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

The following is a conversation with Charan Ranganath, a psychologist and neuroscientist at UC Davis, specializing in human memory. He's the author of Why We Remember Unlocking Memories Power to Hold On to What Matters. And now a quick few second mention of each sponsor, check them out in the description, it's the best way to support this podcast. We got Riverside for recording remote podcasts, the zippercrooter for hiring, notion for note-taking and team collaboration, masterclass for learning,

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but rather from what you remember of the experience. So can you speak to this interesting difference that you write about in your book of the experiencing self and the remembering self? Danny really impacted me because I was an undergrad at Berkeley and I got to take a class from them long before I won the Nobel Prize or anything and it was just a mind-blowing class. But this idea of the remembering self and the experiencing self, I got into it because it's so much about memory,

even though he doesn't study memory. So we're right now having this experience, right? And people can watch it, presumably on YouTube or listen to it on audio. But if you're talking to somebody else, you could probably describe this whole thing in 10 minutes. But that's going to miss a lot of what actually happened. And so the idea there is that the way we remember things is not the replay of the experience. It's something totally different. And it tends to be biased by the beginning and

the end. And he talks about the peaks. There's also the, you know, the best parts, the worst parts, etc. And those are the things that we remember. And so when we make decisions, we usually consult memory. And we feel like our memory is a record of what we've experienced, but it's not. It's this kind of very biased sample, but it's biased in an interesting and I think biologically relevant way. So in a way we construct a narrative about our past, you say that it gives us an illusion of

stability. Can you explain that? Basically, I think that a lot of learning in the brain is driven towards being able to make sense. I mean, really, memory is all about the present and the future. Past is done. So biologically speaking, it's not important unless there's something from the past that's useful. And so what our brains are really optimized for is to learn about the stuff from the past that's going to be most useful in understanding the present and predicting the future.

And so cause-effect relationships, for instance, that's a big one. Now, my future is completely unpredictable in the sense that like you could, you know, in the next 10 minutes pull a knife on me and slip my throat, right? I was playing on it. But having seized over your work, I just, you know, generally my expectations about life, I'm not expecting that. I have a certainty that everything's going to be fine. We're going to have a great time talking today, right? But we're

often right. It's like, okay, so I go to a, see a band on stage, you know, I know they're going to make me wait. The show's going to start late. And, you know, they come on. There's a very good chance there's going to be an encore. I have a memory, so to speak, for that event before I've even walked into the show, right? There's going to be people holding up their camera phones, try to take videos of it now because this is kind of the world we live in. So that's like every day

fortune telling that we do though, it's not real. It's imagined. And it's amazing that we have this capability. And that's what memory is about. But it can also give us the solution that we know everything that's about to happen. And I think what's valuable about that, that illusion is when it's broken, it gives us the information, right? So I mean, I'm sure it being an AI, you know, about information theory. And the idea is the information is what you didn't already have. And so those

prediction errors that we make based on, you know, we make a prediction based on memory. And the errors are where the action is. The error is where the learning happens. Exactly. Exactly. Well, just to linger on Danny Kahneman and just this whole idea of experiencing self versus remembering self, I was hoping you can give a simple answer of how we should live life.

Based on the fact that our memories could be a source of happiness or could be the primary source of happiness, that an event when experienced bears its fruits the most when it's remembered over and over and over and over and maybe there is some wisdom in the fact that we can control to some degree, how we remember it, how we evolve our memory of it, such that it can maximize the long-term happiness of that repeated experience. Okay. Well, first I'll say, I wish I could take you on the

road with me. Such a great description. Can I be your opening actor? Oh my God. No, I'm going to open for you, dude. Otherwise, it's like, you know, everybody leaves after you're done. Leave me. I did that in Columbus, Ohio once. It wasn't fun. Like the opening acts like Drank our bar tab. We spent all this buddy going all the way there. There was only that everybody left after the opening acts were done. And there was just that stoner dude with the dreadlocks hanging

out. And then next to you know, we blew like our savings and getting a hotel run. So we should as a small tangent, your legit touring act. When I was in grad school, I played in a band and yeah, we traveled. We would play shows. It wasn't like we were in a hardcore touring band, but we did some touring and had some fun times. And yeah, we did a movie soundtrack. Nice. Henry Portrait of Serial Killer. So that's a good movie. We were on the soundtrack for the sequel, Henry 2, Mask of

Sanity, which is a terrible movie. How's the soundtrack? It's pretty good. It's bad. At least that one part where the guy throws up a milkshake. We're going to have to see. We're going to have to see it. All right, we're getting back to life advice. And happiness. Yeah. One thing that I try to live by, especially nowadays, and since I wrote the book, I've been thinking

more and more about this is, how do I want to live a memorable life? You know, I think if we go back to like the pandemic, right, how many people have memories from that period, aside from the trauma of being locked up and seeing people die and all this stuff. I think it's like one of these things where we were stuck inside looking at screens all day, doing the same thing with the same people. And so I don't remember much from that in terms of those good memories that you're talking about,

right? You know, when I was growing up, my parents worked really hard for us. And you know, we went on some vacations, but not very often. And I really tried to do now vacations to interesting places as much as possible with my family, because like those are the things that you remember,

right? So I really do think about what's going to be like something that's memorable and then just do it, even if it's a pain in the ass, because the experiencing self will suffer for that, but the remembering self will be like, yes, I'm so glad I did that. Do things that are very unpleasant in the moment, because those can be reframed and enjoyed for many years to come. That's probably a good advice or at least when you're going through

