Speaker 1: When you look at medieval European art, why do the
Speaker 1: people look fine but the lions look so strange? And
Speaker 1: what does this have to do with Native American folklore
Speaker 1: or I witness memory of a car accident, or what
Speaker 1: a person remembers three years after watching the nine to
Speaker 1: eleven attack on the World Trade Center, And what does
Speaker 1: any of this have to do with flashbulb memories or
Speaker 1: misinformation or the telephone game that you played as a child.
Speaker 1: Welcome to Inner Cosmos with me, David Eagleman. I'm a
Speaker 1: neuroscientist and an author at Stanford, and in these episodes
Speaker 1: we sail deeply into our three pound universe to understand
Speaker 1: why and how our lives look the way they do.
Speaker 1: Today's episode is part one of a two parter about
Speaker 1: memory and why it rifts. So I want to start
Speaker 1: with this fascinating observation that you can notice if you
Speaker 1: look across visual painting in Europe all through the Middle Ages.
Speaker 1: Painters got better and better through time at painting architecture
Speaker 1: and the human form and mountain scapes, but they were
Speaker 1: absolutely terrible at painting lions. If you look at lions
Speaker 1: in these medieval paintings, you'll see that they generally look
Speaker 1: quite different from their real life counterparts. They have exaggerated
Speaker 1: features like overly large heads and bodies that are too long,
Speaker 1: and tufted tails that aren't really like actual lion tails,
Speaker 1: and they often look more like large, fierce dogs or
Speaker 1: mythical creatures. I'll put some pictures on eagleman dot com
Speaker 1: slash podcasts so you can see how strange these lions are.
Speaker 1: But why is this? The answer is the medieval European
Speaker 1: painters spent a lot of time with architecture and with
Speaker 1: people and with mountainscapes, but almost none of them had
Speaker 1: ever been to Africa and therefore seen a real lion,
Speaker 1: or for that matter, had been to India and seen
Speaker 1: an asiatic lion. So they had the extremely tough challenge
Speaker 1: of painting something they had never actually seen. Now, to
Speaker 1: be clear, it's not that they had never seen a lion,
Speaker 1: it's that they had never seen a real lion. All
Speaker 1: they had ever seen were versions of lions painted by
Speaker 1: other medieval painters, who presumably had seen pictures of lions
Speaker 1: painted by other medieval painters, and so on back to
Speaker 1: someone who had at some point seen a real lion,
Speaker 1: and so This notion of what a lion looks like
Speaker 1: gives us a visual example of the operator game. This
Speaker 1: is also known as the telephone game or Russian scandal
Speaker 1: or pass the secret. So you remember doing this as
Speaker 1: a kid. One person whispers, let's say a word or
Speaker 1: a little phrase in your ear, and then you whisper
Speaker 1: it to the next person, and they whisper it to
Speaker 1: the next person, and so on, and by the time
Speaker 1: it gets to the last person, she shouts it out
Speaker 1: and you all get to see if it's the same
Speaker 1: word or phrase that the first person said. And the
Speaker 1: joy of the game, of course, is that the message
Speaker 1: gets distorted in transmission, and by the time it ends
Speaker 1: up somewhere it can be very different from how it began.
Speaker 1: So today and next week we're going to dive into
Speaker 1: a strange question, how your own memories are like the
Speaker 1: Operator game. In other words, we tend to erroneously believe
Speaker 1: that when something happens, we record that in the brain.
Speaker 1: It's written down in the brain as a memory, the
Speaker 1: way that a computer might hold a little file. And
Speaker 1: then every time we retrieve that memory, every time we
Speaker 1: pull that back up, we are viewing that little movie again.
Speaker 1: So it comes as a surprise that real human memory
Speaker 1: in the brain is nothing like a movie, but much
Speaker 1: more like the Operator game, wherein the message becomes increasingly distorted.
