One Counterintuitive Way to Forget Unwanted Memories

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“Try to pose for yourself this task: not to think of a polar bear, and you will see that the cursed thing will come to mind every minute.”
— Fyodor Dostoevsky, (Winter Notes on Summer Impressions, 1863)

You can try Daniel Wegner’s famous “white bear” experiment on successful though suppression right now: As you’re reading this post, try NOT to think about this polar bear image.
Source: cocoparisienne/Pixabay

In the 1980s, Daniel Wegner (1948-2013)—who was a pioneering social psychologist at Harvard University best known for his groundbreaking research on thought suppression—stumbled upon the above-mentioned Dostoevsky “polar bear” quote, which inspired him to dedicate the rest of his life to deconstructing the best way to deliberately forget about something.

As Dostoevsky writes in Winter Notes on Summer Impressions, “Try to pose for yourself this task: not to think of a polar bear, and you will see that the cursed thing will come to mind every minute.” We all know from daily life experience that Dostoevsky is right: The more you try to forget about something or suppress a visual image in your mind, the more you think about that topic or conjure up the ‘vetoed’ image in your mind’s eye.

Daniel Wegner was so intrigued by Dostoevsky’s “polar bear” hypothesis that he designed a psychological experiment to test this 19th-century observation in a 20th-century laboratory setting.

During Wegner’s first thought-suppression study, participants were explicitly instructed not to think about a white bear for five minutes as they verbalized stream of consciousness thoughts. Throughout these five minutes, every time someone (who had been told, “don’t think about white bears!“) thought about a white bear, he or she was instructed to ring a bell. Most study participants rang the bell multiple times during the five-minute test.

In a follow-up experiment, Wegner and colleagues instructed another group of participants to only think about white bears for five minutes. When the researchers compared the number of “thought tokens” relating to white bears from both groups, Wegner et al. found that being told not to think about white bears made the unwanted thought more omnipresent in people’s minds.

The main takeaway from the initial “white bear” thought-suppression experiments: The more people tried not to think about white bears; the more they thought about white bears. In 1987, Wegner published these findings in a paper, “Paradoxical Effects of Thought Suppression,” which is credited with kickstarting the modern-day field of thought-suppression research.

Wegner and co-authors summed up their findings on the paradox of trying to suppress thoughts about white bears: “These observations suggest that attempted thought suppression has paradoxical effects as a self-controlstrategy, perhaps even producing the very obsession or preoccupation that it is directed against.”

A Million-Dollar Thought Suppression Question: What Is the Best Way to Stop Thinking Unwanted Thoughts?

Throughout the late-20th century, Wegner fine-tuned his “Ironic Process of Mental Control” theory. By the dawn of this century, it became clear to Wegner that people were hungry for some take-home advice based on the paradoxical findings of his “white bear” experiments. I am one of these people. Anecdotally, everyone reading this probably has a specific unwanted memory or something you tend to ruminate about that you’d like to think about less via successful thought suppression.

In 2011, Wegner gave a presentation at the American Psychological Association’s annual convention that laid out five specific strategies he recommended for helping to “suppress the white bears.” These include:

  1. Pick an absorbing distractor and focus on that instead
  2. Try to postpone the thought
  3. Cut back on multitasking
  4. Meditation and mindfulness
  5. Exposure

Wegner’s fifth recommendation of “exposure” is based on the counterintuitive hypothesis that if you force yourself to consciously focus attention (for a brief period) on thinking about something you’re ultimately trying to forget, the unwanted thought is less likely to pop into your mind at a later date. “This [exposure] is painful,” Wegner said in a 2011 APA statement, “but it can work.”

Although Wegner’s work on thought suppression wasn’t neuroscience-based, recently 21st-century, state-of-the-art fMRI research from the University of Texas at Austin reaffirmed that exposure (purposely thinking about unwanted memories) may, in fact, be the most effective way for someone’s brain to forget about proverbial “white bears.”

Successful Thought Suppression May Require More (Not Less) Attention to Unwanted Memories

A new fMRI-based study on successful thought suppression, “More Is Less: Increased Processing of Unwanted Memories Facilitates Forgetting,” was published today in the Journal of Neuroscience. This research was conducted by first author Tracy Wang of UT Austin along with senior author Jarrod Lewis-Peacock.

Notably, Wang and her colleagues found that successfully discarding specific information or unwanted memories from the brain takes moremental effort than trying to retain visual images.

