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that memory is not a video recorder [but that] it’s a constructive activity that is in many ways accurate but prone to interesting errors and distortions. It’s the constructive side of memory that is most relevant to historians.

Is it the case then that our memories constantly change every time we access them?

That certainly can happen depending on how you recount a memory. What you emphasize. What you exaggerate. What you don’t talk about. All of those things will shape and sculpt the memory for future use. Certainly the potential is there.

Research on memory shows that the more distant in time the event, the more prone to inaccuracy the memory. There are several experiments when subjects recorded impressions of an event soon afterward, then a year later and then a few years later, and the memory changed.Yes. It’s not that the information is lost but, as the memory weakens, you become more prone to incorporating other kinds of information or mixing up elements of other events. This has been seen, for example, in the study of flashbulb memories. Where were you when Kennedy was shot? Where were you when you heard about 9/11?

Isn’t there a tendency to add details or information that may make the story more convincing or interesting later?Yes. That’s more a social function of memory. It may be that you draw on your general knowledge and probable information from your memory in a social context where there may be social demands that lead you distort the memory.

What are the different memory systems?

One reasonably well accepted distinction involves episodic memory, the memory for personal experience; semantic memory, the memory for general knowledge; and procedural memory, the memory for skills and unconscious forms of memory.Those are three of the major kinds of memory and they all have different neural substrates.

Your discussion of the testimony of White House Counsel John Dean about Watergate is illuminating. There was a perception that Dean had a photographic memory and he testified in rich detail about events. Yet later studies of White House tape recordings revealed that he was often inaccurate.

He was perceived because of all the detail with which he reported events and the great confidence to be something analogous to a human tape recorder. Yet there was interesting work done by psychologist Ulric Neisser who went back and analyzed what Dean said at the hearings as compared to available information on the White House taping system and basically found many and significant discrepancies between what Dean remembered and what was actually said. He usually had the gist and the meaning and overall significance right, but the exact details were often quite different in his memory than what actually was said.

That seems to get into the area of false memories and how they present problems in the legal system.We know from DNA exonerations of people wrongfully convicted of crimes that a large majority of those cases -- one of the more recent estimates is that in the first 250 cases of 2011 DNA exonerations, roughly 70 to 75 percent of those individuals were convicted on the basis of faulty eyewitness memory.

One of the interesting recent lines of research that my lab has been involved in over the past few years has been looking at similarities between what goes on between the brain and mind when we remember past events on the one hand and imagine events that might occur in the future or might have occurred in the past. What we have found, particularly with brain scanning studies, is that you get very similar brain networks coming online when you remember past events and imagine future events, for example. Many of the same brain regions or network of structures come online, and this has helped us understand more why, for example, imagining events that might have occurred can be so harmful to memory accuracy because when you imagine, you’re recruiting many of the same brain regions as accessed when you actually remember. So it’s not surprising that some of these imagined events can actually turn into false memories under the right circumstances.

What is the difference between working memory and permanent memory?Working memory is really a temporary memory buffer where you hold onto information, manipulate information, use it, and it’s partly a gateway to long-term memory and also a buffer that you use when you’re retrieving information from long-term memory and that information temporarily resides in working memory, so to speak.

One of the points from that Ross Perot study is that his supporters often misremembered what they felt like at the time he reported he had dropped out of the race. The nature of that misremembering depended on their state at the time they were remembering and what decisions they had made about Perot in the interim affected how they reconstructed their earlier memories.Again, that makes nicely the point that our current emotions and current appraisals of a situation can feed back into our reconstruction of the past and sometimes lead us to distort our memories so that they better support our current emotions and our current selves. We’re often using memories to justify what we currently know, believe and feel.

memory doesn’t work like a video camera or tape recorder.That is the main point. Our latest thinking on this is the idea that one of the major functions of memory is to support our ability to plan for the future, to imagine the future, and to use our past experiences in a flexible way to simulate different outcomes of events.

flexibility of memory is something that makes it useful to support this very important ability to run simulations of future events. But that very flexibility might be something that contributes to some of the memory distortion we talked about. That has been prominent in the last few years in my thinking about the constructive nature of memory.

The historian Daniel Aaron told his students “we remember what’s important.” What do you think of that comment?I think that generally holds true. Certainly, again, more important memories tend to be more significant with more emotional arousal and may elicit “deeper processing”, as we call it in cognitive psychology

Research has repeatedly shown that false memories can feel incredibly real and can be multi-sensory: In some, we can hear, feel, or see things, just like in real memories. Indeed, to be considered a false memory it can't be a lie, it needs to be part of our reality.

