How Your Brain Rebuilds Your Past

Memory Feels Like Evidence

SPEAKER_00 0:01

There's probably a moment from your childhood that you can still see a kitchen, a birthday party, the inside of a car, or somebody's face. Maybe you remember what the room looked like or what somebody said. Maybe even what you were feeling. And when that memory appears, it feels almost physical. Like somewhere inside your head there's a little piece of the pa the past that just survived and you brought it forward. It's waiting for you to press play. But that's not really what's happening. Your brain doesn't store memories like videos, it rebuilds them, like pieces of sights and sounds and emotions. Fragments of information that are scattered across the brain. It's all pulled back together whenever you remember. And here's the weird part. Every time you pull one of those memories back into the present, it can change. A detail gets added, another one disappears. Something you learned later, like it can slip into something that happened years earlier. So sometimes a picture becomes part of the memory, and then sometimes a story your family told you becomes something you could swear that you personally remember. And almost none of that feels uncertain while it's happening, but still, it could be wrong. And that might be the weirdest thing about memory. We build our identities around it. We use it in courtrooms, we use it to decide who we trust and who we love, all while we rely on a system that was never designed to perfectly preserve the past, anyways. So maybe that's the interesting question, isn't it? How do we remember when maybe it's just something a little bit more unsettling? How much of your life happened exactly the way you remember it? And this is the show where we take the ordinary things we live with every single day and we dig into them deep enough that we find out something pretty extraordinary. And usually we discover they're a whole lot weirder than they looked from the surface. And memory might be one of the strangest because memory feels solid. It still feels personal, it feels like evidence. You remember who you were. You remember what happened. You remember what someone said. Except your brain is doing something a lot more complicated than just opening a file and showing it back to you. It's rebuilding, reconnecting, filling gaps that you didn't even know were there. And sometimes it's changing things without ever bothering to even let you know that it changed them. Which means this episode isn't just about how memory works. It's gonna be about childhood, it's gonna be about forgetting, it's gonna be about pictures and eyewitnesses, a little bit of deja vu, maybe some false memories, and the weird way that our brain decides what parts of your life get to stay. And somewhere in the middle of all that is a question I haven't been able to stop asking. If memory is one of the things that makes you feel like you, what happens when memory can't be completely trusted? So today, we're gonna go down the rabbit hole of memory.

The Man Who Could Not Form New Memories

SPEAKER_00 4:45

There's a guy in this movie named 10 Second Tom, and his memory resets every 10 seconds. This first guy that we're gonna talk about was kind of Tom was kind of based off him. We'll start in 1953, in August, where a 27-year-old man named Henry Mulason was lying on an operating table in Hartford, Connecticut. Now, Henry had epilepsy, and not it's not the kind that you know occasionally interrupted his life. His seizures had become so severe and so resistant to the medications that they had at the time that holding down a job and living anything resembling a normal life had become incredibly difficult. So, his neurosurgeon, Dr. William Beecher, Scoville, offered him something drastic, and it was an experimental operation. Scoville believed that Henry's seizures might be coming from structures buried deep inside the temporal lobes of his brain. So do you want to know what Scoville did? He removed substantial portions of the medial temporal lobes on both sides of Henry's brain, including much of the hippocampal region. The operation actually did help control the seizures, but when Henry woke up, something else was missing, and nobody had expected this at all. Henry could talk and he could carry on a conversation, like his intelligence hadn't disappeared, like it was still there. He knew exactly who he was. He remembered a lot of his childhood, and he remembered his parents. He could hold information in his mind for a short period of time. If you introduced yourself to Henry, he could talk to you. He would laugh with you and answer your questions. He could seem completely normal. And then you could leave the room, come back just a little bit later, and introduce yourself again, and he would have no idea that you admit you would have to reintroduce yourself all over again. Because for Henry, in a lot of cases, that first meeting had never become part of his lasting memory. It was just like, you know, he his life could show up and then but much of it wouldn't stick. So scientists would eventually describe what Henry had as a profound enterograde amnesia. So he'd lost much of his ability to form new long-term like declarative memories. The memories, those are the memories for events and facts that we can like consciously call back later. And not every kind of memory disappeared, though. And that distinction would become ridiculously important because something fundamental had been broken. Like the bridge between experiencing something and being able to remember that experience later is just gone with Henry. And Henry was about to change neuroscience forever. For most of his life, the scientific world didn't even know his name. All they knew him as was HM. Now, a few years after Henry's surgery, a kind of a young neuropsychologist, her name was Brenda Milner. She traveled from Montreal to Hartford, Connecticut to study him. And this so here's where it gets kind of interesting. Because if memory were one single thing, Henry should have just been unable to learn. Period. Like But that's that's not what Milner found. She gave Henry a weird, like a funky little task. He had to trace a shape while looking at his hand only through a mirror. So if you've ever tried doing something like watching yourself in a mirror, you know how really, really hard that's it, that is. Everything feels backward. Like your hand goes one way, but the your brain expects the other. So at first Henry wasn't really good at it. Like he just like us, just not good at it. But Milner had him practice and then practice again. And something remarkable happened. He got better. Like his performance improved over repeated sessions, except Henry couldn't remember practicing. Like from his perspective, the task that she had him doing was brand new every single time. There was no he hadn't he didn't remember he'd already done it. She brought up a new practice every single time. So somewhere inside his nervous system, something was remembering. His hands were learning something that Henry, in his mind, himself could not consciously recall learning. So just stop there for a second. Because is that that is the weirdest thing I've ever heard. Somebody can learn without remembering that he learned. Which meant scientists suddenly had a problem. If memory were a single box in the brain, like just a single section, then how was he improving? Because clearly, whatever stored the ability to perform a skill wasn't exactly the same system that let you remember sitting down yesterday and practicing it. And that realization helped change the way we think about memory entirely. There isn't one thing called memory. There are different kinds of memory. You can remember that Paris is the capital of France. You can remember your first day of school, and you can remember how to ride a bicycle. Or say, so you can keep a phone number in your head just long enough to type it and then it goes away. But those all feel like versions of the same thing, but biologically they're not identical. They rely on overlapping but different systems in the brain. So Henry had lost access to some of those systems. Now while others continued working. So and so after studying Henry for a little while, they did realize that memory is not just a section in the brain anymore, it was a whole network.