 Wang et al., JNeurosci (2019)
Figure 2. GLM results for forgetting success (greater activity for successful intentional forgetting relative to successful intentional remembering, P < .001, k = 237). See Table 2 for complete univariate results.
Source: Wang et al., JNeurosci (2019)

A press release from the Society of Neuroscience summed up the latest findings on successful intentional forgetting from Jarrod Lewis-Peacock’s cognitive neuroscience laboratory (The LewPeaLab) at UT Austin:

“Tracy Wang and colleagues instructed healthy young adults to remember or forget images of scenes and neutral faces. An analysis of functional resonance imaging data revealed forgotten images were associated with stronger activation of the visual cortex than remembered images. But not too strong – forgetting was most successful when this brain region was activated at moderate levels. The research provides evidence for a forgetting strategy that involves activation, rather than suppression, of unwanted information. This provides a new link between the voluntary control of visual attention and the long-term fate of memories.”

“We found a perhaps counterintuitive result that the intention to forget a memory is associated with increased memory activation of that memory as compared to the intention to remember a memory,” Wang and her co-authors stated in their paper’s conclusion. “We found that forgetting occurs more often when a memory has a moderate degree of activation (vs. too high or too low) following the instruction to forget. This highlights the contribution of an automatic memory weakening mechanism to deliberate forgetting, and it suggests an alternative strategy for successful forgetting: to weaken an unwanted memory, raise (rather than suppress) its level of activation.”

The recent fMRI-based discovery that increased processing may be required to forget unwanted memories (Wang et al., 2019) from the LewPeaLab at UT Austin advances our neuroscience-based understanding of Wegner’s ‘white bear’ observations and his iconic, “ironic process of mental control” (1994), thought suppression theory.

Now that they know there’s a sweet spot (e.g., not too much, not too little mental attention) for optimal thought suppression, future research from the LewPeaLab will focus on best practices for successfully forgetting unwanted memories. Jarrod Lewis-Peacock’s team at UT Austin recently began a neurofeedback-based study that tracks how much attention someone is giving to various types of memories

“This will make way for future studies on how we process, and hopefully get rid of, those really strong, sticky emotional memories, which can have a powerful impact on our health and well-being,” Lewis-Peacock said in a statement. “We’re learning how these mechanisms in our brain respond to different types of information, and it will take a lot of further research and replication of this work before we understand how to harness our ability to forget.”

Watch Your Thoughts For They Become Your Destiny

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“Watch your thoughts, for they become words.
Watch your words, for they become actions.
Watch your actions, for they become habits.
Watch your habits, for they become your character.
And watch your character, for it becomes your destiny.’

— Frank Outlaw

What we think, we become.

Reality is not neutral. We are always passing judgment on what happens around us. You and I can face the same event, yet will react differently — our thoughts shape our reality, not the other way around.

That’s why most people suggest we think positively — it has become an oversimplified approach to make us feel better.

“Be positive” can be terrible advice.

Telling someone who’s sad or depressed that positive thoughts will change their mental state, can be detrimental. Similarly, being overly optimistic can blind our reality.

Positive thinking is not what you think. We must embrace our whole self, not just the bright side.

The color of your soul

“The soul becomes dyed with the color of its thoughts.” — Marcus Aurelius

Our society loves black or white assessments — you are either an optimist or a pessimist.

Labels are a heavy burden — we get stuck in one place, rather than exploring our possibilities. Our self is fluid. We all have positive or negative thoughts or positive and negative moments.

Pretending to be always happy is harmful. We focus on one aspect and fail to see our blind spots. Labeling oneself as a negative person doesn’t help either — we overplay our dramas and become victims of self-pity.

Research shows that optimists perceive less stress because either they are better able to cope with adversity or because of their positive view. However, when facing severe challenges, optimists suffer a lower immune response than pessimists.

Curiously, a strong belief in hope can make optimists think they can achieve anything they want to, just by trying hard. This perfectionist view can lead to unrealistic expectations — positive thinking can’t make everything come true.

We are not our thoughts, because they are always changing. Understanding our fluid nature is critical to continue growing — we are work in progress, not a finished product.

Bad thoughts are harmful — they create more suffering. However, avoiding our negative emotions won’t make them go away.

The problem with optimism

There’s nothing wrong with negative emotions. We all have them. They are a fundamental part of who we are — emotions express our basic intelligence and energy.

Positivity is a fluid state, not a status. You are not either positive or negative. Overplaying one aspect is deceiving — you must embrace your entire self.

“In America, optimism has become almost like a cult,” the social psychologist Aaron Sackett told Psychology Today. Or, as another American psychologist added, “In this country, pessimism comes with a deep stigma.”

Optimism has become a pervasive dogma. Pessimism gets a bad rap, but positive thinking can be brutally enforced.

“It’s gotten to the point where people really feel pressure to think and talk in an optimistic way,” observes B. Cade Massey, a professor of organizational behavior.

Massey’s research shows that, when asked to forecast the outcomes of events such as a financial investment or a surgical procedure, people make overly optimistic predictions. And wish to be even more optimistic. Many of us have drunk the ‘positivity Kool-Aid’ — We believe optimism is the solution for all our problems.

