Andrew Huberman (Podcast Host/Announcer) (2:16)

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.

Andrew Huberman (2:35)

Dr. David Eagleman, welcome.

Dr. David Eagleman (2:37)

Thanks. Great to see you, Andrew.

Andrew Huberman (2:38)

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 an amazing career also in your laboratory work. And today I want to talk about all of it 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.

Dr. David Eagleman (3:23)

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 half baked brain and then let the world wire up the rest of it. And so, you know, 1953, Crick and Watson, I worked with Crick at the Salk, they burst into the Eagle and Child pub and said, we've discovered the secret to life because they figured 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 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 is 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 and 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 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 succeeded. We've gotten off the planet, we build skyscrapers and compose 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, you know, if you were an alligator born 30,000 years ago, you'd be the same alligator, you know, eat, mate, swim, whatever, and you wouldn't be meaningfully different. But humans, because of our flexibility, we are the dominant species.

Andrew Huberman (6:00)

Such an interesting take on time and human evolution that. And I completely agree with you. I just had never thought of about it this way before that we land when we're born and we're absorbing the outcroppings of all the neuroplasticity that came before us. We often hear that, you know, that the human brain is kind of like a macaque monkey brain with a supercomputer added on top of it. Mostly the prefrontal cortex. A bit more prefrontal cortex. Prefrontal cortex, prefrontal cortex.

Dr. David Eagleman (6:31)

It's actually cortex in general.

Andrew Huberman (6:33)

Interesting.

Dr. David Eagleman (6:34)

We have four times as much cortex as our nearest neighbors in the animal kingdom. And that seems to be the magical.

Andrew Huberman (6:39)

Stuff, not just prefrontal cortex.

Dr. David Eagleman (6:41)

Right. And I'm sure the listenership knows this. But, you know, 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 it detects motion, things like that. If you plug auditory information into it, it becomes auditory corte 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 somatosensory. But all this stuff is really flexible. 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 Mergonka Sor at MIT where he, in a ferret, took the visual information. Visual. The optic nerve, and he plugged it into the visual. Sorry, into the auditory cortex. And then 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 one trick 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 squirrel or a cat or even a macaque monkey, you throw some food in front of it. 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, I'm on a diet, I'm trying, whatever, 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. To simulate what ifs, 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.

Andrew Huberman (8:54)

A couple different questions. I'm a big fan of Magranka's work and I'm so glad you mentioned that work. 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 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, maybe auditory processing, because they rely on it more. So there's really no blank Real estate in the cortex, it's all used.

Dr. David Eagleman (9:30)

That is exactly right. So it turns out, you know, right, people who are born blind, what we call the visual cortex in 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 at touch and so on. They can discriminate things much more finely. Same with people who go deaf. The auditory cortex, all that real estate, nothing lies fallow 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. 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 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 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. And that comes at the cost of other things, let's say social skills that might be needed. But the general story is if you devote a lot of real estate towards something, you're going to get really good at it.

Andrew Huberman (Podcast Host/Announcer) (11:07)

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Andrew Huberman (11:30)

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Andrew Huberman (13:28)

Know if you saw this study that was published in Science recently that explored 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 specializing too early on average doesn't play out so well in terms of kind of peak of success later. Now there are exceptions, right? But turns out that being a bit more diversified in your physical activities and cognitive activities as a young person into the early teens even and beyond is more beneficial. And this to me kind of runs counter to my images of like Tiger woods putting golf balls with his dad when he was kind of still waddling he was so little, right? And then he becomes Tiger woods or the William sisters who were tennis 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 every person. I mean, you have kids, and some of us still are kids who are listening. And we all have plasticity into adulthood. 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.

Dr. David Eagleman (15:15)

So this is really interesting because 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 we find with chess champions and golf champions like woods and so on. 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 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 serving tennis or something, you're taking that from the software to the hardware of the brain. Let's say I'm an amateur tennis player and there's Serena Williams. I'm playing against her, 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 this is one of the big things about plasticity. So people get extraordinarily good by doing Things over and over. These three women, the Polgar sisters, who are chess champions, they're 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 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, you know, you might get better at both of them. But I gotta say, when children grow up, let's say trilingually or even bilingually, 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.

Andrew Huberman (17:49)

Kids still do your second language homework in California. It's, you know, growing up here, it's very useful to know English and some Spanish. Yeah, I mean, very, very useful. In fact, I wish I'd gotten better at Spanish when I was a kid. And my father's born and raised in Buenos Aires.

Dr. David Eagleman (18:05)

Yeah.

Andrew Huberman (18:06)

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, the musical instrument for your own enrichment and those around you. But the second language thing, I think is extremely useful, at least in California. I find it to be very useful.

Dr. David Eagleman (18:23)

But you know, 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.

Andrew Huberman (18:30)

Yeah, but Google Translate is not Google relate.

Dr. David Eagleman (18:33)

I totally agree.

Andrew Huberman (18:34)

You know, I mean, it's. And I'm not, I'm hardly fluent, but I can get by now I'm pretty good. I've been practicing my Spanish more and more, and just by virtue of living in Southern California, that just happens. But I think knowing a second language and being able to have that kind of face to face conversation with someone, it's, even the struggle of it is enriching in a way because you're forcing your brain to do some work.