Memory Is A Network Not A File

SPEAKER_00 11:28

Which brings us back to the question from the beginning of this episode. Where is your memory? Because I think most of us instinctively picture something like a like a storage room. Your eyes, your eyes can see something, and your ears hear something, and then your brain records it like a video camera, and then the memory gets just put somewhere upstairs. And years later, when you want it back, your brain walks in there, grabs the right file, and then opens it. Except there's no little video archive in your head. There isn't there's not like a little tiny version of you sitting inside your your head cataloging things. Which, I mean, is kind of disappointing because that would explain a lot. Instead, remembering is something your brain does. Like an experience begins as an activity. Light hitting your eyes, sound entering your ears, and like the smell of a room, the feeling of the chair underneath you, like your emotional state, what you're paying attention to, what you already know. All of those pieces are being processed through different systems. And for many kinds of new declarative memories, structures in the medial temporal lobe, especially the hippocampal system, are crucial for binding elements of an experience together. So they can later be retrieved as something resembling an actual event. And I want to be careful here, because the hippocampus isn't like a hard drive. Like Henry Malaysan didn't prove that scientists had finally discovered that little drawer labeled memories. Memory is more distributed and complicated than that. The importance of Henry's case, though, was that it showed just how crucial the medial temporal lobe is for forming certain kinds of new memories. And it showed us that storing a memory is a process, not really a location. Think about what happened to you yesterday. And not the big stuff. Just pick something completely ordinary, and maybe so maybe you stepped out at a gas station, and there were just a whole bunch of things happening around you, like cars were pulling in, maybe they were changing the numbers on the gas on the gas pump. Music was playing somewhere, you could smell gasoline, there were signs on the windows, the color of the sky, there were people walking. Maybe there were hundreds or thousands of little tiny pieces of information that were available to your brain in those few minutes. And right now, most of them are gone. And you probably couldn't tell me exactly what the person at the pump next to you was wearing. You couldn't reproduce every single word that you saw that was on the windows or on any ads. You uh couldn't draw the actual arrangement of every car in the parking lot. Your brain didn't fail. It did exactly what your brain's supposed to do. It was selective. So because memory doesn't begin with remembering, it begins with attention. Your brain is constantly deciding what matters enough to process deeply and what it can get rid of and make disappear. And honestly, I mean if you think about it, like thank God, because if you remember every single piece of sensory information that comes into your brain with perfect clarity, it you existence would be unbearable. Like memory isn't built to preserve everything, it's built to preserve what might matter. And sometimes your brain gets that decision really wrong. But you can so you can forget why you walked into the kitchen, but somehow you can remember every word to a song you haven't heard since like middle school. That feels like bad management, really, but there's a reason for it. Different memories are strengthened or weakened by different things. So some are strengthened by repetition, deep attention, or certain emotions can be tied to memories, which is really strong. If there's meaning behind the memory, or if you can associate that memory with something else. So the brain's not asking, you know, will so will Andrew want this information 16 years from now? I don't know that. I mean it's it's reacting to what seems meaningful at the time. And once something does uh become a longer lasting memory, the story's still not quite done because scientists use the word consolidation for processes through which initially fragile memories become more stable. So I mean, I guess even the word stable can be misleading to a point because memory isn't necessarily finished once it's stored. Like a memory can later be brought back, like retrieved, and under some circumstances, reactivation can make aspects of that memory modifiable again. Like before it comes before it becomes stable again, a process researchers call reconsolidation. The details and limits of that process are still actively kind of they're studying it now. Retrieval doesn't automatically rewrite every memory. Like every time you think about it, it's not automatically rewriting it every single time. But the bigger idea is pretty interesting. Memory is dynamic, like the past inside your head is not just sitting there untouched, like you know, behind the glass wall. The act of remembering is actually active, and that changes everything because when you remember your tenth birthday, your brain isn't it's not traveling back in time, it's it's doing something right now, like in the present. It's taking pieces of information that are stored across all the networks in your brain and constructing an experience that represents something that happened years ago. And it's subjective. Like it can feel absolutely real, and that's the magic part of it. We don't experience memories as reconstructions, we experience them as memories. So Henry Malayson lived for another 55 years after his surgery, and the researchers they studied him for his entire life pretty much. More than 100 scientists eventually participated in working with him. And even after Henry died, which he died in 2008, his brain still continued to teach people about memory. Like it was extensively imaged, and eventually they sectioned it into thousands of extraordinarily thin slices so researchers could still study exactly what had been removed and what was still there. Now there there's something kind of I don't know about that. I mean, Henry spent a lot of his life, a lot of his adult life, really unable to build any kind of continuous like record that most of us take for granted. And his life became part of humanity's memory, science's memory. Because of Henry, scientists learned that memory isn't one single ability. That learning can happen through a few things, but they really he really taught everybody that learning can happen without conscious reflection. And that's the region in that brain, I mean it plays a crucial role in forming certain kinds of new memories, maybe most importantly, that the thing we just call remembering is actually a ridiculously huge collection of processes that are happening all over the brain instead of just in one spot. Now, they're so seamless though that we almost never even notice until something goes wrong. But Henry's story kind of creates another question, maybe a bit weirder one, because if remembering isn't just opening a perfectly good file that was stored away, if your brain is reconstructing the past every time you reach for it, then what happens when the same pieces are missing?

