#430 – Charan Ranganath: Human Memory, Imagination, Deja Vu, and False Memories

28:32This is my goal. So this is how I'm going to achieve it and focus everything towards that goal, right? The prefrontal cortex takes forever to develop in humans. The connections are still being tweaked and reformed like into late adolescence early adulthood, which is when you tend to see mental illness pop up, right? So it's being massively reformed. Then you have about 10 years, maybe of prime functioning of the prefrontal cortex. And then it starts going down again and you end up being older and you start losing all that frontal function. So look at this and you'd say, okay, from you sit around episodic memory talks, we'll always say children are worse than adults at episodic memory, older adults are worse than young adults at episodic memory.

29:17And I always say, would say, God, this is so weird. Why would we have this period of time that's so short when we're perfect, right? Or optimal. And I like to use that word optimal now because there's such a culture of optimization right now. And it's like, I realize I have to redefine what optimal is because for most of the human condition, I think we had a series of stages of life where you have basically adults saying, okay, young adults saying, I've got a child and you know, I'm part of this village and I have to hunt and forage and get things done. I need a prefrontal cortex so I can stay focused on the big picture and the long haul goals.

29:58Now, I'm a child. I'm in this village. I'm kind of wandering around and I've got some safety and I need to learn about this culture because I know so little. What's the best way to do that? Let's explore. I don't want to be constrained by goals as much. I want to really be free. Play and explore and learn. So you don't want a super tight prefrontal cortex. You don't even know what the goals should be in. It's like if you're trying to design a model that's based on a bad goal, it's not going to work well. So then you go late in life and you say, why don't you have a great prefrontal cortex then?

30:35But I think, I mean, if you go back and you think, how many species actually stick around naturally long after their childbearing years are over, after reproductive years are over? Menopause, from what I understand, menopause is not all that common. In the animal world, right? So why would that happen? And so I saw Alison Gopnik said something about this. So I started to look into this about this idea that, you know, really, when you're older in most societies, your job is no longer to form new episodic memories. It's to pass on the memories that you already have this knowledge about the world or what we call semantic memory, to pass on indigenous cultures.

31:21That's the role of the elders. They're respected. They're not seen as, you know, people who are pasted and losing it. And I thought that was a very poignant thing that memory is doing what it's supposed to throughout these stages of life. So it is always optimal in a sense, just optimal for that stage of life. Yeah. And for the ecology of the system. So you've got, so I looked into this and it's like another species that has menopause is orcas. Orca pods are led by the grandmother's, right? So there's not the young adults, not the parents or whatever, the grandmother's. And so they're the ones that pass on the traditions to the, I guess, the younger generation of orcas.

32:02And if you look from what little I understand, different orca pods have different traditions, they hunt for different things, they have different play traditions. And that's a culture, right? And so in social animals, evolution, I think, is designing brains that are really around, you know, it's obviously optimized for the individual, but also for kin. And I think that the kin are part of this, like when they're a part of this intense social group, the brain development should parallel that the nature of the ecology. Well, it's just fascinating to think of the individual orca or human throughout its life in stages during a kind of optimal wisdom development.

32:51So in the early days, you don't even know what the goal is and you figure out the goal and you kind of optimize for that goal and you pursue that goal. And then all the wisdom you collect through that, then you share with the others in the system with the other individuals. And as a collective, then you kind of converge towards greater wisdom throughout the generation. So in that sense, it's optimal. Us humans and orcas got something going on. It works. Apex predators. I just got a magnet on tooth. Speaking of Apex predators. It's just imagine the size of that thing. Anyway, how does the brain forget and how and why does it remember?

33:37So maybe some of the mechanisms, you mentioned the hippocampus, what are the different components involved here? So we could think about this on a number of levels. Maybe I'll give you the simplest version first, which is we tend to think of memories as these individual things and we can just access them, maybe a little bit like photos on your phone or something like that. But in the brain, the way it works is you have this distributed pool of neurons and the memories are kind of shared across different pools of neurons. And so what you have is competition where sometimes memories that overlap can be fighting against each other.

34:12Right. So sometimes we forget because that competition just wipes things out. Sometimes we forget because there aren't the biological signals which you can get into. I would promote long -term retention. And lots of times we forget because we can't find the queue that sends us back to the right memory. And we need the right queue to be able to activate it. So, for instance, in a neural network, there is no, you wouldn't go and you'd say, this is the memory. It's like the whole system of memories is in the weights of the neural network. And in fact, you could extract entirely new memories depending on how you feed.

34:52You have to have the right query, the right prompt to access that whatever the part you're looking for. That's exactly right. That's exactly right. And in humans, you have this more complex set of ways memory works. Those, as I said, the knowledge or what you call semantic memory. And then there's these memories for specific events, which we call episodic memory. And so there's different pieces of the puzzle that require different kinds of queues. So that's a big part of it too, is just this kind of what we call retrieval failure. You mentioned episodic memory, you mentioned semantic memory. What are the different separations here?

35:25What's working memory, short -term memory, long -term memory? What are the interesting categories of memory? Yeah. And so memory researchers, we love to cut things up and say, you know, is memory one thing or the two things or two things or three things. And so one of the things that there's value in that. And especially experimental value in terms of being able to dissect thing. And the real world is all connected. Speak to your question, working memory, as a term that was coined by Alan Badley. It's basically thought to be the ability to keep information online in your mind right in front of you at a given time.

36:03And to be able to control the flow of that information, to choose what information is relevant, to be able to manipulate it and so forth. And one of the things that Alan did that was quite brilliant was he said, there's this ability to kind of passively store information, you know, see things in your mind's eye or hear your internal monologue. But, you know, we have that ability to keep information in mind. But then we also have this separate, what he called a central executive, which is identified a lot with the prefrontal cortex. It's this ability to control the flow of information that's being kept active based on what it is you're doing.

36:42Now, a lot of my early work was basically saying that this working memory, which some memory researchers would call short term memory, is not at all independent from long term memory. That is that a lot of executive function requires learning and you have to have like synaptic change for that to happen. But there's also transient forms of memory. So one of the things I've been getting into lately is the idea that we form internal models of events, the obvious one that I always use is birthday parties, right. So you go to a child's birthday party. Once the cake comes out and they start you just see a candle, you can predict the whole frame, you know, set of events that happens later.

37:25And up till that point where the child blows out the candle, you have an internal model in your head of what's going on. And so if you follow people's eyes, it's not actually on what's happening. It's going where the actions about to happen, which is this fascinating, right. See, I have this internal model. And that's a kind of a working memory product. It's something that you're keeping online that's allowing you to interpret this world around you. Now to build that model though, you need to pull out stuff from your general knowledge of the world, which is what we call semantic memory. And then you'd want to be able to pull out memories for specific events that happen in the past, which we call episodic memory.

38:03So in a way, they're all connected, even though it's different. The things that we're focusing on and the way we organize information in the present, which is working memory, we'll play a big role in determining how we remember that information later, which people typically call long -term memory. So if you have something like a birthday party and you've been to many before, you're going to load that from disk into working memory, this model, and then you're most operating on the model. And if it's a new task, you don't have a model. So you're more in the data collection. Yes, one of the fascinating things that we've been studying.

38:42And this is we're not at all the first to do this. Jeff Sachs was a big pioneer in this. And I've been working with many other people. Ken Norman, Leila Devatchi and way, or Columbia has done some interesting stuff with this. As this idea that we form these internal models at particular points of high prediction error, or points of, I believe, also points of uncertainty, points of surprise or motivationally significant periods. And those points are when it's maximally optimal to encode an episodic memory. So I used to think, oh, well, we're just encoding episodic memories constantly, boom, boom, boom, boom, boom.

39:21But think about how much redundancy there is and all that, right? It's just a lot of information that you don't need. But if you capture an episodic memory at the point of maximum uncertainty for the singular experience, right? You're just, it's going to only happen once. But if you capture it at the point of maximum uncertainty or maximum surprise, you have the most useful point in your experience that you grab. And what we see is that the hippocampus and these other networks that are involved in generating these internal models of events, they show a heightened period of connectivity or correlated activity during those breaks between different events, which we call event boundaries.

40:04These are the points where you're like surprised, cross from one room to another and so forth. And that communication is associated with a bump of activity in the hippocampus and better memory. And so if people have a very good internal model throughout that event, you don't need to do much memory processing. You're in a predictive mode, right? And so then at these event boundaries, you encode and then you retrieve and you're like, okay, wait a minute, what's going on here? Brain Gnath is now talking about Orcas, what's going on? And maybe you have to go back and remember reading my book to pull out the episodic memory to make sense of whatever it is I'm babbling about, right?

40:41And so there's this beautiful dynamics that you can see in the brain of these different networks that are coming together and then de -affiliating at different points in time that are allowing you to go into these modes. And so to speak to your personal question, to some extent when we're talking about semantic memory and episodic memory and working memory, you can think about it as these processes that are unfolding as these networks kind of come together and pull apart. Can memory be trained and improved? This beautiful, connected system that you've described, what aspect of it is a mechanism that can be improved through training?

41:22I think improvement depends on what your definition of optimal is. So what I say in the book is is that you don't want to remember more, you want to remember better, which means focusing on the things that are important. And that's what our brains are designed to do. So if you go back to the earliest quantitative studies in memory by Ebbinghaus, what you see is that he was trying so hard to memorize this arbitrary nonsense. And within a day, he lost about 60 % of that information. And he was using, he was basically using a very, very generous way of measuring. So as far as we know, nobody has managed to violate those basics of having people forget most of their experiences.

42:05So if your expectation is that you should remember everything and that's what your optimal is, you're already off because this is not what human brains are designed to do. On the other hand, what we see over and over again is that the brain does, basically, one of the cool things about the design of the brain is it's always less is more, less is more, right? It's like, I mean, I've seen estimates that the human brain uses something like 12 to 20 watts in a day. I mean, that's just nuts, the low power consumption, right? So it's all about reusing information and making the most of what we already have.

42:39And so that's why, basically, again, what you see biologically is, you know, normodulators, for instance, these chemicals in the brain, like Norepinephrine, dopamine, serotonin, these are chemicals that are released during moments that tend to be biologically significant, surprise, fear, stress, etc. And so these chemicals promote lasting plasticity, right? Essentially, some mechanisms for which the brain can say prioritize the information that you carry with you into the future. Attention is a big factor as well, our ability to focus our attention on what's important. And so there's different schools of thought on training attention, for instance.

43:26So one of my colleagues, Amishi Jha, she wrote a book called Peak Mind and talks about mindfulness as a method for improving attention and focus. It's as she works a lot with military, like Navy Seals and stuff to do this kind of work with mindfulness meditation. Adam Gazali, another one of my friends and colleagues has worked on kind of training through video games, actually, as a way of training attention. And so it's not clear to me, you know, one of the challenges, though, in training is you tend to overfit to the thing that you're trying to optimize, right? So you tend to, if I'm looking at a video game, I can definitely get better at paying attention in the context of the video game, but you transfer it to the outside world.

44:11That's very controversial. The implication there is that attention is a fundamental component of remembering something, allocating attention to it, and then attention might be something that you could train. How you allocate attention and how you hold attention on a thing. I can say that in fact, we do in certain ways, right? So if you are expert in something, you are training attention. So we did this one study of expertise in the brain. And you know, some people used to think, let's say if you're a bird expert or something, right? People will go like, if you get really into this world of birds, you start to see the differences in your visual cortex is tuned up.

44:52And it's all about plasticity, the visual cortex and vision researchers love to say everything's visual. But it's like we did the study of attention and working working memory and expertise. And one of the things that surprised us were the biggest effects as people became experts in identifying these different kinds of just crazy objects that we made up. As they developed this expertise of being able to identify what made them different from each other and what made them unique, we were actually seeing massive increases in activity in the prefrontal cortex. And this fits with some of the studies of chest experts and so forth.

45:26It's not so much that you learn the patterns passively. You learn what to look for. You learn what's important, what's not, right? And you can see this in any kind of expert professional athlete. They're looking three steps ahead of where they're supposed to be. So that's a kind of a training of attention. And those are also what you'd call expert memory skills. So if you take the memory athletes, I know that's something we're both interested in. And so these are people who train in these competitions and they'll memorize like a deck of cards in like a really short amount of time. There's a great memory athlete, her name I think is pronounced Yenya Winter Soul.

46:07But she, so I think she's got like a giant Instagram following. And so she had this YouTube video that went viral where she had memorized an entire IKEA catalog. Right. And so how do people do this? By all accounts from people who become memory athletes, they weren't born with some extraordinary memory. But they practice strategies over and over and over again. The strategy that they use for memorizing a particular thing, it can become automatic and you can just deploy it in an instant. Right. So again, it's not necessarily going to one strategy for learning the order of a deck of cards might not help you for something.

46:44Else that you need like remembering your way around Austin, Texas. But it's going to be these whatever you're interested in, you can optimize for that. And that's just a natural byproduct of expertise. There's certain hacks that seem to call the memory palace that I played with. I don't know if you're familiar with that whole technique. And it works. It's interesting. So another thing I recommend for people a lot is I use Anki a lot every day. It's an app that does space repetition. So I think medical students and like students use this a lot to remember a lot of different things. Oh yeah. Okay.

47:21We can come back to this. But yeah, sure. It's the whole concept of space repetition. You just the when the thing is fresh, you kind of have to remind yourself of it a lot. And then over time, you can wait a week a month, a year before you have to recall the thing again. And that way, you essentially have something like note cards that you can have tens of thousands of and can only spend 30 minutes a day and actually be refreshing all of that information, all of that knowledge. It's really great. And then for memory palace is a technique that allows you to remember things like the Ikea catalog or by placing them visually in a place that you're really familiar with, like I'm really familiar with this place.

48:05I can put numbers or facts or whatever you want to remember. You can walk along that low palace and revise you. It's cool. Like there's stuff like that that I think athletes, memory athletes could use, but I think also regular people can use one of those things I have to solve for myself is how to remember names. I'm horrible at it. Yeah. I think it because when people introduce themselves, I have the social anxiety of the interaction. Or I'm like, I know I should be remembering that, but I'm freaking out internally about social social interaction in general. And so therefore, I forget immediately.

48:47So I'm looking for good tricks for that. So I feel like we've got a lot in common because what people introduce themselves to be, it's almost like I have this, like just blank blackout for a moment. And then I'm just looking at them like, what happened? I look away or something. What's wrong with me? So I mean, I'm totally with you on this. The reason why it's hard is that there's no reason we should be able to remember names. Because when you say remembering a name, you're not really remembering a name, maybe in my case, you are. But most of the time, you're associating a name with a face and an identity.

