Science & Tools of Learning & Memory | Dr. David Eagleman

Oftentimes people will ask me like an older person will say, "Hey, I do cross word puzzles. Is that good?" Yeah, it's good until you get good at it and then stop and do something that you're not good at and constantly find the next thing that's a real challenge for you. That's the key thing about plasticity. Your brain is locked in silence and darkness. It's trying to make a model of the outside world. And if you're constantly pushing and challenging it with things it doesn't understand, then it'll keep changing. Welcome to the Huberman Lab podcast where we discuss science and science-based tools [music] for everyday life. I'm Andrew Huberman and I'm a professor of neurobiology and opthalmology at Stanford School of Medicine. My guest today is Dr. David Eagleman. Dr. David Eagleman is a neuroscientist, a best-selling author, and a longtime science public educator. Today we discuss several different features of brain science that impact your everyday life. And once you understand the mechanisms behind these features, it will position you to make better decisions and if you choose to rewire your brain to be a more effective learner. We start by discussing neuroplasticity, which is your brain's ability to change in response to experience or any form of deliberate learning that you are trying to impose on yourself. We talk about the mechanisms for it and how you can get better at learning and unlearning in the context of skills and information. We also discuss memory formation and the relationship between stress and time perception and why it is that people experience things in slow motion if those things are very stressful or traumatic and how that can be useful for undoing traumatic memories. David also takes us through the neuroscience of cultural and political polarization, something that's very timely right now, false memories, deja vu, dreams and the meaning of dreams and a lot more. David is an absolutely legendary science communicator. I say this as a fellow neuroscientist. He is able to embed factual information about the brain into real life stories and in doing so he's able to shed light on how we work as humans and how we can all improve our life experience. He's a true virtuoso of neuroscience and science education more generally. What David shares with us today will change the way that you think about thinking and your own mind and no doubt will also change the way that you view the world. Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is however part of my desire and effort to bring zero cost to consumer information about science and science related tools to the general public. In keeping with that theme, today's episode does include sponsors. And now for my discussion with Dr. David Eagleman. Dr. David Eagleman, welcome. Thanks. Great to see you, Andrew. Man, I feel like the kid that was a freshman when you were a senior because you got into this public facing science education long before I did. And you've had a an amazing career also in your laboratory work. And today I want to talk about all of it, right? um by mostly listening and you doing the talking and there are so many topics in neuroscience that are fascinating as you know but I think perhaps the most fascinating thing about the human brain is its ability to change itself. Yeah. Plasticity. So I know how I think about neuroplasticity. I want to know how you think about neuroplasticity. What it is and how we should think about it and what we could possibly do with that information. Okay, great. I mean, this was mother nature's big trick with humans was figuring out how to drop a creature into the world with a halfbaked brain and then let the world wire up the rest of it. And so, you know, 1953, Crick and Watton, I worked with Crick at the Salt. They burst into the Eagle and Child pub and said, "We've discovered the secret to life." Because they figure out the structure of DNA. But that was really half the secret of life because the other half is all around us. It's every bit of experience that you have. It's your culture. It's your language. It's your neighborhood. All of that stuff gets absorbed by the brain and wires us up. And I often think about this issue of what if you were born 30,000 years ago exactly your DNA? You pop out and you look around and the question is would you be you? The answer is you wouldn't be. You'd look maybe similar because of the same genetic blueprint, but you would have a different culture and a different language and different stories and all that stuff. You'd be a very different kind of person. So, brain plasticity, for anyone who doesn't know, it's it's that the brain is constantly reconfiguring itself every second of your life. You got 86 billion neurons. And really, the way to think about it, these are like little creatures that are all crawling around and moving around. each one is, you know, on average contacting 10,000 of its neighbors, but it's not like a fixed thing like you might see in a textbook. Instead, they're, you know, plugging and unplugging and searching around and finding new places to plug in, of course, changing the strength of those connections. And I actually always find this weird. It's like having all these little creatures in your head that are slithering around, but that's what makes us absorb every single thing in our worlds. And this is what uh you know humans have that other creatures have less of. And that's why we've taken over every corner of the earth. That's why we have succeed. We've gotten off the planet. We build skyscrapers and compos symphonies and so on because each generation we land and we get to spend our first few years absorbing everything that's been discovered before us. And then we springboard off of that and do something new. Because we are able to figure out all the discoveries that have come before us because of this ability to reconfigure our own circuitry. And uh you know if you were a an alligator born 30,000 years ago, you'd be the same alligator. You know, eat, mate, swim, whatever, and you you wouldn't be meaningfully different. But but humans because of our flexibility, we are the the dominant species. Such an interesting take on time and human evolution that uh and I completely agree with you. I just had never thought about it this way before that we land uh when we're born and we're absorbing the um the outcroppings of all the neuroplasticity that came before us. We often hear that, you know, that the human brain is is kind of like a macac monkey brain with a supercomputer added on top of it. Mostly the prefrontal cortex. A bit more prefrontal cortex. Prefrontal cortex. Prefrontal cortex. We actually cortex in general. Yeah. Interesting. We we have four times as much cortex as our nearest neighbors in the animal kingdom. And that seems to be the magical stuff. Not just prefrontal cortex, right? And for I'm sure the listenership knows this, but you know, uh the cortex is just the outer 3 millimeters of the brain. It's that wrinkly bit. And that's the magic stuff because it turns out cortex is a one-trick pony. The reason the cortex looks the same everywhere is because it is the same. It's got the same circuitry. It's got six little layers. It's doing the same algorithms and it gets defined by what you plug into it. So if you plug in a cable that's carrying visual information, then it becomes visual cortex. And we look at it and we say, "Oh, look, it detects the orientation of lines. and a detect motion, things like that. If you plug auditory information into it, it becomes auditory cortex and so on. And it turns out, you know, the way we do this in textbooks is we make a picture and we say, "Look, that's visual cortex, that's auditory, that's the metaensory." But all this stuff is really flexible. It's it's so much more interesting than the textbook model because you can take the fibers and plug them in somewhere else. So you may know this study in 2000 by Morgankaur at MIT where he in a farret took uh the visual information visual uh the optic nerve and he plugged it into the visual sorry into the auditory cortex and then the what would have been the auditory cortex became visually responsive and it started caring about vision. So what does that mean? It means the cortex is a onetrick pony and we got so much more of it including the prefrontal cortex. So that has two major effects. One is that there's a lot more room with our species in between input and output. So with a a squirrel or a cat or even a macac monkey, you know, you throw some food in front of it, it that that sensory cortex is right next to the motor cortex, it's going to eat the thing, but we've got all this computational real estate in between in and out. So we can say, well, I'm on a diet. I'm trying whatever you I'll eat it later. We've got all these other options that we can take. That's one thing. And then the other thing is exactly what you pointed to, which is the prefrontal cortex, which allows us to simulate whatifs. Allows us to think about possible futures, simulate things in a way that we don't have to risk our lives doing it. We can simulate it and say, "Oh, that would be a bad idea. Oh, that'd be a pretty good idea." And then we can take the action. Couple different questions. Um, I'm a big fan of McGranka's work, and I'm so glad you mentioned that work. it it really points to the fact that while there are cortical areas that are genetically devoted by virtue of wiring when we arrive in the world too auditory or visual that there's a lot of crossover especially in the extreme cases so my understanding correct me if I'm wrong is that um if somebody is blind from birth the