How Suggestions Create False Details

SPEAKER_00 20:48

Like when part of those pieces are missing, what happens when your brain fills in the gaps? And you can remember something with just the most complete amount of confidence, but it never happened at all. Because in the like in the next few minutes, we're gonna meet a few people who kind of did exactly that. The students watched cars collide, and then the researchers would start asking questions. And one of those questions was extremely simple, like it's about as simple. As you can get, the same thing everybody would normally ask, anyways. So the question was about how fast do you think the cars were going when they hit each other? Now, except they read it a little bit clearer than that, but except not everyone got the word hit. For some people, the cars contacted each other, and for some other people, they bumped each other. They collided or they smashed into each other. Now some that they had the same films, the same crashes, the only thing they changed was that word in the question. They said hit and collided, just different one word. That's it. And somehow that one word changed the answer. The people who heard smashed estimated that the cars were traveling a lot faster than the people who heard hit or bump. And that alone is interesting, really, because maybe smashed just sounds faster. But then Loftus and Palmer tried something else. A week later, they asked some of the students another question. The question was, had they seen any broken glass? Some of them said yes. There was just one problem. There had been no broken glass at all. And the the people who had previously heard that the cars smashed into one another were more likely to report seeing it. So think about what that means. Nobody showed them fake glass, and nobody sat down and said there was broken glass, so remember this. One word had been introduced after the event. Smashed. And later, some people's reports about the event were different. That phenomenon became part of what psychologists call the misinformation effect. So information you encounter after something happens can influence what you later report remembering about the original event. And suddenly, the question we asked a while ago gets a lot more uncomfortable because apparently the past can be edited from the future. So this is where Elizabeth Loftus enters the story more in depth. And she has spent most of her career asking a question that sounds almost kind of rude. So, how much should we trust our own memory? And it's not whether she wasn't asking whether people lie because that's different. A person can be completely sincere, completely confident, and still be wrong. And that's an important distinction because when someone tells you a memory with confidence, we instinctively like we kind of treat that confidence as evidence itself. So I know what I saw, and I'll never forget his face. Like I remember it like it was yesterday. Those sentences are really, really common, but confidence and accuracy aren't the same thing. And memory is not protected just because the person remembering it is honest. Like, here's one way to think about it. So think about if you and I walked into a restaurant and there's music playing, and a server drops a glass, somebody near the window is wearing a red jacket, and a couple is arguing quietly in a booth. Just enough for you to hear the whispers. There's a basketball game playing on a TV above the bar. We eat, we leave. You know, three days later I ask you, Do you remember the blue truck parked outside the restaurant? Maybe there was a blue truck, maybe there wasn't. But I've just given your brain something new, a blue truck. So now imagine I mention it again later, but then someone else does. And then you picture the parking lot while telling the story. At some point, you've got the original event, but there's information you learned afterwards, like images that you've created while thinking about it. And there are previous memories, like previous versions of the story you've already told. So your brain has to answer a really hard question at this point. Where did each piece of that come from? And psychologists call this problem, they call it source monitoring, because we don't only need information. We need to know the source of that information. So did I did I actually see that? Did someone tell me? Did I see it in a picture, or did I like, did I dream it? Did I imagine it? It's what you gotta think about. Like, did you hear the story so many times that now you can picture it? Usually the brain handles this pretty well, usually, but not always, because that's when something can start to feel like a memory, even when it's not. Which that led Loftus and another researcher, Jaclyn Picker, to find something way more weird. So, in a small study that they published in 1995, they recruited 24 adults. I know it's not a very large sample size, but you get what I'm saying. 24 adults. Before the experiment, researchers contacted relatives of the participants and gathered information about certain events from their childhoods. And then each participant was given descriptions of several childhood experiences, and most of them were real, but there was one that wasn't. Now, the researchers created a story claiming that when the participant was about five years old, they had gotten lost in a shopping mall, and they had supposedly been frightened, they had been separated from their family, eventually an older person helped them, and they were reunited. The relatives had already confirmed that the event had not happened, but the participant didn't know that. As far as they knew, this was just another family story. And they were asked to try to remember it. And then they were interviewed again and again. And some of the people started producing memories. And it's not, yeah, just maybe that happened. Some people actually supplied additional details, like thoughts and feelings, and some images they could remember, pieces that they had not been given by the researchers. So by the researchers' criteria, about a quarter of the participants came to report at least some memory of that event that was completely made up. So we need to be careful here because this experiment gets repeated online in a lot more dramatic form than like than the science actually supports. It doesn't mean that researchers can casually manufacture any memory they want in anybody's brain, but the original study was tiny. Like I said, it's only 24 people. Now, the the event that they came up with was relatively plausible. Like getting lost as a child isn't the same thing as convincing someone they committed a murder or that they were abducted by aliens. And false memory, like false memory research is full of a bunch of debates about what counts as a genuine memory versus accepting a suggestion and developing a belief or imagining an event. And those distinctions are what separate all of it. Like a larger pre-registered publication in 2023 did kind of reproduce the basic effect. But so in that study, researchers classified about 35% of 123 people as reporting a false memory of like the fabricated lost childhood event, compared with about 25% in the original experiment. So, no, not really. Like your brain is not a whiteboard that anybody can erase and rewrite whatever they feel like on it. But your memory can be influenced, and that's the point. And sometimes something that never happened can begin to like mold in with something that did, which makes childhood memories especially difficult and also kind of fascinating because think about your earliest memories.

Family Stories And Childhood Memory Blur

SPEAKER_00 31:35

Like maybe, okay, so maybe you're three or four or five or whatever. Like, from what angle do you see the memory? Like, seriously, pick one. Where are you in the scene? Because sometimes people remember an event from a perspective they could never actually have seen. They see themselves across the room. Like they're standing beside someone. It's like a camera was pointed at them. So you're seeing yourself. And that's sometimes called a third person or like an observer perspective. And it's in something that's called autobiographical memory. And that alone doesn't mean the event is false. Real events can absolutely be remembered that way. But it shows us something important. Your brain isn't necessarily replaying the sensory experience exactly as it originally occurred. It's construction like it's the construction that represents the event. And it has it has a lot more material available now than it did then. So you have family stories to pull from now, you have a bunch of pictures, maybe some home videos. Things that you learned since that Christmas day, your understanding of who everybody in the room was has changed. And you can know information about a memory today that the four-year-old version of you couldn't possibly have known at all. And yet it can all feel like one just seamless memory. And I have memories from childhood that I'm almost certain are mine. And then there are others where I'm not completely sure anymore. Like I don't know if I actually remember that or if I've heard the story so many times that I can see it in my head. And that's a really weird thing to think about because families do this constantly. Like we build this big shared story together. Like, remember when Andrew did this, or you always used to say, or you were terrified of, blah, blah, blah, blah, blah. Then the story gets told at Thanksgiving and then Christmas, and then somebody finds the picture 20 years later, and now the story has pictures and characters, and there's like it's all coming together, but it's almost like a little family movie. And somewhere, but in that 20-year period, it can become really difficult to separate remembering the event from remembering the story of the event. And that doesn't make that doesn't mean that the story is fake. It doesn't even necessarily mean your memory is wrong. It means your autobiographical memory is very messy. Because human beings aren't recording, like we're not recording devices. Like we talked about earlier, your brain isn't 100% just recording everything exactly like it happens. A lot of the times people we're storytellers, and normally that's harmless. Like sometimes it's really cool. Your family's stories help tell where you came from. But there are places where memory carries a lot higher stakes.