Speaker 1: For example, let's say I show you a picture of
Speaker 1: something that you're not super familiar with, like an old
Speaker 1: Polynesian war mass with a sort of strange shape in
Speaker 1: some different lines and circles on it, and then I
Speaker 1: ask you to draw it. Later, your drawing will probably
Speaker 1: drift from what you actually saw, and the next time
Speaker 1: after that, when I ask you to draw it again,
Speaker 1: your memory will presumably be influenced by what you drew
Speaker 1: the last time. And if I ask you to do
Speaker 1: this over and over again, let's say once a month,
Speaker 1: there will be something of a steady progression from drawing
Speaker 1: one to drawing ten, because you are playing the operator
Speaker 1: game with yourself. Each time you retrieve the memory, it
Speaker 1: is influenced by what you thought it was last time.
Speaker 1: So to dig into this, we're going to start today's
Speaker 1: episode with a short story. This is a Native American
Speaker 1: folk story called the War of the Ghosts, and it's
Speaker 1: read here by actor Sean Judge.
Speaker 2: War of the Ghosts. One night, two young men from
Speaker 2: Eguilak went down to the river to hunt seals, and
Speaker 2: while they were there it became foggy and calm. Then
Speaker 2: they heard war cries and they thought maybe this is
Speaker 2: a war party. They escaped to the shore and hid
Speaker 2: behind a log. Now canoes came up, and they heard
Speaker 2: the noise of paddles and saw one canoe coming up
Speaker 2: to them. There were five men in the canoe, and
Speaker 2: they said, what do you think we wish to take
Speaker 2: you along. We are going up the river to make
Speaker 2: war on the people. One of the young men said,
Speaker 2: I have no arrows. Arrows are in the canoe. They said,
Speaker 2: I will not go along. I might be killed. My
Speaker 2: relatives do not know where I have gone. But you,
Speaker 2: he said, turning to the other, may go with them.
Speaker 2: So one of the young men went, but the other
Speaker 2: returned home, and the warriors went on up the river
Speaker 2: to a town on the other side of Kalama. The
Speaker 2: people came down to the water and they began to fight,
Speaker 2: and many were killed. But presently the young man heard
Speaker 2: one of the warriors say, quick, let us go home.
Speaker 2: That Indian has been hit. Now he thought, oh, they
Speaker 2: are ghosts. He did not feel sick, but they said
Speaker 2: he had been shot. So the canoes went back to Aguilak,
Speaker 2: and the young man went ashore to his house and
Speaker 2: made a fire, and he told everybody and said, behold,
Speaker 2: I accompanied the ghosts, and we went to fight. Many
Speaker 2: of our fellows were killed, and many of those who
Speaker 2: attacked us were killed. They said, I was hit, but
Speaker 2: I did not feel sick. He told it all, and
Speaker 2: then he became quiet. When the sun rose, he fell down.
Speaker 2: Something black came out of his mouth, his face became contorted.
Speaker 2: The people jumped up and cried he was dead.
Speaker 1: This probably seems to you like a bit of a
Speaker 1: weird story. It seems like it's not particularly well told
Speaker 1: or clear. So given the strangeness of the story, why
Speaker 1: did it become quite famous in the psychology community almost
Speaker 1: a century ago in nineteen thirty two. It's because of
Speaker 1: a researcher named Frederick Bartlett, who was a psychologist at
Speaker 1: Cambridge University. He chose this story, the War of the Ghosts,
Speaker 1: to examine the way that our memories change with time. Now,
Speaker 1: he chose this particular folk tale because he wanted something
Speaker 1: that wasn't crystal clear, so that it might be slightly
Speaker 1: more susceptible to changes in the retelling. That way, he
Speaker 1: could examine the way in which it changed in the retelling,
Speaker 1: and the retelling after that, and so on into the future.
