effective form of treatment. Roepke and Seligman (2016) reviewed four variations of CBT that emphasize positive expectancies, hopeful thinking, a focus on future-oriented solutions to problems, and goal setting and planning. Initial results with each of these approaches have been positive and are worthy of additional study in randomized trials. Further, Roepke and Seligman (2016) suggest several new future-oriented interventions that might be considered (e.g., using visual imagery to imagine a route to future success).

While new approaches certainly merit exploration, we note that the premise underlying these—namely, that faulty prospection is the core causal process in depression—is open to debate. We believe that the effects of the interpreter and executive attention, in conjunction with mental time travel, should be considered to better understand both MDD ( Figure 1 ) and GAD ( Figure 2 ). From this ensemble perspective, therapies should target all three components rather than focusing only on mental time travel.

For example, mindfulness-based therapies including short-term meditation explicitly address deficits in executive attention. A short-term program (5 days of training for 20 min per day) has been shown to improve attention and self-regulation in a sample of healthy young adults ( Tang et al., 2007 ). Such mindfulness-based interventions have been shown to minimize relapse and offer promise in the treatment of acute symptoms of depression and anxiety, although more research is needed to clearly establish their clinical efficacy ( Edenfield and Saeed, 2012 ). In a different approach, training attention using computer-based tasks has been found beneficial in treating generalized social anxiety disorder ( Schmidt et al., 2009 ). If anxiety disorders as well as depression primarily are influenced by the mental time travel component ( Miloyan et al., 2014 ), then it is difficult to explain why treatments targeting the executive attention deficit would be effective. Yet, it is known that executive functioning matters. Although neurocognitive abilities can improve with CBT treatment for anxiety and depression, individuals with poor attentional control show decreased benefit from such treatment compared to those with adequate executive skills ( Devito et al., 2018 ).

Many techniques in traditional CBT build on the premise of altering the pessimistic explanatory styles employed by depressive and anxious individuals. These techniques are based on the premise that the symptoms and dysfunctional behaviors of these disorders are mediated by cognitive factors. The therapeutic goal, then, is to restructure the dysfunctional thinking and beliefs underlying the disorder. Cognitive distortions must be identified and refuted in restructuring the functions of the interpreter. The evidence supporting CBT as an effective treatment of both anxiety and depression is solid ( Butler et al., 2006 ). As Roepke and Seligman (2016) pointed out, CBT interventions already include a number of techniques that improve future thinking. Even so, the aim of CBT is to alter thinking patterns in general, including past and present thinking as well as future thinking. It is not clear that new approaches that emphasize future-oriented thinking only would be, or even should be, superior to standard CBT.

In terms of future directions, transdiagnostic psychotherapies for depression and anxiety ( Clark, 2009 ) could potentially be understood within and informed by the aspects of the ensemble hypothesis. The ensemble models shown in Figures 1 , 2 suggest that a unified approach to CBT plus mindfulness/attention training might well be plausible for treating both depressive and anxiety disorders. Finally, in recent years, network approaches to psychopathology have emphasized the interplay of symptoms across a variety of traditionally defined, yet comorbid, disorders ( Borsboom and Cramer, 2013 ). The psychopathology network approach contends that such emotional disorders arise from interactions among symptoms, as well as their reciprocally reinforcing relationships ( Borsboom, 2017 ). It may be possible to conceptualize these networks of psychopathology within the context of the ensemble hypothesis of human cognition considered here.

Data Availability Statement

The original contributions presented in the study are included in the article/supplementary material. Further inquiries can be directed to the corresponding author.

Author Contributions

RK developed the concept of the paper. RK and CC wrote the first draft. JG contributed with advice and revisions to subsequent drafts. All authors reviewed the final manuscript.

The funds required for open access fees required to publish this article were provided through Faculty Development accounts available to the first and third authors from the Department of Psychology at Saint Louis University.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Ahrens, A. H., and Haaga, D. A. F. (1993). The specificity of attributional style and expectations to positive and negative affectivity, depression, and anxiety. Cogn. Ther. Res. 17, 83–98. doi: 10.1007/bf01172742

CrossRef Full Text | Google Scholar

Ajilchi, B., and Nejati, V. (2017). Executive functions in students with depression, anxiety, and stress symptoms. Basic Clin. Neurosci. 8, 223–232.

Google Scholar

Alderson-Day, B., and Fernyhough, C. (2015). Inner speech: development, cognitive functions, phenomenology, and neurobiology. Psychol. Bull. 141, 931–965.

Alloy, L. B., Abramson, L. Y., Metalsky, G. I., and Hartlage, S. (1988). The hopelessness theory of depression: attributional aspects. Br. J. Clin. Psychol. 27, 5–21. doi: 10.1111/j.2044-8260.1988.tb00749.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Alvarez, J. A., and Emory, E. (2006). Executive function and the frontal lobes: a meta-analytic review. Neuropsychol. Rev. 16, 17–42. doi: 10.1007/s11065-006-9002-x

American Psychiatric Association (2013). Diagnostic and Statistical Manual of Mental Disorders , 5th Edn. Arlington, VA: American Psychiatric Association.

Arnold, N. R., Bayen, U. J., and Böhm, M. F. (2014). Is prospective memory related to depression and anxiety? A hierarchical MPT modelling approach. Memory 23, 1215–1228. doi: 10.1080/09658211.2014.969276

Barlow, D. H. (1988). Anxiety and its Disorders. New York, NY: Guilford Press.

Beck, A. T. (1974). “The development of depression: a cognitive model,” in The Psychology of Depression: Contemporary theory and Research , eds R. J. Friedman and M. M. Katz (Oxford: John Wiley), 318–330.

Beck, A. T., Brown, G., Steer, R. A., Eidelson, J. I., and Riskind, J. H. (1987). Differentiating anxiety and depression: a test of the cognitive content-specificity hypothesis. J. Abnorm. Psychol. 96, 179–183. doi: 10.1037/0021-843x.96.3.179

Beck, A. T., Wenzel, A., Riskind, J. H., Brown, G., and Steer, R. A. (2006). Specificity of hopelessness about resolving life problems: another test of the cognitive model of depression. Cogn. Ther. Res. 30. 773–781. doi: 10.1007/s10608-006-9081-2

Becker, E. S., Roth, W. T., Andrich, M., and Margraf, J. (1999). Explicit memory in anxiety disorders. J. Abnorm. Psychol. 108, 153–163. doi: 10.1037/0021-843x.108.1.153

Bora, E., and Berk, M. (2016). Theory of mind in major depressive disorder: a meta-analysis. J. Affect. Disord. 191, 49–55.

Borkovec, T. D., Ray, W. J., and Stöber, J. (1998). Worry: a cognitive phenomenon intimately linked to affective, physiological, and interpersonal problems. Cogn. Ther. Res. 22, 561–576.

Borsboom, D. (2017). A network theory of mental disorders. World Psychiatry 16, 5–13.

Borsboom, D., and Cramer, A. O. (2013). Network analysis: an integrative approach to the structure of psychopathology. Annu. Rev. Clin. Psychol. 9, 91–121. doi: 10.1146/annurev-clinpsy-050212-185608

Boyer, P. (2008). Evolutionary economics of mental time travel? Trends Cogn. Sci. 12, 219–224.

Buckner, R. L., Andrews-Hanna, J. R., and Schacter, D. L. (2008). The brain’s default network: anatomy, function, and relevance to disease. Ann. N. Y. Acad. Sci. 1124, 1–38.

Butler, A. C., Chapman, J. E., Forman, E. M., and Beck, A. T. (2006). The empirical status of cognitive-behavioral therapy: a review of meta-analyses. Clin. Psychol. Rev. 26, 17–31. doi: 10.1016/j.cpr.2005.07.003

Clark, D. A. (2009). Cognitive behavioral therapy for anxiety and depression: possibilities and limitations of a transdiagnostic perspective. Cogn. Behav. Ther. 38, 29–34. doi: 10.1080/16506070902980745

Clark, D. A., Beck, A. T., and Stewart, B. (1990). Cognitive specificity and positive-negative affectivity: complementary or contradictory views on anxiety and depression? J. Abnorm. Psychol. 99, 148–155.

Clark, D. M., and Teasdale, J. D. (1982). Diurnal variation in clinical depression and accessibility of memories of positive and negative experiences. J. Abnorm. Psychol. 91, 87–95. doi: 10.1037//0021-843x.91.2.87

Clark, I. A., and Maguire, E. A. (2016). Remembering preservation in hippocampal amnesia. Annu. Rev. Psychol. 67, 51–82. doi: 10.1146/annurev-psych-122414-033739

Derry, P. A., and Kuiper, N. A. (1981). Schematic processing and self-reference in clinical depression. J. Abnorm. Psychol. 90, 286–297. doi: 10.1037//0021-843x.90.4.286

Devito, A. N., Calamia, M., Roye, S., Bernstein, J. P. K., and Castagna, P. (2018). Factor structure of the Attentional Control Scale in younger and older adults: relationships with anxiety and depression. J. Psychopathol. Behav. Assess. 41, 60–68. doi: 10.1007/s10862-018-9705-3

Diamond, A. (2013). Executive functions. Annu. Rev. Psychol. 64, 135–168.

Edenfield, T. M., and Saeed, S. A. (2012). An update on mindfulness meditation as a self-help treatment for anxiety and depression. Psychol. Res. Behav. Manag. 5, 131–141.

Engle, R. W., Tuholski, S. W., Laughlin, J. E., and Conway, A. R. A. (1999). Working memory, short-term memory, and general fluid intelligence: a latent variable approach. J. Exp. Psychol. Gen. 128, 309–331.

Eysenck, M. W., Derakshan, N., Santos, R., and Calvo, M. G. (2007). Anxiety and cognitive performance: attentional control theory. Emotion 7, 336–353. doi: 10.1037/1528-3542.7.2.336

Eysenck, M. W., Payne, S., and Santos, R. (2006). Anxiety and depression: past, present, and future events. Cogn. Emot. 20, 274–294. doi: 10.1080/02699930500220066

Finlay-Jones, R., and Brown, G. W. (1981). Types of stressful life event and the onset of anxiety and depressive disorders. Psychol. Med. 11, 803–815. doi: 10.1017/s0033291700041301

Fresco, D. M., Alloy, L. B., and Reilly-Harrington, N. (2006). Association of attributional style for negative and positive events and the occurrence of life events with depression and anxiety. J. Soc. Clin. Psychol. 25, 1140–1159. doi: 10.1521/jscp.2006.25.10.1140

Frith, C. D., and Frith, U. (2007). Social cognition in humans. Curr. Biol. 17, R724–R732.

Gazzaniga, M. S. (2000). Cerebral specialization and interhemispheric communication: does the Corpus callosum enable the human condition? Brain 123, 1293–1326.