Eyewitness Confidence Can Be Wrong

SPEAKER_00 35:20

Like a courtroom. A witness points across the room and says, you know, that's him. Or there, like, there may not be fingerprints, or there's no DNA. There might not even be video. Because someone remembers a face. And to a jury, it may actually mess you up because that can feel to a juror, it feels like, you know, oh boy, they know that. They've seen the face, they remember the face, that's it. But because we understand that brains can malfunction and memory doesn't really last, labs can also be mishandled. Now, don't get me wrong there. Paperwork can get lost, but in the jury's mind, this person was there. They saw it. Except the same memory that reconstructs your fifth birthday is the one standing in the witness box. So attention matters. And lighting, you know, distance, stress, the amount of time that has passed matters. What happened after that matters. How so even how they do a lineup can matter. So if somebody talks to the witness afterwards, you know, whatever they're told can change the perspective, change the perception. Even feedback after an identification can affect their confidence later. So there was something about on the Innocence Project. So among the Innocence Project's data set, they took 375 DNA exonerations from 1989 through 2020. So eyewitness misidentification was involved in 69% of those cases. And that doesn't mean that eyewitnesses are usually wrong. But DNA exonerates like when they exonerate that case, that is a highly selected group. And it shouldn't be treated as a sample of all criminal cases because it shows how absolutely devastating a mistaken memory or a mistaken ID can be when everything else fails. And here's the part that I think you should really pay the most attention to. Those witnesses, they didn't walk into the courtroom planning to destroy an innocent person's life. Many of them believed what they were saying. Like I mean, they believed it. Like they believed what they were saying was correct. And that's really scary because the problem, it's not that they were dishonest. The problem was that they were uncertain, but they thought they were. We tend to picture memory, like memory errors really, as fuzzy. Like, I don't really remember, I'm kind of fuzzy. But they say maybe or I'm not sure, and sometimes they really are, but a memory can feel so vivid and still contain errors. Like, I mean, that's why the question, how clearly do you remember it, isn't the same question as did it happen exactly that way? Like, vividness isn't a property of the memory, accuracy is a relationship between the memory and actual reality, like actually what happened. Those aren't the same thing. A dream can be vivid, and an imagination, like an imagined conversation, can be vivid. But a story that you've repeated a hundred times can also be vivid. So if you've repeated that story a million times, you know it so well, it's so vivid in your mind that you just have no idea if it's real or not anymore. So, I mean, your brain doesn't stamp every single image with like a little certificate that says like verified historical record. But that would be kind of helpful if they could figure that out. But before we start distrusting every memory we've ever had, there's something important that I need you to understand. Memory being reconstructive isn't some big giant design flaw. I mean, it's probably it's probably the part that makes memory the most useful because your brain isn't primarily trying to preserve everything like it's in a museum. Like it's trying to use the past to help the future. So it's trying to pick what matters and trying to be like, what does this remind me of? Have I encountered something like this before? What should I do next? It tries to take memories that it has preserved from the past to use in the future. So, I mean, it's hard to explain because uh it's a literal recording of everything that has ever happened to you. It would contain if you had that, it would contain a stupidly amount, like stupidly huge amount of unimaginably useless information. Like instead, the brain works on pattern behavior. Like it pulls patterns out of the your daily experiences and attaches anything that's got meaning attached to it or relationships, the general shape of things. I mean, that's that's pretty powerful. It's why an experience from 10 years ago can help you make a decision tomorrow. But the problem is it has a cost, right? Because details can move and sources can become a little confusing, and new information can kind of sneak its way in, like we talked about, and the story can change, which brings us to something a little a little stranger, because so far we've talked about memories the way they change because of information coming from the outside, like a question that someone asked you, or a family story, or a suggestion, but your memories can also change just because you keep remembering them. Like every time you tell the story, you're not necessarily returning to the original event. Sometimes you're remembering the last time you remembered it, and then the time after that, and the time after that. Like a story becomes a lot smoother because certain details they get kept because they make the story work. Others kind of disappear. Like maybe there's a line of dialogue that gets a little bit better, or maybe the order of things changes. Maybe the version that everybody laughs, like if you tell a story and you don't get a laugh, but then you tell it again and it's slightly different and everybody laughs, that might be the version that your brain chooses to remember. And eventually, the memory in the story become almost impossible to even separate at this point. Which raises a question that is somehow. I mean, it it's a lot more different than just a false memory. If remembering something can change it, then why do some memories refuse to disappear at all? Like, why why can you forget an entire year of ordinary Monday, Tuesday, Wednesday, Thursday, just the regular grind? Why can you forget that entire week or year or whatever it is? But you remember 10 seconds from 20 years ago clearly and perfectly. Why does the brain keep that? Why does the brain keep that 10 seconds? Why does a smell suddenly bring back everything you've ever thought about in your childhood? And why can a song open a door you didn't even know was still there? Like to answer that, we have to talk about one of the strongest forces memory has, which is emotion. And the strange memories that are tied to emotion, they feel as if they've been burned into us. That's where we're So we're gonna jump around a little bit.