shit, it's a good way to see the silver lining of it. Yeah, I mean, I think it's one of these things where if you have like people who you've gone through, since you said it, I'll just say, since you've gone through shit with someone. And it's like, that's a bonding experience often, you know, I mean, that can really bring you together. I like to say it's like, there's no point in suffering unless you get a story out of that. So in the book, I talk about the power of the way we

communicate with others and how that shapes our memories. And so I had this near death experience, at least that's how I remember it on this paddle board, where just everything they could have got wrong did go wrong almost. So many mistakes were made and ended up like at some point, just like basically away from my board, pinned in a current like in this corner, like not a super good swimmer. And my friend who came with me, Randy, who's a computational neuroscientist,

and he had just been pushed down past me and so he couldn't even see me. And I'm just like, if I die here, you know, I mean, no one's around, it's like you just die alone. And so I just said, well, failure is not an option. And eventually I got out of it and froze and got cut up. And I mean, the things that we were going through were just insane. But short version of this is, you know, my wife and my daughter and Randy's wife, they gave us all sorts of hell about this,

because they were just like, where are they were ready to send out a search party. So they were giving me hell about it. And then I started to tell people in my lab about this and then friends. And it just became a better and better story every time. And we actually had some photos of just the crazy things like this generator that was hanging over the water and were like ducking under the zeger. These metal gratings. And I'm like going flat on. And I was just nuts,

you know, but it became a great story. And it was definitely, I mean, Randy and I were already tight, but that was a real bonding experience for us. And yeah, I mean, and I learned from that that it's like, I don't look back on that enough actually, because I think we often, at least for me, I don't necessarily have the confidence to think that things will work out that I'll be able to get through a certain thing. But my ability to actually get something done in that moment

is better than I give myself credit for, I think. And that was the lesson of that story that I really took away. Well, actually, just for me, you're making me realize now that it's not just those kinds of stories, but even things like periods of depression or really low points. To me, at least, it feels like a motivating thing that the darker it gets, the better the

story will be if you emerge on the other side. That to me, it feels like a motivating thing. So maybe if people listening to this and they're going through some shit, as we said, one thing that could be a source of light is that it'll be a hell of a good story when it's all over. When you emerge on the other side, let me ask you about decisions. You've already talked about it a little bit, but when we face the world and we're making different decisions, how much does our

memory come into play? Is it the kind of narratives that we've constructed about the world that are used to make predictions that's fundamentally part of the decision making? Absolutely. Yeah. So let's say after this, you and I decided we're going to go for a beer, right? How do you choose where to go? You're probably going to be like, oh, yeah, this new bar

opened up near me at a great time there. That a great beer selection. Or you might say, oh, we went to this place and it was totally crowded and they're playing this horrible EDM or whatever. Right there, valuable source of information. Then you have these things where you do this counterfactual stuff. I did this previously, but what if I had gone somewhere else and said, maybe I'll go to this other place because I didn't try it the previous time. So there's all

that kind of reasoning that goes into it too. Even if you think about the big decisions in life, right, it's like you and I were talking before we started recording about how I got into memory research and you got into AI. And it's like, we all have these personal reasons that guide us in these particular directions. And some of it's the environment and random factors in life. And some of it is memories of things that we want to overcome or things that we build on in a positive way,

but either way they define us. And probably the earlier in life, the memories happen the more defining the more defining power they have in terms of determining who you become. I mean, I do feel like adolescence is much more important than I think people give credit for. I think that there is this kind of a sense like, you know, the first three years of life is the most important part. But the teenage years are just so important for the brain, you know, and so

that's where a lot of mental illness starts to emerge. Now we're thinking of things like schizophrenia as a neurodevelopmental disorder because it just emerges during that period of adolescence in early adulthood. So, and I think the other part of it is is that, you know, I hear so a little bit of a two firm and saying that memory determines who we are. It's really the self is an evolving construct. I think we kind of underestimate that. And when you're a parent, you feel like every

decision you make is consequential in forming this child and plays a role. But so do the child's peers. And so do, you know, there's so much, I mean, that's why I think the big part of education, I think that's so important is not the content you learn. I mean, I think of how much dumb stuff we learned in school, right? But a lot of it is learning how to get along with people and learning who you are and how you function. And, you know, that can be terribly traumatizing,

even if you have a perfect, you know, parents working on you. Is there some insight into the human brain that explains why we don't seem to remember anything from the first few years of life? Yeah. Yeah. In fact, actually, I was just talking to my really good friend and colleague, Simona Getty, who studies the neuroscience of child development. And so we're talking about this.