Dr. David Eagleman (18:55)

My father spoke eight languages fluently, without accent. 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 way, 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. 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 that cocktail happens to map onto curiosity or engagement. I'm slightly older than you are, but 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. Cause 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 and 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 it sticks.

Andrew Huberman (20:41)

Super interesting. I hadn't thought about it that way. I guess I'm reflecting my age 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 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 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.

Dr. David Eagleman (21:20)

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. The other person. 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.

Andrew Huberman (21:34)

Yeah, it's dissolved 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.

Dr. David Eagleman (21:44)

They're the father or whatever. Yeah, yeah.

Andrew Huberman (21:46)

Or the grandfather or whoever. Or the grandmother in some cases. Who knows. Now it gets checked against the Internet and Claude for me or Chat GPT for, for a lot of other people. I realized that the question I'm about to ask can't be answered 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 what the inputs are, some depending on our circumstances.

Dr. David Eagleman (22:21)

It depends what you mean by we. So infants, of course, we have no control over that.

Andrew Huberman (22:24)

As an adolescent, as a teen, as a twenty year old, assuming plasticity extends into adulthood. Still as adults, although it's harder some control over what one learns or does. What do you think are sort of the core elements to 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. 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 maybe kids don't need to learn a second language, but what do you think are sort of the essentials? I mean, obviously learning to communicate and understand, learning to move. But do we have some sense of how you check off 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 doing the quote unquote best that you can with your brain. This is a tough question, I realize.

Dr. David Eagleman (23:26)

I mean, I would say two things. One is try to maximize along every axis. So try to be an athlete, try to be a scholar, try to be somebody who's good at social life and has a lot of friends, 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 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.

Andrew Huberman (24:34)

What are some good ways, in your opinion, to access critical thinking and creativity? I can imagine a number of them, yeah.

Dr. David Eagleman (24:39)

Here's something I find very optimistic about. AI in the realm of education. 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, 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, okay, 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 creativity. Goethe, the German philosopher, had said, there are two bequests 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.

Andrew Huberman (26:31)

Love that, and thank you for making it practical. That's something I think any and all of us could invest some more time. And I also agree it's very easy to waste time on, on, on the Internet. I have a separate phone for social media.

Dr. David Eagleman (26:44)

Oh great.

Andrew Huberman (26:44)

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 amazing. People send me things by text. 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.

Dr. David Eagleman (27:06)

Yes.

Andrew Huberman (27:07)

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 it like a, like a perfect. Like watching a show or doing something that I would devote time for is to not always just scrolling in the background.

Dr. David Eagleman (27:19)

Do you find yourself picking up that phone sometimes? No.

Andrew Huberman (27:22)

And if I do, if I find myself doing that reflexively, I have a, what I call a super max prison lockbox which you can't code out of. And the fun for me and get 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 four hours and then I hit the super max button and then there's this 15 second countdown and then I'll go, five, six, seven, eight, nine hours and I go, okay, cool, like nine 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 that extra hours that I add on and that last thing, it feels like a gift to myself and 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. Before we do that though, 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 some sort of game, who knows? That gives us our capacity for plasticity. More height, more width, as opposed to just the same principles. You need to focus on the thing, then you need to make errors and you need to do some error correction. You get to sleep that night. You rewire, you keep trial and error. We know 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 plasticity?

Dr. David Eagleman (29:01)

Two words, seek novelty. That's the whole game, is you gotta 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. Obviously, we're in a world that's moving very fast. So just keeping up with the technology and figuring out, whoa, there's this new opportunity here with this piece of software, whatever, all that stuff is great. This is the critically important part. You may know these studies. There's been this study going on for decades now called, what is it, the religious orders study 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, you know, examine them, do autopsies on. 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. Contrast this 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. 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. Oftentimes people will ask me, like, an older person will say, hey, I do crossword 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've got good predictions about what's going on, then it stops changing. I mean, that's. Its goal, is to stop changing. And if you're constantly pushing and challenging it with things it doesn't understand, then it'll keep changing.

Andrew Huberman (32:03)

Amen to that. I've been trying to beat the drum that the agitation that one feels when trying to learn something new, it's actually a reflection in part of the catecholamines.

Andrew Huberman (Podcast Host/Announcer) (32:13)

Right.

Andrew Huberman (32:13)

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, because the neurons are not thinking, they're firing.

Andrew Huberman (Podcast Host/Announcer) (32:26)

Right.

Andrew Huberman (32:26)

And so. And so that neurochemical milieu associated with frustration is one of the triggers that generates plasticity. Which actually, if 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.

Dr. David Eagleman (32:41)

Yes.

Andrew Huberman (32:42)

And some of the more interesting ones involve boosting the levels of some neuromodulator. Dopamine or acetylcholine or norepinephrine or epinephrine, serotonin. But what's so interesting to me is that it seems like you can boost the levels of any of those and get plasticity. It's not like one neuromodulator gives you the opportunity 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 serotonergic. I remind people of this because people really like to 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 it's 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 equal potential of neuromodulators where boosting any one of them open plasticity or the window or the opportunity for plasticity?