49:24And that's a completely arbitrary thing. Right. I mean, maybe in the olden days, somebody named Miller, it's like they're actually making flowers and like that. But you know, for the most part, it's like these names are just utterly arbitrary. So you have no thing to latch onto. And so it's not really a thing that our brain does very well to learn meaningless arbitrary stuff. So what you need to do is build connection somehow, visualize a connection. And sometimes it's obvious. Or sometimes it's not. I'm trying to think of a good one for you now. But the first thing I think of is Lex Luthor. But that's great.

50:01Yeah. So yeah, Lex Luthor. Lex Luthor, where a suit, I think I know he has a shaved head though. He's bald, but you're not. You got a great head. I trade hair with you any day. But like, you know, but something like that. But if I can come up with something, like I could say, okay, so Lex Luthor is this criminal master. And then I just imagine you talked about stabbing or whatever earlier. Yeah, exactly. I'm kind of connected. That's it. Yeah. Yeah. And I, but I'm serious though that these kinds of weird associations now I'm building a richer network. I mean, one of the things that I find is if I like, you can have somebody's name that's just totally generic like John Smith or something, not that no offense to people that that name.

50:41But you know, if I, if I see a generic name like that, but I've read John Smith's papers academically and then I meet John Smith at a conference, I can immediately associate that name with that face because I have this pre -existing network to lock everything into, right? And so you can build that network. And that's what the method of loci or the memory palace technique is all about. Is you have a pre -existing structure in your head of like your childhood home or this mental palace that you've created for yourself? And so now you can put arbitrary pieces of information in different locations in that mental structure of yours.

51:19And then you could walk through the different path and find all the pieces of information you're looking for. So the method of loci is a great method for just learning arbitrary things because it allows you to link them together and get that cue that you need to pop in and find everything, right? We should maybe linger on this memory palace thing just to make obvious because when people were describing to me a while ago what this says seems insane. I just, you literally think of a place like a childhood home or a home that you're really visually familiar with. And you literally place in that three -dimensional space facts or people or whatever you want to remember.

52:09And you just walk in your mind along that place visually. And you can remember remind yourself of the different things. One of the limitations is there is a sequence to it. So I think your brain somehow, you can't just go upstairs right away or something. You have to walk along the room. So it's really great for remembering sequences but it's also not great for remembering individual facts out of context. So the full context of the tour I think is important. But it's fascinating how the mind is able to do that. When you ground these pieces of knowledge into something that you remember well already, especially visually, fascinating.

52:52You can do that for any kind of sequence. I'm sure she used something like this for the for IKEA catalog. So yeah, absolutely. Absolutely. And I think the principle here is, again, I was telling you this idea that memories can compete with each other, right? Well, I like to use this example and maybe someday I'll regret this but I've used it a lot recently is like imagine if this were my desk, it could be cluttered with a zillion different things, right? So imagine it's just cluttered with a whole bunch of yellow posted notes. And one of them I put my bank password on it, right? Well, it's going to take me forever to find it.

53:26I might, you know, it's just going to be buried under all these other posted notes. But if it's like hot pink, it's going to stand out and I find it really easily, right? So that's one way in which if things are distinctive, if you've processed information in a very distinctive way, then you can have a memory that's going to last. And that's very good, for instance, for name, face associations. If I get something distinctive about you, you know, that it's like that you've got very short hair. And maybe I can make the association with Lex Luthor that way or something like that, right? You know, but I get something very specific.

54:00That's a great cue. But the other part of it is what if I just organized my notes so that I have my finances in one pile and I have my like reminders, my to -do list in one pile and so forth. So I organized them. Well, then I know exactly if I'm going for my banking, you know, my bank password, I could go to the finance pile, right? So the method of low -side works or memory policies work because they give you a way of organizing. There's a school of thought that says that episodic memory evolved from this like kind of knowledge of space and you know, basically this primitive abilities to figure out where you are and so people explain the method of low -side that way.

54:42And you know, whether or not the evolutionary argument is true, the method of low -size is not at all special. So if you know, you're not a good visualizer, stories are a good one. So a lot of memory athletes will use stories and they'll go like, if you're memorizing a deck of cards, they have a little code for the different like the king and the jack and the ten and so forth. And they'll make up a story about things that they're doing and that'll work. Songs are a great one, right? I mean, it's like I can still remember there's a obscure episode of the TV show, Cheers. They think it's a song about Albania that he uses to memorize all these facts about Albania.

55:20And I could still sing that song to you. It's just I saw it on a TV show, you know? So what you mentioned is based repetition. So what do you like this? Processing, maybe, can you explain it? Oh, yeah. If I am trying to memorize something, let's say if I have an hour to memorize as many Spanish words as I can, if I just try to do like half an hour and then later in the day, I do half an hour, I won't retain that information as long as if I do half an hour today and half an hour one week from now. And so doing that extra spacing should help me retain the information better. Now there's an interesting boundary condition, which is it depends on when you need that information.

56:04So many of us, you know, for me, like I can't remember so much from college and high school because I crammed because I just did everything at last minute. And sometimes I would literally study like, you know, in the hallway right before the test. That was great because what would happen is I just had that information right there. And so actually not spacing can really help you if you need it very quickly, right? But the problem is is that you tend to forget it later on. But on the other hand, if you space things out, you get a benefit for later on retention. And so there's many different explanations.

56:42We have a computational model of this. It's currently under revision. But in our computer model, what we say is that an easy maybe a good way of thinking about this is this conversation that you and I are having. It's associated with a particular context, a particular place in time. And so all these little cues that are in the background, these little guitar sculptures that you have and that big light umbrella thing, right? All these things are part of my memory for what we're talking about the content. So now later on, you're sitting around and you're at home drinking a beer and you think, God, what a strange interview that was, right?

57:19So now you're trying to remember it, but the context is different. So your current situation doesn't match up with the memory that you pulled up. There's error. There's a mismatch between what you pulled up and your current context. And so in our model, what you start to do is you start to erase or alter the parts of the memory that are associated with a specific place in time and you heighten the information about the content. And so if you remember this information in different times and different places, it's more accessible at different times and different places because it's not overfitted in a AI kind of way of thinking about things.

58:00It's not overfitted to one particular contact. But that's also why the memories that we call upon the most also feel kind of like they're just things that we read about almost. You don't vividly reimagine them, right? It's like there's these things that just come to us like facts, right? And it's a little bit different than semantic memory, but it's like basically these events that we have recalled every, you know, over and over and over again, we keep updating that memory. So it's less and less tied to the original experience. And then we have those other ones which it's like you just get a reminder of that very specific context.

58:34You smell something. You hear a song, you see a place that you haven't been to in a while and boom, it just comes back to you. And that's the exact opposite of what you get with spacing, right? That's so fascinating. So the space repetition one of the its powers is that you lose attachment to a particular context. But then it loses the intensity of the flavor of the memory. That's interesting. That's so interesting. Yeah, but you know, at the same time, it becomes stronger in the sense that the content becomes stronger. Yeah. So it's used for learning languages, for learning facts, for learning, for, you know, for that generic semantic information, depth of memory.

59:15Yeah. And I think this falls into a category we've done other modeling. One of these is published study and plus computational biology where we showed that another way, which is I think related to the spacing effect is what's called the testing effect. So the idea is that if you're trying to learn words, let's say in Spanish or something like that, and this doesn't have to be words, it could be anything. You test yourself on the words and that act of testing yourself helps you retain it better over time than if you just studied it, right? And so from traditional learning some learning theories, anyway, this seems weird.

59:55Why would you do better giving yourself this extra error from testing yourself rather than just, you know, giving yourself perfect input. That's a replica of what it is that you're trying to learn. And I think the reason is is that you get better retention from that error, that mismatch that we talked about, right? So what's happening in our model, it's actually conceptually kind of similar to what happens with back prop and AI. So there are neural networks and say the idea is that you expose, here's the bad connections and here's the good connections. And so we can keep the parts of this cell assembly that are good for the memory and lose the ones that are not so good.

1:00:35But if you don't stress test the memory, you haven't exposed it to the error, fully. And so that's why I think this is kind of, this is a thing that I come back to over and over again, is that you will retain information better if you're constantly pushing yourself to your limit, right? If you are feeling like you're coasting, then you're actually not learning. So it's like, you should always be stress testing the memory system. Yeah, and feel good about it. You know, even though everyone tells me, oh, my memory's terrible. In the moment, they're over confident about what they'll retain later on.

1:01:14So it's fascinating. So what happens is, this is what you test yourself. You're like, oh, my God, I thought I knew that, but I don't. And so it can be demoralizing until you get around that and you realize, hey, this is the way that I learned. This is how I learned best. It's like if you're trying to, you know, star in a movie or something like that, you know, just sit around reading the script, you actually act it out and you're going to botch those lines from time to time, right? No, there's an interesting moment you probably experienced this. I remember a good friend of mine, Joe Rogan, I was on his podcast and we were randomly talking about soccer football.

1:01:57Somebody had grew up watching Diego Armando Mardona, one of the greatest soccer players of all time. And we were here talking about him and his career and so on. And Joe asked me if he's still around. Now, and I said, yeah, I don't know why I thought, yeah, because that was a perfect example of memories. He passed the way. I tweeted about it, how heartbroken I was, all this kind of stuff, like a year before. I know this, but in my mind, I went back to the thing I've done many times in my head, visualizing some of the epic run he had on goal and so on. So for me, he's alive. And so I'm in part of also the conversation when you're talking to Joe, you're the stress and like your, the focus is allocated, the attention is allocated in particular way.

1:02:52But when I walked away, I was like, in which world was Diego Mardona still alive? Like in which, because I was sure my head that he was still alive. There was a moment that sticks with me. I've had a few like that in my life where it just kind of, like obvious things just disappear from mind. And it's cool. Like it shows actually the power of the mind and the positive sense to erase memories you want to erase, maybe. But I don't know, I don't know if there's a good explanation for that. One of the cool things that I found is that some people really just revolutionize a field by creating a problem that didn't exist before.

1:03:37It's got to like why I love sciences. Engineering is like solving other people's problems. And science is about creating problems. I'm just much more like I want to break things in, you know, great problems. Not necessarily move fast, though. But one of my former mentors, Marsha Johnson, whom my opinion is one of the greatest memory researchers of all time, she comes up young woman in the field and this mostly guy field. And she gets into this idea of how do we tell the difference between things that we've imagined and things that we actually remember? How do we tell I get some mental experience?

1:04:12Where did that mental experience come from? And it turns out this is a huge problem because essentially our mental experience of remembering something that happened, our mental experience of thinking about something, how do you tell the difference? They're both largely constructions in our head. And so it is very important. And the way that you do it is, I mean, it's not perfect, but the way that we often do it and succeed is by, again, using our prefrontal cortex and really focusing on the sensory information or the place and time and the things that put us back into when this information happened.

1:04:52And if it's something you thought about, you're not going to have all of that vivid detail as you do for something that actually happened. But it doesn't work all the time. But that's a big thing that you have to do. But it takes time. It's slow and it's again effortful. But that's what you need to remember accurately. But what's cool, and I think this is what you alluded to about how that was an interesting experience, is imaginations exactly the opposite. Imagination is basically saying, I'm just going to take all this information from memory, recombine it in different ways and throw it out there.

1:05:24And so, for instance, Dan Schachter and Donna Attis had done a cool work on this. Demis Hasibis did work on this with Eleanor McGuire and UCL. And this goes back actually to this guy, Frederick Bartlett, who was this revolutionary memory researcher at Bartlett. He actually rejected the whole idea of quantifying memories. He said, there's no statistics in my book. He came from this anthropology perspective. And short version of the stories, he just asked people to recall thing. He would give people stories and ask people to recall them. And what he found was people's memories didn't reflect all of the details of what they were exposed to.

1:06:05And they did reflect a lot more. They were filtered through this lens of prior knowledge, the cultures that they came from, the beliefs that they had, the things they knew. And so, what he concluded was that he called remembering an imaginative construction, meaning that we don't replay the past. We imagine how the past could have been by taking bits and pieces that come up in our heads. And likewise, he wrote this beautiful paper on imagination, saying when we imagine something and create something, we're creating it from these specific experiences that we've had in combining it with our general knowledge.

1:06:40But instead of trying to focus it on being accurate and getting out one thing, you're just ruthlessly recombining things without any necessary kind of goal in mind. I mean, at least that's one kind of creation. So imagination is fundamentally coupled with memory in both directions. I think so. I mean, it's not clear that it is in everyone, but one of the things that's been studied is some patients who have amnesia, for instance, they have brain damage, say, to the hippocampus. And if you ask them to imagine things that are not in front of them, like imagine what could happen after I leave this room, right?

1:07:23They are find it very difficult to give you a scenario what could happen, or if they do, it would be more stereotype, I guess this would happen. But it's not like they can come up with anything that's very vivid and creative in that sense. And it's partly because when you have amnesia, you're stuck in the present because to get a very good model of the future, it really helps to have episodic memories to draw upon, right? And so that's the basic idea. And in fact, one of the most impressive things, when people started to scan people's brains and ask people to remember past events, what they found was there was this big network of the brain called the default mode network.

1:08:03It gets a lot of press because it's like thought to be important. It's engaged during mind wandering. And if I ask you to pay attention to something, it only comes on when you stop paying attention. You know, some people, oh, it's just this kind of, you know, daydreaming network. And I thought this is just ridiculous research who cares, you know. But then what people found was when people recall episodic memories, this network gets active. And so we started to look into it and this network of areas is really closely, functionally interacting with the hippocampus. And so in fact, some would say the hippocampus is part of this default network.

1:08:41And if you look at brain images of people or brain maps of activation, so to speak of people imagining possible scenarios of things that could happen in the future, even things that couldn't really be very plausible, they look very similar. I mean, you know, to the naked eye, they look almost the same as maps of brain activation when people remember the past. According to our theory, and we've got some data to support this, we've broken up this network in various sub pieces, is that basically it's kind of taking apart all of our experiences and creating these little Lego blocks out of them. And then you can put them back together if you have the right instructions to recreate these experiences that you've had, but you could also reassemble them into new pieces to create a model of an event that hasn't happened yet.

1:09:26And that's what we think happens. And when I'm our common ground that we're establishing in language requires using those building blocks to put together a model of what's going on. Well, there's a good percentage of time I personally live in the imagined world. I think of, I do thought experiments a lot. I take the absurdity of human life as it stands and play it forward in all kinds of different directions. Sometimes it's rigorous thoughts, thought experiments, sometimes it's fun ones. So I imagine that that hasn't affected how I remember things. And I suppose I have to be a little bit careful to make sure stuff happened versus stuff that I just imagined happened.