I’m not advocating in favor or against optimism, but to break free from labeling ourselves. A positive approach to life requires embracing both sides rather than living in an exaggerated — positive or negative — fantasy.

Happiness is a state of mind, not something we acquire. We spend more time contemplating what’s missing in our lives rather than what we have. That’s why we suffer.

You are what you think you are

“The mind is everything. What you think you become.” ― Buddha

Connecting to your emotions allows you to respond without reacting — you don’t let judgments or preconceptions shape your behavior. Instead, you decide to explore and understand your emotions — you feed compassion and wisdom, not anger.

Your thoughts define your reality.

The problem with idealizing positive thinking is trying to hide the negativity within us. Bringing a positive spin to what happens is not enough. You must confront and accept all your emotions. And understand how they shape your version of reality.

There’s a difference between our imagined experience ‘in here’ and what’s going on ‘out there.’

As Domyo Burk said, “For me, there is no reality ‘out there,’ separate from my mind; I will never be able to perceive a thing without the involvement of my mind. And what is the use of any reality ‘out there’ that can’t ever be perceived? In a sense, reality is born as we perceive it.”

That doesn’t mean there’s no objective reality. But that our reality lies in the intersection between an object (an event) and a subject (we).

Buddhism has an interesting view of the relationship between positive mind states and reality. It acknowledges the effect of positive thinking on our subjective experience — It’s more pleasant to feel relaxed than upset. If we consciously transform the way we relate to an experience, we can change its nature.

Positive thinking is not doing something to make you feel better, but to stop fighting reality — both positive and negative.

Change your reality with positive thinking

The way we experience something is determined by what we think about it. Positive thinking is helpful. But it only works if you accept your entire reality, not just the bright side. Self-acceptance is our foundation — we can build a stronger life.

The Greek philosopher Epictetus realized this 2,000 years ago when he said, “People are disturbed, not by things, but by the principles and notions which they form concerning things. When therefore we are hindered, or disturbed, or grieved, let us never attribute it to others, but to ourselves; that is, to our own principles.”
Say a car cuts you off when you are driving on a highway. The driver was probably in a hurry and didn’t notice you. It could have caused an accident. How would you react?

It’s normal to get upset or feel attacked — your own self-concern arises, and you want to fight back. Instead, you could try to take some emotional distance and avoid reacting. Imagine you are the driver who cut someone else off. Would you like the person to get mad at you or to be patient and forgiving?

By putting ourselves in someone else’s shoes, we avoid being taken by negativity. Empathy provides room for understanding reality rather than reacting to it.

Life is full of possibilities — you can’t control what happens to you, but you can manage how you react.

Albert Ellis, the father of Rational Emotive Behavior Therapy, discovered that how we react to an event is determined mainly by our view of the incident, not what happened. He believed that people don’t just get upset but contribute to their upset-ness.

Ellis said, “Too many people are unaware that it is not outer events or circumstances that will create happiness; rather, it is our perception of events and of ourselves that will create, or uncreate, positive emotions.”

Blaming never helps; it just feeds negativity. Epictetus believed that those who are perfectly instructed would place blame neither on others nor on themselves. Being in charge of our life requires commanding our emotions.

Let your destiny define your thoughts

The mind is an interesting, powerful ally — mindfulness helps us become more familiar with ourselves.

According to Thich Nhat Hanh, accepting our emotions is key to practice mindfulness correctly: “In mindfulness, one is not only restful and happy but alert and awake. Meditation is not evasion; it is a serene encounter with reality.”

The Vietnamese monk and peace activist believes that many of us have the wrong idea about what happiness is. We think that we need to be positive all the time, but happiness is about being present. We appreciate the here and now.

We all need stars to help us navigate our darkest nights. Your life’s purpose provides clarity, so you don’t crash when navigating troubled waters. It helps your mind steer in the right direction. And reach your destiny.

Your life purpose should define your thoughts, not the other way around.

No matter how negative your reality, your purpose gives you the strength to keep moving forward. It provides a positive outlook. Your purpose brings meaning to your life. When you control your destiny, you control your thoughts.

As Albert Ellis said, “The best years of your life are the ones in which you decide your problems are your own. You do not blame them on your mother, the ecology, or the president. You realize that you control your own destiny.”

The most meaningful purpose of life is to be helpful, not happy.

People who are generous, who genuinely try to help others are more likely to succeed. Generosity doesn’t empty but fills your tank. As Buddha said, “Thousands of candles can be lit from a single candle, and the life of the candle will not be shortened. Happiness never decreases by being shared.”

Having a positive approach to life doesn’t mean being overly optimistic. We must become the best version of ourselves, not a fantasy. Our purpose is “to do the best we can, given a set of circumstances and our current dispositions,” as Isabelle Payette wrote here.