Gotlib, I. H. (1984). Depression and general psychopathology in university students. J. Abnorm. Psychol. 93, 19–30. doi: 10.1037//0021-843x.93.1.19

Grisanzio, K. A., Goldstein-Piekarski, A. N., Wang, M. Y., Ahmed, A. P. R., Samara, Z., and Williams, L. M. (2018). Transdiagnostic symptom clusters and associations with brain, behavior, and daily function in mood, anxiety, and trauma disorders. JAMA Psychiatry 75, 201–209. doi: 10.1001/jamapsychiatry.2017.3951

Heimberg, R. G., Klosko, J. S., Dodge, C. S., Shadick, R., Becker, R. E., and Barlow, D. H. (1989). Anxiety disorders, depression, and attributional style: a further test of the specificity of depressive attributions. Cogn. Ther. Res. 13, 21–36. doi: 10.1007/bf01178487

Hertel, P. T., and Rude, S. S. (1991). Depressive deficits in memory: focusing attention improves subsequent recall. J. Exp. Psychol. Gen. 120, 301–309. doi: 10.1037//0096-3445.120.3.301

Kellogg, R. T. (2013). The Making of the Mind: The Neuroscience of Human Nature. Amherst, MA: Prometheus Books.

Kellogg, R. T., and Evans, L. (2019). The ensemble hypothesis of human cognitive evolution. Evol. Psychol. Sci. 5, 1–12. doi: 10.1007/s40806-018-0159-3

Kendall, P. C., and Ingram, R. E. (1989). “Cognitive-behavioral perspectives: theory and research on depression and anxiety,” in Anxiety and Depression: Distinctive and Overlapping Features , eds P. C. Kendall and D. Watson (San Diego, CA: Academic Press), 27–53.

Kessler, R. C., Gruber, M., Hettema, J. M., Hwang, I., Sampson, N., and Yonkers, K. A. (2007). Comorbid major depression and generalized anxiety disorders in the National Comorbidity Survey follow-up. Psychol. Med. 38, 365–374. doi: 10.1017/s0033291707002012

Levy, E. A., and Mineka, S. (1998). Anxiety and mood-congruent autobiographical memory: a conceptual failure to replicate. Cogn. Emot. 12, 625–634. doi: 10.1080/026999398379475

Luten, A. G., Ralph, J. A., and Mineka, S. (1997). Pessimistic attributional style: is it specific to depression versus anxiety versus negative affect? Behav. Res. Ther. 35, 703–719. doi: 10.1016/s0005-7967(97)00027-2

MacLeod, A. K., and Byrne, A. (1996). Anxiety, depression, and the anticipation of future positive and negative experiences. J. Abnorm. Psychol. 105, 286–289. doi: 10.1037/0021-843x.105.2.286

MacLeod, A. K., and Salaminiou, E. (2001). Reduced positive future-thinking in depression: cognitive and affective factors. Cogn. Emot. 15, 99–107.

MacLeod, A. K., Tata, P., Kentish, J., Carroll, F., and Hunter, E. (1997a). Anxiety, depression, and explanation-based pessimism for future positive and negative events. Clin. Psychol. Psychother. 4, 15–24.

MacLeod, A. K., Tata, P., Kentish, J., and Jacobsen, H. (1997b). Retrospective and prospective cognitions in anxiety and depression. Cogn. Emot. 11, 467–479. doi: 10.1080/026999397379881

MacLeod, C., and McLaughlin, K. (1995). Implicit and explicit memory bias in anxiety: a conceptual replication. Behav. Res. Ther. 33, 1–14. doi: 10.1016/0005-7967(94)e0004-3

Mathews, A., Mogg, K., May, J., and Eysenck, M. (1989). Implicit and explicit memory bias in anxiety. J. Abnorm. Psychol. 98, 236–240. doi: 10.1037/0021-843x.98.3.236

McDowall, J. (1984). Recall of pleasant and unpleasant words in depressed subjects. J. Abnorm. Psychol. 93, 401–407. doi: 10.1037//0021-843x.93.4.401

Miloyan, B., Pachana, N. A., and Suddendorf, T. (2014). The future is here: a review of foresight systems in anxiety and depression. Cogn. Emot. 28, 795–810. doi: 10.1080/02699931.2013.863179

Mineka, S., and Nugent, K. (1995). “Mood congruent memory biases in anxiety and depression,” in Memory Distortion: How Minds, Brains, and Societies Reconstruct the Past , ed. D. L. Schacter (Cambridge, MA: Harvard University Press), 173–192.

Miranda, R., and Mennin, D. S. (2006). Depression, generalized anxiety disorder, and certainty in pessimistic predictions about the future. Cogn. Ther. Res. 31, 71–82. doi: 10.1007/s10608-006-9063-4

Mischel, W., Shoda, Y., and Rodriguez, M. L. (1989). Delay of gratification in children. Science 244, 933–938.

Miyake, A., Friedman, N. P., Emerson, M. J., Witzki, A. H., Howerter, A., and Wager, T. D. (2000). The unity and diversity of executive functions and their contributions to complex “frontal lobe” tasks: a latent variable analysis. Cogn. Psychol. 41, 49–100.

Ólafsson, R. P., Smári, J., Guðmundsdóttir, F., Ólafsdóttir, G., Harðardóttir, H. L., and Einarsson, S. M. (2011). Self reported attentional control with the Attentional Control Scale: factor structure and relationship with symptoms of anxiety and depression. J. Anxiety Disord. 25, 777–782. doi: 10.1016/j.janxdis.2011.03.013

Petersen, C., and Seligman, M. E. P. (1984). Causal explanations as a risk factor for depression: theory and evidence. Psychol. Rev. 91, 347–374.

Petersen, S. E., and Posner, M. I. (2012). The attention system of the human brain: 20 years after. Annu. Rev. Neurosci. 35, 73–89. doi: 10.1146/annurev-neuro-062111-150525

Pomerantz, A. M., and Rose, P. (2014). Is depression the past tense of anxiety? An empirical study of the temporal distinction. Int. J. Psychol. 49, 446–452. doi: 10.1002/ijop.12050

Posner, M. I., and Peterson, S. E. (1990). The attentional system of the human brain. Annu. Rev. Neurosci. 13, 25–42.

Posner, M. I., and Rothbart, M. K. (2007). Research on attention networks as a model for the integration of psychological science. Annu. Rev. Psychol. 58, 1–23.

Reardon, J. M., and Williams, N. L. (2007). The specificity of cognitive vulnerabilities to emotional disorders: anxiety sensitivity, looming vulnerability and explanatory style. J. Anxiety Disord. 21, 625–643. doi: 10.1016/j.janxdis.2006.09.013

Reinholdt-Dunne, M. L., Mogg, K., and Bradley, B. P. (2013). Attention control: relationships between self-report and behavioural measures, and symptoms of anxiety and depression. Cogn. Emot. 27, 430–440. doi: 10.1080/02699931.2012.715081

Reverberi, C., Cherubini, P., Frackowiak, R. S., Caltagirone, C., Paulesu, E., and Macaluso, E. (2010). Conditional and syllogistic deductive tasks dissociate functionally during premise integration. Hum. Brain Mapp. 31, 1430–1445. doi: 10.1002/hbm.20947

Riskind, J. H., and Williams, N. L. (2005). The looming cognitive style and Generalized Anxiety Disorder: distinctive danger schemas and cognitive phenomenology. Cogn. Ther. Res. 29, 7–27. doi: 10.1007/s10608-005-1645-z

Roepke, A. M., and Seligman, M. E. P. (2016). Depression and prospection. Br. J. Clin. Psychol. 55, 23–48. doi: 10.1111/bjc.12087

Roser, M. E., Fugelsan, J. A., Dunbar, K. N., Corballis, P. M., and Gazzaniga, M. S. (2005). Dissociating processes supporting causal perception and causal inference in the brain. Neuropsychology 19, 591–602.

Rude, S. S., Hertel, P. T., Jarrold, W., Covich, J., and Hedlund, S. (1999). Depression-related impairments in prospective memory. Cogn. Emot. 13, 267–276. doi: 10.1080/026999399379276

Sanjuán, P., and Magallares, A. (2009). A longitudinal study of the negative explanatory style and attributions of uncontrollability as predictors of depressive symptoms. Pers. Individ. Dif. 46, 714–718. doi: 10.1016/j.paid.2009.01.030

Schmidt, N. B., Richey, J. A., and Buckner, J. D. (2009). Attention training for generalized anxiety disorder. J. Abnorm. Psychol. 118, 5–14.

Shi, R., Sharpe, L., and Abbott, M. (2019). A meta-analysis of the relationship between anxiety and attentional control. Clin. Psychol. Rev. 72, 1–24. doi: 10.1016/j.cpr.2019.101754

Stefanopoulou, E., Hirsch, C. R., Hayes, S., Adlam, A., and Coker, S. (2014). Are attentional control resources reduced by worry in generalized anxiety disorder? J. Abnorm. Psychol. 123, 330–335. doi: 10.1037/a0036343

Suddendorf, T., and Corballis, M. C. (2007). The evolution of foresight: what is mental time travel, and is it unique to humans? Behav. Brain Sci. 30, 299–313. doi: 10.1017/s0140525x07001975

Tang, Y.-Y., Ma, Y., and Fan, Y. (2007). Short-term meditation training improves attention and self-regulation. Proc. Natl. Acad. Sci. U.S.A. 104, 17152– 17156.

Tulving, E. (2002). Episodic memory: from mind to brain. Annu. Rev. Psychol. 53, 1–25.

Vygotsky, L. (1962). Thought and Language , E. Hanfmann and G. Vakar, trans. Cambridge: MIT Press.

Washburn, D., Wilson, G., Roes, M., Rnic, K., and Harkness, K. L. (2016). Theory of mind in socialanxiety disorder, depression, and comorbid conditions. J. Anxiety Disord. 37, 71–77.

Williams, J. M., and Scott, J. (1988). Autobiographical memory in depression. Psychol. Med. 18, 689–695.

Williams, J. M., Watts, F. N., MacLeod, C., and Mathews, A. (1997). Cognitive Psychology and Emotional Disorders , 2nd Edn, Chichester: John Wiley & Sons.

Wilson, T. D., and Gilbert, D. T. (2005). Affective forecasting: knowing what to want. Curr. Dir. Psychol. Sci. 14, 131–134.

Witheridge, K. S., Cabral, C. M., and Rector, N. A. (2010). Examining autobiographical memory content in patients with depression and anxiety disorders. Cogn. Behav. Ther. 39, 302–310. doi: 10.1080/16506073.2010.520730

Wolford, G., Miller, M. B., and Gazzaniga, M. (2000). The left hemisphere’s role in hypothesis formation. J. Neurosci. 20:RC64.

Keywords : ensemble hypothesis, mental time travel, interpreter bias, executive attention, anxiety, depression

Citation: Kellogg RT, Chirino CA and Gfeller JD (2020) The Complex Role of Mental Time Travel in Depressive and Anxiety Disorders: An Ensemble Perspective. Front. Psychol. 11:1465. doi: 10.3389/fpsyg.2020.01465

Received: 24 April 2020; Accepted: 02 June 2020; Published: 21 July 2020.