real estate that would be allocated to vision becomes allocated to tactile sensation especially if they learn how to braille read um maybe auditory processing and because they rely on it more so there's really no blank real estate in the cortex it's all used. That is exactly right. So it turns out um you know right people who are born blind what we call the visual cortex at the back of the back of the head here that gets taken over. It's no longer visual. It becomes devoted to hearing to touch to memory things like this. And you can demonstrate that people who are born blind are better at hearing and and at touch and so on. They can discriminate things much more finely. Um same with people who go deaf that the auditory cortex all that real estate nothing lies in the brain all that gets taken over for different tasks and they can do things like see your accent you know just by lip reading they can tell where in the country you're from and so on. Um all of this demonstrates that first of all the more real estate you have the better. We are in a sense if you've got all your senses you uh you have to share everything and so we're pretty good at vision and hearing and touch and so on but everything has to get shared. But there are pretty extraordinary things that happen when people devote more real estate towards one task. And by the way, just as a side note, this is one hypothesis about what goes on with savantism in in autism is that somebody for whatever genetic set of reasons ends up devoting a ton of real estate to let's say the Rubik's cube or the piano or memorizing visual scenes or something and then they are absolutely superhuman at it. That comes at the cost of other things. Let's say social skills that might be needed. Um, but the general story is if you devote a lot of real estate towards something, you're gonna get really good at it. I'm excited to share with you that Matina, the Yerba Mate drink that I helped create, is now available at Sprouts Market nationwide. Longtime listeners of the Huberman Lab podcast know that Yerba Mate is my preferred caffeine source. It provides a smooth energy lift without giving you the jitters and it has many other benefits such as helping regulate blood sugar, improving digestion, mild appetite suppression, and more. 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In fact, I consider it a welcome addition to my kitchen. It looks great and the water is delicious. If you'd like to try Rora, you can go to roora.com/huberman and get an exclusive discount. Again, that's r o r a.com/huberman. I don't know if you saw this study that was published in science recently that explored um early specialization in sport or creative endeavor versus kids that played a bunch of different sports or involved in a bunch of different creative endeavors. And it turns out that um specializing too early on average doesn't play out so well in terms of um kind of uh peak of success later. Now there are exceptions, right? But um turns out that being a bit more diversified in in your uh physical activities and cognitive activities as a as a young person into the early teens even um and beyond uh is more beneficial. And this this to me kind of runs counter to my images of like um Tiger Woods uh putting uh golf balls with his uh dad when he was, you know, kind of still waddling. He was so little, right? and then he becomes Tiger Woods or um or the Williams sisters who were you know early on. I think that especially in the United States we have this notion that early specialization is really what sets you up to be spectacularly good later. So I'm curious what your general thoughts are for the the every person. I mean you have kids um and some of us still are kids who are listening and and we all have plasticity into adulthood. you know, is do you think that we come into the world with some genetic leanings toward particular activities being right for us or more right for us? And how do you think about it in terms of how many difficult hard to access things we do just so that we're sure that we have a full experience of life? Because what I hear you saying and I totally subscribe to is that our early experience becomes the funnel through which we have more or less opportunity later. like the kind of width of the of the funnel depends on how many things we did or didn't do early on. So this is really interesting because um first of all take somebody like the Williams sisters they got drilled on tennis from day one and this stuff can be taught and this is why they became champions and this is obvious but this is the same what you find with chess champions and golf champions like Woods and so on. Um you have to really spend the time doing it. Now I find this interesting for a few reasons. One is that cognitively you can understand how to you know what a forehand or a backhand you know is hit in tennis but to actually get good at it you have to burn it down into the circuitry. So actually let me back up for one second which is the reason that we have brain plasticity is because this is how a brain makes things that you do fast and efficient. So when you're doing a task a lot like you know serving tennis or something you're taking that from the software to the hardware of the brain let's say uh I'm an amateur tennis player and and there's Serena Williams I'm playing against her. Um it turns out surprisingly when we're playing she's beaten me like crazy but my brain's the one using all the activity. I'm the one burning all the calories with my brain. Why? Because she has burned tennis into the hardware of the brain. So it's fast and efficient. I, on the other hand, am trying to simulate lots of things and figure out where I should go and all that. So the brain does this for reasons of efficiency. Obviously the brain's main job is to save energy because we are mobile creatures who run on batteries. And so um this is one of the big things about about plasticity. So people get extraordinarily good by doing things over and over. the the these these three women, the Polar sisters who are chess champions. They're, you know, the best to my knowledge are still the best three female chess players in the world. Their father from day one started teaching them how to do chess and so on and they all became uh world champions at this. You know, the thing about whether you need to have diversification, that's an interesting question. I can see why it would be useful because you're learning different ways, different moves about it in the same way that if you learn how to snowboard and ski, um, you know, you might you might get better at both of them. But I got to say, uh, when children grow up, let's say, triilingually, uh, or even bilingually, they they end up having a lower vocabulary in both languages than if they grow up monolingually. Really? Yeah. It's just because of the amount of practice you get with a language. Kids, still do your uh second language homework. [laughter] In California, it's it's, you know, growing up here, it's very useful to know English and some Spanish. I mean, very, very useful. In fact, I wish I'd gotten better at Spanish when I was a kid. Uh, and my father's born and raised in Wanosirus, but we didn't speak Spanish at home, at least not very much. So, you know, I can tell you learn a musical instrument and learn a second language. a musical instrument for your own enrichment um and those around you. But the the second language thing I think is extremely useful at least in California I find it to be really useful. But kids are resisting this by the way now because they say look I can do Google translate or you know my meta sunglasses and so they're resisting it. Yeah. But Google translate is not Google relate. I totally agree. You know I I mean it's and I'm not I'm hardly fluent but I can get by now. I'm pretty good. But I've been practicing my Spanish more and more and just by virtue of living in Southern California, that just happens. But I I think knowing a second language um and being a to have that kind of face tof face conversation with someone, it's um even the struggle of it is enriching in a way because you're forcing your brain to do some work. My father spoke eight languages fluently without accent. Uh and that's because he went to medical school in Europe and did his clinical rotations in different countries and you know he was a young man. So everywhere he went, he got a girlfriend and then he had the incentive to learn the language. And by the maybe we'll come to this, but when it comes to brain plasticity, the reward systems are a big part of what makes change happen in the brain. Actually, let me just mention, this is tangential, but let me just mention this while it's on my mind. Um, you know, a lot of people really for the last 30 years, ever since the internet became a big thing, really worried about what this is going to mean for kids and education. I think it's terrific. I am very optimistic about this because what what kids started getting a few decades ago was this opportunity to learn about something right when they were curious about it. So they want to know how to fix the bicycle tire or what is this space physics thing or whatever and they ask the question and get the answer. Why does that matter? It's because brain plasticity really happens when you have the right cocktail of neurotransmitters present and and that cocktail happens to map on to curiosity or engagement. when I'm I'm slightly older than you are, but when we uh you know, when we were in school, the teacher teaches you the thing. They just dump everything like, "Oh, the Battle of Hastings happened in 1066 and you may or may not ever need to know that." But what