And so there are a bunch of reasons, I would say. So one reason is there's an area of the brain in the called the hippocampus, which is very, very important for remembering events or episodic memory. And so the first two years of life, there's a period called infantile amnesia. And then the next couple of years of life after that, there's a period called childhood amnesia. And the difference is that basically in the lab and, you know, even during childhood and afterwards,

children basically don't have any episodic memories for those first two years. The next two years, it's very fragmentary. And that's why they call childhood amnesia. So there's some, but it's not much. So one reason is that the hippocampus is taking some time to develop. But another is the neocortex. So the whole folded stuff of gray matter all around the hippocampus is developing so rapidly and changing. And a child's knowledge of the world is just massively being built up, right? So

I mean, I'm going to probably embarrass myself. But it's like if you showed like, you know, you trained a neural network and you give it like the first couple of patterns or something like that. And then you bombard it with another like, you know, years worth of data, try to get back those first couple of patterns, right? It's like everything changes. And so the brain is so plastic, the cortex is so plastic during that time. And we think that memories for events are very

distributed across the brain. So imagine you're trying to get back that pattern of activity that happened during this one moment. But the roads that you would take to get there have been completely rerouted, right? So I think that's my best explanation. The third explanation is a child's sense of self takes a while to develop. And so their experience of learning might be more learning what happened as opposed to having this first person experience of high remember I was there.

Well, I think somebody once said to me that kind of loosely philosophically that the reason we don't remember the first few years of life, infantile amnesia is because how traumatic it is. Basically, the error rate that you mentioned when your brain's prediction doesn't match reality, the error rate in the first few years of life, your first few months, certainly

is probably crazy high. It's just nonstop freaking out the collision between your model of the world and how the world works is just so high that you want whatever the trauma of that is not the linger around. I always thought that's an interesting idea because like just imagine the insanity of what's happening in a human brain in the first couple of years. Just you don't know anything. And there's just the stream of knowledge and where somehow given how plastic everything is,

they just kind of mold and figures it out. But it's it's like an insane waterfall of information. I wouldn't necessarily describe it as a trauma and we can get into this whole stages of life thing, which I just love. Basically, those first few years there are, I mean, you know, think about it. A kid's internal model of their body is changing, right? It's like just learning to move. I mean, like, you know, if you ever have a baby, you'll know that like the first three months they're discovering

their toes, right? This is nuts. So everything is changing. But what's really fascinating is, and I think this is one of those, this is not at all me being a scientist, but it's like one of those things that people talk about when they talk about the, you know, positive aspects of children is that they're exceptionally curious and they have this kind of openness towards the world. And so that prediction error is not a negative traumatic thing. I think it's like a very positive thing

because it's what they use, they're seeking information. One of the areas that I'm very interested in is the prefrontal cortex. It's an area of the brain that, I mean, I could talk all day about it, but it helps us use our knowledge to say, hey, this is what I want to do now. This 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 reform, 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, I'll always say children are worse than adults at episodic memory, older adults are worse than young adults at episodic memory. And I always say, let's say, God, this is so weird. Why would we have this period of time that's so short when we're perfect, right? We're 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 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. Now, I'm a child. I'm in this village and 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, right? 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, right? So then you go late in life and you say, oh, why don't you have a great prefrontal cortex then? But 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 and what we call semantic memory, to pass on that semantic memory to the younger generations, pass on the culture. You know, even now in indigenous cultures,

that's the role of the elders and their 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 memories 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 grandmothers,

right? So there's not the young adults, not the parents or whatever, the grandmothers. And so they're the ones that pass on the traditions to the, I guess the younger generation of orcas. And 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, doing a kind of optimal wisdom development. So 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 meglin 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? So 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. 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, right? 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.

You 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, semantic memory, what are the different separations here? What'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. And 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, we have that ability to keep information in mind. But then we also have this separate, what he called a central executive, which has identified a lot with the prefrontal cortex.

That's this ability to control the flow of information that's being kept active based on what it is you're doing. Now, 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. And 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.

So, 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, will 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 mostly 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. And 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 Maria 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. But 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 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've grabbed. 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. These are the points where you're like surprised or you 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 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? And so there's this beautiful dynamics that you can see in the brain of these different networks that are coming together and then deaffiliating at different points in time that are allowing you to go into these modes. And so to speak to your original 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? I 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 it, right? So as far as we know, nobody has managed to violate those basics of having people forget most of their experiences.

So 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 to low power consumption, right? So it's all about reusing information and making the most of what we already have. And so that's why, basically, again, what you see biologically is, you know, neuromodulators, 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. So one of my colleagues, Amishi Jawa, 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 Gazzali, 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, 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. That'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 so 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 and 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 or 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. It'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.

So these are people who train in these competitions and they'll memorize like a deck of cards and like a really short amount of time. There's a great memory athlete. Her name I think is pronounced Yenya Wintersoil. But 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. 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 else that you need like, you know, 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 are familiar with that whole technique. And it works. It's interesting. So another thing I recommend for people a lot is I use Enki a lot every day. It's an app that does space through repetition. So I think medical students and like students use this a lot to remember a lot of different things.

Oh, yeah. Okay. We can come back to this. But yeah, sure. It's the whole concept of space repetition. You just, uh, 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 a memory palace is a technique that allows you to remember things like that. I can catalog or by placing them visually in a place that you're really familiar with. Like I'm really familiar with this place. So I can put, uh, uh, numbers or facts or whatever you want to remember, you can walk along that little palace and it reminds 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's 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. So I'm looking for good tricks for that. So, uh, I'm, I feel like we've got a lot in. Because when people introduce themselves to me, 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

that'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, with a face and an identity. And that's a completely arbitrary thing, right? I mean, maybe in the olden days, somebody named Miller, it's like they're actually

making flour or something like that. But, you know, for the most part, it's like, uh, 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, 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 Luthore,

but that's great. Yeah. So I think Lex Luthore where a suit, I think, I know he has a shaved head though. He's bald, but you're not. You've got a great head. I trade hair with you any day. But, but like, you know, but something like that. But if I can come up with something, like I could say, okay, so Lex Luthore is this criminal mastermind. And then I just imagine you talked about stabbing

