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