Our life will always have both positive and negative experiences. We can choose to add more negativity. And create more suffering. Or we can accept life as is. It’s on us to build our own heaven or hell.

— — —

Positive thinking is not magical thinking — accepting our whole self makes us more self-reliant. Embracing your negative side will help you become more patient and tolerant. It makes it easier to see the good within you and others.

Watch your thoughts because they become your destiny. Better indeed, watch your destiny, and your thoughts will help you get there.

Gustavo Razzetti is a change instigator that helps organizations lead positive change. Author, Consultant, and Speaker on team building and cultural transformation.

This article first appeared on Medium.

5 Thoughts That Are Making Your Work Day Harder Than It Needs To Be

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Whether you work in a traditional office environment or in a more freeform professional atmosphere, the way you personally frame interactions and activities in your mind contributes enormously to your overall career satisfaction. According to Inc. journalist Jessica Stillman, 5 particular thought patterns can interrupt your progress and stifle your ability to find fulfillment in any situation, including in the workplace.

Here, you’ll find the mental scripts to avoid at work and what to do instead.

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1. “It’s about me.”

To a certain extent, we as human beings take every interaction personally. That’s natural and normal. But in the workplace, it’s important to remember that your individual thoughts and feelings aren’t always central to professional discussions. So if your colleague responds to a question more brusquely than you’d like, don’t assume that she dislikes you or that you’ve done something to upset her. She may just be stressed and overworked in ways that have little or nothing to do with you. Keeping perspective on these circumstances will go a long way toward keeping you centered and focused.

2. “This has to be perfect.”

If you constantly strive for excellence at work and feel disappointed if a project turns out less-than-perfect, you may fall victim to an “all or nothing” mentality that can ultimately undermine your professional progress. Remember that there’s no such thing as a flawless triumph, and as long as you’re investing effort and resources in your job-related tasks, you’re setting yourself and your company up for success.

3. “I’m not happy, so it’s not worth it.”

In her piece, Stillman mentions the current cultural fixation on “happiness,” “wellness,” and “joy,” positing that many Americans see these emotions as the be-all-and-end-all of satisfaction and dismiss anything that doesn’t fall into those categories. However, difficult situations and challenging scenarios come with the territory of almost any professional workplace. If you can accept those not-so-fun realities and handle them with aplomb, you’ll be well-positioned for future happiness at work.

4. “Becky is right, this all stinks.”

We’ve all worked in atmospheres populated by dramatic colleagues and tactless managers. These make for a tough office climate, but telling yourself that you won’t fall victim to the negativity of others will keep you motivated and will allow you to focus on the parts of your job that bring you satisfaction.

5. “I’m too stressed to exercise/eat well/sleep more.”

When in the throes of work-related chaos, it’s easy to let your health fall by the wayside. Sleep deprivation, poor eating habits, too much caffeine…that’s all part of the deal, right? Well, it shouldn’t be. Keeping yourself as strong and physically healthy as possible positively affects every aspect of your life, including your work performance. Make these goals the priorities they deserve to be.

A version of this post previously appeared on Fairygodboss, the largest career community that helps women get the inside scoop on pay, corporate culture, benefits, and work flexibility. Founded in 2015, Fairygodboss offers company ratings, job listings, discussion boards, and career advice.

9 Ways To Free Yourself From Rumination

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Of all my symptoms of depression, stuck thoughts are by far the most painful and debilitating for me. The harder I try to move the needle from the broken record in my brain, the louder the song becomes.

Ruminations are like a gaggle of politicians campaigning in your head. Try as you might to detach from their agenda, their slogans are forefront in your mind, ready to thrust you down the rabbit hole of depression. Logic tells you they are full of bull, but that doesn’t keep you from believing what they have to say.

Ever since the fourth grade, I have been fighting obsessive thoughts. So for four decades, I have been acquiring tools for living around them, continuously trying out strategies that will deliver them to the back of my noggin. Sometimes I am more successful than others. The more severe my depression, the more pervasive the thoughts. I don’t promise you tips to get rid of them forever, but here are some ways you lessen their hold over you.

1. Distract Yourself

Distraction is an appropriate first line of defense against ruminations. If you can, divert your attention to a word puzzle, a movie, a novel, or a conversation with a friend, in order to tune out what your brain is shouting. Even a five-minute reprieve from the broken record will help your mood and energy level, allowing you to focus on the here and now. However, if you simply can’t distract yourself — and I fully realize there are times when you can’t — don’t force it. That’s only going to make you feel more defeated.