Dr. David Eagleman (33:45)

Okay, a few things on this. As you well know. You know, all the neuromodulators exist in a dance with each other. 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 on. And it's probably not the right way to look at it. It's 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 baby, 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 a pointillist artist who just dabs things here or there. You get acetylcholine release very locally 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. We always find when we tweak these things that it's complicated. Just as one example, with Parkinson's, people have less dopamine and so the medications are to crank up the dopamine. But what that led to, you may know this fascinating story. This is probably 25 years ago now, where observant clinicians noted that people on these Parkinson's medications were becoming hyper compulsive gamblers. They were blowing their family's fortune on online gambling and Las Vegas and so on. 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 contraindication that's listed on the bottle. You know, if you notice gambling, turn down the amount here. So anyway, whenever we start dialing these around, we always find things that are a little bit out of our predictive realm. But 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, you know, there were studies by Logothetis 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 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.

Andrew Huberman (37:25)

Perfect analogy for people to understand, you know, how, how much challenge to embrace. I mean, not trying to, you know, defrag the whole system, you know, 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 nowadays they call it one shotted. They take ayahuasca a couple times and they are forever different in ways that that does not serve them. Those examples don't get talked about quite as often as the Also, many people who, you know, seem to benefit from these things. So plasticity, it seems, is not the goal. Directed plasticity is the goal.

Dr. David Eagleman (38:06)

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 have built. And, you know, that keeps changing. We're always a moving target 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, oh, I wish I could learn this as well as I did when I was seven, but generally it's not a state that you would desire.

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Andrew Huberman (39:36)

You've mentioned a few times future self. I think all of us are inherently interested in our future selves and whether the things of our past, present and what we have control over going forward is going to put us in the best future self possible.

Dr. David Eagleman (39:51)

Right?

Andrew Huberman (39:51)

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 just avoid that loop de loop and get real stoic about it and just live in 10 minute time blocks or 1 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?

Dr. David Eagleman (40:21)

Yeah. Our capacity to think about our future selves is the most special part of being humans. And if we didn't do it, if we said, I'm going to be stoked about, yeah, you'd eat the cupcake. And you do what? Like all the things that wouldn't serve.

Andrew Huberman (40:35)

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. Right. What would the stoic do?

Dr. David Eagleman (40:43)

That's right. So, 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, to do all the things 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, 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 want to stay fit. And so in part of your brain says, okay, maybe I'll eat part of it, but I'll go to the gym later or, you know, I promised my girlfriend that I'll go do this thing. Like, we've got all these voices. You can cuss at yourself, you can cajole 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've 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, 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 Ulysses Contract. And where this term comes from is in the Odyssey, Odysseus, otherwise known as Ulysses, 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 everyone crashes into the rocks and dies. Ulysses really wants to hear the song, but he knows, like any mortal man, he's going to fall for this and crash in the rocks. So what does he do? He has his men lash him to the mast so he can't move. He has them put beeswax in their ears so they can't do anything. 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 Ulysses of sound mind is making a contract for the future Ulysses, who he knows is going to behave badly, so he's lashing him to the mast. 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 lockboxes 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 gonna be tempt. So you take away that temptation. By the way, I recently met 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.

Andrew Huberman (44:07)

Yeah, I don't have a money spending thing, and I actually have pretty good control 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 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 things that I feel like are trying to control me.

Dr. David Eagleman (44:29)

Yeah, exactly.

Andrew Huberman (44:30)

Which I do not like.

Dr. David Eagleman (44:31)

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 Ulysses contracts. And I've been studying this for years and I. Yeah. Anyway, so I decided 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 cut those off. I'll give a couple examples. One is it's super useful to get social pressure involved. So, for example, I'm guessing you and I both do this. 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 gotta go because he's gonna be there. So getting social pressure involved is a good idea. I found this thing where it's 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 jabs, jumping jacks, and they scream your name until you come out.

Andrew Huberman (45:43)

Amazing.

Dr. David Eagleman (45:44)

Yeah, it's really good to get that. To commit to that sort of thing so that you're really going to show up. 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 Ulysses contracts, but what they have in common is how do you lash yourself to the mask? So you'll Keep the good behavior you want.

Andrew Huberman (46:29)

Yeah. The example of this woman writing the check is interesting because I could ask, why couldn't she access her inner. Clearly has a lot of inner fight. Right. Like, she really stands so strongly in one camp, which I agree, the kkk, horrible organization. You would never want to support them in any way whatsoever. And. 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 access our best choices. 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 we can't handle the discomfort of our present self. It's almost like. And so we tether those in this Ulysses contract.

Dr. David Eagleman (47:26)

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. 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 alcoholics anonymous is, clear all the alcohol out of your house. Because you might think, okay, I'm done. I'm firmly gonna 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 to 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, we can think about who we want to be. It's worth setting into place some walls.

Andrew Huberman (48:24)

So that's about avoiding bad behaviors. 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. How does Ulysses contract play in when it's not about the sirens? When it's about 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 in general? Yeah, better or worse than avoiding bad behavior.

Dr. David Eagleman (49:00)

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. So it's just as important with the positive things to hook things to that. 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. And then you've given your money to this company and you have to get to that point so you get your money back. There are lots of ways to do this. You know, obviously putting, you know, I think you had James clear on a little while ago. And there's all kinds of good ideas that he's got about, you know, put your running shoes near the door or whatever so that it's easy, 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 gonna be a little bit lazy and tired.

Andrew Huberman (50:08)

I have friends that are. I'll just call them what I would call them to their face. Cause it's a friendly exchange. Are kind of neurotic, right. They tend to overthink things. If they're going to go running at 8:00am and it's 8:02, they're like, I can't go because it's 8:02, not 8. I'll go at 9. 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. I think we assume that the chatter, the neuroses, doesn't exist for them, but I think it does. They're just better at saying, like, ignoring that inner voice. 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.