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Copyright © 2020 Kellogg, Chirino and Gfeller. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Cristina A. Chirino, [email protected]

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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Human brains are capable of ‘mental time travel,’ study says.

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The passage of time is all in your mind. 

Human brains independently measure episodic movement — that’s a trippy finding reported by French and Dutch researchers in a new study published Monday in the Journal of Neuroscience . 

Our brains possess “an internal or inherent flow of time, that was not driven by something going on in the external world,” neuroscientist and lead study author Leila Reddy told Vice of her team’s findings, which she referred to as evidence of the human mind’s “mental time travel” ability.

To get evidence of this hard-to-conceptualize concept, Reddy and her team studied the brains of epileptics who already needed invasive electrode implants in their brains independent of the research. 

“These patients have severe, drug-resistant epilepsy and are awaiting surgery,” Reddy told Vice of the study participants. “Part of the pre-surgical procedure involves implanting electrodes in the brain to monitor seizure activity. Once the electrodes are inserted in the brain, we ask the patients if they are willing to participate in short experiments for us, and we can record from single neurons to test different hypotheses.” 

Researchers found the participants’ brains’ “time cells” fired at specific moments, including moments when there weren’t external stimuli, suggesting they were responding to an internal sense of sequencing. 

“I think a big question here is to ultimately understand how memories are encoded,” Reddy told Vice. “Episodic memory, in particular, is the memory of what happened, when, and where. Time cells could provide the scaffolding for representing the ‘when.’ Emerging evidence suggests that the same hippocampal neurons might also encode the ‘where’ and the ‘what,’ providing a broader framework for encoding memories.”

Moving forward, to better understand how humans process time, she believes researchers will need to look even closer at the mechanisms by which the brain encodes both time’s passage and memories. 

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• Published: 03 March 2023

Mental time travel ability influences the representation of events and emotional expressions: evidence from microblogs

• Zaoyi Sun 1 ,
• Qingyan Li 1 ,
• Fei Luo 1 &
• Liang Xu 1  

BMC Psychology volume  11 , Article number:  57 ( 2023 ) Cite this article

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Mental time travel (MTT) ability allows people to project themselves mentally into the past and future. It is associated with people’s mental representation of events and objects. Using text analysis methods, we explore the linguistic representation and emotional expression of people with various MTT abilities. In Study 1, we assessed the users’ MTT distances, text lengths, visual perspectives, priming effects of temporal words, and emotional valences by analyzing 2973 users’ microblog texts. From our statistical analysis findings, users with far MTT incorporated longer text length and more third-person pronouns in their microblogs and are more likely to relate the future and past with the present than people with near MTT. However, the study showed no significant difference in emotional valence between people with different MTT distances. In Study 2, we explored the relationship between emotional valence and MTT ability by analyzing the comments of 1112 users on “procrastination.” We found the users with far MTT more positive toward procrastination than those with near MTT. By analyzing users’ social media platform data, this study re-examined and verified previous findings indicating that users who mentally travel different temporal distances represent events and emotional expressions differently. This study serves as an important reference for MTT studies.

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It is often said that “only by remembering the past can we look forward to the future.” People can remember their past and plan for the future [ 1 , 2 ]. The human ability to remember and reconstruct past events and visualize and anticipate future events is defined as mental time travel (MTT) [ 3 , 4 , 5 ]. This is through a human’s episodic memory as the events in mental time are constructed around personally experienced past and future constructs [ 6 ]. Specifically, the episodic memory’s main role is to provide information from the past as the scaffolding of the future. Various lines of evidence suggest that MTT into the past shares cognitive resources with mental construction of potential future episodes. For example, participants reported a decrease in phenomenological richness of both past and future episodes with increased distance from the present[ 7 ]. Empirical studies have found that the temporal distribution of past events people envisage follows the same power function as the temporal distribution of anticipated future events [ 8 ]. MTT has a considerable association with an individual’s cognition, emotion, and behaviors. Extensive researches has showed that mentally traveling into the past allows people to review events, draw lessons from previous experiences, and respond to present and future issues better [ 9 ], whereas mentally traveling into the future may help people adjust their current actions by pre-experiencing future events [ 10 ]. A prior study found that children between the ages of three to five began to develop MTT ability so that their current behavior could be directed to secure not just present, but individually anticipated future needs [ 11 ]. Therefore, MTT allows people to adapt to the past and present and combine existing experiences to make better plans.

MTT is a fundamental characteristic of people mentally representing events and objects [ 12 ]. Construal level theory (CLT) suggests that people’s mental representation of events and objects depends on the temporal distance at which those events and objects are imagined [ 13 , 14 ]. Recently, a series of experiments have found that thinking about events that are close in time induces a “low-level construal”, characterized by more concrete or detailed processing related to the event. In contrast, thinking about events that are farther away induces a “high-level construal,” characterized by more abstract or holistic processing[ 15 ]. CLT considers the temporal distance effects and focuses on the events and objects, whereas MTT focuses on the mental ability of individuals. The ability to travel mentally at different temporal distances may affect the individuals’ representation of events and behavioral patterns [ 16 , 17 ]. The increased mental temporal distance made people integrate more information and improve their comprehensive decision making [ 18 ]. People with near-future sightedness are more likely to be addicted to alcohol and gambling [ 19 ], and people with far-future sightedness behave more cautiously in long-term savings [ 20 ].

The concept of time perspective emerged in psychology as a way to understand how people cognize, understand, and feel time [ 21 ]. Time perspective is related to many outcomes of interests such as well-being and achievement, which explains the propensity of individuals for MTT [ 22 ]. Although the time perspective includes three basic elements (the perception and experience of past, present, and future), many studies only investigated the influences of one temporal perspective on human behavior [ 23 , 24 ]. Recent studies have shown that the regions of the brain used for thinking about the past are also active during the prospective thinking process [ 25 , 26 , 27 ]. In addition, many studies have used the questionnaire method or lab experiments to investigate the relationship between people’s MTT abilities and representation of events, limiting them in terms of sample size and ecological validity. Considering the accessibility of online big data, this study proposes to mine users’ text data on social media platforms and investigate how people’s MTT abilities affect their text representation and emotional expression.

MTT and text representation

Studies have been increasingly exploring the relationship between temporal distance and event representation in recent years. Some natural studies based on CLT have found that people’s representation of far-future events contains more goal-related knowledge, and representation of near-future events containing more details of actions [ 28 ]. Some researchers investigated the relationship between temporal distances and the level of lexical abstractness by analyzing the word meanings in a large language corpus [ 29 ]. They found that the tweets mentioning temporally proximate dates used more concrete words than those mentioning distant dates. Based on the data extracted from the New York Times Annotated Corpus, a previous study conducted factor analysis and generated a “Conceptual Abstractness and Uncertainty” dimension underlying the co-occurring patterns [ 30 ]. The results confirmed a positive correlation between temporal distance and conceptual abstractness/uncertainty. The present study also proposes to investigate how people’s perception of time affected their representations in social media text. However, quantifying the representation of abstract concepts remains a challenge. The above studies relied on manual evaluation under different rules, but this method has limitations in terms of efficiency and objectivity. Following previous quantitative linguistic studies [ 31 ], we considered text length as a more objective and measurable variable for automatic computing text length is one of the main indexes of complexity [ 32 ]. Besides, a related work accessed text’s abstractness by the frequency of concrete nouns and the average abstractness of nouns [ 33 ]. For further analysis of abstractedness in our study, a dictionary of abstractness ratings for 9877 two-character Chinese words was used for lexical matching [ 34 ]. So we defined “abstractedness” with these indices: the average abstractness of texts, the frequency of abstract words and the text length. Therefore, we assume that people with far MTT prefer to use longer text, more abstract words and higher abstractness ratings of texts on social media platforms compared to those with near MTT (Hypothesis 1).

A visual perspective is the use of different personal pronouns to describe past or imagined events[ 35 ], this is an important factor in MTT research as well. Experimental and natural studies have found that people tend to use a third-person rather than first-person perspective for remembering distant past events [ 36 , 37 , 38 , 39 , 40 ]. The visual perspective is related with individual’s two cognition process defined by the origin of information: top-down and bottom-up. Top-down signals were derived from the knowledge about the task volitionally whereas “bottom-up” signals were derived from salient stimuli automatically[ 41 ]. Third-person perspective is more appropriate for “top-down” abstractions and the first-person perspective more appropriate for concrete and “bottom-up” processing [ 42 ]. Thus, the longer the time distance, the more people are inclined to abstract “top-down” cognitive processing. People mentally traveling to the future tended to use more third-person pronouns as the temporal distance increased [ 27 ]. This study proposes to retest the above findings by analyzing users’ social media text. We hypothesize that people with far MTT use more third-person pronouns in their blogs than people with near MTT (Hypothesis 2).

In the field of semantic priming, the priming effect was first defined as facilitating the recognition process by spreading activation from one word to neighboring words [ 43 ]. Individuals form these activations to link concepts in mind. These activation tags are more accessible in one’s mind and affect the evaluation of subsequent information [ 44 ]. For example, people tended to recognize the word school faster when it was preceded by the word teacher than when it was preceded by the word bread. In the case of temporal orientation, some researchers redefined the priming effect as the increased probability of referring to the future and past after referring to the present [ 23 ]. By identifying tweets that referred to the present, they examined the tweets that followed within 3 min of that tweet were examined for the proportions of times that they mentioned the past, present, and future. These likelihoods were compared with the likelihood of past, present, and future references in tweets not occurring within 3 min of a present reference. Based on the user’s natural language on social platform, this work adopted the text analysis methods to verify the references to the present primed references to the future, and such priming effects was stronger for the people with far future temporal distance. These results can be explained by CLT [ 13 , 14 ] that people who look far into the future tend to talk less concretely about the present. Furthermore, the point where the level of abstractness in the present matches the level of abstractness in the future will tend to be farther into the future (and past) for those with far MTT than for those with MTT. This method inspired us to explore whether the users of Chinese social platforms with far (vs. near) MTT tend to relate the present more (vs. less) with the future and past. Following the previous work, we focus on the users’ MTT in both past and future directions. We thus hypothesize that people with far MTT have stronger priming effects; that is, they tend to mention more past and future references after the present references(Hypothesis 3).

MTT and emotional expressions

Studies have found that the perceived valence (positive or negative) of events is influenced by its temporal distance. Participants were asked to provide an important event that they had experienced in the past or would experience in the future, and indicate how positive the emotions for the event they experienced. It was found that distant past events were generally more negative than recent ones; in contrast, far future events were more positive and higher in their relation to identity and their effect on the self [ 45 ]. The above studies focus on how the emotional valences of events changed with different temporal distances from past and future time orientations. This study proposes to explore how peoples’ MTT abilities influence their emotional expressions. As an enhanced activation, the neural mechanism of future MTT has been found to occur in areas of the brain related to optimism [ 46 ]. Since MTT is an integrated time perception mechanism, we hypothesize that the text expressions in emotional valence are different between people with far and near MTT abilities(Hypothesis 4).