I found that if someone has a false memory, we probably can't tell just by looking at the memory. What may be more surprising is that people also seem to be no better than chance at identifying true memories.

Source confusion. What we learn from multiple sources about the same topic can very quickly become confused.

In both studies, participants were no better than chance at spotting whether a memory was true or false

It seems people were actively relying on bad cues when listening to the memories, and somehow these cues made them worse than had they tossed a coin.

Participants watched a video of a person recounting a true emotional memory, and the same person recount a false memory. They were told "All, some, or none of the videos you are about to watch involve memories of real accounts. Your task is to identify after each video whether you think the account described actually happened or not.".

What this means is that if you already have false memories of what you have done, heard, or seen during the COVID-19 pandemic, you probably can't spot them.

This can lead to creating false memories based on source confusion, which is when we misattribute where you learned something.

During these unusual times you may want to consider implementing additional safeguards to keep your memories safe.

Co-witness contamination. We are all witnesses of this world event, witnesses who are talking to each other all the time. If the COVID-19 pandemic were a crime scene, this would be really bad news.

Sameness. Every day we hear unprecedented news or horrific medical stories. But after weeks or months of the same type of information, with a reduction in the amount of new and exciting things happening elsewhere, it gets difficult to separate this long stream of information into meaningful bits.

Too late? Already think you or someone else has false memories? Look for independent evidence. You can check the news to see when you actually went into lockdown, or whether you tweeted something about how you felt, or maybe ask a friend what you said to them. That can help establish whether you have a false memory or not.

If you want reliable memories of this highly emotional time you need to keep a journal.

Assume that those feelings, ideas, fears, beliefs, and experiences will be forgotten. People are generally bad at remembering these details later on.

Fake news. Some of the content we see online will be false or misleading.

Research has repeatedly shown that false memories can feel incredibly real and can be multi-sensory: In some, we can hear, feel, or see things, just like in real memories.

But this week new research takes this even further, and shows that false memories also look real to other people.

Both your memory of the news, and your memories of emotional events that are happening in your life are possibly being changed or contaminated.

Prevention and evidence are what you need, because it's likely that once you have a false memory, neither you nor anyone else will be able to spot it.

People believe that memory should be effortless, but their expectations for how much they should remember are totally out of whack with how much they’re capable of remembering.1

What is the most common misconception about memory?

Another misconception is that memory is supposed to be an archive of the past. We expect that we should be able to replay the past like a movie in our heads.

we don’t replay the past as it happened; we do it through a lens of interpretation and imagination.

How much are we capable of remembering, from both an episodic2 2 Episodic memory is the term for the memory of life experiences. and a semantic3 3 Semantic memory is the term for the memory of facts and knowledge about the world. standpoint?

I would argue that we’re all everyday-memory experts, because we have this exceptional semantic memory, which is the scaffold for episodic memory.

If what we’re remembering, or the emotional tenor of what we’re remembering, is dictated by how we’re thinking in a present moment, what can we really say about the truth of a memory?

But if memories are malleable, what are the implications for how we understand our “true” selves?

your question gets to a major purpose of memory, which is to give us an illusion of stability in a world that is always changing. Because if we look for memories, we’ll reshape them into our beliefs of what’s happening right now. We’ll be biased in terms of how we sample the past. We have these illusions of stability, but we are always changing

And depending on what memories we draw upon, those life narratives can change.

I know it sounds squirmy to say, “Well, I can’t answer the question of how much we remember,” but I don’t want readers to walk away thinking memory is all made up.

One thing that makes the human brain so sophisticated is that we have a longer timeline in which we can integrate information than many other species. That gives us the ability to say: “Hey, I’m walking up and giving money to the cashier at the cafe. The barista is going to hand me a cup of coffee in about a minute or two.”

There is this illusion that we know exactly what’s going to happen, but the fact is we don’t. Memory can overdo it: Somebody lied to us once, so they are a liar; somebody shoplifted once, they are a thief.

If people have a vivid memory of something that sticks out, that will overshadow all their knowledge about the way things work. So there’s kind of an illus

we have this illusion that much of the world is cause and effect. But the reason, in my opinion, that we have that illusion is that our brain is constantly trying to find the patterns

I think of memory more like a painting than a photograph. There’s often photorealistic aspects of a painting, but there’s also interpretation. As a painter evolves, they could revisit the same subject over and over and paint differently based on who they are now. We’re capable of remembering things in extraordinary detail, but we infuse meaning into what we remember. We’re designed to extract meaning from the past, and that meaning should have truth in it. But it also has knowledge and imagination and, sometimes, wisdom.

memory, often, is educated guesses by the brain about what’s important. So what’s important? Things that are scary, things that get your desire going, things that are surprising. Maybe you were attracted to this person, and your eyes dilated, your pulse went up. Maybe you were working on something in this high state of excitement, and your dopamine was up.