Dr. David Eagleman (50:51)

Yeah.

Andrew Huberman (50:51)

And it's interesting to think about, okay, different career paths, different life requirements and so forth. But I feel like people fall into 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. I won't tell you where I land. I think I'm kind of in the middle. No, I'm just kidding. It depends on what's at hand. For most people, I think. What do you think that's about? The ability to suppress the various versions of oneself or not the inner voice?

Dr. David Eagleman (51:32)

Yeah. I would say one of the most fascinating things we've discovered in neuroscience, for my money, is just this issue that along anything we measure, there's a spectrum. So just take something like the internal voice. For my wife, for example, she describes it as her inner radio. She's always hearing her inner voice. I don't really have one. I just never hear that. So we're on opposite ends of the spectrum that way. But one of the things I've studied is aphantasia all the way to hyperphantasia. That means 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 hyperphantasia. Some people have no picture at all in their head. That's called aphantasia. And. And everywhere, everyone is somewhere in between on the spectrum.

Andrew Huberman (52:16)

What does the middle look like? So if I do that, if I. Maybe everyone can do this right now. It's a fun experiment. If you're driving, don't close your eyes.

Dr. David Eagleman (52:25)

Picture sun coming over the mountain and the rays of the sun poking through the clouds. And then it starts raining, and rain's coming down. 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 1 to 5, where 5 is a movie, 1 is no visual at all, and 3 is in between. Where do you stand on that?

Andrew Huberman (52:50)

I feel like I can see it, quote, unquote, in my mind's eye, but it's almost like I'm looking at a silhouette of it. So even though I want to see bright rays of sunshine, one of my favorite things in life, I know they're there, but they're actually pale yellow. It's almost as if it's more opaque than it would be in real life.

Andrew Huberman (Podcast Host/Announcer) (53:08)

Yeah.

Andrew Huberman (53:08)

You're saying people with hyper. Hyperphantasia see it as a. The same way I would on.

Dr. David Eagleman (53:14)

On my phone, Essentially, yes. They're seeing it like. Like vision now I happen to be aphantasic, 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. For years, I've talked with Ed Catmull about this. Ed Catmull is the guy who started Pixar. Pixar with all these terrific animated films and so on. 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 aphantasiac. 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 magisterium of Pixar. But 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, 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, okay, how does that work? And so on. And they get better at drawing as a result. And that's why all his best animators and drawers are people who grew up aphantasic.

Andrew Huberman (54:36)

Interesting. I'm just thinking about that movie. Have you seen that movie, Bowfinger? No. With Steve Martin and Eddie Murphy, which is. Bowfinger is the. You know, for those just listening, it's where you put kind of make two, you know, L, an L and a sort of reverse L. And it's like how, you know, it's about making a movie in la and it's hilarious. It's spectacularly funny. It's got those two folks I just mentioned, Heather Graham, a bunch of other people, 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 a 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. Here's the script, and then they can't really imagine it, and so they have to put more work into materializing it.

Dr. David Eagleman (55:27)

Yeah. 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. So they just end up getting more practice and they get better at it.

Andrew Huberman (55:47)

I love this stuff. Because what we're really getting at here is, 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 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. 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 fill in blanks.

Dr. David Eagleman (56:39)

Right.

Andrew Huberman (56:39)

There's, you know, I.

Dr. David Eagleman (56:40)

That's right.

Andrew Huberman (56:41)

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.

Dr. David Eagleman (56:48)

Right.

Andrew Huberman (56:49)

So. And maybe that's best. So big, big picture question. Do you think that. That human evolution and the progress of building technologies reflects the fact that people get siloed into 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 detrimental to our species if everybody got sort of a core neuroplasticity training, learning how to do a little bit of everything?

Dr. David Eagleman (57:26)

Right.

Andrew Huberman (57:28)

Or is 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.

Dr. David Eagleman (57:41)

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. He's got like, I don't know, seven feet between his fingertips or something. There's no way I'm going to be able to be as good as he is. That's a genetic thing that he drops in the world with, that I don't. Fine. 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 can take any different trajectory as long as it still exists within the ice cream cone. Okay. So, 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. 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 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 this extraordinarily complicated formula of things that we'll never understand, but they go through one door and not the others. Kierkegaard 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 saxophonist or whatever, but you're going to Die having done exactly what you did did 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.

Andrew Huberman (59:58)

Kierkegaard seemingly understood that the nervous system starts out hyper wired and then a lot of learning is the pruning back of connections and strengthening of the remaining ones.

Dr. David Eagleman (60:09)

Exactly right. Exactly right. So as you of course know, 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 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 hyper connection 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 the way the pruning happens is based on what you're experiencing in the world. The world is what prunes your garden and strengthens particular paths and lets other.

Andrew Huberman (60:44)

Paths go as a bridge, perhaps between plasticity and time perception, which we've been sort of doing already. I have this practice that I've been doing for a few years in hopes that it's beneficial for something, and I'd just like your thoughts on it. I'm not looking for approval here, truly, but here's the idea. I was struck by the somewhat obvious thing that we can close our eyes, focus on our interoception, our skin, our breathing. We can meditate, bring our awareness into the quote, unquote, present the breathing seems like a good way to do that. 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 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'd like your thoughts on that. And I just started devoting a little bit of time to stepping from one of these to another and just spending some time trying to think and exist in the different time domains in my head. And so I'll do that maybe for two, 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 because I felt like it's not a meditation, it's a perceptual exercise. 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 maybe what we can do with this? Or could we evolve this perceptual exercise so that I and others, perhaps, if they want to, can start to access different 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 choppy here, but this is something that feels very important.