kids get now is information right in the context of their curiosity and that makes a big difference because stuff really sticks and I have been extraordinarily impressed with young people that I meet. I meet all these young people who say these extraordinary things. I say, "Wow, how did you know that?" and they, you know, they've watched TED talks, they've asked Alexa, they've talked to ChatGpt and they get the information and and it sticks. Super interesting. I hadn't thought about it that way. I uh I guess I'm reflecting my age um to everyone when I say that, you know, I remember being interested in something and then having to bike or skateboard down to Tower Books or go to the library um and look things up. And I tell myself that the effort involved in going to get it actually is useful. But you're right, had I been able to um kind of look up what I was interested in and get it right then, I probably would have spent more time implementing the information because I was interested in all sorts of things that usually involved building something or doing something that was going to make a big mess and frustrate my parents, right? But I spent a lot of time searching for the information. Yeah. Um, plus you remember how dinner table conversations used to go, which is that everyone argues about something and then they someone says, "Well, I think it's this." And the other person says, "No, I think it's that." And then it just sort of stops there because no one knows the right answer. But now everyone whips out their phone, gets the answer, and then and then it keeps going, which is really terrific. Yeah. It's dissolved um some of the social dominance that comes about when one person's word is the word that everyone has to just kind of believe just because they say it with more certainty. They're the father or whatever. Exactly. Yeah. Or the grandfather or whoever. Or the grandmother. in some cases, who knows? Now, it gets checked against the internet and uh uh claude for me or chat GBT for for a lot of other people. I realize that um the question I'm about to ask can't be answered uh completely but given what you know about plasticity and the fact that yes you know we come in to the world with some pre-programming of our of our brain circuitry but we have some control over uh what the inputs are some depending on our circumstances. It depends what you mean by we. Uh, so as infants, of course, we have no control over that. As an adolescent, as a teen, as a 20-year-old, assuming plasticity extends into adulthood, still as adults, although it's harder, um, some control over what one learns or does. What do you think are um sort of the core elements to uh making sure you build a healthy, well-rounded nervous system? Nobody's really ever attempted to answer this question. you know, a howler monkey learns all the things that a howler monkey needs to do. Um, humans, we have, as you said, the benefit of all the technology that comes from the plasticity of those that came before us. And so, you know, maybe kids don't need to learn a second language, but what do you think are sort of the the essentials? I mean, obviously learning to communicate and understand, learning to move, but do we have some sense of of how you check off the like the core 10 boxes of neuroplasticity to make sure that by time you land in adulthood or even if you're still an adult that you're you're doing the quote unquote best that you can with your brain? This is a tough question, I realize. I mean, I would say two things. One is um you know, try to maximize along every axis. So try to be an athlete, try to be a scholar, try to be uh you know, somebody who's good at social life and has a lot of friends. All all of these axes of life, it's worth spending the time doing that. And if obviously we're in an era, especially now, where there are a million ways to waste time. I sit on airplanes next to people and they're playing Candy Crush for the whole flight. And I just feel like what a shame because there's so much you could be putting into your brain and making happen. You could be reading books, you could be listening to podcasts, anything like that. Okay. So, there's that. But the other half that I would say is um a lot of what we care to be depends a lot on what's going on in the future. And I'm fascinated by for children now in schools, what choices they should make because who the heck knows what careers are going to exist in 20 or 30 years from now. Therefore, the main things they can concentrate on, I think, are critical thinking and creativity. Those are the main things for them to figure out how to do. What are some good ways in your opinion to access critical thinking and creativity? I I can imagine a number of them. Yeah. Here's something I find very optimistic about AI in the realm of education. Um, you know, in any classroom, it's going too fast for half the kids and too slow for the other half of the kids. What we now have the opportunity for is really individualized education. One way this could be implemented is AI debate. So you take any hot button issue, abortion, gun control, whatever you want, and you debate with the AI and you get graded based on the quality of your arguments and then you switch sides and you take the other side and you argue again. This is the kind of thing you could never have enough teachers for. They would never have enough patience for. AI is terrific at this. And by the way, it's really important so that students get a 360 view of issues instead of ideological capture. So this is a terrific way to teach critical thinking to every student, not just the kids on the speech and debate team. Okay. Creativity, that's easy. That has to do with learning the foundational stuff and then doing remixes, bending, breaking, blending, doing new versions of it. And I think schools can implement this easily and without any extra expense which is you have to teach the foundational stuff but you compress that so you have one extra week at the end of each semester and then that last week you say great take everything you've learned and now make your own thing with it using all the elements that we've learned bend it break it blend it make your own version of this. That kind of exercise is that is creativity. That's all creativity is is taking your storehouse of knowledge and doing remixes. We should be teaching that. So critical thinking and uh creativity. Gerta the the German philosopher had said uh there are two uh bequests that a that a parent can give a child. One is roots and one is wings. And my interpretation of that has always been critical thinking and creativity. Love that and thank you for making it practical. That's something I think any and all of us could invest some more time in. I also agree it's very easy to waste time on on uh on the internet. Uh I have a separate phone for social media. Oh, great. That solved a lot of issues. Not that it was really contaminating my life that much. I like social media. I like teaching and learning there and some entertainment there. But by putting it on an old phone, so X and Instagram are just on that phone. It's amaz people send me things by text and I I have to transfer them over. Sometimes I see them, sometimes I don't. My default setting is no longer to just look at my phone and look at social media. Yes, it has increased my productivity and just my happiness and my level of attention. Also, when I do social media, that's I'm doing like a like a purposeful like watching a show or doing something that I would devote time for is to not always just scrolling in the background. Do you find yourself picking up that phone sometimes? Actually, no. If I do, if I find myself doing that reflexively, I have a uh what I call a supermax prison lock box, which you can't code out of. And the fun for me, and get this, this is like really weird. I don't know what this says about my psychology. I'll put it in there and I'll dial in, you know, okay, like 4 hours, and then I hit the supermax button, and then there's this 15-second countdown, and then I'll go 5, six, seven, eight, nine hours. And I go, okay, cool. Like 9 hours. So, there's this weird thing where you don't want to let it go, but then you I really enjoy the freedom from it. so much that the extra hours that I add on and that last thing it feels like a gift to myself and then I'm like I'm going to have a great day and then when I get back on it certainly there's this dopamine dynamics thing where you go oh this is a lot of fun but you have to be super careful because it'll suck you in. I'm just amazed at how fast time goes which we're going to talk about time perception. I before we do that though, I I have a question about plasticity that I've been waiting to ask you and only you because we have a lot of friends that are neuroscientists, but I have a feeling you've thought about this more than anyone, which is are there any things that we can do to extend the window of plasticity? Or are there activities like learning an instrument or or some sort of game who knows that gives us our capacity for plasticity uh more height, more width um as opposed to just you know the same principles. You need to focus on the thing then you need to make errors then you need to do some error correction. You get to sleep that night you rewire you trial and error. I mean, we know that the basics now. I think most people have heard them. But what can we do to broaden our ability or heighten our ability to get uh plasticity? Two words, seek novelty. That's the whole game is you got to continually challenge the brain. And this is something that as we get older is more important than ever. It's finding new things