Flashbulb Memories And Public Tragedy

SPEAKER_00 44:25

To January twenty-eighth, nineteen eighty-six. So I wasn't even born yet. But at eleven thirty-eight in the morning, the Space Shuttle Challenger lifted away from Kennedy Space Center. For the first minute, everything looked normal. The shuttle climbed over Florida, mission control gave the crew permission to throttle up. Commander Dick Scoby answered, and then 73 seconds after liftoff, the Challenger was gone. All seven people aboard were killed, and millions of people were left with one of those moments. The kind where the world just divides itself into two pieces, like before you knew and after. NASA's investigation would eventually determine that the disaster began with the failure of SEALs in the right solid rocket booster. Now that was worsened by unusually cold conditions before launch. But psychologists were about to become interested in something else. And it's not what happened to the Challenger, but what happened inside the minds of the people who heard about it. Because this was exactly the kind of event that seemed capable of creating something researchers had been fascinated by for years. Like it was a memory so vivid and so detailed and so emotionally powerful that it almost felt like a picture, like a real picture. Nine years before that, there were two psychologists, Roger Brown and James Kulik, who had given those memories a name, and they're called flashbulb memories. Their classic example was the assassination of John F. Kennedy. And as somebody, like, ask anybody who lived through the November 22nd, 1963, who lived through that, ask about Kennedy's assassination. And many people, like a lot of people, could tell you way more than just Kennedy was killed. They remembered exactly where they were, when they heard it, what they were doing, they remember who told them, who else was in the room. Like they remember everything about it. And it's it's perfectly clear. And that's the weird part is that sometimes there were meaningless little details about that day that survived too, like you know, what you were holding or something like that. So Brown and Kulik thought something unusual might be happening there. Maybe when an event was really, really surprising or important or emotional, your brain essentially decided to say, you know, save this right now. Like in this very moment, that's where they get the flashbulb from. So they're proposed the way they thought about it, their the way they termed it really was their mechanism was called now print. Like the brain had a camera hidden somewhere inside of it, and it was taking something enormous that happens and just taking a flash and it fired. Now that moment gets preserved. And I mean, the explanation feels right because you've probably experienced something like this. Like there are ordinary days from 10 years ago that are almost completely gone. But there's a random Wednesday where something really huge happened to you, and you remember every bit of it. You remember the room, you remember whatever phone call you got, the expression on someone's face. I mean, maybe it was terrible news, maybe it was really, really good news. Nobody knows. But it was the moment someone decided that that was your flashbulb memory. Like the moment you found out someone had died, or the moment you got the job, there's a million ways you can have a flashbulb memory. But there's an issue here. Was it a flashbulb memory or was it not? Did your brain actually take the picture? So on the morning after the Challenger disaster, researchers Ulrich Nesser and Nicole Harsh gave questionnaires to college students at Emory University. So it hadn't even been 24 hours yet since this happened. The students were supposed to write down how they'd first learned what happened. Like where were you at? What were you doing? Who told you? Who was with you, and what happened afterward. Now, these weren't people trying to remember something from years earlier. The event had just happened yesterday. So the researchers had something unusually valuable at this point. It was a record. So a version of the memory written down almost immediately after the event. And then they put it away. They put it away for years. And eventually 44 of those students were brought back. 32 to 34 months, I think, after the challenger happened. And the researchers asked them the questions again. Where were you? How did you hear? What were you doing? Who was there? The students actually remembered. Many of them remembered it vividly. They were confident they could tell the story, there was only one problem. Their stories often didn't match the stories they written the morning after it happened, though. A couple of details had moved, and some had completely disappeared, and others had appeared all together. And in some cases, the entire scene through which the person remembered receiving the news had changed. So one one weird little pattern that showed up involved TV. Like a student might originally have recorded learning the news somewhere else, and then watching TV coverage later, that's when that's what they brought back in their mind. The television coverage could migrate backwards in the story. So now they remembered learning about the challenger from the TV, but they had put that someone told them earlier. The pieces were real, but the order was not. So the brain had apparently assembled them into a different scene. And then the people telling those scenes weren't super unsure. It's I mean, I guess it's the opposite. They were extremely confident, which gave the psychologist a clue. Maybe flashbulb memories aren't actually pictures like photographs after all. They're just ordinary memories with extraordinary confidence attached to them. And then we jump forward just a little bit to September eleventh, two thousand one. Researchers got another terrible opportunity to study the same question. The day after the terrorist attacks, there were two psychologists again, Jennifer Telerico and David Rubin, asked fifty-four Duke University students to write down two memories. First, how did you learn about the September eleventh attacks? And second, tell us about an ordinary event from around the same time. Then the researchers brought different students back after one week, then six weeks, or thirty-two weeks. And something interesting happened there. As time passed, the consistency of both kinds of memories declined. The ordinary memories changed, but so did the flashball memories. The difference wasn't that one remained perfect. The difference was how the memories felt. Confidence in the ordinary memories declined and their vividness declined. People became a lot less convinced that they were remembering them perfectly. But their memories of learning about September 11th continued to feel vivid. People continued to believe in them, and that feeling of certainty, it survived better than the details themselves. So the researchers eventually put it pretty pretty nicely in the title of their paper, which was Confidence, not consistency characterizes flashbulb memories. And that's pretty incredible. Emotion might not give us a perfect recording, but it may give us something psychologically even more powerful. The feeling that we have one. So why? Why does emotion do this? Why can a moment of enormous emotional significance feel so different from everything around it?