Dr. David Eagleman (62:54)

I love that. I think that's brilliant. 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, that deal with thinking about long eras of time and seconds and sub seconds. Totally different mechanisms going on here. And we can demonstrate this in the laboratory. So time perception is something I've been studying since graduate school and I'm happy to say I've got papers in Science and Nature and the top journals on this topic. Why? Because it's such a weird thing that's so understudied about why we perceive time the way we do. So let me say a few things about it. One is that it is these longer timescales what you're referring to, thinking about being 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 seventh grader and you talk about the Roman Empire and What was happening 2200 years ago, it doesn't mean anything. It's like, okay, 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 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. Eventually you get outside and you look down long highways in Utah and you really start getting a better sense of this. To my knowledge, there's no data on what it would be to sort of throw yourself back and forth between these different space time scales. I love it though. One of the classes I teach at Stanford is called Brain and Literature. I've always been a lover of literature. And one of the things that I love is when authors do exactly this, where they zoom in on something really tight and they really paying attention and then they zoom way out. That is the most extraordinary sort of feeling. So anyway, I commend you on coming up with that version of space time meditation or whatever it is. That's very smart.

Andrew Huberman (65:13)

Yeah, it was born out of this thing, you know, the, the Victor Frankl 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, 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, and you know, then you go for a.

Andrew Huberman (Podcast Host/Announcer) (65:39)

Walk or a hike.

Andrew Huberman (65:40)

And I have this obsession with the idea that when we see horizons, we have a different time perception than when we can't see horizons. And there's too many variables to do this right. You could do it in VR, in a VR experiment, but. Because when there are close walls, you have claustrophobia. But there are ways 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, and I'm a scientist and a weirdo, so I, I, I do these things. But you're the expert in time perception. So I wanted to ask, and I also want to ask about time perception. How good are people at perceiving time? And why am I always late.

Dr. David Eagleman (66:25)

Then? Why are you always late? That has to do with Ulysses contract thing, which is just it, it requires a commitment to say I' 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. 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. So 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. Cause I busted the crib form 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. This is. I was 8 years old. 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 watched the hood crumple and the rearview mirror fall off and I was looking at the face of the other guy and whatever, 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 that?

Andrew Huberman (68:23)

This? Yes and no. Yes, I'm familiar with the paper. No, I've never heard it this way. So keep talking.

Dr. David Eagleman (68:29)

Okay, great. So what I did is I rounded up 23 volunteer subjects and I dropped them from 150 foot tall tower in freefall backwards. And they're caught by a net below going 70 miles an hour.

Andrew Huberman (68:41)

I want to be in your experiments.

Dr. David Eagleman (68:43)

Yeah, you would have loved this. But it's terrifying. 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 back right backwards. Okay. What I did is I then built a device. My students, I built this device that 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 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 drop 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 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 secondary memory track mediated by the amygdala. 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. 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're in a life threatening situation, you write more down. You think it took longer to transpire. And by the way, this, 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, the 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, we've sort of seen all the patterns before. And so what we're doing, you know, when we look back into summer, we don't have much new footage to sort of anchor on. So we say, oh, well, it was the winter, now it's the fall. Okay, fine, I guess that was really fast.

Andrew Huberman (71:14)

Amazing.

Dr. David Eagleman (71:15)

So this is why time speeds up as we as we grow older.

Andrew Huberman (Podcast Host/Announcer) (71:18)

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Andrew Huberman (72:25)

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Andrew Huberman (Podcast Host/Announcer) (72:25)

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Andrew Huberman (72:48)

I mean, I feel like these are. What you're covering today is like, like the most interesting things about life and experience. I have a question about the fall experiment.

Dr. David Eagleman (72:59)

Yeah.

Andrew Huberman (73:00)

Is it accurate to say that your perceptual frame rate during a highly stressful experience is not different?

Dr. David Eagleman (73:08)

Is no different.

Andrew Huberman (73:09)

You're not taking a higher frame rate movie. Okay. Which is more. Frame rate is how they generate slow motion, for instance. Makes sense as opposed to strobe frame rate. Or I just.

Dr. David Eagleman (73:21)

Right.

Andrew Huberman (73:22)

But that in some sense your unconscious frame rate is because the amygdala is tracking more information than you normally would have access to in, say, a calm, everyday experience. And so the memory is higher frame rate, but the experience is not, you know.

Dr. David Eagleman (73:39)

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 amygdala 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 Bayesian issue, your brain thinks, okay, a certain amount of memory must equal a certain amount of time. Now you 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 know, this guy got in a motorcycle accident and had, you know, come off the motorcycle and turn over and over and over on the road. And he said as he was rolling over and over, he was like composing a little ditty 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. But it seemed to have taken a long time. And when he saw footage of it afterwards, the whole thing took whatever, a second or two, but it seemed to him to have taken six seconds. But again, it's in retrospect when he's thinking what happened? What was the event like? By the way, I'll just mention after I published this paper, sometimes people would come up to me after a talk and say, I know that's not true because I was in a car accident, I know it took a long time. And I said, okay, look, the person on the passenger seat next to you who was screaming no. Did it actually sound like they were saying no? Because if time we're running in slow motion, that has to be the consequence that everything is spread out. And they had to allow that it didn't sound like sounds were distorted and so on. So it is really about having more higher density of memory.