The present study

In sum, this study investigated the text representation and emotional expression of people with different MTT abilities by analyzing their microblogs. In Study 1, we calculated the users’ MTT, text length, words’ abstractness, visual perspectives, priming effects of temporal words, and expressions of emotional valences. We hypothesized that people with far MTT present longer text length, higher abstractness ratings of words, use more third-person pronouns, show stronger priming effects, and reveal more positive emotional valence in their text than those with near MTT. In Study 2, we further explored the relationship between people’s emotional valence and MTT ability by analyzing their text under the topic “procrastination.”

In Study 1, we analyzed text based on the original content on Sina Weibo. Sina Weibo, or microblogs, a Chinese version of Twitter, is the largest social media platform in China [ 47 ]. According the report released by China Internet Network Information Center, 55.3% of Chinese netizens use Sina Weibo as their major social media software. Based on user relationships, Weibo realize information sharing, dissemination and acquisition. Therefore, with the representative samples and rich user-generated content, Sina Weibo enabled us to the text’s characteristics of people with different MTT abilities.

Data collection procedure

This study did not require an ethics approval, as it was a text mining retrospective study of publicly posted information on social media. Following the principle of intensity sampling [ 48 ], for each province of China, the users who had at least 100 original microblogs were selected as they could more information for the text analysis. We downloaded 236,629 original microblogs of 3850 users who had at least 100 original microblogs each. We collated the users’ personal information, such as gender and number of followers. As users with numerous followers are usually affiliated with professional organizations, we deleted those with more than 10,000 followers because most of their microblogs contain advertisements, which may have distorted the results. Our final sample included 213,201 microblogs of 2973 users (sample utilization rate: 77.42%; 81.32% females). The regional distribution of the simple covered 34 provinces and the top three were Guizhou Province (4.5%), Sichuan Province (4.1%) and Zhejiang Province (4.0%).

Feature calculation instruments

Mtt ability.

The temporal reference words appearing in microblog text can help in quantifying users’ MTT distance [ 23 ]. For example, in the sentence “it will rain tomorrow,” the word “tomorrow” is a future indicator. The Chinese language, unlike English, has no specific grammatical rules to distinguish the different directions of time. Therefore, we first constructed a corpus of temporal reference words for past, present, and future directions based on a Chinese temporal corpus [ 49 ]. A total of 287 words and rules were contained in the corpus. Second, we converted the above Chinese temporal references into numerical expressions by the rules of SUTime [ 50 ]. SUTime is a rule-based temporal tagger for recognizing and normalizing temporal expressions in English text. It supports three basic types of time objects: Time, Duration, Interval. A time point indicating a particular instance on a time scale. SUTime recognize both relative times (e.g., last Friday) and absolute times (e.g., December 11, 2022). Duration refers to a combination of a unit (e.g., day, month, year, etc.) and a numeric value (the quantity associated with the unit). Interval means a time range defined by a start and end time points, such as November 12 to December 10, 2022. SUTime can recognize these ranges and represent them a Duration with begin and end times. Thus, the Chinese temporal reference words we built were classified into these types and then the user’s MTT distance could be recognized automatically. The above temporal references and rules together allowed SUTime to recognize the time-related expressions in microblog text automatically. Third, we extracted users’ MTT distances from the microblogs using the SUTime temporal tagger. The microblogs were classified under absolute dates, relative time, and a mixture of absolute and relative time. For relative time, we used document dates as references, while SUTime estimated the MTT distance of a microblog as follows: the time at which the microblog was created subtracted from the date and time referred to by the microblog. As there is more than one temporal reference in a microblog, the MTT distance is the average of these references; that is, \({\text{S}}\left( {\text{t}} \right) = \sum\nolimits_{{\text{r}}} {\frac{{{\text{M}}\left( {\text{r}} \right)}}{{\text{n}}}}\) , where r is the temporal reference, M ( r ) is the number of days the reference projects into the past or future, and n is the number of temporal references in the microblog. User i ’s MTT microblog distance is then averaged as follows: \({\text{S}}\left( {\text{i}} \right) = \sum\nolimits_{{\text{t}}} {\frac{{{\text{S}}\left( {\text{t}} \right)}}{{\text{n}}}}\) , where t is one of the user’s microblogs and n is the total number of microblogs created by user i .

Measurement of abstractedness

We quantified "abstractedness" with these indices: the average abstractness of a single microblog, the average abstractness of a single word and the text length. The text length of one’s microblog is the average length of the microblog, indexed as the microblog’s total number of words divided by the number of microblogs as follows:

\({\text{L}}\left( {\text{i}} \right) = \sum\nolimits_{{\text{t}}} {\frac{{{\text{L}}\left( {\text{t}} \right)}}{{\text{n}}}}\) ,where t is the user’s microblog, L ( t ) is the total number of words in the microblog, and n is the user’s number of microblogs.

The average abstractness of words was indexed as the total words' abstractedness ratings divided by the number of user's microblogs. The average abstractness of a single word was indexed as the frequency of abstract words in the abstractness dictionary divided by the total number of words in the user’s original microblogs.

Visual perspective

As an objective measurement of language vocabulary, language inquiry and vocabulary counting (LIWC) is a computerized text analysis program for classifying and quantifying the user’s features of language application [ 51 ]. To apply this method to simplified Chinese, a simplified Chinese LIWC (SC-LIWC) program was established based on the original LIWC [ 52 ]. SC-LIWC contains the categories of first and third person pronouns useful for our visual perspective analysis. The words used in the microblogs are then matched with the above personal pronouns. Finally, the user’s first/third-person perspective can be calculated as follows:

\(\it {\text{F}}\left( {\text{i}} \right) = \sum\nolimits_{{\text{t}}} {\frac{{{\text{F}}\left( {\text{t}} \right)}}{{\text{n}}}}\) ,

where t is user i ’s microblog, F ( t ) is the frequency of using first/third-person pronouns in the microblog, and n is the user’s total number of microblogs.

Priming effects of temporal words

We used a temporal reference corpus for the MTT distance calculation processing. Each user’s temporal references are identified using SUTime. We then used the proportions of past and future references to compute the priming condition (in microblogs occurring 0–3 h after a present reference) and non-priming condition (in all other microblogs).

The index of priming effects is the proportion of past and future references occurring 0–3 h after a present reference is divided by the proportion of the references not occurring after the present reference.

Emotional valence

Emotional valence is evaluated using a simplified Chinese version of the National Taiwan University Sentiment Dictionary (NTUSD), which includes 2810 positive and 8276 negative words [ 53 ]. The NTUSD automatically labeled the user’s emotional words found in the microblogs during the lexical matching process. For each user, one positive word is given 1 point and one negative word is given − 1 point. The average emotional valence score of user t is then indexed as the sum of the positive and negative word scores as follows:

where p is a positive emotional word, n is a negative emotional word, E ( p ) is the total score of user t ’s positive emotional words, E ( n ) is the total score of user t ’s negative emotional words, and N is the total number of user t ’s emotional words (including positive and negative words).

Data analysis

All analyses were conducted using IBM SPSS v.23. The descriptive statistics of the variables are shown in Table 1 . Then we first used the Kolmogorov–Smirnov test ( KS test) to examine the normality of sample distribution. We found that the MTT distance ( KS  = 0.45), text length ( KS  = 0.19), the average abstractness of a single word ( KS  = 0.07), the average abstractness of a single microblog ( KS  = 0.12) and emotional valence ( KS  = 0.15) are non-normally distributed (all p  < 0.001). Therefore, the Mann–Whitney U-test was conducted for the future different test. r can be calculated as an effect size for the Mann–Whitney U-test using the formula: \(r=\frac{z}{\sqrt{N}}\) [ 54 ]. According to Cohen’s guidelines, a large effect is 0.5, a medium effect is 0.3, and a small effect is 0.1 [ 55 ].

Second, a Spearman correlation analysis showed that the user’s MTT distance is positively correlated with the text length ( r  = 0.61, p  < 0.001), the average abstractness of a single microblog ( r  = 0.06, p  < 0.05) and the average abstractness of a single word ( r  = 0.08, p  < 0.01). The text length is positively correlated with the average abstractness of a single microblog ( r  = 0.12, p  < 0.001) and the average abstractness of a single word ( r  = 0.14, p  < 0.001). The correlations between the other variables are not significant ( p  > 0.05).

According to the critical ratio method, the MTT distances of all the users were sorted, the first 27% were enrolled in the far MTT group (73.5% females), and the last 27% were enrolled in the near group (84.4% females) for the further analysis.

Indices of abstractedness

We then conducted a Mann–Whitney U test to examine the differences in the average abstractness of a single microblog, the average abstractness of a single word and the text length between the near MTT and far MTT groups. As shown in Table 2 , all the three variables of users with far MTT was significantly higher than that of users with near MTT p  < 0.001), supporting Hypothesis 1.

Visual perspectives

As the data were non-normally distributed (first-person pronoun frequency KS  = 0.34, third-person pronoun frequency KS  = 0.49; all p  < 0.001), we performed a Mann–Whitney U test to compare the usage of personal pronouns between the far MTT and near MTT groups. As shown in Fig.  1 , the results indicated a significant difference in frequency of third-person pronoun use between the far MTT and near MTT groups (Z 0.01/2  = 4.33, p  < 0.001, effect size: r  = 0.12). Individuals who travel farther in mental time are more likely to use third-person pronouns.

The difference in relative frequency of personal perspective between near versus far MTT groups. Error bars: the relative frequency of personal perspective’s standard error ( SE ) of each group. ***: significant at 0.001 level.”

Priming effects analysis

We calculated the frequencies of future and past temporal word use of those with different MTT distances under both priming and non-priming conditions. As the data did not conform to a normal distribution (all p  < 0.001), we used the Mann–Whitney U test for the difference test. As shown in Table 3 , there were significant differences between the near MTT and far MTT groups in both future and past temporal word usage under priming and non-priming conditions (all p  < 0.001). Specifically, users with far MTT are more likely to use past and future temporal words in both conditions. Thus, compared with users with near MTT, those with far MTT are more likely to prime by the present references and regard the future and past more associated with the present.

As a user may refer to many temporal words in one priming procedure, we calculated the users’ frequency of future (or past) temporal word usage divided by the total prime time as the primed temporal words’ strength. We also calculated the strength of the non-primed temporal words using this method. We then conducted a Mann–Whitney U test to examine the difference between the two MTT groups in the strength of the above temporal words. The strengths were consistent (see Table 4 ) with the frequencies (see Table 3 ). The far MTT group used more past and future temporal words after mentioning the present temporal words in one priming procedure than did the near MTT group (all p  < 0.001). From these results, far MTT users may have a stronger priming effect, thus supporting Hypothesis 3.