that we haven't done before. You always have to keep yourself between the levels of frustrating but achievable. And as long as you're trying new things, so yes, a new instrument is great. Speaking a new language is great. Um, you know, obviously we're in a world that's moving very fast. So just keeping up with the technology and figuring out, wow, there's this new opportunity here with this piece of software, whatever. All that stuff is great. This is the critically important part. Um, you may know these studies. There's been this this study going on for decades now called the the what is it? religious orders study uh up in Chicago area where there's a whole bunch of nuns and priests that agreed to donate their brains when they passed away. And then when they donate their brains, the researchers uh you know examine them, do autopsies on them. What the researchers found is that some fraction of these nuns had Alzheimer's disease, but nobody knew it when they were alive. Nobody saw any cognitive deficits. Why? It's because these these women died in their 90s. And to the day they died, they lived in these convents. And in the convents, they had social responsibilities. They had chores. They were fighting with their sisters. They were playing games with their fellow sisters. They were singing songs. They were doing things all the time. So they kept their brain active. So even as their brain was physically degenerating with Alzheimer's disease, they were building new roadways. They were building new bridges over these areas. This is one of the big things that tells us that uh you know contrast this with with people who retire at 65 and they go home and they sit on a couch and watch the television. They don't have as good an outcome because they're not challenging their brain anymore. Um so it is so important to be doing things. You know I once heard the expression that there's nothing as hard that the brain does than other people. And so for these for these women living in convents, they were constantly dealing with because you never know what somebody's going to say or how they're going to react or what they're going to do. So this is great challenge opportunity for the brain. Anyway, the point is we need to always find that with ourselves. Often times people will ask me uh like an older person will say, "Hey, I do cross word puzzles. Is that good?" Yeah, it's good until you get good at it and then stop and do something that you're not good at and constantly find the next thing that's a real challenge for you. That's the key thing about plasticity. Essentially, the backstory is this. As you well know, your brain is locked in silence and darkness. It's trying to make a model of the outside world. And its whole goal is to make a successful model. And when it succeeds at that and says, "Oh, okay, wait. I I've got good predictions about what's going on." Then it stops changing. I That's its goal is to stop changing. And if you're it'll keep changing. Amen to that. I I been trying to beat the drum that the agitation that one feels when trying to learn something new, it's actually a reflection in in part of the catakolamines, right? Like adrenaline and norepinephrine, the frustration and the agitation that we feel. That's the feedback signal to the brain that hey, this is different than the stuff you know how to do. I mean, because the neurons are not thinking, they're firing, right? And so and so that neurochemical millu associated with frustration is one of the triggers that uh generates plasticity which actually you can resolve this question for me. I'm struck by the fact that there's so many studies showing that the adult brain can change. Yes. And some of the more interesting ones um involve boosting the levels of some neurom modulator dopamine or acetylcholine or norepinephrine or epinephrine serotonin. But what's so interesting to me is that seems like you can boost the levels of any of those and get plasticity. It's not like one neurom modulator gives you uh the opportunity for for plasticity. So many of the interesting studies on psychedelics are using psychedelics that are kind of like serotonin. I mean they act on different receptors, but they're very serotonic. I I remind people of this because people really like to um beat up on SSRIs. And I agree they have their problems and side effects, but they've also helped a great number of people. But whether it's SSRIs or psilocybin, they're both just tools for plasticity that drive serotonin. But we know you can amplify acetylcholine, get a window of plasticity. This is a speculative question, but why do you think it is that there's this sort of equip potential of neuromodulators where boosting any one of them can open plasticity or the window or the opportunity for plasticity? Okay, a few things on this. as as you well know you know all the neurom modulators exist in a dance with each other and and fundamentally I think we're going to come to understand this in 50 years as you know sort of combination locks of things and the way we keep looking at it in science currently is ah here's acetylcholine or here's serotonin or so and it's probably not the right way to look certainly not how the neurons are looking at it okay that said acetylcholine really feels to me like the main one involved in plasticity when you are a Maybe you've got acetylcholine going everywhere whenever you're trying to figure out the world. Whenever something's not matching a prediction and you've got acetylcholine going everywhere that says, "Hey, I got to figure out what just happened and how to link this with what I did and so on." As you get older, it's more like, you know, a pointalist artist who just dabs things here or there. You get to see the colon release very locally in very in small places and that's where you make changes. Why? That's because as you get to be an adult, you've got a better and better model of the world. You don't want to change everything. You just change like, "Oh, I didn't realize there was that button on the coffee machine that did this new thing or whatever." So, you just change little bits at a time here. We're in this really interesting situation in in the history of our species where now we can do things like, "Hey, what if we just crank up acetylcholine or, you know, obviously we've done lots of things with with dopamine." Um, we always find when we tweak these things that it's complicated. Just as one example, you know, with Parkinson's, people get have less dopamine and so the medications are to crank up the dopamine. What that led to, you may know this fascinating story, this probably 25 years ago now, where you know, observant clinicians noted that people on these Parkinson's medications were becoming hypercompulsive gamblers. They were blowing their family's fortune on online gambling and Las Vegas and so on. And and what they realized is when you crank up the dopamine that changes your risk aversion such that people are taking. So now it's a it's a contra indication that's listed on the bottle. You know if you notice gambling turn down the the the the amount here. So anyway whenever we whenever we start dialing these around we always find things that are a little bit out of our predictive realm. Um, but uh the general story is that your brain's trying to put together this model of what's going on and as it gets better and better, it's doing less and less plasticity. I do want to point out though that parts of the brain become less plastic and others stay plastic your whole life. As an example, your primary visual cortex at the back of the head that locks down early. You really can't do much to change that. And um you know there were studies by Logitus' lab years ago where they looked at changes to let's say the retina in an adult monkey and they expected to see changes in the visual cortex of the monkey and they didn't see any changes at all and that surprised them given all the plasticity literature. But it's because the visual cortex locks down. In contrast, these downstream areas from the visual cortex that care about things like recognizing faces or new brands of fast food restaurants or whatever it is, those stay plastic your whole life because there's constantly new data coming in on those. So the general story is the primary areas are like the I think about it like the the software kernels where you know if you're at Microsoft for example there's parts of the code that no one ever touches because that's like how to add two numbers and multiply whatever that's the kernel of the code you never touch that but you get these higher and higher application layers on top of that and that's essentially how to think about primary sensory cortices and then all the stuff downstream from there perfect analogy I um for people to understand, you know, how how much challenge to embrace. I mean, you're not trying to um, you know, defrag the whole system, you know, and and and I mentioned psychedelics. I, you know, I do think they have some interesting therapeutic potential. I I also worry about and I can tell you examples of people that got I guess now they nowadays they call it one-shotted. They take Iawaska a couple times and they are forever different in ways that does not serve them. those examples don't get talked about quite as often as the also many people who you know um seem to benefit from these things. So um plasticity it seems is not the goal. Directed plasticity is the goal. That's right. And it's very hard to direct. So I feel like you know let's imagine you could take some cocktail of neurotransmitters and get total plasticity of your brain. I don't think you'd want that. You wouldn't be you anymore. who we are