or whatever earlier. Yeah, exactly. I kind of connected. And 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 fenced people that that name, but 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 low sigh 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. And then you could walk through the different path and find

all the pieces of information you're looking for. So the method of low sigh is a great method for just learning arbitrary things because it allows you to link them together and get that queue 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 is 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. And 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 it's, I think your brain somehow you need, you can't just like go upstairs right away or something. You have to like walk along the room. So it's really great for remembering sequences

but it's also not great for remembering like 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. You could 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 some Dale 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. I 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 associate should Lex Luth or that way or something like that, right? You know, but I get something very specific. That'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 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, there's primitive abilities to figure out where you are and so people explain the method of low-side that way. And, you know, whether or not the evolutionary argument is true, the method of low-size not at all special. So if you're not a good visualizer,

um, 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, um, 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, uh, I can still remember there's a obscure episode of the TV show, Cheers. They think a song about Albania that he uses to

memorize all these facts about Albania. And I could still sing that song to you. It's just I saw it on a TV show, you know. Uh, so what you mentioned space repetition. So what, um, do you like this process? 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 I 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 a interesting boundary condition, which is it depends on when you need that information. So 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 the 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 as 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. We 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 a 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? So 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. And in an AI kind of way of thinking about things, it'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 just 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. You 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 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, but you know, for that generic semantic information depth of memory. Yeah. And I think this falls into a category we've done other modeling. One of these is a published study in 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

theories, some learning theories, anyway, this seems weird. Why 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 the 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 the cell assembly that are good for the memory and lose the ones that are not so good. But if you don't stress test the memory, you have an exposure 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 is terrible. In the moment, they're overconfident about what they'll retain later on. So it's fascinating. So what happens is

when you test yourself, you're like, oh, my God, I thought I knew that, but I don't. And so it could be demoralizing until you get around that and you realize, hey, this is the way that I learned. This is, 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 acted out. And you're going to botch those lines from time to time, right?

No, there's an interesting moment you probably have experienced this. I remember a good friend of mine, Joe Roganos on his podcast. And we were randomly talking about soccer football. Somebody 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. No, and I said, yeah, I don't know why I thought, yeah, because that was a perfect example of memories.

He passed away. 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, Ronti, Adon, Goal and so on. So for me, he's alive. 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. But 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. And it 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 in 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. So I got to like why I love sciences. Like engineering is like solving other people's problems. And science is about creating problems. I'm just much more like I would break things and you know,

create problems. Not necessarily move fast though. But one of my former mentors, Marsha Johnson, whom I pinnays 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? Where did that mental experience come from? Right? 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. And 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, re-combine it in different ways and throw it out there. And 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 is 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

poem, 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. And 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. But 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, or 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? They are find it very difficult to give you a scenario

what could happen. Or if they do, it would be more stereotype, like, yes, 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. It 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, as a people, oh, it's just this

kind of, you know, daydreaming network. And I thought, this is just ridiculous research, who cares? 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. And 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. And 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. And all kinds of different directions. Sometimes it's rigorous thought experiments. Sometimes it's fun one. So

I imagine that that has an effect on 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. And 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. Just the eski 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 of 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 into this. Those described by this really famous neurosycologist from Russia named Luria. And so this guy was named Solomon Sharashewski. 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. And 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 a point had trouble

differentiating his imagination from reality. 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 that your internal signals are being confused with actual things in the outside world, right? Well, 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 support a little longer? There's something called the USA Memory Championship. Like what are these athletes? Like, what does it mean to be like elite level at this? Have you interacted with any of them or

reading about them? What have you learned about these folks? There'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, what are 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 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. So 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. And 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. Yeah, 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 are used to kind of load up the quote unquote working memory. Yeah, yeah. And to see a psychologist 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, but usually about recalling a sequence of numbers in some kind of semi complex way. Are you do 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 in 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 a mix of interpretations and imagination

with perception. And so the new direction we're going in is understanding navigation and our memory for places. And the reason is 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 memories we can bring to bear our past experiences, to economically learn new ones. And 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. And 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. And 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. 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. And 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. 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 that those ripples seem to increase at navigational important points when

you're making a decision or when you reach a goal. So this speaks to the emotion thing, right? And 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 general in our MRI studies is 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? What'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 an animal is actually doing something in the world. So 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 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. And it's real role in helping you see the connections between different events that you've experienced. So during sleep is one of the connections that formed?

The connections between different events. Yeah. 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 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? This 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. And 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 far to memorize. But 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

radiofrequency 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 radiofrequency pulses and the static field. And you have things called gradients, which change the strength of the magnetic field and 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 in some part

of the brain, the blood flows there. And 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 GIF, as you like to say. Yeah, we had all for effort intense argument about with this pronounced GIF or GIF, but that's 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 GIF said it's pronounced GIF, but that's the only person that pronounces GIF. Anyway, yes, you sent a GIF of, this would be basically a whole, a 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. And 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. And 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 decode, it gets so forth. And now there's a lot of forward encoding models and 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? Super 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. 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. So 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 should be like you've got a folder on your computer, right? And I'd

open it up, there's a bunch of files there. I can sort those files by 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. So 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 and he 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? And 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 are two different people and you 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. And 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. 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. These 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 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 like brilliant with blood and detecting the

activations or the excitation because blood flows to that area. What's like the latency of that? What's the blood dynamics in the brain? 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 has 50. 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 or is it a bug? 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. So 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 flowed oxygen, all this stuff. It's such a long chain of going from neural activity to magnetic fields. And 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 to start getting

active after you release it in the gap between the two neurons called synapse. So what's interesting is if you leave that you know imagine you're just flooded with this like liquid in there right if 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 so that you can 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 you know anaerobic

metabolism. So 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 of my mind. 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 now looking off to the earth. 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 sudden 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 inner and of itself even though I'm not seeing anything there is particularly interesting.