Speaker 1: In other words, he used this story to see if
Speaker 1: he could really shine a light on the constructive character
Speaker 1: of memory. In other words, the way that recalling a
Speaker 1: memory is something like reconstructing what happened your brain rebuilding
Speaker 1: its best guess at a memory, rather than the way
Speaker 1: a computer simply retrieves a file of zeros and ones
Speaker 1: without loss. So in Bartlett's study, he had participants read
Speaker 1: the War of the Ghosts. Then they were instructed to
Speaker 1: recall and write down the story as perfectly as they could.
Speaker 1: Now it's only been about a minute since you heard
Speaker 1: the story, Think about how you would retell it now,
Speaker 1: what details you would remember from that story. Not surprisingly,
Speaker 1: Bartlett found that the story drifted from the original upon
Speaker 1: the retelling. Here, for example, is a person who is
Speaker 1: asked to remember and reproduce the story, and he did
Speaker 1: this multiple times. Here he is on his tenth reproduction.
Speaker 2: War of the Ghosts. Two Indians were out fishing for
Speaker 2: seals in the Bay of Manpapan when along came five
Speaker 2: other Indians in a war canoe. They were going fighting.
Speaker 2: Come with us, said five of the two, and fight.
Speaker 2: I cannot come, was the answer of the one, for
Speaker 2: I have an old mother at home who has dependent
Speaker 2: on me. The other also said he could not come
Speaker 2: because he had no arms. That is no difficulty. The
Speaker 2: others replied, for we have plenty in the canoe with us.
Speaker 2: So he got into the canoe and went with them
Speaker 2: in a fight. Soon afterwards, this Indian received a mortal wound.
Speaker 2: Finding that his hour was come, he cried out that
Speaker 2: he was about to die. Nonsense, said one of the others.
Speaker 2: You will not die, But he did now.
Speaker 1: Bartlett also had other participants read the story and then
Speaker 1: reproduce it at intervals very far apart. In some cases
Speaker 1: this is over years. So here's another participant. This is
Speaker 1: subject p on his first reproduction.
Speaker 2: War of the Ghosts. Two youths were standing by a
Speaker 2: river about to start seal catching when a boat appeared
Speaker 2: with five men in it. They were all armed for war.
Speaker 2: The youths were at first frightened, but they were asked
Speaker 2: by the men to come and help them fight some
Speaker 2: enemies on the other bank. One youth said that he
Speaker 2: could not come, as his relations would be anxious about him.
Speaker 2: The other said he would go and entered the boat.
Speaker 2: In the evening, he returned to his hut and told
Speaker 2: his friends that he had been in a battle. A
Speaker 2: great many had been slain, and he had been wounded
Speaker 2: by an arrow. He had not felt any pain, he said.
Speaker 2: They told him that he must have been fighting a
Speaker 2: battle of ghosts. Then he remembered that it had been queer,
Speaker 2: and he was very excited. In the morning, however, he
Speaker 2: became ill, and his friends gathered round. He fell down
Speaker 2: and his face became very pale. Then he writhed and shrieked,
Speaker 2: and his friends were filled with terror. At last he
Speaker 2: became calm. Something hard and black came out of his mouth,
Speaker 2: and he lay contorted and dead.
Speaker 1: And here he is again when he's asked to reproduce
Speaker 1: the story. After thirty months.
Speaker 2: War of the ghosts, some warriors went to wage war
Speaker 2: against the ghosts. They fought all day, and one of
Speaker 2: their number was wounded. They returned home in the evening
Speaker 2: bearing their sick comrade. As the day drew to a close,
Speaker 2: he became rapidly worse, and the villagers came round him.
Speaker 2: As sunset, he sighed something black came out of his mouth.
Speaker 3: He was dead.
Speaker 1: So what he generally found is that the story became
Speaker 1: shorter with each reproduction. But here was the key. He
Speaker 1: realized that this was more than just the telephone game,
Speaker 1: where a signal just becomes noisier each time it's repeated. Instead,
Speaker 1: with the War of the Ghosts, he found there was
Speaker 1: a pattern to the way the story changed. First of all,
Speaker 1: it typically became more coherent to the speaker, as Bartlett wrote,
Speaker 1: quote no trace of an odd or supernatural element is left.