After calculating the users’ emotional valence scores ( M  = 0.23, SD  = 0.53), we conducted a Mann–Whitney U test to analyze the difference in emotional valence between the far MTT and near MTT groups. The results showed no significant difference in emotional valence scores between the two groups (see Fig.  2 : Z 0.05/2  = − 0.99, p  = 0.3 r  = − 0.02), not supporting Hypothesis 4.

Emotional valence scores of near and far MTT distance groups. Error bars: the relative frequency of personal perspective’s standard error ( SE ) of each group. ***: significant at 0.001 level.”

Study 1 investigated the difference between the far MTT and near MTT groups in text representation and emotional expression by analyzing the users’ microblogs. We found that far MTT users have more abstract expressions, stronger priming effects, and more third-person pronoun use in their original content than near MTT users.

Previous studies have found that the temporal distance of an event positively correlated with its representational abstractness [ 29 ]. Using the text analysis method, we found the users’ MTT positively correlated with the text length, the average abstractness of a single microblog and the average abstractness of a single word. However, the effect sizes of the abstractness-related indexes were small when the number of words or microblogs were controlled. These results indicated that the people with far MTT tended to represent events with longer text, not just more abstract words. Computational linguistics studies have often adopted text length as an index of content complexity to find that language complexity is positively correlated with an event’s temporal distance [ 56 ]. Therefore, our findings may indicate that people with far MTT show higher language complexity. In addition, some studies have found that low-level future time perspective individuals describe their future events vividly [ 57 ]. These findings agree with our priming effects results that people with far MTT tend to use more temporal words (past and future) in both priming and non-priming conditions. Thus, individuals with far MTT refer to both events with far temporal distance and temporal related events more frequently.

We also found that users with far MTT tended to use more third-person pronouns in their original text. This finding agrees with previous research that as the temporal distance increased, the user tended to adopt the observer perspective more frequently [ 27 ]. This difference in expression style reflects the user’s cognitive tendency at different temporal distances. Specifically, with the increase in time distance, the user’s involvement degree decreased, and the user tended to adopt observer perspectives more frequently as the event was formed with less clarity and intensity [ 3 ].

For the priming effect, we found results similar to the findings that users with far MTT referred to more temporal words after mentioning present events than did those with near MTT [ 23 ]. The priming effect results indicated that MTT allows users to connect the past and future with the present. This is consistent with the definition of MTT that people use this ability to reflect on the past, anticipate the future, and construct alternate mental realities [ 58 ].

Generally, Study 1 found that people’s MTT affects their language representation, including their text length, abstractness of words, visual perspective usage, and priming effects of temporal words. These results can be explained by the CLT theory that temporal distance influences individuals’ cognitive style toward events. However, we found no significant difference between the far MTT and near MTT groups in terms of emotional valence. One possible reason is that a user’s microblog may involve various event types and emotional valences. An analysis of the whole content cannot distinguish the group differences toward a specific event because event type is an important factor affecting the relationship between emotional expression and temporal distance [ 7 ]. Therefore, in Study 2, we further analyzed the differences in emotional valence toward a specific topic between the far MTT and near MTT groups. As Study 1 integrated the future and past time orientations as the overall MTT ability of each user, in this study, we distinguished between the two time orientations.

Study 1 indicated that the overall emotional valences of users with different MTT distances were not significantly different. As the user’s original content consisted of different types of topics, the results could be misleading. Therefore, Study 2 selected the topic of procrastination for further analysis. Procrastination implies the lack of self-regulation and a behavioral tendency to postpone what is necessary for goal achievement [ 59 ]. Procrastination is always a self-handicapping and dysfunctional behavior [ 60 ]. The reasons we focused on the posts about procrastination are as follows: First, in order avoid the floor effect and ceiling effect, the topic selected in study 2 should not evoke most people’s congruent emotional valence. According to the related works, people expressed diversified attitudes towards the topic of “procrastination”. Second, Time management is a strong factor in mediating between procrastination and self-regulation [ 61 ]. As referred in the Introduction, People’s MTT ability has important effect on time management behavior. Previous studies focused on the relationship between future temporal perspective (i.e. goal-setting) and procrastination [ 61 ]. Therefore, the users in study 2 were divided into 4 groups in order to clarify the relationship between MTT abilities and emotional valences toward procrastination for both past and future temporal orientations.

Thus, we selected this topic in study 2 to explore the relationship between user’s MTT ability and emotional valences towards procrastination. Third, as a widespread problematic behavior and a stable individual tendency across time and different contexts, procrastination is familiar to most people in China over recent years. Many users posted their attitudes, feelings, experiences under this topic, which offered nature and rich resources for our research. In this study, we considered the user’s content on procrastination and compared the emotional valences of the far MTT and near MTT groups. We also hope that these results may provide an insight into how people’s MTT abilities affect their attitudes towards procrastination, which would have potential implications for effective prevention of procrastination.

This study did not require an ethics approval, as it was a retrospective text mining study of publicly posted information on social media. We downloaded 4605 comments of microblog users on procrastination and collected the users’ original microblog texts using their user IDs and their comments. As in Study 1, we first removed the data of users who had more than 800 followers to finally obtain 1864 users with a total of 145,010 microblogs. Second, we filtered the data of 625 users who had no temporal or emotional words in their original content. Third, we merged the data of users having the same ID. Finally, we included the data of 1112 users for the following analysis (83% women).

As in Study 1, we used a simplified Chinese version of the NTUSD and a self-constructed temporal word corpus in Study 2. We also calculated each user’s average MTT distance and emotional valence in the same manner as in Study 1.

3.1.3 Data analysis

The user’s emotional valence scores showed a mean value of − 0.02 ( SD  = 0.07). As the distribution of all the users’ emotional valence scores and MTT distances was non-normal ( p  < 0.001), we conducted a Spearman rank correlation analysis. As shown in Table 5 , the users’ average emotional valence scores were positively correlated with the past and future MTT distances (both p  < 0.001). From these results, the farther a user’s MTT, the more positive is their attitude toward procrastination. We also found a positive correlation between the users’ past and future mental travel distances ( p  < 0.001), suggesting that the users’ past and future mental distances were intrinsically connected.

Difference test in emotional valence

The users’ data were grouped by the past and future MTT distance mean scores and labeled under four groups: far-past MTT ( n  = 235), near-past MTT ( n  = 877), far-future MTT ( n  = 184), and near-future MTT ( n  = 928). Notably, a user may belong to more than one group. As the past and future MTT abilities are intrinsically connected, users with far-past MTT ability are likely to also have far-future MTT ability. Because the users’ MTT distance distribution is non-normal, we used a Mann–Whitney U test for the difference test. For both past and future temporal orientations, we found that the far MTT group tended to describe procrastination more positively than the near MTT group (past: T past−far  = 643.28 >  T past−near  = 533.25, Z 0.01/2  = 4.67, p  < 0.001, effect size r  = 0.12); future: T future−far  = 645.68 >  T future−near  = 538.82, Z 0.01/2  = 4.13, p  < 0.001, effect size r  = 0.10).

In Study 2, we analyzed the users’ comments under procrastination, exploring whether those with different MTT distances showed different emotional valence. We found that in both past and future temporal orientations, the far MTT group described procrastination more positively than the near MTT group. These findings support Hypothesis 4.

The results of study 2 suggest that the user’s time perception is related to the attitude towards procrastination. Procrastination is a dysfunctional behavior related to failing in meeting deadlines within a specific time-frame. Although people generally consider procrastination a stressful event in daily life, all procrastination behaviors do not have negative effects. Some researchers conceptually differentiated between two types of procrastinators: passive procrastinators and active procrastinators [ 62 ]. Passive procrastinators do not procrastinate intentionally but always find it difficult to make decisions. They then act quickly to complete their tasks on time. In contrast, active procrastinators handle their issues in a timely manner, suspend their issues deliberately, and pay attention to other valuable work at hand [ 63 ]. Passive and active procrastinators have different cognitive, affective, and behavioral dimensions [ 64 ]. Active procrastination reflects good self-regulation and planning [ 65 ]. Self-regulation includes self-generated thoughts, feelings, and actions that are directed towards the attainment of personal goals [ 66 ]. Procrastination has been increasingly viewed as involving a failure in self-regulation [ 67 ]. Specifically, passive and active procrastinators have differences in the elasticity in time perception and use patterns. Positive procrastinators are able to properly estimate the minimum amount of time required to finish a task and push themselves to proceed efficiently toward the future goal, whereas passive procrastinators tend to underestimate the time needed to complete a particular task and thus to be overwhelmed or overstressed by time pressure at the last minute [ 62 ]. Therefore, our results were consistent with previous works that time management is a strong factor in mediating between procrastination and self-regulation [ 68 ].

Procrastination may have different meanings for users with different MTT abilities because a person with far MTT usually adopts more long-term planning [ 20 ]. Our results indicate that people with different MTTs represented different emotional valences toward procrastination. Users with far MTT regard procrastination more positively. A possible explanation is that people with far MTT may engage in active procrastination and strategically adopt decisions to complete their tasks before the deadline methodically. Far MTT ability allows people with “foresight” to establish a comprehensive vision and reasonably arrange and allocate what they want to do [ 65 ]. Therefore, people with far MTT ability focus on the task at hand when adopting active procrastination.

We also found a positive correlation between past and future MTT distances ( p  < 0.001), indicating that people with far MTT would travel farther in both past and future orientations. In addition, Study 2 found that regardless of past and future orientations, people with far MTT are more positive toward procrastination. In Study 1, the priming effects of past and future temporal words showed similar tendencies, indicating that MTT may have a common mechanism in the two orientations. The results of Study 2 indicated it’s reasonable and feasible to comprehensively consider the two temporal orientations of MTT as a whole ability of time perception.

General discussion

From the perspective of social psychology, people’s MTT ability is highly correlated with their social cognitive ability [ 58 ]. The language people use on social platforms reflects what they are thinking about and how they organize and analyze the environment [ 69 ]. Unlike self-report surveys and lab experiments, language is a natural and reliable mode for people to translate their thoughts into records that others can understand [ 70 ]. Psychologists have recently explored people’s cognitive abilities through the text analysis of user-generated content (UGC) [ 71 ].

Unlike previous studies that mainly adopted surveys and lab experiments to explain the cognitive characteristics of a person’s MTT ability, we explored the difference in text representation and emotional expression between users with different MTT abilities through text analysis. The findings of Study 1 support the conclusions of CLT and other related work that temporal distance influences people’s cognition and behavior patterns. Furthermore, Study 2 showed that users with different MTT distances have different emotional valances toward procrastination. This finding is intriguing because it implies that how people cognitively engage with time influences how they cognitively engage with social events [ 72 ]. This means that, for the same event, people with different MTT abilities would adopt different cognition styles and express different emotions.