There'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 something you're listening to the Lex Friedman podcast right. You'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 you 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. You'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. What 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? I 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 our 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 active remembering can change the memory can strengthen it but it can also distort it if you get misinformation at the time. And 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 you're like oh wait a minute I left my watch in the kitchen that'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 and 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 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 in 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 I 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 thing 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 the 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 you're in the metaverse whatever right 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 a crappy metaverse so now I can take a wrap record from this hippocampus

and prefrontal cortex in all these areas with these really new electrodes to 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 he 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 you know 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 in 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 that basically it's the guts of LLM's right you 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 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 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 or conditions of humans and what find construct models that help you find the commonalities or like the the core thing that makes somebody navigated the metaverse for example yeah 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 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 I suppose it's mash and pumpkins well I'll just wrath an accade despite all of your rage that's mash and pumpkins I think all despite all of your rage at gifs you're still just ratnacage oh yeah all right good callback and good callback see

these memory retrieval exercises of doing they're actually helping you build a lasting memory of this god recession and it's strengthening the the visual thing I have of you with James Brown on stage just 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 Reese I've got you know 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 and 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 you 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 mice 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 there's a bunch more complexity to us time scales are very important so primate brains and human brains are especially good at integrating and

and holding on to information across longer and longer periods of time right and 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 you know but still what can you understand by studying mice I mean just basic almost behavioral stuff about memory well yes but that's very important right so you can understand for instance how do neurons talk to each other but that's a

really big big question neural computation in and of it so 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 it's not like Twitter

where what area of the brain is shouting than another area of the brain is stuck listening to this crop it's like they're actually interacting on the millisecond scale right how does that happen and 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 it's a

like why study memory in humans what I could study learning in a mouse and then just like oh my god I'm gonna get my funding from somewhere else so well let me ask you some random fascinating questions yeah sure how does deja vu work so deja vu is it's actually one of these things I think that 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've experienced this moment sometime before I've

been here before and actually there's all sorts of variants of this the French have all sorts of names for various versions of the shami voo parley voo I don't know all these different vues yeah but deja vu is this sense that it can be like almost disturbing intense sense of familiarity

um so there was a researcher named wilder penfield actually this goes back even earlier to some of the earliest like hoolings jaxson was this neurologist who first care who 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 so 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 in 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 that they just have this intense feeling of being somewhere before and 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 where I am right but you know there's a great set of studies

done by Anne 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 so it's like a partial match that's eliciting this kind of a sense of familiarity and 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's 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 a bigger your brain's gonna 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 your brains very tuned up to process it efficiently but root a bigger takes a little bit longer and more intense and 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 memories if it's the real memory this 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 such a it's a partial

match to something that we have and it's not enough to trigger that sense of you know 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 but it's also like a space show

temporal familiarity so like 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 how time relates 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

it's like and so the basic idea is 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 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

when people remember that they'll often remember well 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 is that sometimes things can really get out of hand where

people have troubled 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 real pioneer

in this work and there's lots of other work that's been done since but 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 and as they keep trying to remember that event more and more what happens 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 yeah absolutely um I mean uh 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 at the same event it's no longer your memory or my memory it'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 and there's all sorts of interesting ways in which misinformation

can happen there's a great example of when John McCain and uh George Bush Jr. were um in a primary and there are these poles 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 I 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 you know policy uh 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 in memory yeah it's um it's really interesting so it's not just about truth and falsehoods like us as intelligent reasoning machines but it's the formation of memories where they become like visceral you can rewrite history if you just look

throughout the 20th century uh some of the dictatorships with Nazi Germany with uh 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 maybe initiated by the propaganda machine can spread faster than others you could see that in modern day certain conspiracy theories there's just something about them that they are like

really effective at spreading there's something sexy about them to people to to wear something about the human mind eats it up and then uses that to construct memories as almost as if they almost were there to witness whatever the content of the conspiracy theory is 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 ideas true or not you're like it's at the core of your being that you you feel like you were there to watch the thing happen

yeah I mean there's so much in what you're saying I 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 you know 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 so a lot of the stories we put together are based on our perspectives right and so let's let's just zoom out for the moment from like misinformation take something even

more fascinating but not as like you know scary um you know I was reading uh 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 um after the war was over and so he went back to his family to get their

stories about the war and they called it the American War not the Vietnam War right 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 America came in right and

that's based on their perspective which is a very valid perspective um and so that just gives you this idea of the way we put together these narratives based on our perspectives and I think the the 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 they were trying to ban two live crew or you know it just think about letty Bruce got canceled for cursing Jesus Christ you know it's like this is nothing new yeah people don't like to hear things that disagree with them but um 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 but 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 um 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 um 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 and 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 there's a natural clustering of people and opinions and you just kind of you form these kind of bubbles I think that's it to me personally I think that's a technology problem that can be solved if there's a little bit of interaction kind respectful