Emotion Strengthens Memories Unevenly

SPEAKER_00 53:41

Part of the answer takes us back into the brain, and specifically a small collection of structures buried really, really deep inside the temporal lobes, which is the amygdala. Now the amygdala gets oversimplified constantly. You've probably heard it called the brain's fear center, which is one of those explanations that's useful for about 15 seconds and then it starts creating a few problems. The amygdala is involved in a lot more than just fear. I mean, among other things, it's really involved in processing like big emotionally significant information. And then it's also significant in influencing how emotional arousal affects memory. Remember the hippocampal system that we talked about through him Henry? So the system involved with emotion and the systems involved with forming memories interact. So when something emotionally significant happens, the brain doesn't simply just write the word important on the memory. Emotional arousal can affect the biological process that's involved in like strengthening and consolidating what happened. So stress hormones and neurotransmitter systems, they kind of become involved. Like activity in the amygdala can influence memory-related processing in other regions, though. And under a lot of circumstances, emotionally strong experiences are remembered better than neutral ones. Which I mean, it makes sense with evolution, I guess. If you're an animal moving through the world, the ability to remember emotionally significant events is pretty useful if you think about it. That plant the plant that it ate, it made it very sick. Or that animal almost killed it. You know, they know to avoid that plant, they know to avoid that animal. So that I mean, they think about that and it works. That's how a lot of this stuff goes. I mean, remember, so remembering important experiences can change what you do the next time something similar happens. Emotion is the one way, like one of the ways, anyways, the brain helps decide what matters and what doesn't. It doesn't really preserve everything equally, though. So suppose something really shocking happens in front of you, and your attention snaps over to it. The important thing becomes incredibly uh important. If you think about it, the the main focus of that becomes really important. Like and the wallpaper on the walls, no. The clock on the wall, no. The person sitting past that event in the background? Maybe not. Researchers have found that emotions can sometimes create a difficult kind of memory trade-off. Which I mean, certain like certain central or emotionally important parts of an experience may be remembered really, really well, while like the context of it or the smaller details can be remembered a lot less reliably. So that's where it gets you know the general idea of the memory, but you can't remember the smaller parts about it or anything surrounding it. And even that's not like a universal rule. Emotions' effects on memory depend on what kind of information we're talking about, and how your attention is directed, and the type of intensity of emotion and other circumstances, but memory refuses to give us easy rules, and that's the problem. But I mean the the broader point survives, like the biggest chunk, the what the general idea. Remembering only one part of an emotional event really, really well, it doesn't mean you remember every single part really, really well. You might remember the faces, but not the room, or the sounds, but not what time it was. The sentence that somebody said, but not exactly what happened right before it. And your brain can take that one little fragment and make an entirely like strong memory feel real, feel vivid. And that's the that's the distinction there. Because vividness feels like evidence, but it's not necessarily evidence. That's the problem. Think about a photograph. If I show you an old picture from your childhood, and every like every single pixel came from the same instant, the person in the corner, the wallpaper, your shirt, the chair, expression on your face, they all locked together. Because if one part of the picture is sharp, you don't expect another part to just turn into something else. Memory isn't like that though. Memory can contain pieces with different levels of reliability. So one detail might be ridiculously accurate, and another one might be reconstructed out of the same picture. But they all come together as a memory. That's why it gets kind of tricky because you don't know which pieces are accurate and which ones aren't. And then there's repetition. I mean, because major emotional events get remembered differently from ordinary Tuesdays for obvious reasons. We keep remembering them and we talk about them when we tell the story. Somebody asks, you know, where were you when you heard? So you retrieve the memory, and then another person asks, and you retrieve it again. So it's always brought up. It's constantly being thrown back through your head. So the memory feels more permanent because we've returned to it so many times. There is something strange about the phrase, I'll never forget, though. We say it after important moments, I guess. We say it after, you know, I'll never forget this for the first time I saw her, or I'll never forget that phone call, or I'll never forget where I was. And I mean, maybe that's true. Maybe the memory really will stay with you for the rest of your life. But staying is not the same thing as like re as staying unchanged. And that's what I keep coming back to because a memory doesn't have to disappear to be altered. You can remember something forever and still remember parts of it differently than you did once before. Like the emotional core kind of stays the same. You remember being scared or happy or sad, but then a million things could change out of that somewhere. That's the one thing, like, okay, so think of it this way. I don't think that memory isn't the super extraordinary thing that we think it is. Your brain takes an experience that existed for just a few seconds and turns it into physical changes inside actual living tissue, which is pretty cool.

Smell And The Proust Phenomenon

SPEAKER_00 1:01:34

It'll keep the version of it through the years, like birthdays and stuff like that, and then one afternoon, something happens. Like somebody says a name, or a song comes on the radio, or you open an old box and you smell, or you smell something. That's even better. And suddenly you're not thinking about the past, you're actually there, like you're in the room. You can smell it, you you're you can feel it. It's that's one of the strongest things is smell whenever it comes to memories. This is just it's weird because smell like there was okay, so think of it this way There's a guy who takes a spoonful of tea up to his mouth, and there are crumbs of cake floating in it. So he takes a taste of it, and then suddenly the entire world comes back. Like it's not it's not that it's a fact or a name or a place. There's just so much of everything that came back because he didn't remember a version of him that had been gone for years. Like that moment appeared. Okay, so this that was actually from the beginning of a book that was published in 1913. It was the first volume of what would become In Search of Lost Time. So his name was Marcel Proust, and the narrator he tastes a Madeline softened in tea, and at first he doesn't understand why the sensation affects him the way it does. He knows something is happening, and like something something is buried in there. And when the connection arrives, when he was a child in Cambrai, his aunt used to give him pieces of A Madeline dipped in tea. The taste had dug that up. Like he couldn't consciously remember where he knew that from. He knew he knew it. And then it just popped in. Now Proust was writing literature, like he wasn't conducting science experiments and stuff like that. He was just writing. But I mean, more than a century later, psychologists still use his name for something really, really similar, which is called the Proust phenomenon. That strange experience when a small like smell or flavor suddenly triggers a memory. It's usually without permission. You just it pops in. You're sitting there trying to remember fourth grade, and you walk through a store and someone opens a bottle, or a breeze comes through the window, or you see a little sticker or something, and then boom, you're nine years old again. There are smells that I can describe, like coffee and gasoline and fresh cut grass and rain. But there are other smells that aren't really smells anymore. They're places. Like one smell is somebody's house, and another is school and summer and like a person. You might not even know what chemical you're detecting, really. You may not have a good word for it, but your brain does something almost instantaneously. Like, I know this. And then comes the stranger part. So I know it from somewhere. But that's where smell becomes different. Because sometimes you don't simply recognize the odor itself, you get sucked backwards into it. Like the researchers have actually tried to measure that feeling, and the evidence really suggests that Prouss was onto something. In 2002, psychologists did an experiment. Psychologists named Rachel Hurz and Jonathan Schooler compared autobiographical memories experienced in the presence of odor cues with the same kinds of memories prompted by visual and verbal cues. The smell didn't necessarily make every memory more accurate or produce some kind of magical perfect recording of the past, but odor associated memories were rated as more emotional. And so participants tend to report a stronger sensation of being brought back to the original event by smell. Like, I mean, they they want. To say, like, you know, I remember grandma's kitchen, but they're they're leaning more towards for half a second I was in grandma's kitchen. So they're not really the same experience. You're remembering, but most people were reporting that for half a second I was in the kitchen. To understand why smell is so good at doing this, we need to follow what happens after you breathe in. I mean, somewhere in the air around you are molecules and they enter your nose, and inside your nasal cavity, they go up to the olfactory bulb, which is has receptor neurons. Humans have hundreds of different types of functional odor receptors. And odors typically activate combinations of all of those. So those neurons send signals into structures just above your nose called the olfactory bulbs. And from there, things get a little interesting because smell takes on an it takes an unusual route through the brain. Most of our major sensory systems pass through the thalamus before reaching their primary area. Vision does, hearing does, all that kind of stuff. Olfactory is different. Like signals leaving the olfactory bulb can project directly onto the forebrain. Like there's no there's no moving around, no nerves, no traveling here, there. It goes directly onto the forebrain. And they're deeply connected with networks involved in emotion and memory. So you'll sometimes hear that hear it in like a simple form is like smell bypasses the thalamus. They say that. But I mean it doesn't have the same relay as everything else does. So, anyways, the real story is better. It's so it's early wiring places olfactory information unusually close to structures involved in emotion, association, and memory. And that's according to NCBI. So, in other words, the architecture matters. The system handling a smell is already communicating with some of the machinery. But it's just asking, like, what does this mean to me? Which I mean, smells are pretty personal, that's why they become so personal. Fresh cut grass and your grandma's cookies and stuff like that, and Christmas, especially any Christmas smells. But I mean, I feel like I've rambled on quite a bit on this episode, but we're gonna wrap it up just real quick. I've got a couple things we're gonna talk about. We're gonna go ahead and move over to a couple of things that we forget.