Andrew Huberman (75:31)

Super interesting. What about for non stressful, non life threatening circumstances? Like let's pick a purely happy event. Yes, yes, one would hope day of one's wedding. Yeah, you know, I was about to say birth of a child, but depending on how you know who's doing the majority of the work and how stressful it was. I mean, of course the birth of a healthy child is a super wonderful event, but it can be very stressful too under certain circumstances. So let's pick something purely happy. Right. A terrific wedding, a great party, maybe a vacation with your spouse or family where it just is like bliss day. Are you clocking more experiences?

Dr. David Eagleman (76:12)

So anytime you're doing something novel, and this actually ties back to the conversation we had before about seeking novelty, whenever you're doing something novel, you're writing down more memory. And that's the whole key. So, for example, if you spent your last weekend going off and doing something wacky that you'd never done before, parasailing and over sharks or whatever, the thing is, you'd come back and you'd think, wow, it seems like it was so long since Friday, now it's Monday. It's been forever since I was back in the studio. But if you have a normal weekend where you're not doing much of anything but surfing Instagram or something, then you come back and you think, God, it was just Friday. The difference is just how much memory you clocked and therefore what you can draw on in terms of footage. I actually think this happens with drugs, where people, you know, people sometimes have the experience on marijuana, where they think, wow, I've been standing here forever. And it's because they're having a hard time anchoring down on footage about, like, when did I arrive to the kitchen, when what happened since I've been here? And so they just, they don't know. But anyway, the point is, sometimes people have this idea about time speeding up as you get older. They say, well, you know, to an eight year old, a summer is this big fraction of their life, but to a 50 year old, it's a smaller fraction. But I don't think that's it at all. It's that it's what you did this past weekend can make the weekend seem longer. When it comes to some great new event like the birth of a child or a wedding or whatever it is, it has to do with how much attention you're paying and how much memory you're writing down. And that means it is to some degree in our control. If we really attend to things and write down memories instead of letting life just wash over us, we can seem as though we've lived longer. I'm not talking about longevity, I'm just talking seeming as though you've lived longer, which is, look, here's something that I try to do all the time is just switch stuff up. For example, brushing your teeth with your other hand, not hard to do, but it's just one of a million ways of knocking yourself off a path. One thing I try to do every time I drive Home from Stanford is. I try to take a different drive home, a different route home. You know, wastes an extra minute, whatever. But it's. I'm seeing new things. I'm observing new things about the neighborhood or whatever that I hadn't noticed before. One thing that's very easy to do is just rearrange your office. Like, push your desk over here, Take two paintings and just swap them on the wall. All this stuff is super easy, but it really matters. It's important because what it's doing is enhancing brain plasticity in the sense of just challenging. You know, your internal model says, okay, I've got this world. And then suddenly says, oh, there's something new. There's something interesting going on in this world. And it makes it seem as though you've lived longer because you're writing down more memories about. About everything.

Andrew Huberman (78:52)

Gosh, this time perception thing, I spend way too much time thinking about it. And. And I'm still trying to wrap my. My head around how much time we should spend trying to be present. So I have a. And this is not an official definition, but my kind of understanding of the dopamine system and addiction. As I say, and people have heard me say before, you know, an addiction is a progressive narrowing of the things that bring you pleasure. It also involves continued use or behavior despite negative consequences. But I mentioned the other definition of addiction, Progressive narrowing of the things that bring you pleasure. Because I was trying to come up with some at least accurate, but not exhaustive definition of enlightenment. When people talk about enlightenment, all these monks who get so present through all this meditation, or people go to big Sur and they get, you know, they're so present, present, present enlightenment. I think of an. One definition might be, okay, I'm not the authority on this, but might be a progressive expansion of the things that bring you pleasure. But to really get pleasure out of a sip of water. I'm not terribly thirsty right now. If I take a sip of water, it doesn't taste anything like if I were very thirsty. But we need to pay attention. We need to be in the. What is paying attention? It's being most of the time in the present, right? Paying attention to these things. But if we spend all our time in the present, we eliminate Ulysses contract. So the extremes can't be good. But I think examining the extremes, like the free fall experiment, they're useful windows into time perception and how we measure life.

Dr. David Eagleman (80:32)

It could be that by establishing Ulysses contracts in many aspects of our lives, we get more of an opportunity to be in the Present, because we know, look, I don't have to worry about my future self. I'm not going to eat that cookie. I am going to go to the gym, whatever, because I've already set up up these contracts. I don't have any cookies in my house. I'm meeting my buddy at the gym, whatever. Then you have more of an opportunity to be in the present. You don't have to simulate all kinds of futures. Yeah, I think paying attention to things matters a lot, but we have to be smart about what we pay attention to. I mean, it might be lovely to really love the water and so on, but not your Instagram feed or something. So it's just a matter of, of thinking clearly about what you want to pay attention to and devote your memories to. And this, this translates into what you set up. Like I'm going to set up a dinner at my house. I'm going to invite my close friends and I'm going to have this dinner and pay 100% attention to this dinner. I'm going to be present at this thing because that's the stuff of life.