compassion 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 but that's a technology problem because uh naturally left our own devices we want to cluster up in a tribe yeah and that's the human problem you know 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 I mean one of my fears about AI is not what AI will do but what people will do I mean take text messaging right it's like pain in the ass to text people is for me and so what happens is the communication becomes very Spartan and devoid of

meaning right it's this very telegraphic and that's people adapting to the medium right I mean look at you you've got this uh the keyboard right that's like got these like dome shaped things and you've adapted to that to communicate right that's not the technology adapting to you that's you adapting

to the technology and I think with you know 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 right and so what happens is 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

and 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. I 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 on that are a positive or 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 happier all that kind of stuff and so there I think technology on that is has been and I think maybe hope will always will always be on that positive thing. Do 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 but 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 they would be much happier. The question is in terms of every single problem they've had is not solved. Uh-huh. There's not food. There is guaranteed survival shelter and all this kind of stuff.

Well you're asking is a deeper sort of biological question. Do we want to be a Werner Herzog and a movie of happy people like Nataga? Do we want to be busy 100% of our time hunting gathering, 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 uh 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 and uh there's many more activities that you could perform or creative 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 you know uh maybe it's about like functioning in social groups that are meaningful and like having time but I do think this is there was an interesting memory related thing which is that if you look at like 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. You mainly learn if deviates from your expectation of what you're supposed to get right so it's like you get a paycheck every you know month from MIT or whatever right and it's like you're kind of you probably don't even kind of get

excited about it when you get the paycheck but if they cut your salary you're going to be pissed and if they increase your salary oh good I got a bonus you know and 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 you know so people talk about dopamine for instance being this pleasure chemical and 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 right and so you could 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 you know and it's 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 to 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 and again that was not driven by the answer per se 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 that's like a hardcore band car name yeah yeah that's pretty good but I also like the hedonic treadmill the dog tread most 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 reading a 1984 where sorry for the dark turn of our

conversation but through torture you can make people say anything and essentially remember anything I wonder towards degree there's like truth to that if you look at the torture that happened the Soviet Union to 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 at physical

demands that they would place that people to get them to talk and you know there's certainly a lot of work in the that's been done by the CIA in terms of enhanced terror interrogation techniques and from what I understand the research actually shows that they just produce what people want to hear

not necessarily the the information that 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 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 maybe 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 they're creating this physical stress and so stress starts to act on you know starts to down regulate 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 and at some point certain people can be very coaxed into creating a memory for something that ever happened and 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 well enough to necessarily accurately give it to you but people could look this stuff up there definitely stories

out there like this where people confess to crimes that they just didn't do and objective evidence came out later on but 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 that centralized power can can use these kinds of tools to destroy lives sad

since there's a theme about music throughout this conversation one of the best topics for songs is heartbreak love in general a 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 uh um

oh it's such a hard one well so I mean part of this is we tend to go back to particular times that are the more emotionally intense periods um and so that's a part of it and again memories designed to kind of capture these things that are biologically significant and attachment is

of you know big part of biological significance for humans right human relationships are super important and sometimes that heartbreak comes with chain massive changes in your beliefs about somebody say cheated on you or something like that um or regrets and you kind of ruminate about

things that you've done wrong there's really so many reasons though but you know I mean I've had this I um my first pet I had as you know was we 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 uh you know so we got a new dog because I kept seeing the dog around and I was just so heartbroken about this and 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 that's just so crucial that drives again these things that we want to remember and that gives us

that longing sometime 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 you know um an appreciation maybe your gratitude whatever it is right that 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 you know grow in new ways but it's hard this uh I often go back to this moment uh this show Louis with uh Louis CK where he's all heartbroken about a breakup with a woman he loves and uh an older

gentleman tells him that that that's actually the best part that 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 you know having the love and losing it like the losing it is when you sometimes feel it the deepest which is an interesting um way to celebrate the past and relive it it's it's sucks that you don't have a thing but when you don't have a thing it's a 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 gonna have to day by day I don't know I'm gonna have

to listen to some more Bruce Brink scene 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 like 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

you think about 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 uh it's something I think about a lot and I'm reminded of like how I talked to somebody who's like you know who's a Buddhist and I was like you know the whole idea

of Buddhism is renouncing attachments. Some way the 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 you said something similar right in your daily routine that you think about things this way right yeah I meditate on mortality uh every day but I don't know

at the same time that really makes you appreciate the moment and live in the moment and I also appreciate the full deep rollercoaster of suffering involved in life the little and the big too so I don't know I'm 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 uh 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 so what they argue and again you could interpret in different ways positive and negative but the argument is 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 like you know

letting go of this idea does this book sell or trying to you know like impress you and let get you laugh at my jokes or whatever and just be more like I'm sharing this information with you and you know getting to know you or whatever it is but it's it's hard right it's like

because we're so driven by the reinforcer of the outcome it's 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 the present and making decisions about the future standing on 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 is that in some sense I think

especially the farther we go back I mean there's all sorts of interesting things that happen so your sense of like if I ask you how different does one hour ago feel from two hours ago you probably say pretty different but if I ask you okay 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 that 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 here'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 so 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 I have no memories of what

happened so it must the week just went by without it 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 it's just that nothing happened because you're doing the same