1:10:17And this also, I mean, some of my best friends are characters inside books that never even existed. And I'm, you know, there's some degree to which they actually existed in my mind. Like these characters exist, authors exist, the St. Yavsky exists, but also brothers Karamazov. I love that book. Yeah. One of the few books I've read. One of the few literature books that I've read. I read a lot in school that I don't remember, but brothers Karamazov's all those stuff. They exist. And I have almost kind of like conversations with them. It's interesting. It's interesting to allow your brain to kind of play with ideas.

1:10:56Of the past, of the imagined and see it all as one. Yeah. There was actually this famous Namanist. He's kind of like back then, the equivalent of a memory athlete, except he would go to shows and do this. Those described by this really famous neurosycologist from Russia named Luria. And so this guy was named Solomon Cherishavsky. Any of this condition called synesthesia, that basically created these weird associations between different senses that normally wouldn't go together. So that gave him this incredibly vivid imagination that he would use to basically imagine all sorts of things that he would need to memorize.

1:11:39And he would just imagine, like just create these incredibly detailed things. And he said that allowed him to memorize all sorts of stuff. But it also really haunted him by some reports that basically it was like he was at some point, you know, and again, who knows the drinking was part of this, but it's some point had trouble differentiating his imagination from reality, right? And this is interesting because it's like, I mean, that's what psychosis is in some ways is you, you know, first of all, you're just learning connections from prediction errors that you probably shouldn't learn. And the other part of it is is that your internal signals are being confused with actual things in the outside world, right?

1:12:23Well, that's why a lot of this stuff is both feature and bug. It's a double edged sword. Yeah, I mean, it might be why there's such an interesting relationship between genius and psychosis. Yeah, maybe they're just two sides of the same coin. Humans are fascinating, aren't they? I think so. Sometimes scary, but mostly fascinating. Can we just talk about memory sport a little longer? There's something called the USA Memory Championship. Like what are these athletes like? What does it mean to be like a elite level at this? Have you interacted with any of them or reading about them? What have you learned about these folks?

1:13:02There's a guy named Henry Roderger who's studying these guys and there's actually a book by Joshua Four called Moonwalking with Einstein where he talks about he actually as part of this book just decided to become a memory athlete. They often have these life events that make them go, hey, why don't I do this? So there was a guy named Scott Hagwood who I write about who thought that he was he was getting chemo for cancer. And so he decided like because the chemo there's a well -known thing called chemo brain where people become like they just lose a lot of their sharpness. And so he wanted to fight that by learning these memory skills.

1:13:43So he bought a book and this is the story you hear in a lot of memory athletes is they buy a book by other memory athletes or other memory experts so to speak. And they just learn those skills and practice them over and over again. They start by winning bets and so forth and then they go into these competitions. The competitions are typically things like memorizing long strings of numbers or memorizing orders of cards and so forth. So there tend to be pretty arbitrary things not like things that would be able you'd be able to bring a lot of prior knowledge. But they build the skills that you need to memorize arbitrary things.

1:14:21Yeah, it's fascinating. I've gotten a chance to work with something called the endback tasks. So there's all these kinds of tasks memory recall tasks that used to kind of load up the quote unquote working memory. Yeah, yeah. And to see the psychologists used it to test all kinds of stuff like to see how well you're good at multitasking. We used it in particular for the task of driving like if we fill up your brain with intensive working memory tasks, how good are you at also not crashing that kind of stuff. So it's fascinating. But again, those tasks are arbitrary in there. Usually we're calling a sequence of numbers in some kind of semi complex way.

1:15:05Do you have any favorite tasks of this nature in your own studies? I've really been most excited about going in the opposite direction and using things that are more and more naturalistic. And the reason is is that we've really moved we've moved in that direction because what we found is that memory works very, very differently when you study it when you study memory in the way that people typically remember. And so it goes into a much more predictive mode and you have these event boundaries, for instance, and you have but a lot of what happens is this kind of fast -dating mix that we've been talking about of mix of interpretations and imagination with perception.

1:15:52And so the new direction we're going in is understanding navigation and our memory for its places. And the reason is that there's a lot of work that's done in rats, which is very good work. They have a rat and they put it in a box and the rat goes chase the cheese in a box. You know, find cells in the hippocampus that fire when a rat is in different places in the box. And so the conventional wisdom is that the hippocampus forms this map of the box. And I think that probably may happen when you have like absolutely no knowledge of the world, right? But I think one of the cool things about human memory is we can bring to bear our past experiences to economically learn new ones.

1:16:39And so for instance, if you learn a map of an IKEA, let's say if I go to the IKEA in Austin, I'm sure there's one here. I probably could go to this IKEA and find my way to the, you know, where the wine glasses are without having to even think about it because it's got a very similar layout, even though IKEA is a nightmare to get around. Once I learned my local IKEA, I can use that map everywhere. White form a brand new one for a new place. And so that kind of ability to reuse information really comes into play when we look at things that are, you know, more naturalistic tasks. And another thing that we're really interested in is this idea of like, what if instead of basically mapping out every coordinate in a space, you form a pretty economical graph that connects basically the major landmarks together and being able to use that as, you know, emphasizing the things that are most important, the places that you go for food and the places that are landmarks that help you get around.

1:17:45And then filling in the blanks for the rest, because I really believe that cognitive maps or mental maps of the world, just like our memories for events are not photographic. I think there's this combination of actual verifiable details and then a lot of inference that you make. What have you learned about this kind of spatial mapping of places? How do people represent locations? There's a lot of variability, I think, that and there's a lot of disagreement about how people represent locations in a world of GPS and physical maps. People can learn it from like basically what they call it, survey perspective, being able to see everything.

1:18:28And so that's one way in which humans can do it. That's a little bit different. There's one way which we can memorize roots. Like I know how to get from here to, let's say if I knew, walk here from my hotel, I can just rigidly follow that route back, right? And there's another more integrative way, which would be what's called a cognitive map, which would be kind of a sense of how everything relates to each other. And so there's lots of people who believe that these maps that we have in our head are isomorphic with the world. They're like these literal coordinates that follow Euclidean space. And as you know, Euclidean mathematics is very constrained, right?

1:19:10And I think that we are actually much more generative in our maps of space so that we do have these bits and pieces. And we've got a small task as it's right now, not yet like we need to do some work on it for further analysis. But one of the things we're looking at is these signals called ripples in the hippocampus, which are these bursts of activity that you see that are synchronized with areas in the neocortex and the default network actually. And so what we find is is that those ripples seem to increase at navigationally important points when you're making a decision or when you reach a goal.

1:19:49So this speaks to the emotion thing, right? Because if you have limited choices, if I'm walking down a street, I could really just get a mental map of the neighborhood with a more minimal kind of thing by just saying, here's the intersections. And here's the directions I take to get in between them. And what we found in our MRI study says, basically the more people can reduce the problem, whether it's space or any kind of decision making problem, the less the hippocampus encodes. It really is very economical towards the points of most highest information content and value. So can you describe the encoding in the hippocampus and the ripples you were talking about?

1:20:35What's the signal in which we see the ripples? Yeah, so this is really interesting. There are these oscillations, right? So there's these waves that you basically see. And these waves are points of very high excitability and low excitability. And at least during, they happen actually during slow wave sleep too. So the deepest stages of sleep when you're just zonked out, right? You see these very slow waves where it's like very excitable and then very unexcitable goes up and down. And on top of them, you'll see these little sharp wave ripples. And when there's a ripple in the hippocampus, you tend to see a sequence of cells that resemble a sequence of cells that fire when, you know, an animal is actually doing something in the world.

1:21:21So it almost is like a little people call it replay. And it's a little bit, I don't like that term, but it's basically a little bit of a compressed play of the sequence of activity in the brain that was taking place earlier. And during those moments, there's a little window of communication between the hippocampus and these areas in the new cortex. And so that I think helps you form new memories, but it also helps you, I think, stabilize them, but also really connect different things together in memory and allows you to build bridges between different events that you've had. And so this is one of hardly star theories of sleep.

1:22:01And it's real role in helping you see the connections between different events that you've experienced. Oh, so during sleep is one of the connections informed. The connections between different events. Right. So it's like, you see me now, you see me next week, you see me a month later, you start to build a little internal model of how I behave and, you know, what to expect of me. And we think sleep, one of the things that allows you to do is figure out those connections and connect the dots and find the signal in the noise. So you mentioned FMRI. What is it and how is it used in studying memory?

1:22:39This is actually the reason why I got into this whole field of sciences. When I was in grad school, FMRI was just really taking off as a technique for studying brain activity. And what's beautiful about it is you can study the whole human brain. And there's lots of limits to it, but you can basically do it in person without sticking anything into their brains. And very non -invasive. I mean, for me, being an MRI scanner is like being in the womb. I just fall asleep. If I'm not being asked to do anything, I get very sleepy, you know. But you can have people watch movies while they're being scanned or you can have them do tests of memory, like giving them words and so forth to memorize.

1:23:21But what MRI is itself is just this technique where you put people in a very high magnetic field. Typical ones we would use would be three Tesla to give you an idea. So a three Tesla magnet, you put somebody in and what happens is you get this very weak, but, you know, measurable magnetization in the brain. And then you apply a radio frequency pulse, which is basically a different electromagnetic field. And so you're basically using water. The water molecules in the brain as a tracer or so to speak. And part of it in FMRI is the fact that these magnetic fields that you mess with by manipulating these radio frequency pulses and the static field.

1:24:08And you have things called gradients, which change the strength of the magnetic field in different parts of the head. So they're all we tweak them in different ways. But the basic idea that we use in FMRI is that blood is flowing to the brain. And when you have blood that doesn't have oxygen on it, it's a little bit more magnetizable than blood that does because you have hemoglobin that carries the oxygen, the iron basically in the blood that makes it red. And so that hemoglobin when it's deoxygenated actually has different magnetic field properties than when it has oxygen. And it turns out when you have an increase in local activity as some part of the brain, the blood flows there.

1:24:51And as a result, you get a lower concentration of hemoglobin that is not oxygenated. And then that gives you more signal. So I gave you, I think I sent you a gift, as you like to say. We had off record intense argument about with this pronounced jiff or gift, but we shall set that aside. We could have called it a stern rebuke perhaps, but rebuke. Yeah, I drew a hard line. It is true, the creator of gifts that is pronounced jiff, but that's the only person that movie of f from r i data. And so when you look at it, it's not very impressive. It looks like these look very pixelated maps of the brain, but it's mostly kind of like white, but these tiny changes in the intensity of those signals that you probably wouldn't be able to visually perceive, like about 1 % can be statistically very, very large effects for us.

1:25:58And that allows us to see, hey, there's an increase in activity in some part of the brain when I'm doing some tasks like trying to remember something. And I can use those changes to even predict, is a person going to remember this later or not? And the coolest thing that people have done is to decode what people are remembering from the patterns of activity, because maybe when I'm remembering this thing, like I'm remembering the house where I grew up, I might have one pixel that's bright in the hippocampus and one that's dark. And if I'm remembering something like more like the car that I used to drive on a 16, I might see the opposite pattern where a different pixels bright.

1:26:41And so all that little stuff that we used to think of noise, we can now think of almost like a QR code for memory, so to speak, where different memories have a different little pattern of bright pixels and dark pixels. And so this really revolutionized my research. So there's fancy research out there where people really, not even that, I mean, by your standards, it would be Stone Age, but you know, a flying machine learning techniques to do decoding, it's so forth. And now there's a lot of forward encoding models that you can go to town with this stuff, right? And I'm much more old school of designing experiments where you basically say, okay, here's a whole web of inter of memories that overlap in some way, shape or form, do memories that occurred in the same place have a similar QR code and do memories that occurred in different places have different QR code and you can just use things like correlation coefficients or cosine distance to measure that stuff, right?

1:27:38Super simple, right? And so what happens is you can start to get a whole state space of how a brain area is indexing all these different memories. And it's super fascinating because what we could see is this little like separation between how certain brain areas are processing memory for who was there. And other brain areas of processing information about where it occurred or the situation that's kind of unfolding and some are giving you information about what are my goals that are involved and so forth. And so, and the hippocampus is just putting it all together into these unique things that just are about when and where it happened.

1:28:15So there's a separation between spatial information, concepts, like literally there's distinct, as you said, QR codes for these. So to speak, let me try a different analogy to that might be more accessible for people, which would be like, you've got a folder on your computer, right? And I open it up, there's a bunch of files there. I can sort those files by, you know, alphabetical order. And now things that both start with letter A are lumped together and things that start with Z versus A are far apart, right? And so that is one way of organizing the folder, but I could do it by date. And if I do it by date, things that were created close together in time are close and things that are far apart in time or far.

1:29:02So every, like, you can think of how a brain area or a network of areas contributes to memory by looking at what the sorting scheme is. And these QR codes that we're talking about that you get from F from R .I. allow you to do that. And you can do the same thing if you're recording from massive populations of neurons in an animal. And you can do it for a recording local potentials in the brain, you know, so little waves of activity in, let's say, a human who has epilepsy, these stick electrodes in their brain, try to find the seizures. So that's some of the work that we're doing now. But all these techniques basically allow you to say, hey, what's the sorting scheme?

1:29:44And so we've found that some networks of the brain sort information and memory, according to who was there. So I might have, like, we've actually shown in one of my favorite studies of all time that was done by a former postdoc Zach Rea. And Zach did the study where we had a bunch of movies with different people in my labs, there are two different people and he filmed them at two different cafes and two different supermarkets. And what you could show is in one particular network, you could find the same kind of pattern of activity more or less, a very, very similar pattern of activity. Every time I saw Alex in one of these movies, no matter where he was, right?

1:30:25And I could see another one that was like a common pattern that happened every time I saw this particular supermarket nugget, you know, and so, and it didn't matter whether you're watching a movie or whether you're recalling the movie is the same kind of pattern that comes up, right? It's so fascinating. It's so fascinating. So now you have those building blocks for assembling a model of what's happening in the present, imagining what could happen and remembering things very economically from putting together all these pieces so that all the hippocampus has to do is get the right kind of blueprint for how to put together all these building blocks.

1:31:03These are all like beautiful hints at a super interesting system that makes me wonder on the other side of it how to build it. But it's like, it's fascinating. Like the way it does the encoding is really, really fascinating. Or I guess the symptoms, the results of that encoding are fascinating to study from this. Just as a small tangent, you mentioned sort of the measuring local potentials with electrodes versus FMRI. Oh yeah. What are some interesting like limitations, possibilities of FMRI? Maybe the way you explain it is brilliant with blood and detecting the activations or the excitation because blood flows to that area.