Forgetting Curves And Tip Of Tongue

SPEAKER_00 1:08:49

Like sometime around 1879, Herman Ebbinghaus began doing something that sounds a little torturous. He sat down and he memorized just a bunch of nonsense. No poetry or history. It wasn't even real words. He made up words that had no meaning to him whatsoever. Like Dax, Bach, and yeah. It was just consonant, vowel, consonant, hundreds and eventually thousands of just stupid syllables constructed specifically so they wouldn't mean anything to him. And he repeated them again and again and again until he could recite a list correctly. Then he stopped, waited 20 minutes, and he'd try again. Or he'd wait an hour, or nine hours, or a day, or two days, or six days. He was experimenting on himself. So he recorded 163 sets of learning and relearning tests to carefully measure how much work it took to learn lists of syllables. Which is ridiculous. Like, that's a long time to just memorize not real words. But the question he was trying to answer that nobody had really been able to measure before, he wanted to know what forgetting looks like. Like, not metaphorically, but like actually mathematically, what does it look like? If you learn something and then leave it alone, how does it disappear? So in 1885, Ebbinghouse published the results in a book called On Memory. And buried inside those experiments, it was a shape that psychology students still kind of learn about today, which is the forgetting curve. Feel free to look that up because that is an interesting rabbit hole in its own. But yeah, I mean, like psychologists Roger Brown and David McNeil studied their own kind of phenomenon in the 1960s, which it's kind of it's hard to explain. So you don't know what you forgot until you forgot it, which was essentially what they were talking about. They gave people definitions of uncommon words and tried to induce what we now call the tip of the tongue state. And people who couldn't retrieve the target word could sometimes still report pieces of the word. Like aspects of it, be the beginning sound or the number of syllables. It's it's on the tip of my tongue. I know it, but you know. Yeah. And then Oh Jesus. So if you think about it, that's pretty weird. The whole memory, the memory isn't available, but pieces of it are. There's something in there, and you can't just get the door open, and then three hours later, while you're sitting there brushing your teeth, you're like, oh, it was it's Willem Defoe. So thanks, Brain. You know, very useful timing. I looked stupid three hours ago when I couldn't think of it. But the there's a lot of things that nobody really goes through here. And memory is one of the most complex, just in-depth things that we have ever studied. And it can be pretty interesting. But I'll tell you what, guys, there's a few things I'm gonna go over with you here. As always, technically, that's where our main story ends. We started by asking how much of your life happened exactly the way you remember it. And the answer is there's probably no way to know. Because some memories may be really, really accurate, and some have changed or disappeared altogether, and some are still there, but they're not accessible. So some things you confidently remember may contain details that added later. Except memory has a few corners we haven't looked into yet, and some of those are ridiculous.