thing over and over so I think it feels 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 that could be also a genetic thing just from

for me I don't know if 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 bird's and so on but the core of who I am and who others I know are events it like that compression of my understanding of the world okay 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 so maybe what it is is that you really like to see connections between things this is like really what motivates me in science actually too but it's like when you start recalling the past to you know and seeing the connections between the past and present now you have this kind of

web of interconnected memories right and so I can imagine in that sense there is this kind of the present is with you right but what's interesting about what you said too that struck me is that your 16 year old self was probably very complex you know and I'm by the way I'm the same way but

it's like it really is the source of a lot of darkness for me so but but when like you can look back at like let's say you hear a song that you used to play like 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 mental you mentally time travel to that particular thing you open up this little compartment of yourself that wasn't there before right that didn't seem accessible for Dan Shactors 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 and we 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 but we have a very multi faceted past and can access different parts of it and change in the moment based on whatever part we want to reach for right 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 there were remembering how things used to be and I think it's it's very complex so as people get older for instance nostalgia can be an enormous source of happiness right and 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 you know 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's sucked partly it sucked more for me but I don't say that even otherwise it'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 a more practical one what what are your thoughts about

BCIs brain computer interfaces and the work that's going on with neural link we'll all we talked about electrodes in different ways of measuring the brain and here neural link is working on basically two way communication with the brain and then more out there question

will be like where is this go but more practically in the near term what do you think about neural link 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 I'm not necessarily seeing any scientific evidence from neural link and maybe that's just 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 gaseous viscies just like genius in this area and they're working on it I think speech prosthetics like they're incorporating you know decoding techniques with AI and

you know 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 right and 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 neural link 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 neural link and there's just so much innovation happening I 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 the more concrete parts of hearing and producing movements right 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 it'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

while saying something isn't just the letters the the words you're saying it's also the intention behind it the feeling behind all that kind of stuff and is it ethical to reveal that full shabang the context of what's going on in our in our brain that's really that's really

interesting that's really I mean our thoughts is it ethical for anyone to have access to our thoughts because right now the resolution the resolution is so low that we're okay with it even doing studies and all this kind of stuff but if there if if neuroscience as a few breakthroughs to 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 there is about the human mind the the better it is but there could be always intermediate battles with how much control does a centralized entity have like a government so on what what is the regulation what are the rules

what are the what's legal and illegal you know 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 control the citizenry all that kind of stuff so people always paranoid and rightfully so

but it's fascinating it's really fascinating you know we talk about freedom of speech you know freedom of thought which is also a very important liberty at the 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 I want 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 so 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 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 behavior yes like tell you give you know under certain conditions anyway I can give you the misinformation and then you can change the people places and so forth right on the crude level there's a lot of work that's being done

on a phenomenon called reconsolidation 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 and 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 the 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 we 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 engineer 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 and so that unpredictability of people was the problem that they were having in you know 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 or what 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 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 so like there's a history to that intersection like J-walking certain intersections allow J-walking a lot more because what happens is where leaders and followers so there's a regular let's say and they 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 cross on red light they will also they will follow

and there's just a dynamic to that intersection there's a spirit to it and if you look at Boston versus New York versus a rural town versus even Boston San Francisco or here in Austin there's different personalities citywide but there's different personalities area out region wide

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 collecting 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 our humans work and 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 no I can't talk can't write length 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 with 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 and like you have to understand all 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 will 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 in 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 but 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 a mile 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 it'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 but for some reason they

ask for like a red like 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 at 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 for using the representation you form that for the case of driving I think it could be quite effective but one of the things that's currently missing even though open AI 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 neurosciences what Steve

Grossberg called the stability plasticity dilemma right when do you say something is new and overwrite your pre-existing knowledge versus going with what you had before and making incremental changes and so you know part of the problem with going through like massive you know I mean

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 O'Reilly 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

in 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 and then we have this knowledge that we've accumulated from our experiences as 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 could 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 and 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 a computational neuroscience people was able 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 this is 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 and 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 fighter flight responses that we associate with particular things are the kind of like reward motivation that we associate with certain things so forth and those things are absent from AI I frankly don't know if we want it

I don't necessarily want to self-motivated LM right it's like and and then there's the 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 what's all interconnected I mean just even the thing you've mentioned is the moment you know if we record a moment like that 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 you have to have you have to include everything you have to include all the emotions evolved all the context all the things that built around it 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 the social way and we adjust it and we evolve yeah yeah I mean well even if we want to go super simple right like Tyler Ronin who's a post doc 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 it's that 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 and then you would find the images where the computer vision models would just struggle and you would 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 were these humans with particular damage to this area called the period of

rental cortex 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 so 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 and 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 the machine learning mostly has to do attention is all you need is about attention transformers about attention so