1:31:49What's the latency of that? What's the blood dynamics in the brain? How quickly can it how quickly can it task change and all that kind of stuff? Yeah. I mean, it's very slow to the brain 50 milliseconds. It's an eternity. Maybe it have 50. Maybe let's say half a second, 500 milliseconds, just so much back and forth stuff happens in the brain in that time. So in FMRI, you can measure these magnetic field responses about six seconds after that burst of activity would take place. All these things, it's like, is it a feature, is it a bug? Right? So one of the interesting things that's been discovered about FMRI is, it's not so tightly related to the spiking of the neurons.

1:32:41So we tend to think of the computation, so to speak, as being driven by spikes, meaning like there's just a burst of, it's either on or it's off and the neurons like going up or down. But sometimes what you can have is these states where the neuron becomes a little bit more excitable or less excitable. And so FMRI is very sensitive to those changes in excitability. Actually, one of the fascinating things about FMRI is, where does that, how is it we go from neural activity to essentially blood flow to oxygen, all this stuff? It's such a long chain of going from neural activity to magnetic fields.

1:33:23And one of the theories that's out there is most of the cells in the brain are not neurons. They're actually these support cells called glial cells. And one big one is astrocytes, and they play this big role in regulating, kind of being a middle man, so to speak, with the neuron. So if you, for instance, like one neuron's talking to another, you release a neurotransmitter, like let's say glutamate, and that gets another neuron starts getting active after you release in the gap between the two neurons called synapse. So what's interesting is if you leave that, imagine you're just flooded with this liquid in there, right?

1:34:01If you leave it in there too long, you just excite the other neuron too much and you can start to basically get seizure activity. You don't want this. So you got to suck it up. And so actually what happens is these astrocytes, one of their functions is to suck up the glutamate from the synapse. And that is a massively, and then break it down and then feed it back into the neurons that you reuse it. But that cycling is actually very energy intensive. And what's interesting is at least according to one theory, and they need to work so quickly that they're working on metabolizing the glucose that comes in without using oxygen, kind of like what anaerobic metabolism.

1:34:41So they're not using oxygen as fast as they are using glucose. So what we're really seeing in some ways may be in FMRI, not the neurons themselves being active, but rather the astrocytes, which are meeting the metabolic demands of the process of keeping the whole system going. It does seem to be that FMRI is a good way to study activation. So with these astrocytes, even though there's a latency, it's pretty reliably coupled to the activations. Oh, well, this gets me to the other part. But so now let's say, for instance, if I'm just kind of like I'm talking to you, but I'm kind of paying attention to your cowboy hat, right?

1:35:24I'm looking up to the room. I'm thinking about the right, even if I'm not looking at it. What you'd see is that there would be this little elevation in activity in areas in the visual cortex, you know, which process vision around that point in space. Okay. So if then something happened like, you know, suddenly the light flashed in that part of, you know, right in front of your cowboy hat, I would have a bigger response to it. But what you see in FMRI is even if I'm not, even if I don't see that flash light, there's a lot of activity that I can measure, because you're kind of keeping it excitable in that internet of itself, even though I'm not seeing anything there that's particularly interesting.

1:36:06There's still this increase in activity. It's so it's more sensitive with FMRI. So there is that a feature or is it a bug, you know, some people who study spikes in neurons and say, well, that's terrible. We don't want that, you know, likewise, it's slow and that's terrible for measuring things that are very fast. But one of the things that we found in our work was when we give people movies and when we give people stories to listen to, a lot of the action is in the very, very slow stuff. It's in because if you're thinking about like a story, let's say you're listening to a podcast or listening to the Lex Friedman podcast, right?

1:36:44You're putting this stuff together and building this internal model over several seconds, which is basically we filter that out when we look at electrical activity in the brain, because we're interested in this millisecond scale. It's almost massive amounts of information, right? So the way I see it is every technique gives you a little limited window into what's going on. FMRI is huge problems. You know, people lie down in the scanner. There's parts of the brain where I'll show you in some of these images where you'll see kind of gaping holes because there's, you can't keep the magnetic field stable in those spots.

1:37:19You'll see parts where it's like there's a vein and so it just produces big increases and decrease in signal or respiration that causes these changes. There's lots of artifacts and stuff like that, you know, every technique has its limits. If I'm lying down in MRI scanner, I'm lying down. I'm not interacting with you in the same way that I would in the real world. But at the same time, I'm getting data that I might not be able to get otherwise. And so different techniques give you different kinds of advantages. What kind of big scientific discoveries, maybe the flavor of discoveries have been done throughout the history of the science of memory, the studying of memory.

1:37:58What kind of things have been like understood? Oh, there's so many. It's really so hard to summarize it. I mean, I think it's funny because it's like when you're in the field, you can get kind of blase about this stuff. But then once I started writing the book, I was like, oh my god, this is really interesting. How did we do all this stuff?

1:38:21I would say that some of the, I mean, you know, from the first studies, just showing how much we forget is very important. Showing how much schemas, which is organized knowledge about the world, increase our ability to remember information, just massively increase in a studies of expertise, showing how experts like chess experts can memorize so much in such a short amount of time because of the schemas they have for chess. But then also showing that those lead to all sorts of distortions in memory, the discovery that the act of remembering can change the memory, can strengthen it, but it can also distort it if you get misinformation at the time.

1:39:05And it can also strengthen or weaken other memories that you didn't even recall. So just this whole idea of memories and ecosystem, I think, was a big discovery. I could go, this idea of like breaking up our continuous experience into these discrete events, I think was a major discovery. So the discreetness of our encoding of events? Maybe. Yeah. I mean, you know, and again, there's controversial ideas about this, right? But it's like, yeah, this idea that, and this gets back to just this common experience of you walk into the kitchen and you're like, why am I here? And you just end up grabbing some food from the fridge and you go back and like, oh, wait a minute, I left my watch in the kitchen.

1:39:44That's what I was looking for. And so what happens is, is that you have a little internal model of where you are, what you're thinking about. And when you cross from one room to another, those models get updated. And so now, when you're in the kitchen, you have to go back and mentally time travel back to this earlier point to remember what, what it was that you went there for. And so these event boundaries turns out like in our research. And again, I don't want to make it sound like we've figured out everything. But in our research, one of the things that we found is that basically, as people get older, the activity in the hippocampus at these event boundaries tends to go down.

1:40:25And but independent of age, if I give you outside of the scanner you're done with the scanner, I just scan you while you're watching a movie, you just watch it. You come out, I give you a test of memory for stories. What happens is you find this incredible correlation between the activity and the hippocampus at these singular points in time, these event boundaries and your ability to just remember a story outside of the scanner later on. So it's marking this ability to encode memories, just these little snippets of neural activity. So I think that's a big one. There's all sorts of work and animal models that I can get into, you know, sleep.

1:41:05I think there's so much interesting stuff that's being discovered and sleep right now. Being able to just record from large populations of cells and then be able to relate that. And when I think the coolest that gets back to this QR code thing, because like what we can do now is like I can take FMRI data while you're watching a movie or let's do better than that. Let me get FMRI data while you use a joystick to move around in virtual reality. It's here in the metaverse, whatever. But it's kind of a crappy metaverse because there's always so much metaverse that you can do in an MRI. So there's this crappy metaversing.

1:41:42So now I can take a wrap, record from this hippocampus and prefrontal cortex in all these areas with these really new electrodes, get massive amounts of data, and have it move around on a track ball in virtual reality in the same metaverse that I did. And record that rats activity. I can get a person with epilepsy who we have electrodes in the brain any way to try to figure out where the seizures are coming from. And it was a healthy part of the brain, record from that person, right? And I can get a computational model in one of the one of the brand new members in my lab, Tyler Bonn has just doing great stuff.

1:42:20He relates computer vision models and looks at the weaknesses of computer vision models and relates it to what the brain does well. And so you can actually take a ground truth code for the metaverse basically. And you can feed in the visual information, let's say the sensory information or whatever that's coming in, to a computational model that's designed to take real world inputs, right? And you could basically tie them all together by virtue of the state spaces that you're measuring in neural activity and these different formats and these different species and in the computational model, which is, just I just find that mind blowing you could do different kinds of analyses on language and basically come up with just like basically it's the guts of LLMs, right?

1:43:12You have, you could do analyses on language and you could do analyses on, you know, sentiment analyses of emotions and so forth. I put all this stuff together. I mean, it's almost too much. But if you do it right and you do it in a theory driven way as opposed to just throwing all the data at the wall and see what it sticks, I mean, that to me is just exceptionally powerful. So you can take FMRI data in across species and across different types of humans, the conditions of humans and what find construct models that help you find the commonalities or like the the core thing that makes somebody navigate through the metaverse, for example.

1:43:56Yeah, yeah, I mean, more or less. I mean, there's a lot of details. But yes, I think and not just FMRI, but you can relate it to like I said, recordings from large populations of neurons that could be taken in a human or even in a non -human animal that is, where you think it's an anatomical homologue. So that's just mind blowing to me. What's the similarities in humans and mice? That's what it's, Masha Pumpkins. Well, I'll just wrap an accage. You said that's Masha Pumpkins. Despite all of your rage, that's Masha Pumpkins, I think, despite all of your rage at GIFs, you're still just ratnacage.

1:44:36Yeah, all right, good callback. Good callback. See these memory retrieval exercises that doing are actually helping you build a lasting memory of this god recession. And it's strengthening the visual thing I have of you with James Brown on stage. Come stronger, stronger by the second. But animal studies work here as well. Yeah, yeah, so okay, so let's go to the, so I think I've got great colleagues who I talk to, who study memory and mice. You know, and there's some, one of the valuable things in those models is you can study neural circuits in an enormously targeted way because you could do these genetic studies, for instance, where you can manipulate like particular groups of neurons.

1:45:25And it's just getting more and more targeted to the point where you can actually turn on a particular kind of memory, just by activating a particular set of neurons that was active during an experience, right? So there's a lot of conservation of some of these neural circuits across, you know, evolution in mammals, for instance. And then some people would even say that there's genetic mechanisms for learning that are conserved even going back far, far before. But let's go back to the mice in humans question, right? There's a lot of differences. So for one thing, the sensory information is very different.

1:46:05Mice and rats explore the world largely through smelling, all -faction. But they also have vision that's kind of designed to kind of catch death from above. So it's like a very big view of the world. And we move our eyes around in a way that focuses on particular spots in space where you get very high resolution from a very limited set of spots in space. So that makes us very different in that way. And we also have all these other structures as social animals that allow us to respond differently. There's language. There's like, you know, so you name it. There's obviously gobs of differences. Humans aren't just giant rats.

1:46:44There's a bunch more complexity to us. Time scales are very important. So primate brains and human brains are especially good at integrating and holding on to information across longer and longer periods of time, right? And also, you know, finally, it's like our history of training data, so to speak, is very, very different than, you know, I mean, humans' world is very different than a wild mouse's world. And a lab mouse's world is extraordinarily impoverished relative to an adult human. But still, what can you understand by studying mice? I mean, just basic almost behavioral stuff about memory?

1:47:22Well, yes, but that's very important, right? So you can understand, for instance, how do neurons talk to each other? That's a really big, big question. Neural computation, Internet, you think it's the most simple question, right? Not at all. I mean, it's a big, big question. And understanding how two parts of the brain interact, meaning that it's not just one area speaking. It's not like, you know, it's not like Twitter. Where are the raised shout -aegs in another area of the brain just stuck listening to this graph? It's like they're actually interacting on the millisecond scale, right? How does that happen?

1:48:00And how do you regulate those interactions, these dynamic, you know, interactions? We're still figuring that out, but that's going to be coming largely from model systems that are easier to understand. You can do manipulations, like drug manipulations, to manipulate circuits and, you know, use viruses and so forth and lasers to turn on circuits that you just can't do in humans. So I think there's a lot that can be learned from mice. There's a lot that can be learned from non -human primates. And there's a lot that you need to learn from humans. And I think, unfortunately, some of the people in the national institutes of health think you can learn everything from the mouse.

1:48:39It's like why study memory in humans, what I could study learning in a mouse. And just like, oh my god, I'm going to get my funding from somewhere else. Well, let me ask you some random fascinating questions. How does deja vu work? So deja vu is actually one of these things I think some of the surveys suggest that like 75 % of people report having a deja vu experience one time or another. I don't where that came from, but I've pulled people in my class and most of them say they've experienced deja vu. It's this kind of sense that I experienced this moment sometime before. I've been here before.

1:49:21And actually, there's all sorts of variants of this, the French have all sorts of names for various versions of the chamivu, parley vu, I don't know, all these different vues. But deja vu is this sense that it can be like almost disturbing in 10 sense of familiarity. So there was a researcher named Wilder Penfield. Actually, this goes back even earlier to some of the earliest, like Hughlings Jackson was this neurologist who first did a lot of the early characterizations of epilepsy. And one of the things he notices in epilepsy patients, some group of them right before they would get a seizure, they would have this intense sense of deja vu.

1:50:04So it's this artificial sense of familiarity. It's a sense of having a memory that's not there, right? And so what was happening was there was electrical activity in certain parts of these brains. And so this guy penfield later on when he was trying to look for how do we map out the brain to figure out which parts we want to remove and which parts don't we. He would stimulate parts of the temporal lobes of the brain and find you could elicit the sense of deja vu. Sometimes you'd actually get a memory that a person would re -experience just from electrically stimulating some parts. Sometimes they just have this intense feeling of being somewhere before.

1:50:43And so one theory, which I really like is is that in higher order areas of the brain they're integrating for many, many different you know sources of input. What happens is that they're tuning themselves up every time you process a similar input, right? And so that allows you to just get this kind of a fluent sense that I'm very familiar. You're very familiar with this place, right? And so just being here, you're not going to be moving your eyes all over the place because you kind of have an idea of where everything is. And that fluency gives you a sense of like I'm here. Now I wake up in my hotel room and I have this very unfamiliar sense of where I am, right?

1:51:25But you know there's a great set of studies done by Ann Cleary at Colorado State where she created these virtual reality environments and we'll go back to the metaverse. Imagine you go through a virtual museum, right? And then she would put people in virtual reality and have them go through a virtual arcade. But the map of the two places was exactly the same. She just put different skins on them. So one looks different than the other where they've got same landmarks and same places, same objects and everything, but carpeting colors theme everything's different. People will often not have any conscious idea that the two are the same, but they could report this very intense sense of deja vu.

1:52:07So it's like a partial match that's listening this kind of a sense of familiarity. And that's why, you know, in patients who have epilepsy that affects memory, you get this artificial sense of familiarity that happens. And so we think that, and again, this is just one theory amongst many, but we think that we get a little bit of that feeling. It's not enough to necessarily give you deja vu, even for very mundane things, right? So it's like if I tell you the word root -abega, your brain's going to work a little bit harder to catch it than if I give you word like apple, right? And that's because you hear apple lots of your brains very tuned up to process it efficiently, but root -abega takes a little bit longer and more intense.