Andrew Huberman (81:29)

Where I'm getting to with this is that there's beauty and there's tragedy at every spatial scale, scale and every temporal scale. Right. Unfortunately, in my neighborhood, you know, this issue has not been resolved in many places. You know, we have a, we have a homelessness and drug addicted and mental illness population and those intersect in very complicated ways. That is so extreme that you can see people who are paying immense amount of attention to what anyone else would consider trivial, like the, the, you know, know, bits of dirt in the, on the sidewalk. And so, and we, and it's so tragic. Right. We can see that that's not a good use of one's time, attention and focus. Right. But there's also beauty at all sorts of scales. Right. I mean, I think one of the obsessions that people have with like fractals and, and you know, these organization at very small scales, all the way up to very large scales, is it, it brings us to this like, relationship with life. Like there's all this stuff we can't see and it's beauty at every scale. Scale. Tragedy at every scale.

Dr. David Eagleman (82:31)

Right.

Andrew Huberman (82:32)

I mean there, I don't even have to mention a tragedy at massive scale because they're all over the world and they have been throughout human history, frankly.

Dr. David Eagleman (82:38)

By the way, I was just, I was just in Las Vegas at CES giving a talk yesterday and as I was leaving I looked out the window and there was, you know, this Chinese lion statue. And there was this homeless woman smoking a cigarette and she was rubbing this thing very vigorously. And the guy driving the car told me, oh, that's good luck if you rub the statue. Which is of course ridiculous, but the woman was rubbing and rubbing and we're at a red light and I watched her for, you know, like 60 seconds doing this. And yeah, and it was tragic to me because her brain has set up an association which is if I do this action, there will be this result. That's what her future simulation is telling her. And as far as we can tell, that's not true that she'll have good luck from doing that. But yeah, that was an example of tragedy.

Andrew Huberman (83:21)

Yeah. It's almost like the worst thing for any human suffering from mental illness or not is to perseverate on one spatial or time scale to like get in the tunnel of the thing that's right in front of you or to be lost out. You know, you. We see people and we even know some people are arguably a little bit strange.

Andrew Huberman (Podcast Host/Announcer) (83:41)

And they don't.

Andrew Huberman (83:42)

Not maybe, perhaps to the extent of full pathology, but they have their head in the clouds all the time. You can't really function in life. They need handlers. Right. I know some creative people like this. The only reason why they, they are not like the first person I described.

Andrew Huberman (Podcast Host/Announcer) (83:55)

Is because they have handlers to handle.

Andrew Huberman (83:57)

All the stuff that's at closer spatial scale. Get the. Get organized, get, you know, and. But actually a good example. I'll just give a concrete example because he was so awesome. I didn't know him personally, but Shane McGowan, the singer for the Pogues, who had severe, this is not a secret, had severe issues with alcohol. His teeth had rotted out. Later in life, they gave him teeth. But I was once going to see the Pogues in San Francisco. Love the Pogues. And that day I got to the city early, brought my work up there. I see this guy walking along, Gary. I didn't know who it was at the time. He's got like this really nice, like it looked like almost like a silk shirt and the tag is still on it. And he's just shuffling out into traffic and I'm like, oh my God, this guy's gonna get killed. So I get out, it's Shane McGowan. And then his team comes running over like, oh, we got to get him back. He was so blasted, he didn't even know where he was. And apparently that's how he was much of his life. That evening he got on stage barely Made it to the microphone and gave a legendary. One of many legendary pogue shows. Right. I mean, it's just. And for those that don't know the pogues, you should look it up. And if you do, I mean, they're in tons of movies. And the love you till the end song that's in every romantic comedy, that's them. And you know, it's just so there are people like that and oftentimes the ultra creatives, they're adrift. But you can in it seems to help. I'm not suggesting the alcohol, but they. But to be able to kind of pull all that into the moment seems to be their super skill. Most people, it seems. And I. I wonder if you think a definition of mental health is the ability to switch out from these different time domains because you also don't want to be in a watchmaker mode all the time. That watchmaker needs to pay attention to his or her kids.

Dr. David Eagleman (85:37)

Well, I tell you, Albert Einstein said that he really enjoyed tasks like fixing a doorknob in his house or something. And I knew that all the time. I need lots of rep. I live in this very old house, house. And I'm doing lots of little dinky repairs all the time. And I love that just crossing these scales. But I do want to say something about addiction because I think this is an awesome example about brain plasticity and something that I wrote about in my book Livewired about this, which is addiction is all about brain plasticity. You put a certain drug in your system, and what your brain does is it upregulates the receptors for that drug, which is its way of saying, oh, I didn't know the world consisted of this stuff. Good, I'm going to prepare for this now and I expect more of it. So then you give it more and it says, great, I'm going to upregulate the receptors again. And it comes to expect that this is in the world. And then if you stop, you have these awful drug withdrawal symptoms precisely because you've changed your system. Now it's expecting the world to have that. So I draw an analogy between that and heartbreak. Because when somebody that you love, let's say, dies or leaves town or whatever, the thing is, is your brain has come to expect the presence of that person in your world, has thought, okay, the world consists of this. And now that person is gone. And heartbreak is a really painful physiological thing that you have to go through as your brain readjusts to the world without that person.