Speaker 1: We have a perfectly straightforward story of a fight and
Speaker 1: a death end quote. So Bartlett studied the character of
Speaker 1: the changes, and he found that these happened by transforming
Speaker 1: details into things that are more familiar and conventional to
Speaker 1: the person doing the remembering. Sometimes the order of events
Speaker 1: would change, and things would commonly get omitted, like the
Speaker 1: ghosts getting sliced out of the story pretty early on,
Speaker 1: or the wound becoming a matter of flesh not spirit.
Speaker 1: All in all, he was interested in the way that people,
Speaker 1: through time made the parts grow more coherent for themselves.
Speaker 1: In other words, the distortions were driven by a person's schema. Now,
Speaker 1: what does that mean. It means that people morphed the
Speaker 1: story to make it consistent with what's going on in
Speaker 1: their heads. In other words, the changes you make to
Speaker 1: the story are navigated by your internal model, or what
Speaker 1: psychologists call your schema, your mental framework for organizing knowledge
Speaker 1: and guiding perception. This is your brain's unique way of
Speaker 1: seeing the world. So the way the story was distorted
Speaker 1: in terms of the plot and characters and events is
Speaker 1: different in your brain versus someone else's brain. There's a
Speaker 1: lot of differences between individual schema, which is to say,
Speaker 1: if you read the story to someone who's really into boats,
Speaker 1: they might remember something differently than someone who's really into
Speaker 1: Native American history, or someone who's a physician and thinks
Speaker 1: about what causes a person to die. And by the way,
Speaker 1: it's not just individual differences, but also your culture plays
Speaker 1: a massive role in shaping the way that you interpret
Speaker 1: and remember information. So as you recall a story, you
Speaker 1: unconsciously mold it to align with your cultural background and
Speaker 1: your beliefs and your expectations. So this all has to
Speaker 1: do with the differences in internal models. Bartlet's study the
Speaker 1: way that people can't label something until it is recognizable,
Speaker 1: So transformations moved in the direction of the conventions in
Speaker 1: their head. So I think about Bartlett's study all the time,
Speaker 1: for example, and how we consume news. Any news story
Speaker 1: we read this month is remembered differently by you than
Speaker 1: by someone else who reads it through a different political lens.
Speaker 1: Watch anything on the news, and then talk to anyone
Speaker 1: you know who sees the world a little differently, and
Speaker 1: you'll find that it's not impossible that they remember different
Speaker 1: parts of the story than you did, and or they
Speaker 1: remembered them differently. Their distortions in the story are not accidental,
Speaker 1: and nor are yours. They are ways of making things
Speaker 1: internally consistent. Now, psychologists have a lot of ways of
Speaker 1: talking about this, like confirmation bias, which means we tend
Speaker 1: to seek out and remember information that is consistent with
Speaker 1: our internal models, and there are other ways of talking
Speaker 1: about this. I recently did an episode on conspiracy theories,
Speaker 1: and one of the things I highlighted is the way
Speaker 1: that we are attracted to theories that reduce our cognitive
Speaker 1: load or our cog of dissonance. In other words, we
Speaker 1: prefer a clear and easy story, and all this is
Speaker 1: consistent with what Bartlett found in nineteen thirty two. We
Speaker 1: don't remember the story as it is presented to us,
Speaker 1: but rather as our filters allow us to store it
Speaker 1: and recall it. And when I think about the driftiness
Speaker 1: of memory, there are other angles that need to be surfaced.