2. Analyze the Thought

Obsessions usually contain a kernel of truth, but they are almost always about something else. Understanding the root of the thought and placing it in its context can often help you to let go of it, or at least minimize the panic over what you think it’s about. For example, a friend of mine was obsessing about the size of his backyard fence. A few times a day, he knelt beside the fence with a measuring stick, fretting that it wasn’t tall enough. The obsession was never really about the fence. It was about his wife who had just been diagnosed with dementia. Scared of losing her, he exercised what control he did have over the fence.

My recent ruminations are similar. I was obsessing about a mistake I made, or a decision I made that had consequences I didn’t consider. Once I realized that my obsession was really about something that happened 30 years ago, I breathed a sigh of relief.

3. Use Other Brains

It can be extremely difficult to be objective when you’re in the heat of ruminations. The politicians are incredibly convincing. That’s why you need the help of other brains to think for you — to remind you that your rumination isn’t based in reality. If you can, call on friends who have experienced obsessive thoughts themselves. They will get it. If you don’t have any, consider joining Group Beyond Blue on Facebook. This online depression support group is full of wise people who have guided me out of ruminations many times.

4. Use Your Mantras

I have ten mantras that I repeat to myself over and over again when cursed with obsessive thoughts. First, I channel Elsa in Disney’s “Frozen” and say or sing “Let it go.” I also repeat “I am enough,” since most of my ruminations are based on some negative self-assessment — usually how I handled a certain situation.

The most powerful mantra for ruminations is “There is no danger.” Panic is what drives the obsessive thoughts and makes them so disconcerting. You believe you are literally going to die.

In his book Mental Health Through Will Training psychiatrist Abraham Low writes, “You will realize that the idea of danger created by your imagination can easily disrupt any of your functions … If behavior is to be adjusted imagination must interpret events in such a fashion that the sense of security … overbalances the sentence of insecurity.” In other words, there really is no danger.

5. Schedule Rumination Time

Sometimes a rumination is like a tantruming 2-year-old who just wants a little attention. So give it to him. Some parenting experts say by acknowledging the kid, you provoke more tantrums. However, my experience with tantruming toddlers and with ruminations is that sometimes if you turn your attention to the kid or the thought, the screaming ends. You don’t want to stay indefinitely with the thought, but sometimes you might get a reprieve by setting aside a certain amount of time for your brain to go wherever it wants. Let it tell you that you are a despicable human being and that you screwed everything up once again. When the time is up, say, “Thank you for your contribution. I need to do other things now.”

6. Lessen Your Stress

Like most people I know, the severity of my ruminations are directly proportional to the amount of stress in my life. Recently, when the stress at work and at home were off the charts, so, too, were my ruminations. My brain was literally on fire, and no technique could quiet the thoughts.

Be proactive about lessening your stress. You might not have to make the dramatic changes that I did — resigning from a job. A little tweak in your schedule to allow for some relaxation may be all you need.

7. Do a Thought Log

Take a sheet of paper and draw three columns. In the first column, record your thought and assign a percentage of how strongly you believe it. For example, “I’m never going to recover from that mistake,” 90 percent. In the second column, list the cognitive distortions associated with that thought. For example, the above example involves “mental filtering,” “all or nothing thinking,” “jumping to conclusions,” “overgeneralization” and “catastrophizing.” In the third column, write a compassionate response to the thought THAT YOU BELIEVE and a percentage.

For example, “My decision may or may not have been a mistake, but it surely isn’t the end of me, and chances are that I can learn a lesson from it that will improve my life in the future,” 90 percent. If your percentage of the compassionate statement is lower than the original thought, tweak the compassionate response until the percentage is equal or higher than the original thought.

8. Be Kind to Yourself

The most important thing you can do to relieve the anguish of these thoughts is to be kind and gentle with yourself. In her book Self-Compassion Kristin Neff, Ph.D., offers a beautiful mantra she developed to help her deal with negative emotions, a reminder to treat herself with self-compassion when discomfort arises: “This is a moment of suffering. Suffering is part of life. May I be kind to myself in this moment. May I give myself the compassion I need.”

Ruminations are, without doubt, moments of suffering. Self-compassion is your most powerful antidote.

9. Admit Powerlessness

If I have tried every technique I can think of and am still tormented by the voices inside my head, I simply cry Uncle and concede to the stuck thoughts. I get on my knees and admit powerlessness to my wonderful brain biochemistry. I stop my efforts to free myself from the obsessions’ hold and allow the ruminations to be as loud as they want and to stay as long as they want because, here’s the thing, they do eventually go away.

How the Brain Keeps Its Memories in the Right Order

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IT BEGAN ABOUT a decade ago at Syracuse University, with a set of equations scrawled on a blackboard. Marc Howard, a cognitive neuroscientist now at Boston University, and Karthik Shankar, who was then one of his postdoctoral students, wanted to figure out a mathematical model of time processing: a neurologically computable function for representing the past, like a mental canvas onto which the brain could paint memories and perceptions. “Think about how the retina acts as a display that provides all kinds of visual information,” Howard said. “That’s what time is, for memory. And we want our theory to explain how that display works.”