It could be any of those things, but they’re all important in some way, because if you’re a brain, you want to take what’s surprising, you want to take what’s motivationally important for survival, what’s new.

On the more intentional side, are there things that we might be able to do in the moment to make events last in our memories? In some sense, it’s about being mindful. If we want to form a new memory, focus on aspects of the experience you want to take with you.

If you’re with your kid, you’re at a park, focus on the parts of it that are great, not the parts that are kind of annoying. Then you want to focus on the sights, the sounds, the smells, because those will give you rich detail later on

Another part of it, too, is that we kill ourselves by inducing distractions in our world. We have alerts on our phones. We check email habitually.

When we go on trips, I take candid shots. These are the things that bring you back to moments. If you capture the feelings and the sights and the sounds that bring you to the moment, as opposed to the facts of what happened, that is a huge part of getting the best of memory.

this goes back to the question of whether the factual truth of a memory matters to how we interpret it. I think it matters to have some truth, but then again, many of the truths we cling to depend on our own perspective.

There’s a great experiment on this. These researchers had people read this story about a house.8 8 The study was “Recall of Previously Unrecallable Information Following a Shift in Perspective,” by Richard C. Anderson and James W. Pichert. One group of subjects is told, I want you to read this story from the perspective of a prospective home buyer. When they remember it, they remember all the features of the house that are described in the thing. Another group is told, I want you to remember this from the perspective of a burglar. Those people tend to remember the valuables in the house and things that you would want to take. But what was interesting was then they switched the groups around. All of a sudden, people could pull up a number of details that they didn’t pull up before. It was always there, but they just didn’t approach it from that mind-set. So we do have a lot of information that we can get if we change our perspective, and this ability to change our perspective is exceptionally important for being accurate. It’s exceptionally important for being able to grow and modify our beliefs

Two of the most important factors, Peterson explained, are whether the memory “has emotion infused in it,” and whether the memory is coherent: Does the story our memory tells us actually hang together and make sense when we recall it later?

A professor at the University of North Carolina-Chapel Hill, Reznick explained that shortly after birth, infants can start forming impressions of faces and react when they see those faces again; this is recognition memory. The ability to understand words and learn language relies on working memory, which kicks in at around six months old. More sophisticated forms of memory develop in the child’s second year, as semantic memory allows children to retain understanding of concepts and general knowledge about the world.

I formed earlier memories using more rudimentary, pre-verbal means, and that made those memories unreachable as the acquisition of language reshaped how my mind works, as it does for everyone.

False memories do exist, but their construction appears to begin much later in life

A study by Peterson presented young children with fictitious events to see if they could be misled into remembering these non-existent events, yet the children almost universally avoided the bait. As for why older children and adults begin to fill in gaps in their memories with invented details, she pointed out that memory is a fundamentally constructive activity: We use it to build understanding of the world, and that sometimes requires more complete narratives than our memories can recall by themselves.

as people get older, it becomes easier to conflate actual memories with other stimuli.

He explained that recognition memory is our most pervasive system, and that associations with my hometown I formed as an infant could well have endured more than 20 years later, however vaguely.

give me enough time, and I’m sure that detail will be added to my memory. It’s just too perfect a story.

Experts have managed to turn people off all sorts of foods by convincing them it had made them ill when they were a child

“People have a life story, particularly as they get older and for some people it needs to stretch back to the very early stage of life,”

The prevailing account of how we come to believe and remember things is based around the concept of source monitoring. “Every time a thought comes to mind we have to make a decision – have we experienced it [an event], imagined it or have we talked about it with other people,” says Kimberley Wade

Most of the time we make that decision correctly and can identify where these mental experiences come from, but sometimes we get it wrong.

Wade admits she has spent a lot of time recalling an event that was actually something her brother experienced rather than herself, but despite this, it is rich in detail and provokes emotion

Memory researchers have shown it is possible to induce fictional autobiographical memories in volunteers, including accounts of getting lost in a shopping mall and even having tea with a member of the Royal Family

Based on my research, everybody is capable of forming complex false memories, given the right circumstances – Julia Shaw

In some situations, such as after looking at pictures or a video, children are more susceptible to forming false memories than adults. People with certain personality types are also thought to be more prone.

But carrying around false memories from your childhood could be having a far greater impact on you than you may realise too. The events, emotions and experiences we remember from our early years can help to shape who we are as adults, determining our likes, dislikes, fears and even our behaviour.