Speaker 1: And here's the main thing that we're going to talk
Speaker 1: about today. Rather than memory being an accurate video recording
Speaker 1: of a moment in your life, it is a fragile
Speaker 1: brain state from a bygone time that has to be
Speaker 1: resurrected for you to remember. So here's an example. You're
Speaker 1: at a restaurant with a couple that you know who
Speaker 1: are visiting town, and everything you experience triggers particular patterns
Speaker 1: of activity in your brain. For example, there's a particular
Speaker 1: pattern of activity sparked into life by the conversation between
Speaker 1: you and your friends. Another pattern is activated by the
Speaker 1: smell of the coffee. Another pattern is activated by the
Speaker 1: taste of a madeleine cookie. The fact that the waiter
Speaker 1: is limping with a cast on his leg is another
Speaker 1: memorable detail, and that's represented by a different configuration of
Speaker 1: neurons firing. All of these constellations become linked with one another,
Speaker 1: in a vast network of neurons that the hippocampus replays
Speaker 1: over and over until the associations between these scattered neurons,
Speaker 1: these distant points of light, this all becomes fixed into place.
Speaker 1: The neurons that are active at the same time will
Speaker 1: establish stronger connections between them. Sells that fire together wire together.
Speaker 1: The resulting network is the unique signature of that event,
Speaker 1: and it represents your memory of the dinner with them. Now,
Speaker 1: let's imagine that six months later, you taste one of
Speaker 1: those Madeleine cookies just like the one you tasted at
Speaker 1: the dinner with the couple. This very specific key can
Speaker 1: unlock the whole web of associations. The original constellation lights
Speaker 1: up like the lights of a city coming online, and
Speaker 1: suddenly your back in that memory. But although we don't
Speaker 1: always realize it, the memory is not as rich as
Speaker 1: you might have expected. You know that your two friends
Speaker 1: were there, and he must have been wearing a button
Speaker 1: up shirt because he always wears a button up shirt,
Speaker 1: and she was wearing a blue dress, or maybe it
Speaker 1: was purple, might have been green. If you really probe
Speaker 1: the memory, you'll realize that you can't remember the details
Speaker 1: of any of the other diners at the restaurant, even
Speaker 1: though the place was full. So your memory of their
Speaker 1: dinner visit has started to fade. Why well, you have
Speaker 1: a finite number of neurons and they are each required
Speaker 1: to multitask. Every neuron in your head participates in different
Speaker 1: constellations at different times. Your neurons operate in a dynamic
Speaker 1: matrix of shifting relationships, and heavy demand is always placed
Speaker 1: on them to wire with others. So your memory of
Speaker 1: the dinner has become muddied as the neurons involved have
Speaker 1: become co opted to participate in other memory constellations. The
Speaker 1: enemy of memory isn't time, it's other memories. Each new
Speaker 1: event needs to establish new relationships among a finite number
Speaker 1: of neurons. Now, the surprise is that a faded memory
Speaker 1: doesn't feel faded to you. You assume, or at least
Speaker 1: you into it, that the full picture is there. And
Speaker 1: the situation is even worse than this, because because it's
Speaker 1: not just that the memory is fading, it's actually drifting.
Speaker 1: So imagine that in the intervening year since the dinner,
Speaker 1: your two friends have broken up. Thinking back on the dinner,
Speaker 1: you might now misremember sensing red flags. Wasn't he more
Speaker 1: quiet than usual that night? Weren't there moments of awkward
Speaker 1: silence between the two? Well, it'll be difficult to know
Speaker 1: for certain, because the knowledge that's in your network now,
Speaker 1: now that they've broken up, that changes the memory that
Speaker 1: corresponds to. Then you can't help but have your present
Speaker 1: color your past, so an event may be perceived somewhat
Speaker 1: differently by you at different moments in your life now.
Speaker 1: Psychologists have been studying the malleability of memory for many decades,
Speaker 1: and one of the pioneers in the field is Elizabeth
Speaker 1: Loftis at the University of California, Irvine. She transformed the
Speaker 1: field of memory research by showing how susceptible memories are.
Speaker 1: So one of her experiments goes like this. She has
Speaker 1: people watch films of car crashes and then she asks
Speaker 1: them a series of questions to test what they remembered.