is the sum of our memories and the sum of our skills that we've built and you know that keeps changing. We're always a moving target. Um and who you will be in five or 10 years will be different. But I don't think we'd want the plasticity of an infant even though when you're doing let's say language learning you say I wish I could learn this as well as I did when I was seven. But uh generally it's not a state that you would desire. I think if you're a regular listener of the Huberman Lab podcast, you've no doubt heard me talk about the vitamin mineral probiotic drink AG1. And if you've been on the fence about it, now's an awesome time to give it a try. For the next few weeks, AG1 is giving away a full supplement package with your first subscription to AG1. They're giving away a free bottle of vitamin D3 K2, a bottle of omega-3 fish oil capsules, and a sample pack of the new sleep formula, AGZ, which by the way is now the only sleep supplement I take. It's fantastic. My sleep on AGZ is out of this world good. AGZ is a drink, so it eliminates the need to take a lot of pills. It tastes great, and like I said, it has me sleeping incredibly well, waking up more refreshed than ever. I absolutely love it. Again, this is a limited time offer, so make sure to go to drinkagg1.com/huberman to get started today. You've mentioned a few times future self. I think uh all of us are inherently interested in our future selves and whether the things of our past, present, uh and what we have control over going forward is going to put us in the best future self possible. Right? Humans love to optimize or fantasize about optimal. But how should we think about thinking about our future self? Or should we not do that? Right? Should we should we should we just avoid that loop-de-loop and um and uh get real stoic about it and just live in 10-minute time blocks or one minute time blocks? It raises a really interesting question, I think, of where should we set our time horizon to not just feel the best, but to be our best and to feel our best going forward. Yeah. Our capacity to think about our future selves is the most special part of being humans. And you if we didn't do it, if we said, "I'm gonna be stoked about it." Yeah. You'd eat the the cupcake and you do what? Like all the things that wouldn't serve your future self. Never eat the cupcake like a real stoic and then starve to death, right? Even if the cupcake were the only thing, [laughter] right? What would the stoic do? That's right. So, um, yeah, we actually spend most of our time not in the here and now. We're reminiscing about the past and we're simulating possible futures. Your your mind is a movie theater. We're constantly thinking about where things are going. But this is great. This is what makes us able to do all the things that that humans do successfully. And in our own lives, this matters so much because we're able to think about who do I want to be? Now, as you know, we've got this rivalry in the brain. You've got all these voices going on at the same time, all these different networks running. So, for example, if I put the cupcake down in front of you, um, you know, part of your brain wants to eat that. It's delicious. It's a rich energy source. Part of your brain says, "Don't eat it. You know, I I want to stay fit." And so, part of your brain says, "Okay, maybe I'll eat part of it. Uh, but I'll go to the gym later." Or, you know, I promise my girlfriend that I'll go do this thing. What? Like, we've got all these voices. You can cuss at yourself. You can cajol yourself. You can contract with yourself. And the question is, who's talking to whom? It's all you, but it's parts of you that have these different drives. Now, the part that's really amazing about us is we got lots of short-term drives, but we also have this capacity to look into the future and think about who we want to be. And that is essentially subserved by our prefrontal cortex, which as we mentioned earlier is something that is a, you know, the size of it is unique to humans. All of our closest cousins in the animal kingdom don't have a prefrontal cortex that's a fraction of what we have. That's what allows us to unhook from the here and now. Okay. Now, here's the thing. I have been fascinated by this for a long time about how we sometimes know, okay, my future self is going to act badly in this situation. So, I'm going to do something now so that my future self can't act badly. So, this is the topic of my next book. It's called the Ulisses Contract. And where this term comes from is in the Odyssey, Odysius, otherwise known as Ulisses, is coming home from the Trojan War. And he realizes that way up ahead, he's going to pass the island of the sirens where you've got these beautiful female creatures who sing these songs that are so beautiful it beggars the mind of the sailors and and everyone crashes into the rocks and dies. Ulisses really wants to hear the song, but he knows like any mortal man, he's going to fall for this and crash the rocks. So what does he do? He has his men lash him to the mass. So he can't move. He has them put beeswax in their ears so they can't do anything. And and he tells them, "No matter what I do, no matter how much I'm screaming, just keep going. Just keep sailing." Smart, right? It's smart because what is happening is the Ulisses of sound mind is making a contract for the future Ulisses who he knows is going to behave badly. So he's lashing him to the mass. And what I've been fascinated by is the ways that we do this in our lives all the time. So the example you gave a few minutes ago about locking up your phone in one of these lock boxes is a perfect example because what you're making sure is that the Andrew of two hours from now can't do the wrong thing because you know he might you know he's going to be tempted. So you take away that temptation. By the way, I recently met uh an older gentleman who told me about an older woman that he'd met years ago who used to take her money, her cash, and freeze it in a block of ice in the freezer so that she couldn't spend the money until she really needed it. Yeah. I don't have a money spending thing. And I actually have pretty good control uh with with the phone and with social media. For me, there's also a I don't want to call it a sick pleasure. There's a uh a bit of a pleasure in knowing that it's completely off limits because it means I can't even look at it for 10 seconds. I don't know. I think it involves something over control of of things that I feel like are trying to control me. Yeah. Exactly. Which I do not like. Exactly. Because you care about your future self and you want future Andrew to do the right thing. So there are a million ways to make these Ulyses contracts and I've been studying this for years and I Yeah. Anyway, so I decided to to write a book on this because the way that we deal with our future selves is just this fascinating thing because your future self is a little different than who you are now. But with time, we come to understand that our future self will behave badly in different situations. And so we just try to to cut those off. I I'll give I'll give a couple examples. One is it's super useful to get um social pressure involved. So, for example, I'm guessing you and I both do this. You know, going to the gym is something we enjoy, but it's really useful to have a buddy where you say, "Hey, I'll meet you at the gym at 8 tomorrow morning." And then even if you wake up, you're a little tired, your shoulder hurts, or whatever, you got to go because he's going to be there. So, getting social pressure involves a good idea. I I I found this thing where it's a a boot camp where you sign up for it and every morning, you know, go jogging together and do push-ups, whatever. But if you don't show up, the group jogs to your house and they stand on your front lawn and they do jumping jack jumping jacks and they scream your name until you come out. Amazing. Yeah, it's really good to get that to commit to that sort of thing so that you're really going to show up. Um there are ways to do this where you put money on the line. So you can say, for example, there was a woman who was trying to quit smoking and she tried for years to quit smoking. So, what she did is she wrote a $10,000 check and gave it to her friend and said, "If you catch me smoking, I want you to donate this check to the KKK, which to her was the most aversive thing that could ever happen with her money." And that's what prevented her from smoking because the sting of knowing that she gave her money to the KKK was the worst thing that she could imagine. So, there are a million ways to do these Ulisses contracts, but what they have in common is how do you lash yourself to the mass so you'll keep the good behavior you want? Yeah, the example of this woman writing the check is interesting because um I could ask why couldn't she access her inner clearly has a lot of inner fight right like she really stands so strongly on one camp which um I agree the KKK horrible organization would never want to support them in any way uh whatsoever and um and yet she needed to do that right she needed a punishment a potential punishment And so it speaks to how even if we know something and feel something so strongly in the present, yes, it still becomes very hard to um to access our best choices. Um but there's something about the future self that we're not even in yet that we fear our future self so much more than than we uh can't handle the the discomfort of our present self. It's almost like and so we tether those in this Ulyses contract. Yeah. It's a kind of wisdom that we come to understand how we will behave when we're not in our