Memories before the age of three are more than likely to be false. Any that appear very fluid and detailed, as if you were playing back a home video and experiencing a chronological account of a memory, could well also be made up. It is more likely that fuzzy fragments, or snapshots of moments are real, as long as they are not from too early in your life.

We crave a cohesive narrative of our own existence and will even invent stories to give us a more complete picture

Interestingly, scientists have also found positive suggestions, such as “you loved asparagus the first time you ate it” tend to be more effective than negative suggestions like “you got sick drinking vodka”

“Miscarriage of justice, incarceration, loss of reputation, job and status, and family breakdown occur,

One of the major problems with legal cases involving false memories, is that it is currently impossible to distinguish between true and fictional recollections

Efforts have been made to analyse minor false memories in a brain scanner (fMRI) and detect different neurological patterns, but there is nothing as yet to indicate that this technology can be used to detect whether recollections have become distorted.

the most extreme case of memory implantation involves a controversial technique called “regression therapy”, where patients confront childhood traumas, supposedly buried in their subconscious

“Memories are malleable and tend to change slightly each time we revisit them, in the same way that spoken stories do,”

“Therefore at each recollection, new elements can easily be integrated while existing elements can be altered or lost.”

This is not to say that all evidence that relies on memory should be discarded or regarded as unreliable – they often provide the most compelling testimony in criminal cases. But it has led to rules and guidelines about how witnesses and victims should be questioned to ensure their recollections of an event or perpetrator are not contaminated by investigators or prosecutors.

Any memories that appear very fluid and detailed, as if you were playing back a home video, could well also be made up

While this may seem like a bit of fun, many scientists believe the “false memory diet” could be used to tackle obesity and encourage people to reach for healthier options like asparagus, or even help cut people’s alcohol consumption.

Children are more susceptible to forming false memories than adults, especially after looking at photographs or films

And we may not want to rid ourselves of these memories. Our memories, whether fictional or not, can help to bring us closer together.

Loftus’s research has already rattled our justice system, which relies so heavily on eyewitness testimonies.

“It’s so powerful when somebody tells you something and they have a lot of detail,” Loftus said. “Especially when they express emotion. To just say, ‘Oh my god it must be true.’ But all those characteristics are also true of false memories, particularly the heavily rehearsed ones that you ruminate over. They can be very detailed. You can be confident. You can be emotional. So you need independent corroboration.”

When later asked about the events, the superior memory subjects indicated the erroneous facts as truth at about the same rate as people with normal memory.

been able to successfully convince ordinary people that they were lost in a mall in their childhood, pointed out that false memory recollections also occur among high profile people.

All memory, as McGaugh explained, is colored with bits of life experiences. When people recall, “they are reconstructing,” he said. “It doesn't mean it’s totally false. It means that they’re telling a story about themselves and they’re integrating things they really do remember in detail, with things that are generally true.”

“puzzling why (Highly Superior Autobiographical Memory) individuals remember some trivial details, such as what they had for lunch 10 years ago, but not others, such as words on a word list or photographs in a slideshow,” Patihis and colleagues noted in the PNAS study. “The answer to this may be that they may extract some personally relevant meaning from only some trivial details and weave them into the narrative for a given day.”

For all of us, the stronger the emotion attached to a moment, the more likely those parts of our brains involved in memory will become activated.

“Why did evolution do that?” McGaugh said. “Because it was essential for our survival.

We now know animals are likely susceptible to memory distortions too, as MIT researchers recently were able to successfully plant false memories in mice.

“We’re all creating stories. Our lives are stories in that sense.”

“but you as the writer have the obligation to get as close to the truth as you possibly can,” Meyer said

The mind and its memory do not just record and retrieve information and experiences, but also infer, fill in gaps, and construct, wrote Bryan Boyd wrote in On the Origin of Stories. “Episodic memory’s failure to provide exact replicas of experiences appears to not be a limitation of memory but an adaptive design.”

Our lack of appreciation for the fallibility of our own memories can lead to much bigger problems than a misattributed quote.

Memory failures that resemble Dr. Tyson’s mash-up of distinct experiences have led to false convictions, and even death sentences. Whose memories we believe and whose we disbelieve influence how we interpret controversial public events, as demonstrated most recently by the events in Ferguson, Mo.

, for false memories, higher confidence was associated with lower accuracy.

In general, if you have seen something before, your confidence that you have seen it and your accuracy in recalling it are linked: The more confident you are in your memory, the more likely you are to be right

. This fall the panel (which one of us, Daniel Simons, served on) released a comprehensive report that recommended procedures to minimize the chances of false memory and mistaken identification, including videotaping police lineups and improving jury instructions.