But it’s fairly straightforward to represent a tableau of visual information, like light intensity or brightness, as functions of certain variables, like wavelength, because dedicated receptors in our eyes directly measure those qualities in what we see. The brain has no such receptors for time. “Color or shape perception, that’s much more obvious,” said Masamichi Hayashi, a cognitive neuroscientist at Osaka University in Japan. “But time is such an elusive property.” To encode that, the brain has to do something less direct.


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Original story reprinted with permission from Quanta Magazine, an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences.

Pinpointing what that looked like at the level of neurons became Howard and Shankar’s goal. Their only hunch going into the project, Howard said, was his “aesthetic sense that there should be a small number of simple, beautiful rules.”

They came up with equations to describe how the brain might in theory encode time indirectly. In their scheme, as sensory neurons fire in response to an unfolding event, the brain maps the temporal component of that activity to some intermediate representation of the experience—a Laplace transform, in mathematical terms. That representation allows the brain to preserve information about the event as a function of some variable it can encode rather than as a function of time (which it can’t). The brain can then map the intermediate representation back into other activity for a temporal experience—an inverse Laplace transform—to reconstruct a compressed record of what happened when.

The cognitive neuroscientists Marc Howard (at left) and Karthik Shankar, now at Boston University, have devoted the better part of the past decade to developing a general mathematical framework for how the brain builds a temporal context for episodic memories.

Just a few months after Howard and Shankar started to flesh out their theory, other scientists independently uncovered neurons, dubbed “time cells,” that were “as close as we can possibly get to having that explicit record of the past,” Howard said. These cells were each tuned to certain points in a span of time, with some firing, say, one second after a stimulus and others after five seconds, essentially bridging time gaps between experiences. Scientists could look at the cells’ activity and determine when a stimulus had been presented, based on which cells had fired. This was the inverse-Laplace-transform part of the researchers’ framework, the approximation of the function of past time. “I thought, oh my god, this stuff on the blackboard, this could be the real thing,” Howard said.

“It was then I knew the brain was going to cooperate,” he added.

Invigorated by empirical support for their theory, he and his colleagues have been working on a broader framework, which they hope to use to unify the brain’s wildly different types of memory, and more: If their equations are implemented by neurons, they could be used to describe not just the encoding of time but also a slew of other properties—even thought itself.

But that’s a big if. Since the discovery of time cells in 2008, the researchers had seen detailed, confirming evidence of only half of the mathematics involved. The other half—the intermediate representation of time—remained entirely theoretical.

Until last summer.

Orderings and Timestamps

In 2007, a couple of years before Howard and Shankar started tossing around ideas for their framework, Albert Tsao (now a postdoctoral researcher at Stanford University) was an undergraduate student doing an internship at the Kavli Institute for Systems Neuroscience in Norway. He spent the summer in the lab of May-Britt Moser and Edvard Moser, who had recently discovered grid cells—the neurons responsible for spatial navigation—in a brain area called the medial entorhinal cortex. Tsao wondered what its sister structure, the lateral entorhinal cortex, might be doing. Both regions provide major input to the hippocampus, which generates our “episodic” memories of experiences that occur at a particular time in a particular place. If the medial entorhinal cortex was responsible for representing the latter, Tsao reasoned, then maybe the lateral entorhinal cortex harbored a signal of time.

The kind of memory-linked time Tsao wanted to think about is deeply rooted in psychology. For us, time is a sequence of events, a measure of gradually changing content. That explains why we remember recent events better than ones from long ago, and why when a certain memory comes to mind, we tend to recall events that occurred around the same time. But how did that add up to an ordered temporal history, and what neural mechanism enabled it?

Tsao didn’t find anything at first. Even pinning down how to approach the problem was tricky because, technically, everything has some temporal quality to it. He examined the neural activity in the lateral entorhinal cortex of rats as they foraged for food in an enclosure, but he couldn’t make heads or tails of what the data showed. No distinctive time signal seemed to emerge.

Tsao tabled the work, returned to school and for years left the data alone. Later, as a graduate student in the Moser lab, he decided to revisit it, this time trying a statistical analysis of cortical neurons at a population level. That’s when he saw it: a firing pattern that, to him, looked a lot like time.

He, the Mosers and their colleagues set up experiments to test this connection further. In one series of trials, a rat was placed in a box, where it was free to roam and forage for food. The researchers recorded neural activity from the lateral entorhinal cortex and nearby brain regions. After a few minutes, they took the rat out of the box and allowed it to rest, then put it back in. They did this 12 times over about an hour and a half, alternating the colors of the walls (which could be black or white) between trials.