present, you know, sober, rational moment. Um, we come to understand, for example, people who are trying who are alcoholics and they're trying to break that. The first thing they're told at, um, Alcoholics Anonymous is clear all the alcohol out of your house. Because you might think, okay, I'm done. I'm firmly going to not drink anymore. So, you put the alcohol away up in a high shelf. But on a festive Friday night or a lonely Sunday night or something, you might go up there. Your future self might do that. So what you do is you get rid of the temptation. Same thing with people who are trying to battle drug addictions. They're told, "Never carry more than $20 of cash in your pocket because at some point you're going to run into some guy who's trying to sell you drugs and if you got the money, it's burning a hole in your pocket. You buy the drugs." I don't think we can trust our future selves. When we're in a moment of reflection and we can think about who we want to be, it's worth setting into place some walls. So that's about avoiding uh bad behaviors. Um what about building toward future self where we're trying to envision a better version of ourselves that involves actively doing things. So there's always dos and don'ts in order to become our better self. Um, how does Ulys's contract play in when it's not about the sirens? When it's about um knowing that we want to be this person or have these attributes or having done something and trying to tie our future self to our present behavior, how good are we at that? Um, in general, yeah, better or worse than avoiding bad behavior? Oh, we're terrible at all this stuff. I mean, take New Year's resolutions. I mean, everybody makes New Year's resolutions. they rarely last a week or two before they drop off. People get busy, people get tired or whatever. Um, so it's just as important with the positive things to hook things to that. Um, for example, this idea of putting money on the line. There are various websites where you can do this. You say, "Okay, look, I'm going to put, you know, 50 bucks on the line that I want to be able to bench 250 by this date or something like that." Um, and then you've given your money to this company and you have to get to that point. So, you get your money back. Um, there are lots of ways to do this. Um, you know, obviously putting, you know, I think you had James Clear on a little while ago and and there there's all kinds of good uh ideas that he's got about, you know, put your running shoes near the door or whatever so that it's easy. You get the you get rid of the friction to go do things like that. But all of those moves are for your future self. When you put your shoes near the door before you go to sleep that night, you are doing something because you know your future self's going to be a little bit lazy and tired. I have friends that are uh I'll just call them what what I would call them to their face because it's a friendly exchange. Are are kind of neurotic, right? They tend to overthink things. If they're going to go running at 8 a.m. and it's 8:02, they're like, "I can't go because it's 8:02, not 8. I'll go at 9:00. Got to do it on the hour." This kind of thing. And then I know people who are like you just do things and you don't think about it as much and they're good at suppressing that voice. Um I think we assume that the the chatter the the neurosis doesn't exist for them but I think um I think it does. They're just better at saying like like ignoring that inner voice. Um we're never trained how to do this. We're never taught as kids here's when you need to really think and deliberate and here's when you just need to just do it. Yeah. And it's interesting to think about, okay, different career paths, different life requirements, and so forth. But, um, I feel like people fall into kind of two camps with this. Some people need to think and analyze less and do more. And some people actually need to, you know, probably still do, but maybe think a little bit more about their behavior and reflect a bit more. And they would probably both say, "I'm crazy about this." Um, I won't tell you where I land. I think I'm kind of in the middle. No, I'm just kidding. Um, [laughter] it depends on on what's at hand. Yeah. for most people I think. Um what do you think that's about the ability to suppress the various versions of oneself or not? The inner voice. Yeah. You know, I would say one of the most fascinating things we've discovered in neuroscience to for my money is is just this issue that along anything we measure there's a spectrum. So just take something like the internal voice. Uh for my wife for example, she describes it as her inner radio. She's always hearing her inner voice. I I don't really have one. I just never hear that. So, we're on opposite ends of the spectrum that way. But, you know, one of the things I've studied is um aphantasia all the way to hyperfantasia. That means when you know, if I ask you to visualize an ant crawling on a tablecloth towards a jar of purple jelly, some people see it like a movie in their head. That's called hyperfantasia. Some people have no picture at all in their head. That's called aphantasia. And everywhere is everyone is somewhere in between on the spectrum. What does the middle look like? So, if I do that, if I maybe everyone can do this right now. It's a a fun experiment. If you're driving, don't close your eyes. Um [laughter] uh picture sun coming over the mountain and the rays of the sun poking through the clouds and then it starts raining and rains coming down. Mhm. So, the question is, do you see it as clearly as a movie or do you have really no visual anything in your head or are you somewhere in between? Typically, this is judged on a scale from one to five where five is a movie, one is no visual at all and, you know, three is in between. Where where do you stand on that? I feel like I can see it quote unquote um in my mind's eye, but um it's almost like I'm looking at a silhouette of it. So, even though I want to see bright, you know, rays of sun, sunshine, one of my favorite things in life. I know they're there, but they're actually pale pale yellow, it's almost as if it's more opaque than it would be in real life. Yeah. You're saying people with it with hyper hyperfantasia see it as a same way I would on a on my phone essentially. Yes. They're seeing it like like vision. Now I happen to be aphantasia. So it's very hard. You know I've studied this for years. I've interviewed hundreds of people on this and so I get their description but I can't I can't picture that myself. By the way it's an interesting quick tangent. Um for years I've talked with Ed Catmol about this. Ed Catmull is the guy who started Pixar. Pixar with all these terrific animated films and so on. Um Ed has all these patents on like how to do ray tracing to get the you know to get these animated characters looking as amazing as they do. He was surprised when he discovered that he was afantasic. He doesn't picture anything in his head. So he ended up giving this questionnaire to everybody at Pixar. And it turns out most of his best directors and animators are aphantasic. They don't see anything in their head. And nobody I think would have predicted that because it seems so strange this visual, you know, magisterium of of Pixar. But I I have a hypothesis about why this is. It's because the kid who grows up who's aphantasic, when they're asked, "Okay, draw a horse." You know, the kid sitting next to them who's hyper fantasic says, "Oh, I know what a horse looks like." And just draws it. But the poor aphantasia kid has to really stare and figure out like that, okay, how does that work? And so on and and they get better at drawing as a result. That's why all his best animators and drawers are people who grew up a fantasic. Interesting. I'm just uh thinking about that movie. Have you seen that movie Bow Finger? No. With with Steve Martin and uh Eddie Murphy, which is Bowfinger is the you know, for those just listening, it's where you put kind of make two uh you know L an L and and a sort of reverse L. And it's like how you know it's about making a movie in LA and uh it's it's hilarious. It's it's spectacularly funny. It's got those two folks I just mentioned, Heather Graham, a bunch of other people, but but he's constantly going around and kind of envisioning, you know, that this is the movie. This is the movie. Exactly. And so I always thought people that make movies are going through life thinking, okay, like there's the shot and there's the shot. But I think what you're saying is that there's somewhere in between where people have this kind of fantasy life of like, okay, here's this um here's the script and then um they can't really imagine it and so they have to put more work into uh materializing it. Okay. Well, they have a dialogue with the page. So, if you're a guy drawing and you know you're looking at the horse or you're picturing what you know, Ariel the mermaid looks like or whatever, you're you're trying lines and scratching and doing things, you don't come to the table always saying, "Oh, I know what a mermaid looks like." And you draw it. Um, so they just end up getting more practice and they get better at it. I love this stuff because what we're really getting at here is um, you know, I think as you mentioned, everyone has kind of individualized hardware and software, but there are some commonalities. And you know, wouldn't it be spectacular if we knew, you know, which you know, just like we learned, okay, here are the macronutrients and you perhaps want them in different proportions depending on who you are and what you need and, you know, and uh you need to, as a