When we recall our own memories, we are not extracting a perfect record of our experiences and playing it back verbatim. Most people believe that memory works this way, but it doesn’t. Instead, we are effectively whispering a message from our past to our present, reconstructing it on the fly each time. We get a lot of details right, but when our memories change, we only “hear” the most recent version of the message, and we may assume that what we believe now is what we always believed.

Studies find that even our “flashbulb memories” of emotionally charged events can be distorted and inaccurate, but we cling to them with the greatest of confidence.

With each retrieval our memories can morph, and so can our confidence in them. This is why the National Academy of Sciences report strongly advised courts to rely on initial statements rather than courtroom proclamations:

In fact, the mere act of describing a person’s appearance can change how likely you are to pick him out of a lineup later. This finding, known as “verbal overshadowing,” had been controversial, but was recently verified in a collective effort by more than 30 separate research labs.

The science of memory distortion has become rigorous and reliable enough to help guide public policy. It should also guide our personal attitudes and actions.

It is just as misguided to conclude that someone who misremembers must be lying as it is to defend a false memory in the face of contradictory evidence. We should be more understanding of mistakes by others, and credit them when they admit they were wrong. We are all fabulists, and we must all get used to it.

Subliminal is a good book on this subject, as is Thinking, Fast and Slow. It is not merely that our memory is a game of telephone in which we garble the memory as we retrieve and re-store it. It appears to be a very useful part of existence, which has stayed with us or gotten stronger with evolution. There seems to be utility in forgetting, misremembering, and having memories coalesce with those of others in our social groups.

For many reasons, then, it would be very useful to understand how visual memory facilitates these mental operations, as well as constrains our ability to perform them

Visual working memory is where visual images are temporarily stored while your mind works away at other tasks—like a whiteboard on which things are briefly written and then wiped away. We rely on visual working memory when remembering things over brief intervals, such as when copying lecture notes to a notebook.

UC Davis psychologists Weiwei Zhang and Steven Luck have shed some light on this problem. In their experiment, participants briefly saw three colored squares flashed on a computer screen, and were asked to remember the colors of each square. Then, after 1, 4 or 10 seconds the squares re-appeared, except this time their colors were missing, so that all that was visible were black squares outlined in white.

The participants had a simple task: to recall the color of one particular square, not knowing in advance which square they would be asked to recall. The psychologists assumed that measuring how visual working memory behaves over increasing demands (i.e., the increasing durations of 1,4 or 10 seconds) would reveal something about how the system works.

If short-term visual memories fade away—if they are gradually wiped away from the whiteboard—then after longer intervals participants’ accuracy in remembering the colors should still be high, deviating only slightly from the square’s original color. But if these memories are wiped out all at once—if the whiteboard is left untouched until, all at once, scrubbed clean—then participants should make very precise responses (corresponding to instances when the memories are still untouched) and then, after the interval grows too long, very random guesses.

Which is exactly what happened: Zhang & Luck found that participants were either very precise, or they completely guessed; that is, they either remembered the square’s color with great accuracy, or forgot it completely

But this, it turns out, is not true of all memories

In a recent paper, Researchers at MIT and Harvard found that, if a memory can survive long enough to make it into what is called “visual long-term memory,” then it doesn’t have to be wiped out at all.

Talia Konkle and colleagues showed participants a stream of three thousand images of different scenes, such as ocean waves, golf courses or amusement parks. Then, participants were shown two hundred pairs of images—an old one they had seen in the first task, and a completely new one—and asked to indicate which was the old one.

Participants were remarkably accurate at spotting differences between the new and old images—96 percent

In a recent review, researchers at Harvard and MIT argue that the critical factor is how meaningful the remembered images are—whether the content of the images you see connects to pre-existing knowledge about them

This prior knowledge changes how these images are processed, allowing thousands of them to be transferred from the whiteboard of short-term memory into the bank vault of long-term memory, where they are stored with remarkable detail.

Together, these experiments suggest why memories are not eliminated equally— indeed, some don’t seem to be eliminated at all. This might also explain why we’re so hopeless at remembering some things, and yet so awesome at remembering others.

In short, Nader believes that the very act of remembering can change our memories

Much of his research is on rats, but he says the same basic principles apply to human memory as well. In fact, he says, it may be impossible for humans or any other animal to bring a memory to mind without altering it in some way.