1:52:52And you can actually see a difference in brain activity in areas in the temporal lobe when you hear a word just based on how frequent it is in the English language. So we think it's tied to this basic, it's basically a byproduct of our mechanism of just learning, doing this error -driven learning as we go through life to become better and better and better to process things more and more efficiently. So I guess deja vu was just an extra elevated stuff coming together, firing for this artificial memory as if it's the real memory. I mean, why does it feel so intense? Well, it doesn't happen all the time, but I think what may be happening is it's a partial match to something that we have, and it's not enough to trigger that sense of that ability to pull together all the pieces, but it's a close enough match to give you that intense sense of familiarity without the recollection of exactly what happened when.

1:53:52But it's also like a space show temporal familiarity. So it's also in time, because there's a weird blending of time that happens. And we'll probably talk about time, because I think that's a really interesting idea of time released to memory. But you also kind of artificial memory brings to mind this idea of false memories that comes in all kinds of context, but how do false memories form? Well, I like to say there's no such thing as true or false memories, right? It's like a Johnny Rotten from the Sex Pistols he had to say, and it's like, I don't believe in false memories anymore than I believe in false songs, right?

1:54:33And so the basic idea is that we have these memories that reflect bits and pieces of what happen, as well as our inferences and theories, right? So I'm a scientist and I collect data, but I use theories to make sense of that data. And so a memory is kind of a mix of all these things. So where memories can go off the deep end and become what we would call conventionally as false memories, are sometimes little distortions where we filled in the blanks, the gaps in our memory based on things that we know, but don't actually correspond to what happened, right? So if I were to tell you that I'm like, you know, a story about this person who's like worried that they have cancer or something like that, and then, you know, they see a doctor and the doctor says, well, things are very much like you would have expected or like, you know, what you were afraid of or something.

1:55:31When people remember that, they'll often remember what the doctor told the patient that he had cancer, even if that wasn't in the story, because they're infusing meaning into that story, right? So that's a minor distortion. But what happens is that sometimes things can really get out of hand where people have trouble telling the difference in things that they've imagined versus things that happen. But also, as I told you, the act of remembering can change the memory. And so what happens then is you can actually be exposed to some misinformation. And so Elizabeth Loftus was a real pioneer in this work and there's lots of other work that's been done since.

1:56:11But basically, it's like if you remember some event and then I tell you something about the event later on when you remember the event, you might remember some original information from the event as well as some information about what I told you. And sometimes if you're not able to tell the difference, that information that I told you gets mixed into the story that you had originally. So now I give you some more misinformation or you're exposed to some more information somewhere else. And eventually your memory becomes totally detached from what happened. And so sometimes you can have cases where people, this is very rare, but you can do it in lab too or like a significant not everybody, but you know, a chunk of people will fall for this where you can give people misinformation about an event that never took place.

1:57:04And as they keep trying to remember that event more and more, what happens is they start to imagine they start to pull up things from other experiences they've had. And eventually they can stitch together a vivid memory of something that never happened because they're not remembering an event that happened. They're remembering the act of trying to remember what happened. And basically putting it together into the wrong story. So it's fascinating because this could probably happen at the collective level. Like this is probably what successful propaganda machines aim to do. This creating false memory across thousands of not millions of minds.

1:57:45Yeah, absolutely. I mean, this is exactly what they do. And so all these kind of foibles of human memory get magnified when you start to have social interactions. There's a whole literature on something called social contagion, which is basically when misinformation spreads like a virus like you remember the same thing that I did, but I give you a little bit of wrong information. Then that becomes part of your story of what happened because once you and I share a memory, like I tell you about something I've experienced and you tell me about your experience of the same event, it's no longer your memory or my memory.

1:58:21It's our memory. And so now the misinformation spreads and the more you trust someone or the more powerful that person is, the more of a voice they have in shaping that narrative. Right. And there's all sorts of interesting ways in which misinformation can happen. There's a great example of when John McCain and George Bush, Jr. were in a primary. And there are these polls where they would do these, like I guess they were like not robo calls, but real calls where they would poll voters. But they actually inserted some misinformation about McCain's beliefs on taxation, I think, and maybe it was something about illegitimate children.

1:59:03I don't really remember. But they included misinformation in the question that they asked, like, do you know, how do you feel about the fact that he wants to do this or something? And so people would end up becoming convinced he had these policy things or these personal things that were not true, just based on the polls that were being used. So it was the case where interestingly enough, the people who were using misinformation were actually ahead of the curve relative to the scientists were trying to study these effects and memory. Yeah, it's, it's really interesting. So it's not just about truth and falsehoods like us as intelligent, reasoning machines.

1:59:50But it's the formation of memories where they become like visceral. You can rewrite history. If you just look throughout the 20th century, some of the dictatorships with Nazi Germany with the Soviet Union effective propaganda machines can rewrite our conceptions of history. How we remember our own culture are upbringing all this kind of stuff. And you could do quite a lot of damage in this way. And then there's probably some kind of social contagion happening there. Like certain ideas that may be initiated by the propaganda machine can spread faster than others. You could see that in modern day, certain conspiracy theories is just something about them that they are like really effective at spreading.

2:00:35There's something sexy about them to people to wear. There's something about the human mind eats it up and then uses that to construct memories as almost, as if they're almost were there to witness whatever the content of the conspiracy theory is. It's fascinating because once you feel like you remember a thing, I feel like there's a certainty. There's a emboldens you to like say stuff. Like you really like, it's not just you believe in the DS true or not. You're like, it's at the core of your being that you feel like you were there to watch the thing happen. Yeah, I mean, there's so much in what you're saying.

2:01:18I mean, one of the things is that people's sense of collective identity is very much tied to shared memories. If we have a shared narrative of the past or even better, if we have a shared past, we will feel more socially connected with each other and I will feel part of this group. They're part of my tribe. If I remember the same things in the same way, and you brought up this weaponization of history, and it really speaks to, I think, one of the parts of memory, which is that if you have a belief, you will find and you have a goal in mind, you will find stuff in memory that aligns with it, and you won't see the parts in memory that don't.

2:01:58A lot of the stories we put together are based on perspectives. Let's just zoom out for the moment from misinformation, take something even more fascinating, but not as scary. I was reading Ton Viet Nguyen, but he wrote a book about the collective memory of the Vietnam War. He's a Vietnamese immigrant who was flown out as after the war was over. We went back to his family to get their stories about the war. And they called it the American War, not the Vietnam War. And that just kind of blew my mind to having grown up in the US and I've always heard about it as a Vietnam War. But of course they call it the American War because that's what happened.

2:02:43America came in. And that's based on their perspective, which is a very valid perspective. And so that just gives you this idea of the way we put together these narratives based on our perspectives. And I think the opportunities that we can have in memory is if we bring groups together from different perspectives and we allow them to talk to each other and we allow ourselves to listen. I mean, right now you'll hear a lot of just jammering, you know, people going blah, blah, blah, about free speech, but they just want to listen to themselves. Right? It's like, let's face it, the old days before people were supposedly woke.

2:03:26They were trying to ban two live crew or, you know, just think about letty Bruce got cancel for cursing. Jesus Christ, you know, it's like, this is nothing new. People don't like to hear things that disagree with them. But if you're in it, I mean, you can see two situations in groups with memory. One situation is you have like people who are very dominant who just take over the conversation. And they basically what happens is the group remembers less from the experience. And they remember more of what the dominant narrator says, right? Now, if you have a diverse group of people, and I don't mean diverse and necessarily the human resources sense of the word, I mean, diverse in any way you want to take it, right?

2:04:10But diverse in every way, hopefully. And you give everyone a chance to speak and everyone's being appreciated for their unique contribution. You get more accurate memories and you get more information from it, right? Even two people who come from very similar backgrounds, if you can appreciate the unique contributions that each one has, you can do a better job of generating information from memory. And that's a way to inoculate ourselves, I believe, from misinformation in the modern world. But like everything else, it requires a certain tolerance for discomfort. And I think when we don't have much time, and I think when we're stressed out and when we are just tired, it's very hard to tolerate discomfort.

2:04:53And I mean, social media has a lot of opportunity for this because it enables this distributed one -on -one interaction that you're talking about where everybody has a voice. But still our natural inclination, as you see this on social media, as a natural clustering of people and opinions, and you just kind of form these kind of bubbles. I think that's to me personally, I think that's a technology problem that can be solved. If there's a little bit of interaction, kind, respectful, compassionate interaction with people that have a very different memory, that that respectful interaction will start to intermix the memories and ways of thinking to where you're slowly moving towards truth.

2:05:38But that's a technology problem because naturally, left -iron devices, we want to cluster up in a tribe. Yeah, and that's the human problem. I think a lot of the problems that come up with technology aren't the technology itself as much as the fact that people adapt to the technology in maladaptive ways. One of my fears about AI is not what AI will do, but what people will do. I mean, take text messaging. It's like pain in the ass to text people. At least for me. And so what happens is the communication becomes very Spartan and devoid of meaning. It's this very telegraphic. And that's people adapting to the medium.

2:06:20Look at you've got the keyboard that's got these dome -shaped things. And you've adapted to that to communicate. That's not the technology adapting to you. That's you adapting to the technology. And I think with one of the things I learned when Google started to introduce auto -complete in emails, I started to use it. And about a third of the time I was like, this isn't what I want to say. A third of the time I'd be like, this is exactly what I wanted to say. And a third of the time I was saying, well, this is good enough. I'll just go with it. And so what happens is that it's not that the technology necessarily is doing anything so bad as much as it's just going to constrain my language because I'm just doing what's being suggested to me.

2:07:04And so this is why I say, you know, kind of like my mantra for some of what I've learned about everything in memory is to diversify your training data, basically, because otherwise you're going to be so like humans have this capability to be so much more creative than anything generative AI will put together, at least right now, who knows where this goes. But it can also go the opposite direction where people could become much, much less creative if they just become more and more like resistant to discomfort, you know, and resistant to exposing themselves to novelty, to cognitive dissonance and so forth.

2:07:43I think there is a dance between natural human adaptation of technology and the people that the design, the engineering of that technology. So I think there's a lot of opportunity to create like this keyboard things that are net or positive for human behavior. So we adapt and all this kind of stuff. But when you look at the long arc of history across the years and decades, has humanity been flourishing? Are humans creating more awesome stuff? Are humans happy? Are all that kind of stuff? And so there, I think technology on that has been, and I think maybe hope will always will always be on that positive thing.

2:08:26Do you think people are happier now than they were 50 years ago or 100 years ago? Yes. Yes. I don't know about that. I think humans in general like to reminisce about the past, like the times are better. And complain about the weather today or complain about whatever today, because we, there's this kind of complaining engine that's just there's so much pleasure in saying, you know, life sucks for somebody's. And that's why I love punk rock. Exactly. I mean, there's something in humans that loves complaining, even about trivial things. But complaining about change, complaining about everything.

2:09:06But ultimately, I think on net, on every measure, things are getting better. Life is getting better. Life is getting better. But I don't know the necessarily that tracks people's happiness, right? I mean, I would argue that maybe, who knows? I don't know this, but I wouldn't be surprised if people in hunter gatherer societies are happier. I mean, I wouldn't be surprised if they're happier than people who have access to modern medicine and email and cell phones. Well, I don't think there's a question whether you take hunter gatherer folks and put them into modern day and give them enough time to adapt.

2:09:44They would be much happier. The question is, in terms of every single problem they've had is not solved. There's not food. There is guaranteed survival shelter and all this kind of stuff. What you're asking is a deeper sort of biological question. Do we want to be a winner, herzag, and a movie, a happy people life in the tiger? Do we want to be busy 100 % of our time, hunting, gathering, surviving, worried about the next day? Maybe that constant struggle ultimately creates a more fulfilling life? I don't know. But I do know this modern society allows us to, when we're sick to find medicine, to find cures, when we're hungry to get food much more than we did even 100 years ago.

2:10:35There's many more activities that you could perform or create of all these kind of stuff that enables the flourishing of humans at the individual level. Whether that leads to happiness, I mean, that's a very deep philosophical question. Maybe struggle, deep struggles necessary for happiness. Or maybe cultural connection. Maybe it's about functioning in social groups that are meaningful and having time. But I do think there's an interesting memory -related thing, which is that if you look at things like reinforcement learning, for instance, you're not learning necessarily every time you get a reward, if it's the same reward, you're not learning that much.

2:11:21You mainly learn if deviates from your expectation of what you're supposed to get. It's like you get a paycheck every month from MIT or whatever. You probably don't even get excited about it when you get the paycheck. But if they cut your salary, you're going to be pissed. If they increase your salary, oh, good, I got a bonus. That adaptation and that ability that basically you learn to expect these things, I think, is a major source of, I guess, it's a major way in which we're kind of more, in my opinion, wired to strive and not be happy to be in a state of wanting. And so people talk about dopamine, for instance, being this pleasure chemical.

2:12:05And it's like, there's a lot of compelling research to suggest it's not about pleasure at all. It's about the discomfort that energizes you to get things, to seek a reward. And so you give an animal that's been deprived of dopamine, a reward, and I enjoy it. It's pretty good. But they're not going to do anything to get it. And just one of the weird things in our research is we got into curiosity from a postdoc in my lab, Matthias Gruber. And one of the things that we found is when we gave people a question, like a trivia question that they wanted the answer to, that question, the more curious people were about the answer, the more activity in these dopamine related circuits in the brain we would see.

2:12:55And again, that was not driven by the answer per say, but by the question. So it was not about getting the information, it was about the drive to seek the information. But it depends on how you take that. If you get this uncomfortable gap between what you know and what you want to know, you could either use that to motivate you and energize you, or you could use it to say, I don't want to hear about this. This disagrees with my beliefs. I'm going to go back to my echo chamber, you know. Yeah. I like what you said that maybe we're designed to be in a kind of constant state of wanting, which by the way is a pretty good either band name or rock song name state state of state of wanting.

2:13:40That's like a hardcore band. Yeah. Yeah. It's pretty good. But I also like the hedonic treadmill. The dog treadmill is pretty good. Yeah. Yeah. We could use that for like our techno project, I think. You mean the one we're starting? Yeah, exactly. Okay. Great. We're going on tour soon. This is our announcement. We could build a false memory of a show. In fact, if you want, let's just put it all together. So we don't even have to do all the work to play the show. We just create a memory of it and might as well happen because the remember itself is in charge. Anyone. So let me ask you about we talked about false memories, but you know, in the legal system, false confessions, I'm operating a 1984 where sorry for the dark turn of our conversation, but through torture, you can make people say anything and essentially remember anything.