In contrast to previous studies that focused on one orientation of the time perspective, we explored the users’ MTT in both past and future orientations. Consistent with previous findings that an individual’s past and future MTT shared some common neural networks and cognitive structures [ 73 ], we found that the users’ past and future MTT distances positively correlated. People’s past and future MTT orientations are influenced by their inner instructions in a similar way and generate external versus internal events as well as positive versus negative events at different temporal distances from the present [ 26 ]. Brain imaging studies have shown a great amount of overlapping neural activity while visualizing personal past versus future experiences [ 74 ]. Therefore, our findings support the above conclusions.

Finally, this study has several limitations as well as future directions. First, the gender ratio of the sample data was unbalanced, with a higher proportion of female than male users (approximately: Study 1—men: women = 1:4; Study 2—men: women = 1:5). In fact, women are more likely to use social networking sites [ 75 ] and express opinions and emotions in online social platforms than males [ 76 ].Therefore, future studies could explore the MTT effect by gender. Second, as age is sensitive and private information for some people, some users’ age information was not provided or randomly given (e.g., 120 years old). Thus, we could not analyze the users’ MTT distances by age group. Future studies could collect data with more valid age information and explore the MTT abilities by age group. Although Weibo is the largest social media platform in China, the present findings should be further examined considering the possible differences in some personality traits between Weibo users and non-users. Third, we constructed a Chinese temporal lexicon based on an English temporal lexicon. However, owing to semantic fuzziness in the Chinese language, we could not recognize all the temporal expressions. Therefore, future studies could optimize the Chinese temporal lexicon used in this study by using advanced text mining algorithms.

Conclusions

This study explored the text representation and emotional expression of users with different MTT distances by analyzing their original texts in Sina microblogs. Study 1 found the users’ text representation related to their MTT abilities through text analysis. Specifically, compared to users with near MTT, those with far MTT provided longer text length, were more involved in observer perspectives, and had a stronger priming effect of temporal words. As for emotional expression, the whole text showed no significant difference between users with far and near MTTs. Study 2 examined the relationship between users’ emotional valences toward procrastination and their MTT abilities. It found that users with far MTT were more positive toward procrastination than those with near MTT.

Availability of data and materials

The data can be made available upon reasonable request from the corresponding author.

Berntsen D, Jacobsen AS. Involuntary (spontaneous) mental time travel into the past and future. Conscious Cogn. 2008;17:1093–104.

Article   PubMed   Google Scholar  

D’Argembeau A, Renaud O, Van Der Linden M. Frequency, characteristics and functions of future-oriented thoughts in daily life. Appl Cogn Psychol. 2011;25:96–103.

Article   Google Scholar  

Berg JJ, Gilmore AW, Shaffer RA, McDermott KB. The stability of visual perspective and vividness during mental time travel. Conscious Cogn. 2021. https://doi.org/10.1016/j.concog.2021.103116 .

Fortunato VJ, Furey JT. The theory of MindTime: the relationships between thinking perspective and time perspective. Pers Individ Dif. 2010;48:436–41.

Suddendorf T, Corballis MC. Mental time travel and the evolution of the human mind. Genet Soc Gen Psychol Monogr. 1997;123:133–67.

PubMed   Google Scholar  

Suddendorf T, Corballis MC. The evolution of foresight: What is mental time travel, and is it unique to humans? Behav Brain Sci. 2007. https://doi.org/10.1017/S0140525X07001975 .

D’Argembeau A, Van Der Linden M. Phenomenal characteristics associated with projecting oneself back into the past and forward into the future: Influence of valence and temporal distance. Conscious Cogn. 2004;13:844–58.

Spreng RN, Levine B. The temporal distribution of past and future autobiographical events across the lifespan. Mem Cogn. 2006;34:1644–51.

Coelho S, Guerreiro M, Chester C, Silva D, Maroco J, Paglieri F, et al. Mental time travel in mild cognitive impairment. J Clin Exp Neuropsychol. 2019;41:845–55.

Breeden P, Dere D, Zlomuzica A, Dere E. The mental time travel continuum: on the architecture, capacity, versatility and extension of the mental bridge into the past and future. Rev Neurosci. 2016;27:421–34.

Suddendorf T, Busby J. Making decisions with the future in mind: developmental and comparative identification of mental time travel. Learn Motiv. 2005;36:110–25.

Fortunato VJ, Furey JT. The theory of MindTime: the relationships between future, past, and present thinking and psychological well-being and distress. Pers Individ Dif. 2011;50:20–4.

Trope Y, Liberman N. Temporal construal. Psychol Rev. 2003;110:403–21.

Trope Y, Liberman N. Construal-level theory of psychological distance. Psychol Rev. 2010;117:440–63.

Article   PubMed   PubMed Central   Google Scholar  

Wyer NA, Hollins TJ, Pahl S. Remembering social events: a construal level approach. Personal Soc Psychol Bull. 2022;48:1238–54.

Liberman N, Trope Y. The psychology of transcending the here and now. Science. 2008;322:1201–5.

Peetz J, Wilson AE, Strahan EJ. So far away: the role of subjective temporal distance to future goals in motivation and behavior. Soc Cogn. 2009;27:475–95.

Halamish V, Liberman N. How much information to sample before making a decision? It’s a matter of psychological distance. J Exp Soc Psychol. 2017;71:111–6.

Hodgins DC, Engel A. Future time perspective in pathological gamblers. J Nerv Ment Dis. 2002;190:775–80.

Liu W, Aaker J. Do you look to the future or focus on today? The impact of life experience on intertemporal decisions. Organ Behav Hum Decis Process. 2007;102:212–25.

Ashkanasy NM, Gupta V, Mayfield MS, Trevor-Roberts E. Future orientation. New York: Sage Publications; 2004.

Google Scholar  

Levasseur L, Shipp AJ, Fried Y, Rousseau DM, Zimbardo PG. New perspectives on time perspective and temporal focus. J Organ Behav. 2020;41:235–43.

Thorstad R, Wolff P. A big data analysis of the relationship between future thinking and decision-making. Proc Natl Acad Sci. 2018;115:E1740–8.

Chang Y, Chien C, Shen LF. Telecommuting during the coronavirus pandemic: future time orientation as a mediator between proactive coping and perceived work productivity in two cultural samples. Pers Individ Dif. 2021. https://doi.org/10.1016/j.paid.2020.110508 .

Baumeister RF, Hofmann W, Summerville A, Reiss PT, Vohs KD. Everyday thoughts in time: experience sampling studies of mental time travel. Personal Soc Psychol Bull. 2020;46:1631–48.

Berntsen D, Bohn A. Remembering and forecasting: the relation between autobiographical memory and episodic future thinking. Mem Cogn. 2010;38:265–78.

Hamilton J, Cole SN. Imagining possible selves across time: characteristics of self-images and episodic thoughts. Conscious Cogn. 2017;52:9–20.

Liberman N, Sagristano MD, Trope Y. The effect of temporal distance on level of mental construal. J Exp Soc Psychol. 2002;38:523–34.

Bhatia S, Walasek L. Event construal and temporal distance in natural language. Cognition. 2016;152:1–8.

Dai XT. A Multi dimensional Approach to Temporal Distance in Language. MD Thesis, Zhejiang University. 2018.

Kohlschütter C, Fankhauser P, Nejdl W. Boilerplate detection using shallow text features. In: WSDM 2010 - Proceedings of the 3rd ACM International Conference on Web Search and Data Mining. 2010. p. 441–50.

Renate AS, Wu NQ, Yan J. How to measure and predict the readability of foreign language works? Foreign Lang Teach Abroad. 1983;3:36–8.

Mikk J, Kukemelk H. The relationship of text features to the level of interest in science texts. Trames. 2010;14:54–70.

Xu X, Li J. Concreteness/abstractness ratings for two-character Chinese words in MELD-SCH. PLoS ONE. 2020;15(6): e0232133.

Rice HJ. Seeing where we’re at: a review of visual perspective and memory retrieval. In: The act of remembering: toward an understanding of how we recall the past. 2010. p. 228–58.

Pronin E, Ross L. Temporal differences in trait self-ascription: when the self is seen as an other. J Pers Soc Psychol. 2006;90:197–209.

Piolino P, Desgranges B, Clarys D, Guillery-Girard B, Taconnat L, Isingrini M, et al. Autobiographical memory, autonoetic consciousness, and self-perspective in aging. Psychol Aging. 2006;21:510–25.

Piolino P, Desgranges B, Manning L, North P, Jokic C, Eustache F. Autobiographical memory, the sense of recollection and executive functions after severe traumatic brain injury. Cortex. 2007;43:176–95.

Rice HJ, Rubin DC. I can see it both ways: first- and third-person visual perspectives at retrieval. Conscious Cogn. 2009;18:877–90.

Sutin AR, Robins RW. Phenomenology of autobiographical memories: the memory experiences questionnaire. Memory. 2007;15:390–411.

Buschman TJ, Miller EK. Top-down versus bottom-up control of attention in the prefrontal and posterior parietal cortices. Science. 2007;315:1860–4.

Libby LK, Eibach RP. Self-enhancement or self-coherence? Why people shift visual perspective in mental images of the personal past and future. Personal Soc Psychol Bull. 2011;37:714–26.

Meyer DE, Schvaneveldt RW. Facilitation in recognizing pairs of words: evidence of a dependence between retrieval operations. J Exp Psychol. 1971;90:227–34.

Trifonova IV, Adelman JS. Repeated letters increase the ambiguity of strings: evidence from identification, priming and same-different tasks. Cogn Psychol. 2022;132:101445.

Ikier S, Duman Ç, Gökel N. Phenomenological experience of mental time travel with a counterpart self. Appl Cogn Psychol. 2022;36:536–47.

Sharot T, Riccardi AM, Raio CM, Phelps EA. Neural mechanisms mediating optimism bias. Nature. 2007;450:102–5.

Wang J, Zhou Y, Zhang W, Evans R, Zhu C. Concerns expressed by Chinese social media users during the COVID-19 pandemic: content analysis of Sina Weibo microblogging data. J Med Internet Res. 2020. https://doi.org/10.2196/22152 .

Sharp CA. Qualitative research and evaluation methods (3rd ed.). Evaluation Journal of Australasia. 2003;3:60–1.

Wu M, Li W, Lu Q, Li B. CTEMP: A Chinese temporal parser for extracting and normalizing temporal information. In: Lecture Notes in computer science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). 2005. p. 694–706.

Chang AX, Manning CD. SUTIME: a library for recognizing and normalizing time expressions. In: Proceedings of the 8th international conference on language resources and evaluation, LREC 2012. 2012. p. 3735–40.

Pennebaker JW, Chung CK, Ireland M, et al. The development and psychometric properties of LIWC2007. Austin, 2007.

Gao R, Hao B, Li H, Gao Y, Zhu T. Developing simplified Chinese psychological linguistic analysis dictionary for microblog. In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). 2013. p. 359–68.