Speaker 1: And what she found is that just the way she
Speaker 1: asks the question influences the answer she gets back. So
Speaker 1: if she asks how fast were the cars going when
Speaker 1: they hit each other, she gets an estimate of the speed.
Speaker 1: But if she asks how fast were the cars going
Speaker 1: when they smashed into each other, witnesses give a different estimate.
Speaker 1: Not surprisingly, they believe the cars were going faster when
Speaker 1: she uses the word smashed. Now, if you heard my
Speaker 1: episode on eyewitness testimony, you know that these sorts of
Speaker 1: problems are seen all the time in the legal system.
Speaker 1: For example, there's a related issue known as the misinformation
Speaker 1: of effect. If you witness an event, but then later
Speaker 1: you're told something about that event in terms of what
Speaker 1: happened at the scene, or who is there or what
Speaker 1: they look like, that will become part of your memory too,
Speaker 1: and you may not be able to distinguish what you've
Speaker 1: been told from what actually happened. So Loftus and her
Speaker 1: team study this, for example, by showing people a picture
Speaker 1: of a car at a stop sign, and then afterwards,
Speaker 1: after the picture is removed, they give a text description
Speaker 1: of the same picture, but in the text they say
Speaker 1: it was a yield sign. And then they have people
Speaker 1: draw the picture as they remember it, and people tend
Speaker 1: to draw the original scene with a yield sign. So
Speaker 1: even after an memory is encoded, new information coming in
Speaker 1: like that it was a yield sign will change the retrieval.
Speaker 1: You'll believe that the whole time you saw a yield
Speaker 1: sign there instead of a stop sign. Now all the
Speaker 1: sounds surprising at first. You think I can distinguish my
Speaker 1: own memory from something someone else said, But it turns
Speaker 1: out we can't. And we'll dive more into this in
Speaker 1: a quite shocking way in next week's episode. But I
Speaker 1: want to give you a deeper sense of this now,
Speaker 1: about the changeability of memories. So here's another problem. It's
Speaker 1: a relative of the misinformation effect that psychologists and legal
Speaker 1: theorists have studied, and this is the issue of cowitness contamination.
Speaker 1: The idea is that if you see a crime and
Speaker 1: I'm standing there and I see it too, and then
Speaker 1: we start talking with one another about it, we can't
Speaker 1: help but influence each other's memories. If you remember that
Speaker 1: she had curly hair, but I say I'm pretty sure
Speaker 1: she had straight hair. Or if you think she was unathletic,
Speaker 1: but I say, no, she was really athletic, each of
Speaker 1: our statements become part of each other's memory, and we
Speaker 1: more and more come to believe things that we didn't originally.
Speaker 1: And we see these kinds of memory problems all the time.
Speaker 1: In police lineups. For starters, it's really difficult to remember
Speaker 1: the face of a perpetrator in a crime scene. So
Speaker 1: police and researchers have tried every which way for people
Speaker 1: to have an easier time reconstructing a face. You maybe
Speaker 1: describe it to an artist, or you reassemble the face
Speaker 1: from a selection of different possible eyes and nose shapes
Speaker 1: and mouths, and in the last decades you can do
Speaker 1: this with three D avatars on a computer. But whatever
Speaker 1: tech is introduced, it doesn't matter. People's performance is terrible.
Speaker 1: Why because memories are not like photographs. So one issue
Speaker 1: that researchers started noticing and studying in the nineteen sixties
Speaker 1: was police suggestibility. So imagine you're shown a lineup with
Speaker 1: several people and you have to decide which person you
Speaker 1: saw doing the crime. But imagine that the police already
Speaker 1: have their man in mind. They already think that it's Steve.