kid, you should probably learn how to like climb and run and, you know, and assuming you have access to all of that, you know, and um and jump a little bit, but you know, maybe you won't be an athlete, but you need to like be active at some point and then you be and we tend to figure out what we're good at and then really lean into those trenches and then by then we're getting evaluated for it and the way we're evaluated puts us on a career track and there's very little opportunity to go back and kind of fill in blanks. Um, right there's, you know, I I'm never going to be a musician in part because I'm just not willing to put in the work because there are other things I'd rather do with my plasticity. Right? So, um, and maybe that's best. So, big big picture question. Um do you think that human evolution and the progress of building technologies um reflects the fact that people get siloed into um different tracks and on the whole that's advancing our species right you've got people that are hunter gatherers still very good at that and building and other people building weaponry and other people building AI technologies and that that it would be uh detrimental to our species if everybody got sort of core neuroplasticity training, learning how to do a little bit of everything, right? Um, or is that the the what we see as chance actually part of the reasons why humans are the curators of the earth? Not just the prefrontal cortex, not just the extended window of plasticity, but how we are afforded different opportunities to work with that plasticity. Yeah, I'd say a couple things. One is we're clearly predisposed to particular things. And so, for example, I'd like to be a swimmer as good as Michael Phelps, but I just don't have the wingspan that he does. is he's got like I don't know seven feet between his fingertips or something. Gez, there's no way I'm going to be able to be as good as he is. Um that's a genetic thing that he drops in the world with that I don't fine. Um so given that people are off on different trajectories anyway, the way I think about this, I don't know how this will translate just in terms of audio, but like a space-time cone in physics is where you start in one spot and then there are all these different trajectories you can take into the future. Picture this like you're starting at the bottom of the ice cream cone and you can you you can take any different trajectory as long as it still exists within the ice cream cone. Okay. So, um you know, we drop into the world with our genetic skills and predispositions. We have childhoods that we don't choose. We're born into a cultural language and era that we don't choose. And that defines the limits of the ice cream cone about where we can go with that. As far as specialization goes, you know, economists will argue this is part of what makes a very healthy society is that, you know, some people become the lumberjacks and some the lawyers and some the accountants and whatever. Um, you know, I do feel like we're in a really great era though in general in humankind where kids do get very broad educations and they're sort of encouraged to try everything and spend a few years in karate and in soccer and in piano lessons and so on. That's wonderful. So the my father was a psychiatrist and he always said really the whole job of a parent is just to open doors for the child. That's it. So you give the child all these lessons, you open all these doors and then the kid takes their own path depending on you know this extraordinarily complicated formula of things that we'll never understand but they go through one door and not the others. Kirkagard said every man starts as a thousand men and dies as one. And what he meant, of course, was that you start with all this potential. You could do all you could have been a great saxoponist or whatever, but you're going to die having done exactly what you did and and not the other path. So, what's weird about life is that yeah, every door that you choose, some others close as a result. Kirkard uh seemingly understood that the nervous system starts out hyperwired and then a lot of learning is the pruning back of connections and strengthening of the remaining ones. That's exactly right. Exactly right. You know, so as you of course know, the the brain starts out, you got essentially a fixed number of neurons. There's some debate about whether there's a few new neurons born in humans or not. Put that aside. What happens is over the first two years, those neurons connect more and more and more and more. And what you end up getting is this hyperconnection by the time you're two years old. And from there, it's just a matter of pruning an overgrown garden. And that's all that's happening. And and the way the pruning happens is based on what you're experiencing in the world. the world is what prunes your garden and and strengthens particular paths and lets other paths go as a bridge perhaps between plasticity and time perception which we've been sort of doing already. Uh I have this um practice that I've been doing for a few years um in hopes that it's beneficial for something and I I just like your thoughts on it. Um I'm not looking for approval here uh truly but here's the idea. I was struck by the somewhat obvious thing that, you know, we can close our eyes, uh, focus on our interosception, our skin, our breathing. We can meditate, bring our awareness, you know, into the quoteunquote present. The breathing is seems like a good way to do that. Um, or we can open our eyes and we can focus on something some distance away. Or we can imagine the pale blue dot and we're just this little thing running around on this pale blue dot. And you know when we move through those different uh realms of space, not just outer space, but from body to out of outside our body to outer space, there's a different time association with each of those. And I' I'd like your thoughts on that. And I I just started devoting a little bit of time to stepping from one of these to another and just spending some time trying to uh think and exist in the different time domains um in my head. And so I'll do that maybe for 2, three minutes or four minutes or five minutes. And I told myself, and I still tell myself, that it affords me some flexibility when something's happening in the moment and you want to get perspective. It's about getting out of that time domain and realizing this isn't going to go on forever even though it feels like it. So, I developed this as a bit of a practice for myself. Um, because I I felt like it's just a it's not a meditation. It's a perceptual exercise. Um, so what I'm curious about is the relationship between time perception and where we place our attention. That's the first question. And then you know maybe what we can do with this or or could we evolve this uh perceptual exercise so that um I and and others perhaps if they want to can start to access different um space-time representations which sounds so fancy but it's really just a way of like getting outside yourself or getting within yourself. Sorry if I'm being um choppy here but but this is something that feels very important. I I love that. I think that's brilliant. Um, one of the things that is so striking about time perception is that you don't have a single part of the brain that deals with that. You actually have different mechanisms that deal with thinking about long eras of time and seconds and subseconds. Um, totally different mechanisms going on here. Uh, and and we can demonstrate this in the laboratory. So, time perception is something I've been studying since graduate school. And um you know I'm happy to say I've got papers in science and nature and you know the top journals on this topic. Why? Because it's such a weird thing that's so understudied about how why why we perceive time the way we do. So um let me say a few things about it. One is that it is a these longer time scales what you're referring to thinking about being uh far away in space and time. This is a cognitive development. children can't do this well and they learn better and better. So, for example, if you talk to a a seventh grader and you talk about the Roman Empire and what was happening 2,200 years ago, it's re it doesn't mean anything to, you know, it's like, okay, so that's the past and whatever. But as you get older, if you become, let's say, a professional historian, you get better and better at understanding that. Why? because you've lived decades and so now you can sort of think you can sort of feel what a century might look like and you can sort of with practice get better at at these things. But the point is that is something we learn how to do both in space and time. Obviously when you're an infant in the crib, space is just a really close thing and eventually it's your whole world. It's your whole world and eventually you get outside and you look down long highways in Utah and you you you really start getting a better sense of this. I I to my knowledge there's no data on on what it would be to to sort of throw yourself back and forth between these different space-time uh scales. I love it though. One of the classes I teach at Stanford is called the brain and literature. Uh, I've always been a lover of literature and one of the things that I love is when authors do exactly this where they they zoom in on something really tight and they're really paying attention and then they zoom way out. That is the most extraordinary sort of feeling. Um, so anyway, I commend you on coming up with that version of space-time meditation or whatever it is. That's very smart. Yeah, it was um it was born out of this thing, you know, the the Victor Frankle thing like