Yuan B, Liu Y, Li H. Sentiment classification in Chinese microblogs: lexicon-based and learning-based approaches. Int Proc Econ Dev Res. 2013;68:1–5.

Fritz CO, Morris PE, Richler JJ. Effect size estimates: current use, calculations, and interpretation. J Exp Psychol Gen. 2012;141:2–18.

Coolican H. Research methods and statistics in psychology. 2nd ed. Sage: Routledge; 2019.

Kim JY. Predicting L2 writing proficiency using linguistic complexity measures: a corpus-based study. Engl Teach. 2014;69:27–51.

Rebetez MML, Barsics C, Rochat L, D’Argembeau A, Van der Linden M. Procrastination, consideration of future consequences, and episodic future thinking. Conscious Cogn. 2016;42:286–92.

Epstude K, Peetz J. Mental time travel: a conceptual overview of social psychological perspectives on a fundamental human capacity. Eur J Soc Psychol. 2012;42:269–75.

Knaus WJ. Procrastination, blame, and change. J Soc Behav Pers. 2000;15:153–66.

Chun Chu AH, Choi JN. Rethinking procrastination: positive effects of “active” procrastination behavior on attitudes and performance. J Soc Psychol. 2005;145:245–64.

Zarrin SA, Gracia E, Paixão MP. Prediction of academic procrastination by fear of failure and self-regulation. Educ Sci Theory Pract. 2020;20(3):34–43.

Kim S, Fernandez S, Terrier L. Procrastination, personality traits, and academic performance: when active and passive procrastination tell a different story. Pers Individ Dif. 2017;108:154–7.

Zanjani S, Yunlu DG, Beigh JNS. Creative procrastinators: Mapping a complex terrain. Pers Individ Dif. 2020. https://doi.org/10.1016/j.paid.2019.109640 .

Zhou M. The role of personality traits and need for cognition in active procrastination. Acta Psychol (Amst). 2019. https://doi.org/10.1016/j.actpsy.2019.102883 .

Okuda J, Fujii T, Ohtake H, Tsukiura T, Tanji K, Suzuki K, et al. Thinking of the future and past: the roles of the frontal pole and the medial temporal lobes. Neuroimage. 2003;19:1369–80.

Luxford Ethan TSFJTSJMRLFJJD. Self-regulation as a mediator of the associations between passion for video games and Weil-being. Cyberpsychol Behav Soc Netw. 2022;25:310–5.

Steel P, Taras D, Ponak A, Kammeyer-Mueller J. Self-regulation of slippery deadlines: the role of procrastination in work performance. Front Psychol. 2022. https://doi.org/10.3389/fpsyg.2021.783789 .

Abdi Zarrin S, Gracia E, Paixão MP. Prediction of academic procrastination by fear of failure and self-regulation. Educ Sci Theory Pract. 2020;20:34–43.

Sun Z, Ji Z, Zhang P, Chen C, Qian X, Du X, et al. Automatic labeling of mobile apps by the type of psychological needs they satisfy. Telemat Inform. 2017;34:767–78.

Tausczik YR, Pennebaker JW. The psychological meaning of words: LIWC and computerized text analysis methods. J Lang Soc Psychol. 2010;29:24–54.

Geng R, Chen J. The influencing mechanism of interaction quality of UGC on consumers’ purchase intention–an empirical analysis. Front Psychol. 2021. https://doi.org/10.3389/fpsyg.2021.697382 .

Soderberg CK, Callahan SP, Kochersberger AO, Amit E, Ledgerwood A. The effects of psychological distance on abstraction: two meta-analyses. Psychol Bull. 2015;141:525–48.

Rasmussen AS, Berntsen D. The reality of the past versus the ideality of the future: emotional valence and functional differences between past and future mental time travel. Mem Cogn. 2013;41:187–200.

Addis DR, Wong AT, Schacter DL. Remembering the past and imagining the future: common and distinct neural substrates during event construction and elaboration. Neuropsychologia. 2007;45:1363–77.

Hargittai E. Whose space? Differences among users and non-users of social network sites. J Comput Commun. 2007;13:276–97.

Zhang Y, Dang Y, Chen H. Research note: examining gender emotional differences in Web forum communication. Decis Support Syst. 2013;55:851–60.

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This work was supported by the National Natural Science Foundation of China (Grant Number 32200885), the Natural Science Foundation of Zhejiang Province (Grant Number LQ22C090006) and the Social Science Pre-Research Foundation of Zhejiang University of Technology (Grant Number GZ22191080016).

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Lane reopens following multi-vehicle accident on I-10

BALDWIN COUNTY, Ala. ( WALA ) - The Alabama Law Enforcement Agency has released a statement regarding an accident that happened Saturday afternoon.

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How Often Should You Replace Your Pillows?

As with mattresses , pillows don’t have a hard-and-fast expiration date, so the only truly honest answer for when to replace them is a resounding “It depends.” The basic rule of thumb — and what I’ve heard over and over from experts — is to replace your pillows every two years, especially if you have asthma, a dust-mite allergy, or sensitive skin. But a well-maintained pillow can certainly last longer if it’s still supportive enough that you aren’t waking up with aches and pains. Whether it has been two years or not, here are the main things to consider before buying a new pillow .

Above all, make sure your pillow is supporting your head and neck

Beyond comfort, the main reason for sleeping with a pillow at all is to keep your head and neck in a neutral alignment with your spine. And because you sleep on it for hours every night, your pillow will inevitably wear out over time. If you’re dealing with any kind of neck pain , it may be a sign that your pillow isn’t doing its job, especially if it has gotten too flat or compressed after years of use, says chiropractor Dr. Jordan Duncan .

To test the supportiveness of your pillow, you can try what Dr. Joshua Tal , a psychologist who specializes in sleep disorders, calls the “shoe test,” which was created by Dr. Michael Breus , a clinical psychologist and founder of the Sleep Doctor wellness company. “What you do is you fold your pillow in half, put a shoe on the back side of the pillow, and then let go of the pillow,” explains Tal. “If the pillow folds back into shape and flings the shoe off of it, you’re good. If it doesn’t, it’s kind of lost its ability to hold your head up properly.” (Be sure to use a substantial shoe and not, say, a flip-flop.)

Tal also mentioned another test he uses with his patients: “I advise clients to stand up against the wall as if you were sleeping — so a back sleeper would stand with their back to the wall; a side sleeper would stand with their side to the wall — and then rest your head on the wall and notice how far it has to move to do that,” he says. “Then put your pillow in between where you’re resting your head and see if you’re standing up straight. That’s the key: You should be standing up straight if you have a good pillow.”

If your pillow looks or feels very lumpy — a possibility for down , down-alternative, or shredded-foam pillows — that may also be a sign it’s losing some of its structural integrity.

Pillows can get pretty gross over time

Because you’re essentially smashing your face and hair into them every night, and because they’re not always washing machine–friendly, pillows tend to need replacing more often than other bedding, solely from a hygiene perspective. The main concerns are asthma , allergies, and skin: According to Melanie Carver, chief mission officer of the Asthma and Allergy Foundation of America (AAFA), the fabric of a pillow is permeable to dust mites, and after two years of use, your pillow can be 10 percent dead dust mites and their droppings. Icky, yes, as well as particularly bad for people with dust-mite allergies . Other potential allergy triggers like pet dander and mold can also be absorbed by your pillow and cause symptoms to flare. If you have asthma, allergens in your pillow can make your symptoms worse.

Pillows can also trap dirt, oil, and dead skin cells, and according to board-certified dermatologist Dr. Annie Chiu , all of these can be irritants for your skin — even if you are diligently washing your pillowcase . Chiu explains that a pillowcase won’t act as a complete barrier, so irritants in your pillow can still cause trouble, especially if you have sensitive skin or persistent acne .

Yellowing or stains can be an indicator that your pillow has absorbed lots of moisture — from sweat, drool, skin-care or hair-care products, or going to sleep with wet hair — and needs to be replaced.

How important is the “every two years” rule, really?

If you’re balking at the idea of replacing your pillow every two years, you’re not alone. Two years is what AAFA officially recommends — and just about every expert I spoke to echoed it. But my own informal polling of friends and colleagues and a deep dive into Reddit discussions on how often to replace pillows suggest many people aren’t replacing their pillows as frequently as every two years, no matter what the experts say. Ultimately, while you may need to replace basic fiber pillows even sooner than two years because they may flatten more quickly, pillows made of sturdier materials can last much longer. You should mainly be mindful of whether issues like asthma, allergies, or neck pain are getting worse the longer you have your pillow.

Keeping your pillow as clean as possible will help it last as long as possible

Carver told me that washing your pillow once a month in hot water (130 degrees Fahrenheit) can help remove allergens like dust mites. However, this advice only really applies to pillows that are totally washable — and in my experience, the majority of them are not. Synthetic-fill down-alternative pillows and down pillows are the most likely to be washing machine–friendly, so if you have allergies or asthma and want to follow Carver’s guidance, you may want to seek out those fill types.

Most memory-foam and latex pillows have only a washable cover since the foam itself usually cannot be washed. And a 2013 paper from the American Academy of Allergy, Asthma & Immunology (AAAAI) found that foam pillows are just as susceptible to dust mites as feather pillows, so it’s still important to wash your pillow covers regularly. Memory-foam pillows are often recommended as allergy-safe since the foam itself isn’t a food source to dust mites the way natural materials like feathers are, but like other types of synthetic pillows, foam can still collect your dead skin, which feeds the mites.

You can sometimes clean memory foam by sprinkling it with baking soda and vacuuming it, as recommended by cleaning expert Jolie Kerr, to help remove dust mites or dead-skin buildup. And while some experts (including Kerr) say it’s possible to clean memory foam in water as long as you hand-wash it, I have attempted this and forewarn you that it will take a long time for the foam to dry. (This means you may be risking mold or mildew, so proceed with caution and make sure you’ve got a well-ventilated space and a fan to speed up the process.) For latex pillows, you can follow a similar process as with memory foam. Latex manufacturer Turmerry recommends vacuuming the latex and then spot-cleaning with a damp cloth and mild detergent.

Consider a pillow protector

In addition to cleaning, Carver also recommends using an Asthma & Allergy Friendly–certified pillow protector to keep out dust mites and other allergens in the first place — they’re like mattress protectors for your pillow that go around the pillow before you add your actual pillowcase. But even with these precautions, AAFA still recommends replacing your pillow every two years.

Additional reporting by Hilary Reid and Chloe Anello .

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Their AI works as a force-multiplier for teams at major firms like PwC and Allen & Overy. While it won’t replace human attorneys altogether, Harvey could make big law much more efficient.

Pendulum Therapeutics: Super Probiotics for Diabetes?  

This biotech startup is doing cutting-edge work with “good” gut bacteria to develop novel treatments and probiotics. Their leading product has been clinically shown to help manage type 2 diabetes by restoring a healthy microbiome.