Speaker 1: Whether or not that's correct, they believe it's Steve, and
Speaker 1: they want you to say it's Steve. There are all
Speaker 1: kinds of ways that they can suggest that to you,
Speaker 1: even if it's unconscious on their part. So for example,
Speaker 1: positive feedback. If you say I think that's the guy,
Speaker 1: they say, yeah, good job, that's what we think. Also,
Speaker 1: it turns out that the positive feedback influences the confidence
Speaker 1: of the eyewitness, and then when the trial starts months later,
Speaker 1: the eyewitness says, I'm absolutely certain that it was Steve,
Speaker 1: even though he doesn't remember that. He was not certain
Speaker 1: at all, but because of the positive feedback, which can
Speaker 1: even be quite subtle, his confidence goes way up. And
Speaker 1: decades of psychology studies in the laboratory have verified the
Speaker 1: power of this kind of suggestibility. The main thing that
Speaker 1: everybody's worried about with lineups is false identification. In other words,
Speaker 1: if the perpetrator is in the lineup and you miss him,
Speaker 1: that's one kind of problem, But the deeper problem is
Speaker 1: sending an innocent person to prison with the false certainty
Speaker 1: that you remember his face. Now, a particularly interesting study
Speaker 1: was done by my colleague Elizabeth Phelps and her collaborators
Speaker 1: at New York University. On September eleventh, two thousand and one,
Speaker 1: Phelps saw the World Trade Center towers collapse from inside
Speaker 1: her offices, and she, like everyone else in downtown New
Speaker 1: York and around the nation, was completely horrified and thrown
Speaker 1: off balance by the events. But Elizabeth is a neuroscientist,
Speaker 1: and she started thinking about this issue of flashbulb memories. Now,
Speaker 1: this is an idea that's been around for a while
Speaker 1: that maybe really important, shocking public events get flashed into
Speaker 1: the brain in a different way than normal memory, like
Speaker 1: a flashbulb on an old camera that lights up a
Speaker 1: room and captures the moment. And the idea of flashbulb
Speaker 1: memories is that maybe them more consistent. But this sort
Speaker 1: of thing is very difficult to test because you can't
Speaker 1: give people genuinely horrifying experiences in the laboratory, so you
Speaker 1: have to wait for something to happen in real life.
Speaker 1: And Elizabeth and her colleagues realized that this might be
Speaker 1: such a moment to be able to put this to
Speaker 1: the test, So she and another researcher, John Gabrielli, rapidly
Speaker 1: developed a survey, and within a week a whole group
Speaker 1: of researchers from her lab were in the city surveying
Speaker 1: people on what they remembered. And the important part is
Speaker 1: that they conducted this survey one week after September eleventh,
Speaker 1: But then they called up all these people again a
Speaker 1: year later and gave them the same survey, And then
Speaker 1: they did the same thing three years after the attack.
Speaker 1: And eventually they did a follow up study ten years later,
Speaker 1: and this involved more than three thousand participants. Now, the
Speaker 1: key was these events from nine to eleven were highly emotional,
Speaker 1: and in those cases you lay down memory on essentially
Speaker 1: a secondary memory track controlled by the amygdala. So it's
Speaker 1: not just your normal hippocampus mediated memories. These were flashball memories.
Speaker 1: And the question is do emotional memories like this, Are
Speaker 1: they unforgettable or in other words, are they less likely
Speaker 1: to find themselves drifting with time. Well, I'll tell you
Speaker 1: the results, but let's start with asking the question of
Speaker 1: how confident are people in the accuracy of their memory.