between stimulus and response, you know, and but there's something about the autonomic nervous system like when we're in a heightened state of stress. Um we're not good at getting outside of the moment, you know, people like take 10 breaths or whatever and it wasn't that I was having struggles with that. I just thought so interesting like you watch a movie and it seems to be placed in a different time domain in each scene or um and you know then you go for a walk or a hike and I I have this obsession with the idea that when we see horizons we have a different time perception than when we uh can't see horizons um and there's too many variables to do this right you could do it in VR in a VR experiment but um because when there are close walls you have claustrophobia but there there ways to do this correctly how you change your your your vision or visualization changes your time perception. So, I don't know. I just look at it as a flexibility exercise. And um and I'm a scientist and a weirdo, so I I I do these things. Um but uh you're the expert in time perception. So, I wanted to ask um and I also want to ask about time perception. Um how good are people at perceiving time? And um why am I always late? [laughter] The why are you always late? That has to do with Ulys's contract thing, which is just it it requires a commitment to say, I'm going to be the kind of guy who's always on time. And the way to do that is to say, I'm going to commit to always being five minutes early. So, you get to a place early and you just hang out in your car and you, you know, take care of some texts or whatever. That's the way to be always on time. Okay. But are people good at perceiving time? No. We're actually quite terrible at it. Um, and some people are better than others. But one of the lessons that's emerged from my research on this stuff is that a lot of time is is illusory. Um, so you you may know I did this experiment years ago. I was very interested in this question of does time run in slow motion when you're in fear for your life? Because when I was a child, I fell off of a roof of a house. I almost died. I landed on my I landed in a push-up position and busted my nose so badly that they had to remove all the cartilage and so on. And I've had a terrible sense of smell ever since because I busted the cri cribopform plate and everything. But the part that interested me even as a child was that the whole fall seemed to take so long. It felt like, oh my god, that was this really long thing. Obviously, I was totally calm during it. I was thinking about Alice in Wonderland as I was falling and how this must have been what it was like for her to fall down the rabbit hole. Um, this is typical. I was 8 years old. Wow. And this is typical when people are in life-threatening situations is that there's a sense of total calmness and bizarre thought, but also it seems to have taken a long time. You know, people report this all the time when they're in car accidents. They say, "Oh, I I watched the hood crumple and the rearview mirror fall off and I was looking at the face of the other guy and whatever." People experience this in gunfights like police officers and so on. Everything seems to take a longer time. What happened is when I grew up and became a neuroscientist, I realized no one had ever studied that. And I got really curious about is it the case that time seems to run in slow motion while you're experiencing it or is it a trick of memory somehow? So I ran what to my knowledge are still the only experiments that have ever been done on this. Do you know about this? So yes and no. Yes, I'm familiar with the paper. No, I've never heard it this way. So keep going. Okay, great. So what I did is I rounded up 23 volunteer subjects and I dropped them from 150ft tall tower in freefall backwards and they're caught by a net below going 70 m an hour. I want to be in your experiment. Yeah, you you would have loved this. It's a re but it's terrif I did it myself three times first to make sure it was all running and it's equally terrifying all three times because you're falling backwards. Okay. What I did is I then built a device. My students, I built this device. It fits on people's wrist and it flashes information at them in such a way that we could measure the speed at which they're taking in information. Essentially, we're taking uh we're taking advantage of what's called flicker fusion frequency where we're flashing lights really quickly and you can see that at a certain rate of lights, you can see exactly what's going on. And just faster than that alternation rate, you can't see anything. Okay. So we draw people, we had them read the numbers on the wristband and we're finding out are people actually seeing in slow motion during a life-threatening situation. This is on 23 people, the results are very clear. People do not see any faster in a life-threatening situation. And yet when we ask people retrospectively with a stopwatch to judge how long their fall was versus watching someone else do the fall, their own fall felt much longer to them. Okay, turns out this is all a trick of memory, which is to say when you're in a life-threatening situation, you recruit not just your hippocampus for laying down memory, but a a secondary memory track mediated by the amydala, you're you've got this emergency control center, and you're writing down memories in this other secondary track. When you read that back out, you say, "What just happened? What just happened?" You've got all this density of memory that you don't normally have because you've written down every detail. So your brain says, "Oh my gosh, this is what happened and the hood crumpled and so on." Um, but it's because all we're ever conscious of is our memory of an event, as in what happened during the event. So when you write more down. You think it took longer um to uh to transpire. And by the way, this issue about memory equals time explains a lot of things. For example, the issue of when you're a child and a summertime seems to take forever and then by the time you're our age, summertime seems to disappear. It's because as a child, you're figuring out the world. You're writing down lots and lots of memory during that summer. Oh, this is the first time I ever saw a waterfall and went hiking here and did this thing. But by the time you're our age, you've sort of seen all the patterns before. And so what we're, you know, when we look back at a summer, we don't have much new footage to sort of anchor on. So we say, "Oh, well was the winter, now it's the fall. Okay, fine. I guess that was really fast. So, this is why time speeds up as we as we grow older. Glucose is a key player in how our body functions, not just in the long term, but in every moment of our lives. That's because it is the major fuel for our cells, especially our brain cells. 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Lingo has helped me to better understand what foods to eat, when to eat, and how things like a brief walk after a meal can help keep my glucose stable, and much more. If you'd like to try Lingo, Lingo is offering Huberman podcast listeners in the US 10% off a four-week Lingo plan. Terms and conditions apply. Visit hellingo.com/huberman for more information. The Lingo glucose system is for users 18 and older, not on insulin. It is not intended for the diagnosis of diseases, including diabetes. Individual responses may vary. I mean, I feel like these are what you're covering today is uh like the the most interesting things about life and experience. I have a question about um the fall experiment. Yeah. Is it accurate to say that your perceptual frame rate during a highly stressful experience is not different? Is no different. You're not taking uh a um higher frame rate movie. Yeah. Okay. Which is more frame rate is how they generate slow motion for instance. Makes sense. Like as opposed to strobe frame rate or you know just right. Um but that in some sense your unconscious frame rate is because the amydala is tracking more information than you normally would have have access to in say a calm everyday experience and so the memory is higher frame rate but the experience is not you know yeah it's really close I wouldn't say I wouldn't use the term frame rate in there it's just that you have under normal circumstances you write down almost nothing you just everything's passing through you're not really remembering much but in an emergency situation, your amydala being the emergency control center says, "Everybody stop what you're doing. This is the most important thing going on. Everyone pay attention to this." So, you're noticing every detail and you're not used to that. So, just for anyone who knows what I'm referring to here as a basian issue, um you know, you you your brain thinks, "Okay, a certain amount of memory must equal a certain amount of time." Now, you've got just a lot more detail. And so, it says, "Oh, well, that must have been, you know, six seconds or something." I what I did by the way I collected hundreds and hundreds of subjective reports from people who had been in accidents of various sorts. You this guy got in a motorcycle accident and had you know come off the motorcycle and had turned over and over and over on the road and he said as he was rolling over and over he was like composing a little diddy in his head like a little song to the sound of his helmet hitting the road and so on because this is the kind of bizarre thought that people have. But it seemed to have taken a long time and when he saw footage of it afterwards, you know, the whole thing took whatever a second or two, but it seemed…

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