With big-name backers like Sequoia Capital and endorsements from celebrities like Halle Berry, Pendulum could transform probiotics from dietary supplements into FDA-approved drugs.

Bobbie: The Challenger Taking on Baby Formula Giants

When the 2022 baby formula shortage hit, organic upstart Bobbie was perfectly positioned. By selling direct to consumers and building rabid loyalty, Bobbie managed to steal market share from massive incumbents like Abbott and Nestlé.

With revenue projected to soar 97% to $165 million in 2024, this could be the David that takes down Goliath in formula.  

GlossGenius: Software That Beautifies Salon Operations

Anyone who’s gotten their hair or nails done knows that small salons and spas have big operational headaches like scheduling, payment processing and inventory management. GlossGenius digitizes and automates all those tasks through easy cloud-based software. By beautifying the back-office, they’re freeing up salon owners to focus on beautifying their customers.

Those are just seven potential stars from the latest Next Billion Dollar startup list. Of course, every new business is a risk, but one of these companies could just become the next Uber, Airbnb or other household name. Getting in early has its rewards for investors who spot the unicorns.

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This article originally appeared on GOBankingRates.com : The 7 Next Billion-Dollar Startups of 2024 That You Need To Know About

The views and opinions expressed herein are the views and opinions of the author and do not necessarily reflect those of Nasdaq, Inc.

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Checked Bag Fees: Airline-by-Airline Guide for US Travel in 2024

C hecking a bag is something frequent flyers try mightily to avoid. It adds time, extra logistics, and cost to air travel. When little ones come along, however, packing light just isn’t always possible. Flying with a baby or toddler requires gear! The time comes for traveling parents to face the reality of needing to check a bag…or two.

So just how much will checked bags set you back? Checked bag fees vary from airline to airline. It is important to know what the airlines charge before booking your flight. You need to consider the costs as you are comparing ticket prices between different carriers to get the best overall deal. This is especially true for families, because bag fees can add up quickly with multiple people. And with many major airlines increasing checked bag fees again in early 2024, the costs grow ever higher.

Last updated : March 6, 2024. (Updated to include increased bag fees on Delta Airlines. Note that American, United, and Alaska all increased their fees in 2024 a few weeks prior. Those increased fees are reflected below.)

Checked Bag Fees on Every U.S. Airline

So just how much do airlines within the United States charge for checked bag fees?

The only major US airline that doesn’t charge checked baggage fees at all is Southwest Airlines . All of the legacy carriers ( United , American, Delta, Alaska, etc.) tend to charge right about the same for their checked bags – approximately $35 for the first bag as of March 2024.

The ultra-low cost carriers (Frontier, Allegiant, Spirit, etc.) have pricier bag fees that are more opaque. Most of these airlines charge based on variables like flight distance or how early you pre-pay for a bag. Some of these airlines have bag fee check tools on their website, so I highly recommend going there first for an estimate before you waste time going through multiple steps in the booking process.

Related: What are the Best Airlines to Fly with Kids in the USA?

Here’s a chart showing the current bag check fees for domestic travel on all the major US carriers.

Note that most airlines classify a standard checked bag as one weighing up to 50 lbs. The standard dimensions for checked bags on most airlines are normally 62 inches maximum, which is total length + width + depth, allowing for multiple bag shapes. A few airlines, however, have even more restrictive weights and dimensions, so I’ve noted those rules below.

Special Checked Bag Fee Rules To Watch Out For

As the chart makes clear, there are lots of asterisks and fine print in the world of checked bag fees. Here are some special bag check situations and rules to look out for so you aren’t surprised and what may cost you more (or conversely, what you might not expect to be free!).

• Pre-Purchased Bags : Quite a few airlines (in particular low cost carriers) charge you more based on when you pay for your checked bag. If you book a checked bag when you purchase a ticket, you’ll often pay quite a bit less. Sometimes there is an intermediate price if you add a bag after you’ve book, such as at online check-in. Whatever you do, never ever wait to pay until you get to the airport ticket counter. That is when prices are highest – sometimes several times more!
• Car Seats and Strollers : Believe it or not, US domestic carriers do not charge anything for checking a stroller and/or car seat . That’s a nice and rare break for traveling parents. Note though that at least one airline doesn’t allow you to gate check strollers that are either non-folding or that exceed 20 pounds (see tips for flying American Airlines with a stroller ).
• Overweight/oversize bags : Oversized or overweight bags or special equipment like skis or golf clubs can really cost you. Most airlines consider any bag over 50 pounds to be overweight (and >62 inches in total dimension to be oversized). But there are a couple of tricky airlines that set the maximum at 40 pounds (ahem, Frontier & Spirit). This maximum is easy to exceed packing a standard sized suitcase with a reasonable amount in it. What airlines charge for oversize bags varies wildly – even more than regular checked bag fees. So check the fine print closely. The chart below summarizes the major overweight/oversize fee rules for each airline.

Ways to Avoid Checked Bag Fees

Although most airlines charge checked bag fees these days, there are increasingly a number of ways to avoid them or at least minimize them. Here are all the strategies my family and I have used to control our bag check costs over the last decade and a half of flying with kids.

Related: 7 Ways to Avoid Airline Fees

Elite Status

If you have elite status on an airline, you probably get at least one free bag (or more), usually for each person traveling on the same reservation with the elite member. Double check the program benefits for the airline you are flying on, however, because airlines offer different benefits at each elite status level and are constantly tweaking these rules in small ways.

Airline Co-Branded Credit Card

If you have one of the airlines’ credit cards, you (and others booked under the same reservation) usually get a free bag if you have booked your tickets with that credit card. Many of these airline credit cards have annual fees of about $100 a year, so if your family checks two bags on a roundtrip vacation on that airline once a year, you’ll at least break even on the fees.

Credit Card Airline Fee Credit

Some credit cards (especially those with higher annual fees targeted at a traveling demographic) come with perks like an airline fee credit. You may be able to charge bag fees to that card and have some or all of the fees refunded. My husband and I have had several cards the past few years that have this benefit that we’ve used to cover fees on airlines we don’t fly as often. These cards aren’t affiliated with a particular airline program but you may have to select your preferred airline (often once a year in January) in order to access the credit.

Fare Types that Include Free Checked Bags

A number of airlines have fare types or bundles that come with one or more extras. One of the included perks may be a checked bag or two. You’ll of course pay more for these fare types than the cheapest economy ticket, but there may be savings in the overall bundling, especially if you need some of the other perks too like seat assignments or a larger carry on bag.

Premium Cabins

If you are lucky enough to be traveling on a business class or first class ticket, you usually will not have to worry with bag fees. If you are booking these kinds of fares with cash though, you’ll nearly always be paying much more for these cabins, so the “savings” aren’t necessarily savings. Often first and business class passengers are able to check bags that weigh more than the standard sizes (sometimes 70 pounds instead of a 50 pound maximum).

Last but certainly not least, families can often save on bag fees just by packing strategically. Don’t underestimate the savings to be had just by sharing bags or smartly distributing your packed items between and among checked vs. carry on bags, based upon what the airline charges for each.

For example, some legacy carriers like American or Delta don’t charge for carry ons, even for passengers purchasing basic economy tickets. Families may want to carry on more bags when flying those airlines to save on checked bag fees.

Conversely, some ultra low cost carriers charge more for a roll-aboard carry on than a larger checked bag. Families may save more packing clothes for everyone in one or two checked bags instead of bringing larger carry ons at all.

The post Checked Bag Fees: Airline-by-Airline Guide for US Travel in 2024 appeared first on Trips With Tykes .

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Tracking the Remnants of Alberto

By William B. Davis, Madison Dong, Judson Jones, John Keefe, and Bea Malsky

The remnants of Alberto were over Mexico Thursday afternoon Mexico Central Time, according to the National Hurricane Center.

The system had sustained wind speeds of 30 miles per hour.

Where did it rain?

Tropical cyclones typically drop large amounts of rain along and near the storm's path. The slower and more significant the storm’s size, the higher the likelihood of higher rainfall totals. Some storms can drop well over 30 inches of rainfall, like when Hurricane Harvey dropped over 60 inches near Nederland, Texas, in 2017.

What did the storm look like from above?

Satellite imagery can help determine the strength, size and cohesion of a storm. The stronger a storm becomes, the more likely an eye will form in the center. When the eye looks symmetrical, that often means the storm is not encountering anything to weaken it.

Alberto is the first named storm to form in the Atlantic in 2024.

In late May, the National Oceanic and Atmospheric Administration predicted that there would be 17 to 25 named storms this year, an above-normal amount.

This season follows an overly active year, with 20 named storms — including an early storm later given the official name of “Unnamed.” It was the eighth year in a row to surpass the average of 14 named storms. Only one hurricane, Idalia, made landfall in the United States.

Typically, the El Niño pattern that was in force last season would have suppressed hurricanes and reduced the number of storms in a season. But in 2023, the warm ocean temperatures in the Atlantic blunted El Niño’s usual effect of thwarting storms.

The warm ocean temperatures that fueled last year’s season returned even warmer at the start of this season, raising forecasters’ confidence that there would be more storms this year. The heightened sea surface temperatures could also strengthen storms more rapidly than usual.

To make matters worse, the El Niño pattern present last year is also diminishing, most likely creating a more suitable atmosphere for storms to form and intensify.

Hurricanes need a calm environment to form, and, in the Atlantic, a strong El Niño increases the amount of wind shear — a change in wind speed and/or direction with height — which disrupts a storm's ability to coalesce. Without El Niño this year, clouds are more likely to tower to the tall heights needed to sustain a powerful cyclone.

Sources and notes

Tracking map Source: National Hurricane Center | Notes: The map shows probabilities of at least 5 percent. The forecast is for up to five days, with that time span starting up to three hours before the reported time that the storm reaches its latest location. Wind speed probability data is not available north of 60.25 degrees north latitude.

Wind arrivals table Sources: New York Times analysis of National Hurricane Center data (arrival times); U.S. Census Bureau and Natural Earth (geographic locations); Google (time zones) | Notes: The table shows predicted arrival times of damaging, 58 m.p.h. winds in select cities when there is a chance such winds could reach those locations. “Earliest possible” times are times when, if damaging winds do arrive, there is at least a 10 percent chance they will arrive at the time shown. “Most likely” times are times when, if damaging winds do arrive, there is an equal chance that such winds will arrive before and after the time shown.

Radar map Source: National Oceanic and Atmospheric Administration via Iowa State University | Notes: These mosaics are generated by combining the 130+ individual RADARs that comprise the NEXRAD network.

Storm surge map Source: National Hurricane Center | Notes: The actual areas that could become flooded may differ from the areas shown on this map. This map accounts for tides, but not waves and not flooding caused by rainfall. The map also includes intertidal areas, which routinely flood during typical high tides.

Satellite map Source: National Oceanic and Atmospheric Administration| Notes: Imagery only updates between sunrise and sunset of the latest storm location.

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