Memories surrounding a major event like September 11 might be especially susceptible, he says, because we tend to replay them over and over in our minds and in conversation with others—with each repetition having the potential to alter them

cientists have long known that recording a memory requires adjusting the connections between neurons

Each memory tweaks some tiny subset of the neurons in the brain (the human brain has 100 billion neurons in all), changing the way they communicate. Neurons send messages to one another across narrow gaps called synapses

According to this view, the brain’s memory system works something like a pen and notebook. For a brief time before the ink dries, it’s possible to smudge what’s written

Researchers had found that a memory could be weakened if they gave an animal an electric shock or a drug that interferes with a particular neurotransmitter just after they prompted the animal to recall the memory. This suggested that memories were vulnerable to disruption even after they had been consolidated.

If memories are consolidated just once, when they are first created, he reasoned, the drug would have no effect on the rat’s memory of the tone or on the way it would respond to the tone in the future.

Perhaps it’s better if we can rewrite our memories every time we recall them. Nader suggests that reconsolidation may be the brain’s mechanism for recasting old memories in the light of everything that has happened since. In other words, it just might be what keeps us from living in the past.

movement in the nervous system created memories

memories are the encoding of experiences on webs of neurons in the brain

memory involved molecular changes via neurotransmitters in the brain

the neuron cell bodies themselves have some connection to the memory and control over the development and sustainment of synapses.

“Long-term memory is not stored at the synapse,”

part of memory is stored within the cells (neurons) themselves, and that they are using this memory storage to determine how many synapses to form and where.

Long-term memory is a function of the growth of new synaptic connections caused by the serotonin

As long-term memories are formed, the brain creates new proteins that are involved in making new synapses. If that process is disrupted — for example by a concussion or other injury — the proteins may not be synthesized and long-term memories cannot form. This is why people cannot remember what happened moments before a concussion.

Scientists think the brain's prefrontal cortex processes experiences, using sensory input from the eyes, ears, nose and mouth, sorts them into categories, and tags the various memory fragments with specific associations (smells of home, friends from camp, bugs, a pet, for example). When a memory cue comes in, the brain searches its circuits for related fragments and assembles them like a jigsaw puzzle. Some fragments bring associated fragments along, which is why one old memory often leads to others. Tastes and smells are particularly evocative

Each time people bring up the same memory, those related fragments and circuits become stronger. "When you are 80 years old, remembering your kindergarten days, it's really the memory of a memory of a memory," says Dr. Devi. That may help explain why children's earliest memories are so unstable: Their neural traces are weak and shallow, whereas the few memories we revisit as we get older lay down stronger traces. Still, because the brain is constantly reassembling the fragments, they are vulnerable to distortion.

There are countless reasons why tiny mistakes or embellishments might happen each time we recall past events, ranging from what we believe is true or wish were true, to what someone else told us about the event, or what we want that person to think. And whenever these flaws happen, they can have long-term effects on how we’ll recall that memory in the future.

Take storytelling for example. When we describe our memories to other people, we use artistic licence to tell the story differently depending on who’s listening.

And we might change the story’s details depending on the listener’s attitudes or political leaning.

Research shows that when we describe our memories differently to different audiences it isn’t only the message that changes, but sometimes it’s also the memory itself. This is known as the “audience-tuning effect”.

memories can change spontaneously over time, as a product of how, when, and why we access them. In fact, sometimes simply the act of rehearsing a memory can be exactly what makes it susceptible to change. This is known as “retrieval-enhanced suggestibility”.

One theory is that rehearsing our memories of past events can temporarily make those memories malleable. In other words, retrieving a memory might be a bit like taking ice-cream out of the freezer and leaving it in direct sunlight for a while. By the time our memory goes back into the freezer, it might have naturally become a little misshapen, especially if someone has meddled with it in the meantime.

two and a half years later, the questionnaire was given a second time to the same students.

It was then that R. T. recalled, with absolute confidence, her dorm-room experience.

She didn’t know any details of what had happened,

We don’t really remember an uneventful day the way that we remember a fight or a first kiss.

Her hope is to understand how, exactly, emotional memories behave at all stages of the remembering process: how we encode them, how we consolidate and store them, how we retrieve them.

When it comes to the central details of the event, like that the Challenger exploded, they are clearer and more accurate. But when it comes to peripheral details, they are worse. And our confidence in them, while almost always strong, is often misplaced.

Within the brain, memories are formed and consolidated largely due to the help of a small seahorse-like structure called the hippocampus; damage the hippocampus, and you damage the ability to form lasting recollections.

A key element of emotional-memory formation is the direct line of communication between the amygdala and the visual cortex.

Phelps has combined Neisser’s experiential approach with the neuroscience of emotional memory to explore how such memories work, and why they work the way they do.