Memory Extremes Deja Vu Aphantasia

SPEAKER_00 1:12:50

There are people who can give you the date and then tell you what they were doing on that date decades ago. So if you don't know, this is my favorite time of every episode, and we're gonna move into that's wild. But you always come across some slightly insane things. And we've spent the entire episode kind of talking about how memory is complicated and it's reconstructive and emotional, it's connected to places and smells, it forgets things on purpose. We still trust it enough to remember where we put our keys most of the time, except for me, because I lose my keys all the time, and my wallet. My wife hates me because of that. Now, there are a few things about human memory that didn't really fit anywhere else in this story, though, but they were way too just weird to leave behind. So we're gonna lead into that's wild because it's just my favorite part. I love this part. So, number one, I did find that some people can remember almost every single day of their lives. So if I asked you to tell me what you were doing on April 17th, 2011, and you couldn't cheat, do you know what day of the week it was, or what you were doing, or what was happening in the news, or what you ate? Can you tell me everybody that you talked to? For most of us, no way at all. I don't even remember what I did yesterday. But April 17th, 2011 has been swallowed by, you know, every day after that. But there are people who can do something really, really, really, really close to this. And the condition is called Highly Superior Autobiographical Memory, H-S-A-M. It was first described scientifically in 2006 after researchers at the University of California, Irvine, studied a woman that they called AJ. Now her real name was Jill Price. If you give Jill a date from decades before, she can pretty much tell you what day of the week it was, what she was doing, and what was happening in her life. And sometime, like sometimes that was what was happening in the world. But researchers, they spent years testing her. And they started to figure out they found a bunch of other people with similar abilities. I wouldn't say a bunch, but they were they all had similar abilities. UC Irvine researchers, they have by now identified about a hundred people with HSAM. But here's the part that makes this really interesting. People with HSAM don't necessarily have photographic memories. They don't just dominate every memory test that scientists give them. On actually, in reality, most of the standard lab tests, the memory tests, they perform just like everybody else. But their extraordinary ability is specifically tied to their autobiographical memory. So their lives, their days, and their past. Even like, and even they're not even immune to everything we've talked about in this episode because research has found that people with HSAM can still develop false memories. They still forget. Their memory is not a perfect thing, but they just seem really, really good at retrieving their memories, like their past memories, if it revolves around them or is about them or has to do with them. Which kind of sounds like a superpower until you think about it for a while. Because forgetting isn't always something you'd want to lose. Like embarrassing moments, arguments, breakups, or any kind of grief, days that you'd rather just kind of wish would go away. For most of us, as time goes on, it softens the memory and soften the edges of the bad memories. But for somebody whose memory remains just unusually accessible, that's probably gotta suck. The past has to be a lot harder to live in than for us. So apparently, one of the most extraordinary memory abilities ever discovered also comes with a very important reminder that sometimes forgetting is a gift. So there's another one. Number two is memory champions aren't necessarily born with incredible memories. So there's there's there's competitions. I mean, well, of course there are so humans, I mean, we'll turn anything into a sport. I'm telling you, competitors in this sport necessarily, they will memorize playing cards, numbers, and names and faces, lists of words. And some of the performances are just ridiculous. Like elite memory competitors can memorize hundreds of digits in minutes. Like they can learn the order of an entire shuffled deck of cards in seconds, which sounds like the work of some genetically just overdone super brain. Except a lot of memory athletes say something a lot more exciting, or a lot less exciting, actually. They just practiced a lot, and one of their most powerful tools is a technique that's thousands of years old, which is the method of Lochi. And you might know it as a memory palace. Like, okay, so how it works, if you pick somewhere you know extremely well, like your house, imagine walking through it, front door, living room, kitchen, hallway, bedroom, all of those locations become hooks. Then take whatever you're trying to remember and turn it into something vivid, like ridiculous helps. Let's say you need to remember milk or a camera, a pineapple, a shoe. So you picture opening your front door, and then thousands of gallons of milk pour out. Or you and then you fight through the milk and reach your living room. There's a where a giant camera is sitting on your couch taking pictures of you. In the kitchen, there's a six-foot pineapple cooking dinner, and then you walk into your bedroom and there's a shoe tucked into bed. And later, when you need the list, you mentally walk through the house and the objects are waiting for you. So milk, camera, pineapple shoe. It sounds stupid, like it really, it really does, it really is. But it works. Because the technique connects new information to a spatial structure you already know really, really well. Hmm. I mean, I guess I guess I get it. Now, number three, deja vu may you might get it. You might like deja vu may be your brain kind of saying, I remember this, but it's not telling you why. So you walk into a room, somebody says something, and then you turn your head, and suddenly you know. Like you've done this before, that's you haven't done anything similar. Like this, this very thing, the exact room, the exact moment, the exact feeling. Except you also know that you haven't. Like, that's what deja vu really is. The term is French, ready, really, for already seen. And one of the strangest things about deja vu is the contradiction that's built into it. Like your brain is saying familiar, while another part is saying, no, this is new. So you're fighting back and forth. Your brain is like, I I know, I know, I know this, I've been here. But your brain also knows, like, no, you haven't, that's impossible. So researchers really think that the conflict may be central to the whole experience. Recognition normally involves different components. Like sometimes you recollect something, you retrieve details of the earlier event, and other times you just experience familiarity. Like you know, you know you've encountered something without being able to say where. So deja vu kind of involves that familiar signal occurring at the wrong moment. It's really wild. Now there is an opposite of deja vu, which this one is one of my favorites. It's called uh jamaivu, which is roughly never seen. And it's basically the actual opposite of deja vu. Instead of something feeling like something new that feels strangely familiar, something that's completely f familiar to you, like suddenly just feels strange. You've probably experienced a small version of this, I guess, with words. So pick a word or any word. Let's use a door. Door, door, door, door, door. You say it enough times and eventually something happens. Like you look at it and you think, is that really how that's spelled? Like, door. What even is a door? Why does a door sound like why does the word sound like that? The word hasn't changed. You've known it your entire life, but temporarily, like really temporarily, the familiarness of it can collapse. The researchers have actually induced something resembling Jamaivu in like in the lab by asking people to repeatedly write familiar words. In one series of experiments, people often stopped r after roughly 30 repetitions or around a minute because the word had started to feel weird, like feel unfamiliar or feel kind of wrong. And I love this because Deja Vu and Jamain Vu exposed something we almost never really noticed. Familiarity itself is a sensation. So we usually don't feel it because it's working properly, I guess. Your bedroom feels like your bedroom. Your name feels like your name. The word door feels like the word door, and then something just glitches for a second, and some and suddenly you're just like you can see the machinery behind it. Like, you know that you know it, but temporarily you lose the feeling of being informed that you knew it. I mean, that's it's that's kind of wild. So no notes, no notes there. And the last one some people really don't have a mind's eye. Like, I want you to do something. So if you picture an apple, now picture the apple, don't describe the apple. Actually, try to see an apple in your head. The red skin, little brown stem, maybe like a highlight on one side. Can you rotate it or can you make it green? Can you put it on a wooden table? For a lot of people, there's some kind of visual experience happening. It's not identical to actually seeing an apple, but there's an image there. Now, imagine I asked someone else to do that, and there was nothing. Like they know what an apple looks like, and they can describe it. They'd recognize one instantly, but voluntarily creating the picture, no image. That's called apantasia. And researchers estimate that a small percentage of people experience extremely weak or absent voluntary visual imagery. At the other end of the spectrum is hyperphanasia, where mental imagery can be extraordinarily vivid. Now, and this connects directly to memory. So people with aphantasia have absolutely I mean they have memories, like but the study really suggests on average that their autobiographical recollections may contain like fewer memories or like fewer detail. And it can involve like a reduced feeling of reliving the experience. That's according to PubMed. So but it means two people can say, I remember my 10th birthday, and the internal experience behind that is completely different for either one of them. One person might practically see the room and the cake and their like their parents and all that stuff, and then one person just knows that it happened. It's really, really wild. Like you can't it's it's a lot. Hmm.

Listener Rabbit Holes And Closing

SPEAKER_00 1:26:19

But that's it for this episode. I am glad that you guys are here. I'm glad that y'all are hanging out. We have gotten a lot of listeners here lately, and I'm gonna thank y'all for that because I enjoy doing this and I enjoy looking this stuff up and learning and finding my way down the rabbit hole. We do still take up submissions for listener rabbit holes. I've got a few to go through here, but feel free to send that in on our page, adhdtheory.com. Just type in listener rabbit holes and get it submitted. But for now, that's it. Next time, I think we're gonna dig into dreams. That seems like a good place to go for here. We did memory. And kind of curious, I want to learn a little bit about dreams, so we'll see. Thank you guys for being here, and we'll see you next time. But until then, don't be afraid to follow the rabbit hole.