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 it's probably the core of memory too there's so much sensory information there's so much going on so much going on to filter it down to almost nothing and just keep those parts and to 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 yeah attention is a weird one I was I was always fascinated I mean I got a chance to study peripheral vision for a bit

and indirectly study attention through that and 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 yes they're not attending in the right way

if their predictive model is too strong you know so you have these weird things where like the machines can do better than the people it's not that it's like you know so this is the thing is people go oh the machines can do this stuff that's just like humans it's like well the machines make

different kinds of mistakes than the people do and I will never be convinced unless I that you know we've replicated human I don't even like the term intelligence because I think it's a stupid concept but it's like I don't think we've replicated human intelligence unless 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 Chatchee PT will do that

since we're talking about attention is there an interesting connection to you between ADHD and 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 hue 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 so 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 but 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 distractible 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 and 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's 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 from 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 and that's great you know and you they tolerate you're being late for things nothing is really nobody's going to die if you screw up you know that's nice it's not like being a doctor as a figure you have to be like much more responsible and focused you 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 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 right so when

trying to set aside a timer like this is my email time this is my you know 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 I and I sometimes I have to be flexible 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 Kalan you poured on this he wrote deep work and a lot of other amazing books he he talks about tasks switching as a sort of the thing that really

destroys productivity so like you know switching well it doesn't even matter from 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 like curiosity and whatever the dopamine hit from the attention switch like limiting that because otherwise your brain is just not capable to really like loaded 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 and 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 or I'm working on my own talk but often it's like you're doing things that are not paying it and I have the solution while 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 I'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 Ankefer and Anthony Wagner on multitasking 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 your musician take me through how did you get into music like what made you first fall in love with music with 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 ADHD right? Like you know everything from Sargent Pepper is by the Beatles to like Led Zeppelin 2 my dad had both my parents had both those albums so I listened to them a lot and then like the police goes to the machine and but then I got into metal deaf leopard and you know ACDC Metallica went way down the rabbit hole speed metal and that time was kind of like oh like why don't I play 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 when I was doing trumpet I was reading sheet music and 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're supposed to put your it's kind of like paint by numbers right and so 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 I 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 and I realized a part of my problem with doing music

before was I didn't enjoy trying to play stuff that other people play it I just enjoyed music just dripping out of me and just you know spilling out and just doing stuff and so and 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 none none one two three four one two three four one two three whatever I go one two three four five one two three four five and started messing around time signatures then 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 and then next you know it's like the whole world sort of opens up as like the and then what I started to realize especially so you could appreciate this as a musician I think so time signatures right 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 a Floyd fan so think of money by Pink Floyd right yeah bum bum and bum bum bum bum bum bum yeah you feel like it's in four four because it resolves itself but it resolves on the the last note of basically it resolves on the

first note of the next measure so it's got seven beats instead of eight where the riff is actually happening but you're thinking in four because that's how we use we're used to thinking so the music flows a little bit faster than it's supposed to and 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 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 and so playing with those time singing shows allows you to like really break it all open and just I guess there's something about that it 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 so they called it it's just like is there so many weird time-sick what is math oh interesting yeah so that's that's the math part of rock is what the the mathematical disturbances of it or what yeah I guess it would be like so it

said if you might go like instead of playing four beats in every measure no no no no no no no no no you go no no no no no no no no no no no no no no no no no no you know and that's 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 you could just mess around with everything right what does that feel like to listen to there's there's something about symmetry or like patterns that feel good and like relaxing for us or whatever it's like home

and disturbing that can be quite disturbing yeah so is that is that the feeling you would have if you were you know what math rock I mean yeah yeah stressing me out just listen 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 it's so I don't play complicated stuff and 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 or I think I have a theory a 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 and some people are just like no I want to lump every you know I mean maybe 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 thrive on it you know I love it what's uh I what's the name of your band now the cover band I play in is a band called Pavlov Stoggs 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 actually what of your MIT colleagues Earl Miller plays bass plays bass so you play like you do play but you could compete if you want maybe we could audition for audition yeah coming for you all girls gonna kill me

he's like very precise I'll play trying or something or is that where's the cowbell yeah I'll be the cowbell guy and you guys what kind of songs do you guys do so it's mostly uh seven late 70s punk in 80s new wave and and post-punk blonde

romones clash I do I sing age of consent by new order and and level terrorism you said you have a female singer no yeah yeah carry often and also Paula Crocs and and so they do uh they do yes it carried us blondie amazingly well and we do like gigantic by the pixies politas

that one which song do you love to play the most what kind of song is super fun for you that's of someone else's yeah cover yeah cover okay and it's one we do with Pavlov Stoggs mm-hmm I really enjoy playing I want to be your dog by ike and the six kids are which is perfect

because we're Pavlov's dog yeah and Pavlov of course was like basically created learning theory so you know there's this but also it's like but I mean igey in 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 uh fall on the floor and

generate feedback I've like I think in the last version it might have been that or a velvet underground cover in our last show I 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 yes I managed I've had it to break it all metal guitar go figure a bit of a big ridiculous question but let me ask you we've been talking about your science in

general um 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 uh we look at the fmri just the scans and the behavioral stuff the electrodes you know this had collage aspect reading literature on the

biology side neurobiology all of it when you look at it what would 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 yeah it's an incredible mystery all of it funny said dark energy because the same in in astrophysics you look out there look a dark matter and dark energy which is this loose term assigned to the 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 I used to think ha ha hate physics so physicists get the Nobel prize for doing whatever stupid thing it's like there's ten physicists out there I'm just just just strong words yeah no no no I'm kidding it's the physicist who's you neuroscience could be rather opinionated

so sometimes I like to dish out it's all love it's all love that's right I this is an ADHD talking so um but at some point I had this aha mode where 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 uh just a tiny little bit today and revealed the beauty of memory this fascinating conversation thank you for talking

to it 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 itself 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 assign to oblivion memories who can never rub away they remain with us forever like a touchstone thank you for listening i hope to see you next time