Memory for the emotional scenes was significantly higher, and the vividness of the recollection was significantly greater.

hat is, if you were shocked when you saw animals, your memory of the earlier animals was also enhanced. And, more important, the effect only emerged after six or twenty-four hours: the memory needed time to consolidate.

o, if memory for events is strengthened at emotional times, why does everyone forget what they were doing when the Challenger exploded?

The strength of the central memory seems to make us confident of all of the details when we should only be confident of a few.

Our misplaced confidence in recalling dramatic events is troubling when we need to rely on a memory for something important—evidence in court, for instance

After reviewing the evidence, the committee made several concrete suggestions to changes in current procedures, including “blinded” eyewitness identification

standardized instructions to witnesses, along with extensive police training in vision and memory research as it relates to eyewitness testimony, videotaped identification, expert testimony early on in trials about the issues surrounding eyewitness reliability, and early and clear jury instruction on any prior identifications

forgetting seems to be an active mechanism that is constantly at work in the brain.

“To have proper memory function, you have to have forgetting.

Different types of memory are created and stored in varying ways, and in various areas of the brain.

Neurons communicate with each other through synapses — junctions between these cells that include a tiny gap across which chemical messengers can be sent

The more often a memory is recalled, the stronger its neural network becomes. Over time, and through consistent recall, the memory becomes encoded in both the hippocampus and the cortex

Because the hippocampus is not where long-term memories are stored in the brain, its dynamic nature is not a flaw but a feature

Neuroscientists often refer to this physical representation of a memory as an engram. They think that each engram has a number of synaptic connections, sometimes even in several areas of the brain, and that each neuron and synapse can be involved in multiple engrams

The brain is always trying to forget the information it’s already learnt,

Hardt’s lab showed that a dedicated mechanism continuously promotes the expression of AMPA receptors at synapses.

To forget certain things, it seemed that the rat brain had to proactively destroy connections at the synapse. Forgetting, Hardt says, “is not a failure of memory, but a function of it”.

Paul Frankland, a neuroscientist at the Hospital for Sick Children in Toronto, Canada, had also found evidence that the brain is wired to forget

Frankland was studying the production of new neurons, or neurogenesis, in adult mice. The process had long been known to occur in the brains of young animals, but had been discovered in the hippocampi of mature animals only about 20 years earlier. Because the hippocampus is involved in memory formation, Frankland and his team wondered whether increasing neurogenesis in adult mice could help the rodents to remember.

Eventually, it exists independently in the cortex, where it is put away for long-term storage.

Researchers think that the human brain might operate in a similar way

Studies of people with exceptional autobiographical memories or with impaired ones seem to bear this out

People with a condition known as highly superior autobiographical memory (HSAM) remember their lives in such incredible detail that they can describe the outfit that they were wearing on any particular day

Those with severely deficient autobiographical memory (SDAM), however, are unable to vividly recall specific events in their lives

As a result, they also have trouble imagining what might happen in the future

By better understanding how we forget, through the lenses of both biology and cognitive psychology, Anderson and other researchers might be edging nearer to improving treatments for anxiety, PTSD and even Alzheimer’s disease

Hardt thinks that Alzheimer’s disease might also be better understood as a malfunction of forgetting rather than remembering

But more memory researchers are shifting their focus to examine how the brain forgets, as well as how it remembers

In the past decade, researchers have begun to view forgetting as an important part of a whole

Why do we have memory at all? As humans, we entertain this fantasy that it’s important to have autobiographical details,

Forgetting enables us as individuals, and as a species, to move forwards.

A winner of the memory Olympics, for instance, still had to keep sticky notes on the refrigerator to remember what she had to do during the day.

subjects read several sentences. When he tested them 40 minutes later, they could generally remember the sentences word for word. Four days later, though, they were useless at recalling the specific phrasing of the sentences—but still very good at describing the meaning of them.

When you’re an expert in a subject, you can retain new factoids on your favorite topic easily. This only works for the subjects you’re truly passionate about, though

The groups that scored highest on a test of their transactive memory—in other words, the groups where members most relied on each other to recall information—performed better than those who didn't use transactive memory. Transactive groups don’t just remember better: They also analyze problems more deeply, too, developing a better grasp of underlying principles.

Wegner noticed that spouses often divide up memory tasks. The husband knows the in-laws' birthdays and where the spare light bulbs are kept; the wife knows the bank account numbers and how to program the TiVo

Together, they know a lot. Separately, less so.

Wegner suspected this division of labor takes place because we have pretty good "metamemory." We're aware of our mental strengths and limits, and we're good at intuiting the memory abilities of others.