2:14:35I wonder, to reach a degree, there's like truth to that. If you look at the torture that happened, the Soviet Union did for confessions, all that kind of stuff. How much can you really get people to really, yeah, to force false memories, I guess? Yeah. I mean, I think there's a lot of history of this actually in the criminal justice system. You might have heard the term the third degree. If you actually look it up, historically, it was a very intense set of beatings and, you know, starvation, physical demands that they would place that people to get them to talk. And, you know, there was certainly a lot of work in the that's been done by the CIA in terms of enhanced and interrogation techniques.

2:15:22And from what I understand, the research actually shows that they just produce what people want to hear, not necessarily the information that is being looked for. And the reason is that, I mean, there's different reasons. I mean, one is people just get tired of being tortured and just say whatever. But another part of it is that you create a very interesting set of conditions where there's an authority figure telling you something that you did this. We know you did this. We have witnesses saying you did this. So now you start to question yourself. Then they put you under stress. Maybe they're not feeding you.

2:16:01Maybe they're kind of like making you be cold or, you know, exposing you to like music that you can't stand or something, whatever it is, right? It's like they're creating this physical stress. And so stress starts to act on, you know, starts to downregulate the prefrontal cortex. You're not necessarily as good at monitoring the accuracy of stuff. Then they start to get nice to you and they say, imagine, you know, okay, I know you don't remember this, maybe we can walk you through how it could have happened and they feed you the information. And so you're in this weakened mental state and you're being encouraged to imagine things by people who give you a plausible scenario.

2:16:40And at some point, certain people can be very coaxed into creating a memory for something that never happened. And there's actually some pretty convincing cases out there where you don't know exactly the truth. There's a sheriff, for instance, who came to believe that he had a false memory. I mean, that he had a memory of doing sexual abuse based on, you know, essentially, I think it was, you know, I'm not going to tell the story because I don't remember it well enough to necessarily accurately give it to you. But people could look this stuff up. There are definitely stories out there like this where people confess to crimes that they just didn't do when objective evidence came out later on.

2:17:21But there's a basic recipe for it, which is you feed people the information that you want them to remember. You stress them out. You have an authority figure kind of like pushing this information on them or you motivate them to produce the information you're looking for. And that pretty much over time gives you what you want. It's really tragic. But centralized power can use these kinds of tools to destroy lives. Sad.

2:17:59Since there's a theme about music throughout this conversation, one of the best topics for songs is heartbreak. Love in general, heartbreak. Why and how do we remember and forget heartbreak asking for a friend? Oh God, that's so hard to asking for a friend of that. It's such a hard one. Well, so I mean, part of this is we tend to go back to particular times the more emotionally intense periods. And so that's a part of it. And again, memories design to kind of capture these things that are biologically significant. And attachment is a big part of biological significance for humans, human relationships are super important.

2:18:52And sometimes that heartbreak comes with massive changes in your beliefs about somebody, say if you cheated on you or something like that or regrets and you kind of ruminate about things that you've done wrong.

2:19:06There's really so many reasons though. But I've had this. My first pet I had as you know, was, but you got it for a wedding present as a cat and got it after like, but it died of FIP when it was four years old. And you know, I just would see her everywhere around the house. You know, we got another cat that we got a dog, dog eventually died of cancer and the cat just died recently. And you know, so we got a new dog because I kept seeing the dog around and I was just so heartbroken about this. But I still remember the pets that died. It just comes back to you. I mean, it's part of this. I think there's also something about attachment.

2:19:50This is just so crucial that drives again, these things that we want to remember and that gives us that longing sometimes. Sometimes it's also not just about the heartbreak, but about the positive aspects of it, right? Because the loss comes from not only the fact that the relationship is over, but you had all of these good things before that you can now see in a new light, right? And so part of one of the things that I found from my clinical background that really I think gave me a different perspective on memory is so much of the therapy process was guided towards reframing and getting people to look at the past in a different way, not by imposing changing people's memories or not by imposing an interpretation, but just offering a different perspective and maybe one that's kind of more optimized towards learning and appreciation maybe your gratitude, whatever it is, right?

2:20:50That gives you a way of taking, I think you said it in the beginning, right? Where you can have this kind of like dark experiences and you can use it as training data to grow in new ways. But it's hard. I often go back to this moment, this show, Louis, with Louis CK, where he's all heartbroken about a breakup with a woman he loves and an older gentleman tells him that that's actually the best part at heartbreak because you get to intensely experience how valuable this love was. He says the worst part is forgetting it is actually when you get over the heartbreak, that's the worst part. So I sometimes think about that because having the love and losing it, like the losing it is when you sometimes feel it the deepest, which is an interesting way to celebrate the past and relive it.

2:21:55It sucks that you don't have a thing, but when you don't have a thing, it's a good moment to viscerally experience the memories of something that you know appreciate even more. So you don't believe that an owner of a lonely heart is much better than an owner of a broken heart. You think an owner of a broken heart is better than the owner of a lonely heart? Yes, for sure. I think so. I think so. But I'm going to have to day by day. I don't know. I'm going to have to listen to some more Bruce Brinxine to figure that one out. Well, you know, it's funny because it's like after I turned 50, I think of death all the time.

2:22:31Like I just think that, you know, I'm in like, I probably, I have fewer, probably a few years ahead of me than I have behind me. Right. So I think about, I think about one thing, which is what are the memories that I want to carry with me for the next period of time. And also about like just the fact that everything around me could be, you know, I know more people who are, you know, dying for various reasons. And so I'm not lots. I'm not that old, right? But you know, it's something I think about a lot. And I'm reminded of like how I talked to somebody who's like, you know, as a Buddhist, and I was like, you know, the whole idea of Buddhism is renouncing attachments.

2:23:14Some way the idea of Buddhism is like staying out of the world of memory and staying in the moment. Right. And they talked about, you know, it's like, how do you, how do you renounce attachments to the people that you love, right? And they're just saying, well, I appreciate that I have this moment with them and knowing that they will die makes me appreciate this moment that much more. I mean, said something similar, right? And your daily routine that you think about things this way, right? Yeah, I meditate on mortality every day. But I don't know, at the same time, that really makes you appreciate the moment and live in the moment.

2:23:50And I also appreciate the full deep roller coaster of suffering involved in life, the little and the big too. So I don't know, I mean, the Buddhist kind of removing yourself from the world or the stoic and removing yourself from the world, the world of emotion, I'm torn about that one. I'm not sure. Well, you know, this is where Hinduism and Buddhism, or at least some strains of Hinduism and Buddhism differ in Hinduism. Like, if you read the Bhagavad Gita, the philosophy is not one of renouncing the world because the idea is that not doing something is no different than doing something, right?

2:24:32So what they argue, and again, you could interpret in different ways positive and negative. But the argument is that you don't want to renounce action, but you want to renounce the fruits of the action. You don't do it because of the outcome. You do it because of the process, because the process is part of the balance of the world that you're trying to preserve, right? And of course, you could take that different ways, but I really think about that from time to time in terms of letting go of this idea of does this book sell or trying to impress you and get you laugh at my jokes or whatever, and just be more like, I'm sharing this information with you and getting to know you or whatever it is.

2:25:17But it's hard, right? It's like, we're so driven by the reinforcer, the outcome. You're just part of the process of telling the joke, and if I laugh or not, that's up to the universe to decide. Yep, it's my Tharma. How does studying memory affect your understanding of the nature of time? So like, we've been talking about us living in the present and making decisions about the future and understanding the foundation of these memories and narratives about the memories that we've constructed. So it feels like it does weird things to time. Yeah, and the reason is that in some sense, I think, especially the farther we go back, I mean, there's all sorts of interesting things that happen.

2:26:07So your sense of like, if I ask you, how different does one hour ago feel from two hours ago? You'd probably say pretty different. But if I ask you, go back one year ago versus one year and one hour ago, it's the same difference in time. It won't feel very different, right? So there's this kind of compression that happens as you look back farther in time. So it's kind of like why when you're older, the difference between somebody who's like 50 and 45 doesn't seem as big as the difference in like 10 and 5 or something, right? When you're 10 years old, everything seems like it's a long period of time.

2:26:44Here's the point, is that, you know, so one of the interesting things that I found when I was working on the book, actually, was during the pandemic, I just decided to ask people in my class when I were doing the remote instruction. So one of the things I did was I'd pull people. And so I just asked people, do you feel like the days are moving by slower or faster or about the same? Almost everyone in the class said that the days were moving by slower. So then at the, I would say, okay, so do you feel like the weeks are passing by slower, faster or the same? And the majority of them said that the weeks were passing by faster.

2:27:21So according to the laws of physics, I don't think that makes any sense, right? But according to memory, it did because what happened was people were doing the same thing over and over in the same context. And without that change in context, their feeling was that they were in one long monotonous event. And so, but then at the end of the week, you look back at that week and you say, well, what happened? No memories of what happened. So it must, the week just went by without even my noticing it, but that week went by during the same amount of time as an eventful week where you might have been going out and hang out with friends on vacation or whatever, right?

2:28:02It's just that nothing happened because you're doing the same thing over and over. So I think, I feel like memory really shapes our sense of time, but it does so in part because context is so important for memory. Well, that compression you mentioned, it's an interesting process is what I think about when I was like 12, 15, I just fundamentally feel like the same person. It's interesting what that compression does. It makes me feel like it's all we're all connected, not just amongst humans and spatially, but in terms, in back in time, there's a kind of eternal nature, like the timelessness, I guess, to life.

2:28:47That could be also a genetic thing just from me. I don't know everyone agrees to this view of time, but to me, it all feels the same. Like you don't feel the passage of time or... No, I feel the passage of time the same way the students did from day to day. There's certain markers that let you know the time has passed, you celebrate birdism, so on, but the core of who I am and who others I know are or events, it like that compression of my understanding of the world removes time because time is not useful for the compression. So like the details of that time, at least for me, is not useful to understanding the core of the thing.

2:29:29Maybe what it is is that you really like to see connections between things. This is really what motivates me in science, actually, too. But it's like when you start recalling the past to and seeing the connections between the past and present, now you have this web of interconnected memories. I can imagine in that sense, there is this kind of the present is with you. But what's interesting about what you said, too, that struck me is that your 16 -year -old self was probably very complex. And by the way, I'm the same way, but it's like it really is the source of a lot of darkness for me. But when you can look back at, like let's say you hear a song that you used to play before you would go do a sports thing or something like that, you might not think of yourself as an athlete, but once you get back to that mentally, mentally time travel to that particular thing, you open up this little compartment of yourself that wasn't there before, right?

2:30:33That didn't seem accessible for it. Dan Shactor's lab did this really cool study where they would ask people to either remember doing something altruistic or imagine doing something altruistic. And that act made them more likely to want to do things for other people. So that act of mental time travel can change who you are in the present. I mean, tend to think of this goes back to that illusion of stability. I mean, tend to think of memory in this very deterministic way that I am who I am because I have this past.

2:31:15But we have a moment based on whatever part we want to reach for. How does nostalgia connect into this? Like this desire and pleasure associated with going back? Yeah. So my friend Felipe de Brigard wrote this and it just like blew my mind where the word nostalgia was coined by a Swiss physician who was actually studying traumatized soldiers. And so he described nostalgia as a disease. And the idea was it was bringing these people extraordinary unhappiness because they're remembering how things used to be. And I think it's very complex. So as people get older, for instance, nostalgia can be an enormous source of happiness, right?

2:32:04And being nostalgic can improve people's moods in the moment. But it just depends on what they do with it because what you can sometimes see is nostalgia has the opposite effect of thinking those were the good old days and those days are over, right? It's like America used to be so great and now it sucks. Or in a my life used to be so great when I was a kid and now it's not, right? And you're selectively remembering the things that I mean, we don't realize how selective our remembering self is. And so, you know, I lived through the 70s. It sucked. I was like, partly it sucked more for me, but I don't say that even otherwise.

2:32:44It's like there's all sorts of problems going on gas lines. People were like, you know, worried about like Russia, nuclear war, blah, blah, blah. So I mean, it's just this idea that people have about the past can be very useful if it brings you happiness in the present. But if it narrows your worldview in the present, you're not aware of those biases that you have, you will end up, you can end up, it can be toxic, right? Either at a personal level or at a collective level. Let me ask you both a practical question and an out there question. So let's start with the more practical one. What are your thoughts about BCIs, brain computer interfaces and the work that's going on with Neuralink?

2:33:30We talked about electrodes in different ways of measuring the brain and here Neuralink is working on basically two -way communication with the brain. And the more out there question would be like, where does it go? But more practically in the near term, what do you think about Neuralink? Yeah, I mean, I can't say specifics about the company because I haven't studied it that much. But I mean, I think there's two parts of it. So one is they're developing some really interesting technology. I think with these like surgical robots and things like that, BCI though has like a whole lot of innovation going on.

2:34:03I'm not necessarily seeing any scientific evidence from Neuralink and maybe that's just going to be I'm not looking for it, but I'm not seeing the evidence that they're anywhere near where the scientific community is. And there's lots of startups that are doing incredibly innovative stuff. One of my colleagues are Gase of Iskis, just like genius in this area and they're working on it. I think speech prosthetics that are incorporating decoding techniques with AI and movement prospects. It's just like the rate of progress is just enormous. So part of the technology is having good enough data and understanding which data to use and what to do with it.

2:34:43And then the other part of it then is the algorithms for decoding it and so forth. And I think part of that has really resulted in some real breakthroughs in neuroscience as a result. So there's lots of new technologies like NeuroPixels, for instance, that allow you to harvest activity from many, many neurons from a single electrode. I know Neuralink has some technologies that are also along these lines, but I even again, because they do their own stuff. The scientific community doesn't see it, right? But I think BCI is much, much bigger than Neuralink and there's just so much innovation happening.

2:35:22I think the interesting question which we may be getting into is I was talking to Sergei a while ago about, you know, so a lot of language is not just what we hear and what we speak, but also our intentions and our internal models. And, you know, so are you really going to be able to restore language without dealing with that part of it? And he brought up a really interesting question, which is the ethics of reading out people's intentions and understanding of the world, as opposed to the more, you know, the more concrete parts of hearing and producing movements. Just so we're clear, because you said a few interesting things when you say, when we talk about language and BCIs, what we mean is getting signal from the brain and generating the language say you're not able to actually speak.

2:36:12It's as a kind of linguistic prosthetic. It's able to speak for you exactly what you wanted to say. And then the deeper question is, well, saying something isn't just the letters, the words you're saying, it's also the intention behind it, the feeling, all that kind of stuff. And is it ethical to reveal that full shabang, the context of what's going on in our brain? That's really interesting. That's really interesting. I mean, our thoughts is that that's the goal for anyone to have access to our thoughts. Because right now the resolution is so low that we're okay with it, even doing studies and all this kind of stuff.