What looked like time-related neural behavior arose mainly in the lateral entorhinal cortex. The firing rates of those neurons abruptly spiked when the rat entered the box. As the seconds and then minutes passed, the activity of the neurons decreased at varying rates. That activity ramped up again at the start of the next trial, when the rat reentered the box. Meanwhile, in some cells, activity declined not only during each trial but throughout the entire experiment; in other cells, it increased throughout.

Based on the combination of these patterns, the researchers—and presumably the rats—could tell the different trials apart (tracing the signals back to certain sessions in the box, as if they were timestamps) and arrange them in order. Hundreds of neurons seemed to be working together to keep track of the order of the trials, and the length of each one.

“You get activity patterns that are not simply bridging delays to hold on to information but are parsing the episodic structure of experiences,” said Matthew Shapiro, a neuroscientist at Albany Medical College in New York who was not involved in the study.

The rats seemed to be using these “events”—changes in context—to get a sense of how much time had gone by. The researchers suspected that the signal might therefore look very different when the experiences weren’t so clearly divided into separate episodes. So they had rats run around a figure-eight track in a series of trials, sometimes in one direction and sometimes the other. During this repetitive task, the lateral entorhinal cortex’s time signals overlapped, likely indicating that the rats couldn’t distinguish one trial from another: They blended together in time. The neurons did, however, seem to be tracking the passage of time within single laps, where enough change occurred from one moment to the next.

Tsao and his colleagues were excited because, they posited, they had begun to tease out a mechanism behind subjective time in the brain, one that allowed memories to be distinctly tagged. “It shows how our perception of time is so elastic,” Shapiro said. “A second can last forever. Days can vanish. It’s this coding by parsing episodes that, to me, makes a very neat explanation for the way we see time. We’re processing things that happen in sequences, and what happens in those sequences can determine the subjective estimate for how much time passes.” The researchers now want to learn just how that happens.


Howard’s mathematics could help with that. When he heard about Tsao’s results, which were presented at a conference in 2017 and published in Nature last August, he was ecstatic: The different rates of decay Tsao had observed in the neural activity were exactly what his theory had predicted should happen in the brain’s intermediate representation of experience. “It looked like a Laplace transform of time,” Howard said—the piece of his and Shankar’s model that had been missing from empirical work.

“It was sort of weird,” Howard said. “We had these equations up on the board for the Laplace transform and the inverse around the same time people were discovering time cells. So we spent the last 10 years seeing the inverse, but we hadn’t seen the actual transform. … Now we’ve got it. I’m pretty stoked.”

“It was exciting,” said Kareem Zaghloul, a neurosurgeon and researcher at the National Institutes of Health in Maryland, “because the data they showed was very consistent with [Howard’s] ideas.” (In work published last month, Zaghloul and his team showed how changes in neural states in the human temporal lobe linked directly to people’s performance on a memory task.)

“There was a nonzero probability that all the work my colleagues and students and I had done was just imaginary. That it was about some set of equations that didn’t exist anywhere in the brain or in the world,” Howard added. “Seeing it there, in the data from someone else’s lab — that was a good day.”

Building Timelines of Past and Future

If Howard’s model is true, then it tells us how we create and maintain a timeline of the past—what he describes as a “trailing comet’s tail” that extends behind us as we go about our lives, getting blurrier and more compressed as it recedes into the past. That timeline could be of use not just to episodic memory in the hippocampus, but to working memory in the prefrontal cortex and conditioning responses in the striatum. These “can be understood as different operations working on the same form of temporal history,” Howard said. Even though the neural mechanisms that allow us to remember an event like our first day of school are different than those that allow us to remember a fact like a phone number or a skill like how to ride a bike, they might rely on this common foundation.

The discovery of time cells in those brain regions (“When you go looking for them, you see them everywhere,” according to Howard) seems to support the idea. So have recent findings—soon to be published by Howard, Elizabeth Buffalo at the University of Washington and other collaborators—that monkeys viewing a series of images show the same kind of temporal activity in their entorhinal cortex that Tsao observed in rats. “It’s exactly what you’d expect: the time since the image was presented,” Howard said.

He suspects that record serves not just memory but cognition as a whole. The same mathematics, he proposes, can help us understand our sense of the future, too: It becomes a matter of translating the functions involved. And that might very well help us make sense of timekeeping as it’s involved in the prediction of events to come (something that itself is based on knowledge obtained from past experiences).

Howard has also started to show that the same equations that the brain could use to represent time could also be applied to space, numerosity (our sense of numbers) and decision-making based on collected evidence — really, to any variable that can be put into the language of these equations. “For me, what’s appealing is that you’ve sort of built a neural currency for thinking,” Howard said. “If you can write out the state of the brain … what tens of millions of neurons are doing … as equations and transformations of equations, that’s thinking.”