We share the work of remembering, Wegner argued, because it makes us collectively smarter

They were, in a sense, Googling each other.

Transactive memory works best when you have a sense of how your partners' minds work—where they're strong, where they're weak, where their biases lie. I can judge that for people close to me. But it's harder with digital tools, particularly search engines

So humanity has always relied on coping devices to handle the details for us. We’ve long stored knowledge in books, paper, Post-it notes

And as it turns out, this is what we’re doing with Google and Evernote and our other digital tools. We’re treating them like crazily memorious friends who are usually ready at hand. Our “intimate dyad” now includes a silicon brain.

When Sparrow tested the students, the people who knew the computer had saved the information were less likely to personally recall the info than the ones who were told the trivia wouldn't be saved. In other words, if we know a digital tool is going to remember a fact, we're slightly less likely to remember it ourselves

believing that one won't have access to the information in the future enhances memory for the information itself, whereas believing the information was saved externally enhances memory for the fact that the information could be accessed.

Just as we learn through transactive memory who knows what in our families and offices, we are learning what the computer 'knows' and when we should attend to where we have stored information in our computer-based memories,

We’ve stored a huge chunk of what we “know” in people around us for eons. But we rarely recognize this because, well, we prefer our false self-image as isolated, Cartesian brains

We’re dumber and less cognitively nimble if we're not around other people—and, now, other machines.

When humans spew information at us unbidden, it's boorish. When machines do it, it’s enticing.

Though you might assume search engines are mostly used to answer questions, some research has found that up to 40 percent of all queries are acts of remembering. We're trying to refresh the details of something we've previously encountered.

"the thinking processes of the intimate dyad."

We need to develop literacy in these tools the way we teach kids how to spell and write; we need to be skeptical about search firms’ claims of being “impartial” referees of information

And on an individual level, it’s still important to slowly study and deeply retain things, not least because creative thought—those breakthrough ahas—come from deep and often unconscious rumination, your brain mulling over the stuff it has onboard.

you can stop worrying about your iPhone moving your memory outside your head. It moved out a long time ago—yet it’s still all around you.

Depending on the study, you might get as many as 50 percent of people falling for the suggestion and developing a complete or partial false memory.

What exactly is going on when we retrieve a memory? EL: When we remember something, we're taking bits and pieces of experience—sometimes from different times and places—and bringing it all together to construct what might feel like a recollection but is actually a construction. The process of calling it into conscious awareness can change it, and now you're storing something that's different

How do you plant these memories? EL: We use a "false feedback" technique. We gather a whole bunch of data from you, about your personality, thoughts about different foods, all kinds of things. Later, we hand you this computerized profile, which reveals certain things that probably happened when you were a child. In the middle of the list is, say, that you got sick eating strawberry ice cream. We give you false feedback about your data, and then encourage you to elaborate and imagine. Later we ascertain whether you have a belief that it happened to you. Then we offer you a choice from all these different foods. In that example we found that participants didn't want strawberry ice cream as much.

bad governments, bad people, they don't have requirements of conduct. When we recently published a study about planting false memories among U.S. soldiers, I was worried we were putting out a recipe for how you can do horrible things to somebody and then wipe their memory away.

Is there any way to distinguish a false memory from a real one? EL: Without independent corroboration, little can be done to tell a false memory from a true one.

"Our conclusion is that in retrograde amnesia, past memories may not be erased, but could simply be lost and inaccessible for recall," lead author Susumu Tonegawa, director of the RIKEN Brain Science Institute in Saitama, Japan, said in a statement. "These findings provide striking insight into the fleeting nature of memories, and will stimulate future research on the biology of memory and its clinical restoration."

"It's very difficult to be doing this in humans, partly for the ethical reasons — the work is invasive — but also because we tag the memories in the brain before they're learned," Tomas Ryan, a neuroscientist at MIT

Instead, however, while there was indeed detectable neural activity for the so-called attended memory item (AMI)—the one that the subjects knew they would need right away—there was none at all for the unattended memory items (UMI), which the subjects might also need, but not until later.

All the same, when subjects were asked about a UMI, a peak appeared for it just as it did for an AMI. In both cases, working memory worked just fine, but in one case it did so without the benefit of any visible storage system.

unattended memories are maintained in what the researchers called “a privileged state” only as long as they had to be.

Whatever the explanation, the work has implications for understanding not just memory but other cognitive functions like perception, attention and goal maintenance.

if noninvasive brain stimulation techniques can be used to reactivate and potentially strengthen latent memories”—in other words, recovering information that had been forever lost.