Speaker 1: It turns out that if the memory is emotional, you
Speaker 1: have a much higher confidence in its accuracy, but it
Speaker 1: turns out that doesn't necessarily improve the accuracy itself. What
Speaker 1: the study found is that the accuracy of personal recollections
Speaker 1: of nine to eleven decreased over time. So what you
Speaker 1: measure is the consistency of the details, like does the
Speaker 1: person tell the same story that they did originally, And
Speaker 1: what they found was that the consistency was only sixty
Speaker 1: three percent after one year and fifty seven percent after
Speaker 1: three years. People's memories about their emotions were particularly inaccurate,
Speaker 1: with only about forty percent consistency after one year. Despite
Speaker 1: all this, confidence in these memories remained high. So here's
Speaker 1: the thing. Participants were better at remembering factual details about
Speaker 1: the attack which were supported by external reminders, So, for example,
Speaker 1: the number of planes that were involved, that accuracy remains high. Why. Well,
Speaker 1: it turns out this is because there are many facts
Speaker 1: that you learned from all the news around an event,
Speaker 1: and all this external corroboration corrects your memory. But other
Speaker 1: things that are just about your own personal recall these
Speaker 1: drift around in time. In other words, the researchers found
Speaker 1: that they could predict the accuracy of memories just based
Speaker 1: on how much media attention and ensuing conversation there was
Speaker 1: around an event. So if you're asking how many planes
Speaker 1: crashed into the towers, you might get a lot of
Speaker 1: confusion and even misterymembering in the heat of the moment,
Speaker 1: But after a while that all gets straightened out because
Speaker 1: it's a fact that everybody has seen, and conversations and
Speaker 1: news stories can come to eventually agree. In contrast, if
Speaker 1: you have some flashball memory about where you were standing
Speaker 1: and how you were feeling and what you were thinking
Speaker 1: that might drift into inconsistency. There's no one there to
Speaker 1: give you a firm correction on that, and therefore it
Speaker 1: can keep on drifting off in its own direction. And
Speaker 1: as we can extrapolate from Bartlett's War of the Ghost's study,
Speaker 1: the story moves in a direction consistent with who you
Speaker 1: think you are. And this is going to lead us
Speaker 1: into part two. In next week's episode, I'm going to
Speaker 1: talk about what all this means for our identities, as
Speaker 1: most of that data about our personal lives never gets
Speaker 1: correction from the outside. So let's wrap up. I want
Speaker 1: you to take a moment to think about the War
Speaker 1: of the Ghost's story and see what you really remember.
Speaker 1: Take a moment to think about what was in the
Speaker 1: original story, and then rewind to the beginning of this
Speaker 1: episode to see if your memory was actually consistent. What
Speaker 1: the War of the Ghost's Study highlights is the constructive
Speaker 1: nature of memory and the impact of our own internal
Speaker 1: model on the way that we remember narratives. The key
Speaker 1: is that we build our memory, and we are simply
Speaker 1: not built out of the right of machinery to track
Speaker 1: events like perfect records. Instead, we are built of cells
Speaker 1: which have a totally different algorithmic scheme than our computers,
Speaker 1: and as a result, the past can only leave a
Speaker 1: record by modifying the details of neurons and their genetic expression,
Speaker 1: which is a mind blowingly ingenious property of these particular cells.
Speaker 1: But it ain't a hard drive or a video recorder
Speaker 1: that records things accurately, and that's why memory always drifts.
Speaker 1: As I mentioned, in the next episode, we're going to
Speaker 1: zoom in on our personal identity because, after all, who
Speaker 1: we are, who we consider ourselves to be, is fundamentally
Speaker 1: grounded in our memory. Where we've been, what we've done,
Speaker 1: who we were with what happened to us. And this
Speaker 1: is fascinating in the light of what we're talking about today,
Speaker 1: because we've seen that memories are not simply a replaying
Speaker 1: of the past, or not often that accurate. So please
Speaker 1: tune into part two, where we're gonna understand whether our
Speaker 1: notion of the self is based on a mountain of
Speaker 1: narrative that continually drifts from what actually happened. Go to
Speaker 1: Eagleman dot com slash podcast for more information and to
Speaker 1: find further reading. Send me an email at podcasts at
Speaker 1: eagleman dot com with questions or discussion and check out
Speaker 1: Subscribe to Inner Cosmos on YouTube for videos of each
Speaker 1: episode and to leave comments until next time. I'm David Eagleman,
Speaker 1: and we have been drifting together in the Inner Cosmos.