2:36:58But if there, if neuroscience, as a few breakthroughs, where you can start to map out the QR codes for different thoughts, for different kinds of thoughts, maybe political thoughts, you know, the McCarthyism, what if I'm getting a lot of them communist thoughts, or however we want to categorize or label it? That's interesting. That's really interesting. I think ultimately this always, the more transparency there is about the human mind, the better it is. But there could be always intermediate battles with how much control does a centralized entity have, like a government and so on. What is the regulation?

2:37:42What are the rules? What are the what's legal and illegal? If you talk about the police whose job is to track down criminals and so on and you look at all the history, how the police could be abused its power to the control of citizens and real that kind of stuff. So people always paranoid and rightfully so, it's fascinating. It's really fascinating. We talk about freedom of speech, freedom of thought, which is also a very important liberty at the core of this country and probably humanity, starts to get awfully tricky when you start to be able to collect those thoughts. But what I wanted to actually ask you is, do you think for fun and for practical purposes, you'll be able to, we would be able to modify memories.

2:38:38So how difficult is it to, how far away we are from understanding the different parts of the brains, everything we've been talking about in order to figure out how could we adjust this memory at the crude level from unpleasant to pleasant. You talked about we can remember the mall and the people, like the location of the people. Can we keep the people and change the place, like this kind of stuff? How difficult is that? Well, I mean, in some sense, we know we can do it just behaviorally, right? I just like tell you, give, you know, under certain conditions, anyway, I can give you the misinformation and then you can change the people in places and so forth, right?

2:39:20On the crude level, there's a lot of work that's being done on a phenomenon called re -consolidation, which is the idea that essentially when I recall a memory, what happens is that the connections between the neurons and that cell assembly that give you the memory are going to be like more modifiable. And so some people have used techniques to try to, like for instance, with fear memories to reduce that physical visceral component of the memory when it's being activated. Right now, I think I've, as an outsider looking at the data, I think it's like mixed results. And part of it is, and the speaks to the more complex issue, is that you don't, you need somebody to actually fully recall that traumatic memory in the first place.

2:40:09And in order to actually modify it, and then what is the memory? That is the key part of the problem. So if we go back to reading people's thoughts, what is the thought? I mean, people can sometimes look at this like behaviorists and go, well, the memory is like, I've given you a new produce beep. And I think that's a very bankrupt concept about memory. I think it's much more complicated than that. And you know, one of the things that when we started studying naturalistic memory, like memory from movies, that was so hard was we had to change the way we did the studies because if I show you a movie and I show, and I watch the same movie, and you recall everything that happened, and I recall everything that happened, we might take a different amount of time to do it.

2:40:54We might use different words. And yet to an outside observer, we might have recalled the same thing, right? So it's not about the words necessarily, and it's not about how long we spent or whatever. There's something deeper that is there that's this idea, but it's like, how do you understand that thought? I encounter a lot of concrete thinking that it's like, if I show a model, like, you know, the visual information that a person sees when they drive, I can basically reverse engine your driving. Well, that's not really how it works. I went, saw a talk by somebody, or I saw somebody talking in this discussion of between neuroscientists and AI people, and he was saying that the problem with self -driving cars that they had in cities, as opposed to highways, was that the car was okay at, you know, doing the things that's supposed to, but when there are pedestrians around, it couldn't predict the intentions of people.

2:41:52And so that unpredictability of people was the problem that they were having in, you know, the self -driving car design, because it didn't have a good enough internal model of what the people were, you know, what they were doing, what they wanted. And what do you think about that? Well, I spent a huge amount of time watching pedestrians, thinking about pedestrians, thinking about what it takes to solve the problem of measuring, detecting the intention of a pedestrian, really of a human being in this particular context of having to cross the street, and it's fascinating. I think it's a window into how complex social systems are that involve humans, because, you know, I would just stand there and watch intersections for hours, and when you start to figure out is every single intersection has its own personality.

2:42:57So like, there's a history to that intersection, like, J -walking certain intersections allow J -walking a lot more, because what happens is we're leaders and followers. So there's a regular, let's say, and they get off the subway and they start crossing on red light, and they do this every single day. And then there's people that don't show up to that intersection often, and they're looking for cues of how we're supposed to behave here. And if a few people start to J -walking crossing red light, they will also, they will follow. And there's just a dynamic to that intersection. There's a spirit to it.

2:43:34And if you look at Boston versus New York, versus the rural town, versus even Boston, San Francisco or here in Austin, there's different personalities citywide, but there's different personalities area, regionwide, and there's different personalities different intersections. And it's just fascinating for a car to be able to determine that, it's tricky. Now, what machine learning systems are able to do well is collect a huge amount of data. So for us, it's tricky because we get to like, understand the world with very limited information, and make decisions grounded in this big foundation model that we've built of understanding how humans work.

2:44:16And I could literally, in the context of driving, this is where I've often been really torn in both directions. If you just collect a huge amount of data, all of that information and then compress it into a representation of how humans cross streets, it's probably all there. In the same way that you have a known Chomsky who says, no, no, I can't talk, can't write convincing language without understanding language. And you know, more and more, you see large language models without quote unquote understanding can generate very convincing language. But I think what the process of compression from a huge amount of data compressing into a representation is doing is in fact understanding deeply in order to be able to generate one letter at a time, one word at a time, you have to understand the cruelty of Nazi Germany and the beauty of sending humans to space.

2:45:18And like, you have to understand all of that in order to generate, like, I'm going to the kitchen to get an apple and do that, grammatically, correctly. You have to have a world model that includes all of human behavior. You're thinking LLM is building that world model? It has to in order to be good at generating one word at a time, a convincing sentence. And in the same way, I think AI that drives a car, if it has enough data, we'll be able to form a world model that will be able to predict correctly what the pedestrian does. But when we, as humans are watching pedestrians, we slowly realize, damn, this is really complicated.

2:45:57In fact, when you start to self reflect on driving, you realize driving is really complicated. There's like subtle cues we take about like, just, there's a million things I could say. Well, like one of them determining who around you is an asshole, aggressive driver, especially dangerous. I was just thinking about this. Yeah. Or like, you can read it once you get become a great driver. You can see it a mile away. This guy is going to pull an asshole move in front of you. Exactly. He's like way back there, but you know it's going to happen. And I don't know what, because we're ignoring all the other cars.

2:46:33But for some reason, they ask, like, a red, like, a glowing, obvious symbol is just like right there, even in the periphery vision, because we're, again, we're usually when we're driving just looking forward. But we're like using the periphery vision to figure stuff out. And it's like a little puzzle that we're usually only allocating a small amount of our attention to, at least like cognitive attention to. And it's fascinating, but I think AI just has a fundamentally different suite of sensors in terms of the bandwidth of data that's coming in that allows you to form the representation that perform inference on the representation you've used in the representation you form that for the case of driving, I think it could be quite effective.

2:47:19But one of the things that's currently missing, even though OpenAI just recently announced adding memory. And I did want to ask you like how important it is, how difficult is it to add some of the memory mechanisms that you've seen in humans to AI systems? I would say superficially not that hard, but then in a deeper level very hard, because we don't understand episodic memory, right? So one of the ideas I talked about in the book is one of the oldest kind of dilemmas in computational neuroscience is what Steve Grossberg called the stability plasticity dilemma, right? When do you say something is new and overwrite your preexisting knowledge versus going with what you had before and making incremental changes?

2:48:07And so part of the problem with going through massive, part of the problem of things like if you're trying to design an LLM or something like that is especially for English, there's so many exceptions to the rules, right? And so if you want to rapidly learn the exceptions, you're going to lose the rules. And if you want to keep the rules, you have a harder time learning the exception. And so David Marrow is one of the early pioneers in computational neuroscience. And then Jay McClellan and my colleague Randy Arreilles, some other people like Neil Cohen, all these people started to come up with the idea that maybe that's part of what we need and what the human brain is doing is we have this kind of a actually a fairly dumb system which just says this happened once at this point in time, which we call episodic memory, so to speak.

2:49:02And then we have this knowledge that we've accumulated from our experiences as a semantic memory. So now when we want to we encounter a situation that's surprising and violates all our previous expectations, what happens is that now we can form an episodic memory here. And the next time we're in a similar situation, boom, we can supplement our knowledge with this information from episodic memory and reason about what the right thing to do is, right? So it gives us this enormous amount of flexibility to stop on a dime and change without having to erase everything we've already learned. And that solution is incredibly powerful because it gives you the ability to learn from so much less information really, right?

2:49:49And it gives you that flexibility. So one of the things I think that makes humans great is having both episodic and semantic memory. Now can you build something like that? I mean, you know, computational neuroscience people was like, well, yeah, you just record a moment and you just get it and you're done, right? But when do you record that moment? How much do you record? What's the information you prioritize? And what's the information you don't? These are the hard questions. When do you use episodic memory? When do you just throw it away? And these are the hard questions we're still trying to figure out in people.

2:50:25And then you start to think about all these mechanisms that we have in the brain for figuring out some of these things. And it's not just one, but many of them that are interacting with each other. And then you just take not only the episodic and the semantic, but then you start to take the motivational survival things, right? It's just like the fight or flight responses that we associate with particular things are the kind of like reward motivation that we associate with certain things so far. And those things are absent from AI. I frankly don't know if we want it.

2:51:04I the problem of how do you even like build the motivations that should guide a proper reinforcement learning kind of thing, for instance. So a friend of mine, Sam Gershman, I might be missing the quote exactly, but he basically said, you know, if I wanted to train like in a typical AI model to make me as much money as possible, first thing in my due is sell my house. So it's not even just about having one goal or one objective, but just having all these competing goals and objectives, right? And then things start to get really complicated. Well, it's all interconnected. I mean, just even the thing you've mentioned is the moment, you know, if we record a moment, like it's difficult to express concretely what a moment is, like how deeply connected it is to the the entirety of it, maybe to record a moment, you have to make a universe scratch.

2:52:02You have to have you have to include everything. You have to include all the emotions involved, all the context, all the things that built around, all the social connections, all the visual experiences, all the sensory experience, all of that, all the history that came before that moment is built on. And we somehow take all that and we compress it and keep the useful parts and then integrate into the whole thing into our whole narrative. And then each individual has their own little version of that narrative and then we collide in social way and we adjust it and we evolve. Yeah, yeah, I mean, well, even if we want to go super simple, right?

2:52:40Like Tyler Ronin, whose postdoc who's collaborating with me, he actually studied a lot of computer vision and Stanford. And so one of the things he was interested in is some people who have brain damage in areas of the brain that were thought to be important for memory. And but they also seem to have some perception problems with particular kinds of object perception. And this is a super controversial. Some people found this effect. Some didn't. And he went back to computer vision and he said, let's take the best state of the art computer vision models. And let's give them the same kinds of perception tests that we were giving to these people.

2:53:17And then you would find the images where the computer vision models would just struggle. And you'd find that they just didn't do well. Even if you add more parameters, you add more layers on and on and on, it doesn't help, right? The architecture didn't matter. It was just there. The problem. And then you found those were the exact ones where these humans with particular damage to this area called the period of Rhinocortex. That was where they were struggling. So somehow this brain area was being was important for being able to do these things that were adversarial to these computer vision models.

2:53:51So then he found that the that it only happened if people had enough time, they could make those discriminations. But without enough time, if they just get a glance, they're just like the computer vision models. So then what he started to say was, well, maybe let's look at people's eyes, right? So computer vision models sees every pixel all at once. It's not, you know, and we don't. We never see every pixel all at once. Even if I'm looking at a screen with pixels, I'm not seeing every pixel at one. I'm grabbing little points on the screen by moving my eyes around and getting a very high resolution picture of what I'm focusing on.

2:54:28And kind of a lower resolution information about everything else. But I'm I'm not necessarily choosing, but I'm directing that exploration and allowing people to move their eyes and integrate that information gave them something that the computer vision models weren't able to do. So somehow integrating information across time and getting less information at each step gave you more out of the process. I mean, the process of allocating attention across time seems to be a really important process. Even the breakthroughs that you get with machine learning mostly has to do attention is all you need as about attention, transformers about attention.

2:55:19So attention is a really interesting one. Yeah. Well, then like, yeah, but how you allocate that attention again is like, is it the core of like what it means to be intelligent? What it means to process the world, integrate all the important things, discard all the unimportant things. Attention is that the core of is probably the core of memory too. There's so much sensory information. There's so much going on. There's so much going on to filter it down to almost nothing and just keep those parts and to keep those parts. And then whenever there's an error to adjust the models such that you can allocate attention even better to new things that would resolve maybe maximize the chance of confirming the model or disconfirming the model they have and adjusting it since then.

2:56:14Yeah, attention is a weird one. I was always fascinated. I mean, I got a chance to study peripheral vision for a bit and indirectly study attention through that. It's just fascinating how humans, how good humans are looking around and gathering information. Yeah. At the same time, people are terrible at detecting changes that can happen in the environment. They're not attending in the right way if their predictive model is too strong. So you have these weird things where the machines can do better than the people. It's not that it's like, so this is the thing is people go, oh, the machines can do this stuff that's just like humans.

2:56:54It's like, well, the machines make different kinds of mistakes than the people do. And I will never be convinced unless I, that we've replicated human, I don't even like the term intelligence because it's a stupid concept. But it's like, I don't think we've replicated human intelligence. The less I know that the simulator is making exactly the same kinds of mistakes that people do. Because people make characteristic mistakes. They have characteristic biases. They have characteristic like, you know, heuristics that we use. And those I'm have yet to see evidence that Chatchy PT will do that. Since we're talking about attention.

2:57:36Is there an interesting connection to you between ADHD and memory? Well, it's interesting for me because when I was a child, I was actually told my school, I don't know if it came from a school psychologist. They do do some testing on me. I know for like a few and stuff like that. They, or if it just came from teachers who hated me, but they told my parents that I had ADHD. And so this was of course in the 70s. So basically, they said like, you know, he has poor motor control and he's got ADHD. And so, and you know, there was social issues. So like I could have been put a year ahead in school, but then they said, oh, but he doesn't have the social, it isn't social capabilities.

2:58:21So I still had it a big like, you know, an outcast even in my own grade. But but then like I was, so then my parents said, okay, well, they got me on a diet free of artificial colors and flavors because that was the thing that people talked about back then. So I am interested in this topic because I've come to appreciate now that I have many of the characteristics. If not, you know, full blown. It's like I'm definitely timeline this rejection sensitive. You know, they talk about it. It's like impulsive behavior. I can tell you about all sorts of fights I've gotten into in the past. Just you name it.