He and his colleagues have been working on extending the theory to other domains of cognition. One day, such cognitive models could even lead to a new kind of artificial intelligence built on a different mathematical foundation than that of today’s deep learning methods. Only last month, scientists built a novel neural network model of time perception, which was based solely on measuring and reacting to changes in a visual scene. (The approach, however, focused on the sensory input part of the picture: what was happening on the surface, and not deep down in the memory-related brain regions that Tsao and Howard study.)



But before any application to AI is possible, scientists need to ascertain how the brain itself is achieving this. Tsao acknowledges that there’s still a lot to figure out, including what drives the lateral entorhinal cortex to do what it’s doing and what specifically allows memories to get tagged. But Howard’s theories offer tangible predictions that could help researchers carve out new paths toward answers.

Of course, Howard’s model of how the brain represents time isn’t the only idea out there. Some researchers, for instance, posit chains of neurons, linked by synapses, that fire sequentially. Or it could turn out that a different kind of transform, and not the Laplace transform, is at play.

Those possibilities do not dampen Howard’s enthusiasm. “This could all still be wrong,” he said. “But we’re excited and working hard.”

Unwanted Thoughts? Don’t Try to Suppress Them

Author Article

Consider every long song you hear on the radio. How many begin or end with the lyrics, “I can’t get you out of mind”? The human brain is conditioned to obsess — its negative bias makes us worry and fret. Despite our valiant efforts to shift our thoughts, they follow us into the shower and to work meetings.

The Untamed Thought

It’s time to accept the good/bad news: Thought suppression doesn’t work. The harder you try to eliminate something from your mind, the more likely it will stalk you.

1943 study published in the Social Science Research Council Bulletin, for example, found that people instructed to avoid making color associations with stimulus words were unable to stop the associations, even when threatened with shock for doing so.

More recently, Gordan Logan and Carol Barber published a study in the Bulletin of the Psychonomic Society, detailing an experiment to determine whether a stop-signal procedure is sensitive enough to detect the presence of inhibited thoughts. Their results showed that the stop-signal can, in fact, pick up on inhibited thoughts, even when a person is immersed in a complex task.

The White Bear Study

By far the most famous and fascinating study on thought suppression was the one led by Daniel Wegner in 1987, published in the Journal of Personality & Social Psychology. Wegner, a social psychologist, wanted to test a quote he came across in Fyodor Dostoevsky’s “Winter Notes on Summer Suppression,” which said, “Try to pose for yourself this task: not to think of a polar bear, and you will see that the cursed thing will come to mind every minute.”

Wegner conducted an experiment where he asked participants to verbalize their stream of consciousness for five minutes, while not thinking of a white bear. Every time a white bear popped into their thoughts, they were to ring a bell. How many times did the participants ring a bell? On average more than once per minute. That’s a lot of bears.

They then did the same exercise but were asked to think of a white bear. Interestingly enough the group that was originally told not to think of a white bear had far more white-bear thoughts than the group that was never given the first instructions. Apparently the act of suppressing the thought in the first exercise stimulated the brains of the folks in the first group to think of white bears even more often.

Strategies for Unwanted Thoughts

From that study, Wegner went on to develop his theory of “ironic processes” that explains why it’s so hard to tame unwanted thoughts. He conceded that when we try not to think of something, part of our brain cooperates while the other part ensures the thought won’t surface, thereby causing the thought to be even more prominent. While presenting his theory to audiences across the country, people would ask him, “Then what do we do?” In response, he compiled a few strategies to tame unwanted thoughts. Among them:

  • Choose a distractor and focus on that. If you’re given two things to think about, your concentration is fractured, and will give your brain a small break from focusing on the unwanted thought. For example, think of a white bear and a zebra at the same time and see what happens.
  • Postpone the thought. Set aside an “obsession time,” whereby you allow yourself to think about the forbidden thought all you want. Theoretically, this frees up your other minutes. I found the strategy helpful for mild-to-moderate ruminations, but not with severe.
  • Cut back on multitasking. Studies consistently show that multitaskers make more mistakes. However, Wegner asserts that multitasking also leads to more unwanted thoughts. More specifically, his studies show that an increased mental load increases thoughts of death.
  • Think about it. Like the “postpone the thought” strategy, this is a form of exposure therapy where you allow yourself to face your fear in a controlled way. According to Wegner, when you allow yourself the freedom to think the thought, your brain doesn’t feel obligated to check in on removing it, and therefore doesn’t send it to your consciousness.
  • Meditation and mindfulness. Whenever possible stay in the present moment, connect with your breath, and try to calm yourself. However, don’t make the white bear angry by forcing meditation and mindfulness.

The next time a white bear or any other unwanted thought pops into your noggin, don’t fight it. Consider its soft fur, sharp claws, or clumsy run.

Thought suppression doesn’t work. May this truth set you free.