2:59:00But yeah, so ADHD is fascinating though because right now we're seeing like more and more diagnosis of it. And I don't know what to say about that. I don't know how much of that is based on kind of inappropriate expectations, especially for children. And how much of that is based on true kind of like maladaptive kinds of tendency. But what we do know is this is that ADHD is associated with differences in prefrontal function so that attention can be both more, you're more distractable. You have harder time focusing your attention on what's relevant. And so you shift too easily. But then once you get on something that you're interested in, you can get stuck.

2:59:46And so, you know, the attention is this beautiful balance of being able to focus when you need to focus and shift when you need to shift. And so it's that flexibility plus stability again. And that balance seems to be disrupted in ADHD. And so as a result, memory tends to be poor in ADHD. But it's not necessarily because there's a traditional memory problem. But it's more because of this attentional issue, right? And so, in people with ADHD often will have great memory for the things that they're interested in and just no memory for the things that they're not interested in. Is there advice from your own life on how to learn and succeed from that?

3:00:32From just how the characteristics of your own brain with ADHD and so on. How do you learn? How do you remember information? How do you flourish in this sort of education context? I'm still trying to figure out the flourishing per se. But education, I mean, being in science is enormously enabling of ADHD. It's like you're constantly looking for new things, you're constantly seeking that dopamine hit. And that's great. You know, the tolerate, you're being late for things. Nothing is really nobody's going to die if you screw up. It's not like being a doctor or something where you have to be like much more responsible and focused.

3:01:17You could just freely follow your curiosity, which is just great. But what I'd say is that like I'm learning now about so many things like about how to structure my activities more and basically say, okay, if I'm going to be emails like the big one that kills me right now, I'm just constantly like shifting between email and my activities. And what happens is that I don't actually get the email. I just look at my email and I get stressed because I'm like, oh, I have to think about this. Let me get back to it and I go back to something else. And so I've just got fragmentary memories of everything.

3:01:58So when I'm trying to set a side of time, I'm like, this is my email time. This is my writing time. This is my goofing off time. And so blocking these things off, you give yourself the goofing off time. Sometimes I do that. And I sometimes I have to be flexible and go like, okay, I'm definitely not focusing. I'm going to give myself the downtime. And it's an investment. It's not like wasting time. It's an investment in my attention later on. And I'm very much with Kalanu Port on this. He wrote deep work and a lot of other amazing books. He talks about tasks switching as sort of the thing that really destroys productivity.

3:02:37So like, you know, switching. Well, it doesn't even matter from what to what, but checking social media, checking email, maybe switching to a phone call and doing work and switching, even switching between if you're reading a paper, switching from paper to paper to paper. Yeah. Because curiosity and whatever the dopamine hit from the attention switch, like limiting that because otherwise, your brain is just not capable to really like load it in, really do that deep deliberation. I think that's required to remember things and to really think through things. Yeah. I mean, you probably see this. I imagine in AI conferences, but definitely in neuroscience conferences, it's now the norm that people have their laptops out during talks.

3:03:27And, you know, conceivably, they're writing, you know, they're writing notes. But in fact, what often happens if you look at people and we can speak from a little bit of personal experience, is you're checking email and you're like, uh, or I'm working on my own talk. But often it's like, you're doing things that are not paying attention. And I have this solution. Well, I'm paying attention and then I'm going back. And then what happens is I don't remember anything from that day. It just kind of vanished because what happens is I'm creating all these artificial event boundaries. I'm losing all this executive function every time I switch.

3:04:02I'm getting like a few seconds slower. And I'm catching up mentally to what's happening. And so instead of being in a model where you're meaningfully integrating everything and predicting and generating this kind of like rich model, I'm just catching up, you know. And so yeah, there's great research by Melina Unkafer and Anthony Wagner and multi -tasking and people can look up that talks about just how bad it is for memory. And, you know, it's becoming worse and worse for problem. So, uh, your musician, take me through how'd you get into music? Like what, what made you first fall in love with music?

3:04:38With creating music? I, yeah. So I started playing music just when I was like doing trumpet in school for school band. And I would just read music and play. And, you know, it was pretty decent at it, not great, but I was decent. How'd you go from trumpet to a guitar? To guitar, especially the kind of music you're into. Yeah. So basically in high school, yeah. So I kind of was a late bloomer in music, but just kind of MTV grew up with me. I grew up with MTV. And so then you started seeing all this stuff. And then I got into metal was kind of like my early genre. And I always reacted to just things that were loud and had a beat like, uh, I mean, ADHD, right?

3:05:23Like, you know, everything from Sergeant Pepper is by the Beatles to like, um, Led Zeppelin II. My dad had both, my parents had both those albums. So I listened to them a lot. And then like, the police ghost in the machine. And but then I got into metal, deaf leopard and, you know, ACDC, Metallica went way down the rabbit hole speed metal. Uh, and that time was kind of like, Oh, like, when are I playing guitar? I can do this. And I had friends who are doing that. And I just never got it. Like I took lessons and stuff like that. But it was different because in when I was doing trumpet, I was reading sheet music.

3:06:04And this was like, I was learning by looking, there's a thing called tablature, you know, this where it's like, you see like a drawing of the fretboard with numbers. And that's where you supposed to put your, it's kind of like paint by numbers, right? And so, um, I learned it in a completely different way. But I was still terrible at it. And I didn't get it. It's actually taking me a long time to understand exactly what the issue was. But it wasn't until I really got into punk. And I saw bands like, I saw Sonic youth, I remember especially and it just blew my mind because they violated the rules of what I thought music was supposed to be.

3:06:40I was like, this doesn't sound right. These are not power chords. And this isn't just have like a shouty verse and then a chorus part. It's not going, but this is just like weird. And then it occurred to me, you don't have to write music the way it's people tell you it's supposed to sound. I just opened up everything for me. And I was playing in a band and I was struggling with writing music because I would try to write like, you know, whatever was popular at the time. And or whatever sounded like other bands that I was listening to. And somehow I kind of morphed into just like just grabbing a guitar and just doing stuff.

3:07:21And I realized a part of my problem with doing music before was I didn't enjoy trying to play stuff that other people play. I just enjoyed music just dripping out of me and just, you know, spilling out and just doing stuff. And so when I started to say, what if I don't play a chord? What if I just play like notes that shouldn't go together and just mess around with stuff? And I said, well, what if I don't do four beats go, na, na, na, na, one, two, three, four, one, two, three, four, one, two, three, four, whatever I go, one, two, three, four, five, one, two, three, four, five. And started messing around time signatures.

3:07:54Then I was playing in this band with a great musician who was really Brent Ritzel who was in this band with me. And he taught me about arranging songs. And it was like, what if we take this part? And instead of make it go like back and forth, we make it like a circle. Or what if we make it like a straight line, you know, or zigzag, you know, just make it like non -linear in these interesting ways.

3:08:24And then you could appreciate this as a musician, I think, so time signatures. So we are so brainwashed to think in four four, right? Every rock song you can think of almost is in four four. I know you're Floyd fan. So think of money by Pink Floyd, right? Bum bum, bum, bum, bum, bum, bum, bum. You feel like it's in four four because it resolves itself, but it resolves on the last note of, the next measure. So it's got seven beats instead of eight where the riff is actually happening. Interesting. But you're thinking in four because that's how we used to, we're used to thinking. So the music flows a little bit faster than it's supposed to.

3:09:09And you're getting a little bit of prediction error every time this is happening. And once I got used to that, I was like, I hate writing in four four because it was like, everything just feels better if I do it in seven four if I alternate between four and three and doing all this stuff. And then it's like you just, you know, jazz music is like that, you know, they just do so much interesting stuff with this. So playing with those time signatures allows you to like really break it all open and just I guess there's something about that which allows you to actually have fun. Yeah. Yeah. And it's like, so I'm actually like a very I the genre, the one of the genres we used to play in was math rock.

3:09:48So they called it. It's just like, this is somebody weird time sick. What is math? Oh, interesting. Yeah. So that's that's the math part of rock is what the mathematical disturbances of it or what? Yeah, I guess it would be like so instead of you might go like instead of playing four beats in every measure, na na na na na na na na na you go, na na na na na na na na na na na na na, you know, and just do these things. And then you might arrange it in weird ways so that there might be three measures of verse and then one, you know, and then five measures of course and then two measures. So you could just mess around with everything, right?

3:10:25What does that feel like to listen to? There's there's something about symmetry or or like patterns that feel good and like relaxing for us or whatever it is like home and disturbing that can be quite disturbing. Yeah. So is that is that the feeling you would have if you were math rock? I mean, yeah, yeah, stressing me out just listening. Well, yeah, yeah, learning about it. So I mean, it depends. So a lot of my style of songwriting is very much like in terms of like repetitive themes, but messing around with structure because I'm not a great guitarist technically. And so I don't play complicated stuff.

3:11:05And there's things you can hear stuff where it's just like so complicated, you know, but often what I find is is like having a melody or and then adding some dissonance to it just enough and then adding some complexity that gets gets you going just enough. But I have a high tolerance for for that kind of dissonance and prediction. I think I have a theory that pet theory that it's like basically you could explain most of human behavior as some people are lumpers and some people are splitters, you know. And so it's like some people are very kind of excited when they get this dissonance and they want to like go with it.

3:11:42So people are just like, no, I want to lump every you know, I mean, that's even a different thing. But it's like basically it's like I think some people get scared of that discomfort. And I really drive on it. You know, I love it. What's I what's the name of your band now? The cover band I play in is a band called Pavlov's Dogs. And so yeah. So it's a it's a band unsurprisingly of mostly memory researchers neuroscientists. I love this. I love this so much. Yeah. Actually, what have your MIT colleagues Earl Miller plays base? Place base. So you play like do you play better? But you could compete if you want.

3:12:20Maybe we could audition. For audition. Yeah. Coming for you. Earl's going to kill me. He's like very precise. I'll play triangle or something. Or is it where's a cowbell? Yeah. I'll be the cowbell guy. What kind of songs do you guys do? So it's mostly late 70s punk in 80s new wave and post punk. Blondie, Ramones, clash. I do I sing Age of Consent by New Order and and level terrorism. You said you have enough. Yeah. Yeah. Carry up and also Paula Crocs and and so they do they do. Yeah. So carried as Blondie amazingly well. And we do like gigantic by the pixies. Paula does that one. Which song do you love to play the most?

3:13:13What kind of song is super fun for you? Of someone else's? Yeah. Cover. Yeah. Cover. Okay. And it's one we do with Pavlov's Dogs. I really enjoy playing. I want to be your dog by Iki and the students. Which is perfect because we're Pavlov's dogs. Yeah. And Pavlov of course was like they created learning theory. So you know, there's this but also it's like but I mean Iki and the stooge is that song. So I play and sing on it but it's just like it devolves into total noise and I just like fall on the floor and generate feedback. I was like I think in the last version it might have been that or a velvet underground cover in our last show.

3:13:53I actually I have a guitar made of aluminum that I got made and I thought this thing's indestructible. So I kind of like was just you know moving it around had it upside down and all this stuff to generate feedback. And I think I broke one of the I broke one of the tuning pegs and oh yeah. I've added a break in all metal guitar go figure. A bit of a big ridiculous question but let me ask you we've been talking about neuroscience in general. What do you you've been studying the human mind for a long time. What do you love most about the human mind? Like when you look at it we look at the FMRI just the scans and the behavioral stuff the electrodes you know this had college aspect reading literature on the biology side neurobiology all of it.

3:14:43When you look at it what what what is most like beautiful to you? I think the most beautiful but incredibly hard to put your finger on is this idea of the internal model that it's like there's everything you see and there's everything you hear and touch and taste you know every breath you take whatever but it's all connected by this like dark energy that's holding that whole universe of your mind together right. And without that it's just a bunch of stuff. And somehow we put that together and it forms our so much of our experience and being able to figure out where that comes from and how things are connected to me is just amazing but just this idea of like that the world in front of us we're sampling this little bit and trying to take so much meaning from it and we do a really good job not perfect I mean you know but that ability to me is just amazing.

3:15:48Yeah it's an incredible mixture of all of it. It's the dark energy because the same in astrophysics you look out there the good dark matter and dark energy which is this loose term a scientist thing we don't understand which makes out which helps make the equations work in terms of gravity and the expansion of the universe in the same way it seems like there's that kind of thing in the human mind that we're like striving to understand. Yeah yeah you know it's funny that you mentioned that so one of the reasons I wrote the book amongst many is is that I really felt like people needed to hear from scientists and like COVID was just a great example of this because like people weren't hearing from scientists one of the things I think that people didn't get was the uncertainty of science and how much we don't know and I think every scientist lives in this world of uncertainty and when I was writing the book I just became aware of all of these things we don't know and so I think of physics a lot I think this idea of like overwhelming majority of the stuff that's in our universe cannot be directly measured.

3:16:57I used to think ha ha hate physics so physicists get the Nobel Prize for doing whatever stupid thing it's like there's 10 physicists out there I'm just just this strong words yeah no no no I'm the physicist who do neuroscience could be rather opinionated so sometimes I like to dish out it's all love it's all love that's right I'm 80 HD talking so but at some point I had this aha mode or I was like to be aware of that much that we don't know and have a beat on it and be able to go towards it that's one of the biggest scientific successes that I could think of you are aware that you don't know about this gigantic section overwhelming majority of the universe right and I think the more what keeps me going to some extent is realizing the changing the scope of the problem and figuring out oh my god there's all these things we don't know and I thought I knew this because science is all about assumptions right so if you read the structure of scientific revolutions by Thomas Koon yes that's like my only philosophy really that I've read but it's so brilliant in the way that they frame this idea of like he frames this idea of assumptions being core to the scientific process and the paradigm shift comes from changing those assumptions and this idea of like finding out this kind of whole zone of what you don't know to me is the exciting part you know well you are a great scientist and you wrote an incredible book so thank you for doing that and thank you for talking today you've decreased the amount of uncertainty I have just a tiny little bit today and reveal the beauty of memory this fascinating conversation thank you for talking to me oh thank you it's been blast thanks for listening to this conversation with Sharon Raganath to support this podcast please check out our sponsors in the description and now let me leave you with some words from Haruki Murakami most things are forgotten over time even the word self the life and death struggle people went through is now like something from the distant past we're so caught up in our everyday lives that events of the past are no longer an orbit around our minds there are just too many things we have to think about every day too many new things we have to learn but still no matter how much time passes no matter what takes place in the interim there are some things who can never assigned to oblivion memories who can never rob away they remain with us forever like a touchstone thank you for listening i hope to see you next time