Andrew Huberman (87:04)

Something that I would hope no one would have to experience. But everyone loses people at some point or. Or a pet or. Or both. Do you think that constant engagement in, let's just say like TikTok type social media with it upregulates the quote unquote receptors or of expectation for it that make it harder for people to. To stop using it. Because the drug and addiction definition you gave, which I love, you know, dopamine receptors for methamphetamine or for cocaine or and so on. But. But for an experience, for gambling, for social media, the receptors become more like circuit activations or like the circuits of the brain anticipate it. And if they don't get it, do you think that there's a kind of a withdrawal like effect?

Dr. David Eagleman (87:53)

I don't know how I feel about this. I wonder. When we were growing up, people said, oh, it's the television. It's the television's ruining everyone's attention span.

Andrew Huberman (88:01)

You'll rot your brain. I remember.

Dr. David Eagleman (88:02)

It'll rot your brain.

Andrew Huberman (88:02)

My mom would kick us out. Yeah, it was. This was very common. She say, you got to go outside. She would lock us out of the house. We weren't allowed back in. She said, don't come back until. Until dark.

Dr. David Eagleman (88:11)

Yes, exactly.

Andrew Huberman (88:12)

We. We did not have the option to watch cartoons or for more than a couple minutes after school. We were forbidden. So she could get peace and we could get activity.

Dr. David Eagleman (88:20)

Exactly. And younger people might not know the te is called the boob tube, where a boob was like an idiot. And that was the idea. That's where the term YouTube, you know, was a funny derivation of that. But the. Right. So now what kids are watching is lots of content. We're all watching lots of content on Instagram, TikTok, much of which is great. It's well produced. It's matched to our interests. And so I don't, you know, are we addicted? Yes. Is it an addiction because it's offering better content than many other things in our life? In some sense, yes. So I'm a little torn on it. The other thing that we've all noticed though, is that people don't seem to be happy when they spend time scrolling on it. They're kind of tempted to do it, but when they finish, they never feel like, wow, that was really a great experience. They're kind of drained from it. So in that sense, it has the characteristics of an addiction where you keep going back to it even though you're not getting the high from it that you did the first time.

Andrew Huberman (89:15)

I will say, as long as I use it properly. I love social media and YouTube. I'm not just saying there's a political statement. Teach on YouTube. I learned from you, I learned from others. Like, the other day I wanted to learn about architecture. So, like, during my workout, I put on a YouTube thing and just listened to it. Like a basic history of certain architects in the United States. I was like, I learned so much. Like, we couldn't do that. It's awesome. It's just awesome. And then that set off in the algorithm some really good suggestions of some other things. Yeah. And then when I didn't watch those, it offered some other. And I'm like, down the rabbit hole of stuff that I never, ever, ever would have encountered. It's really cool.

Dr. David Eagleman (89:54)

This is precisely why. Why all these kids have the opportunity, I think, to be so much smarter than we were. Yeah. I'm just super enthusiastic about it. And now with AI, it can be even a whole different level. I mentioned this thing before about using AI to debate, but just even in general, just saying, hey, I'm curious about this. How does this, you know, how does a flying buttress work or something? Hey, chatgpt. Hey, Claude. And you get the answer. Wow, what a great. What a great opportunity for kids growing up. Yep.

Andrew Huberman (90:21)

Are you using YouTube to try and help you. You fix up these things in your house?

Dr. David Eagleman (90:27)

Oh, sure. Everything I fix, I learn how to do it on YouTube first.

Andrew Huberman (90:30)

Yeah, very cool.

Dr. David Eagleman (90:31)

Now I'm using AI to do it. I. I've got this lighting thing and I couldn't figure out, so I took pictures and I said, what am I looking at here? And where's the box and the transformer, whatever. And it was pretty good at. At telling me what. What to do next.

Andrew Huberman (90:43)

That's awesome. You have a company. This is not a promotional. Anytime I mention a company, but actually.

Dr. David Eagleman (90:48)

Wait, can I pause? Yeah, yeah. Neose Sensory, I actually sold six months ago, so I don't have it. Oh, okay. Yeah. All right.

Andrew Huberman (90:54)

So had a company.

Dr. David Eagleman (90:54)

Yeah.

Andrew Huberman (90:55)

Congratulations.

Dr. David Eagleman (90:55)

Thank you.

Andrew Huberman (90:56)

But neurosensory is a really neat idea of combining different senses. People wearing bracelets so they could feel sounds and. And so forth. Can anyone do this? Even if they're not deficient in vision or in hearing or in some other modality.

Dr. David Eagleman (91:11)

Yeah. So I got. I just got really interested in this topic about pushing information into the brain via unusual sensory channels. So, for example, as you referenced, I, you know, I built a wristband that captures sound and turns sound into patterns of vibration on the skin. This is for people who are deaf, and deaf people could learn how to hear that way. Why? Because this is the same thing that your inner ear, your cochlea does. It's just capturing vibrations on the eardrum and translate, breaking that up into different frequencies, shipping that off to the brain in terms of spikes, just these, you know, voltage spikes along nerve nerves. We're doing the same thing, except we're pushing it in through the skin. It goes up the spinal cord to a different part of the brain. But the brain can figure that out. How? Because it's doing correlations. It sees somebody's mouth move, it's feeling the sound, and it figures out how to hear that way. Now, this idea of sensory substitution, I wish I'd invented that, but it actually has a long history. And the more I research, I found out it goes back to the 1800s, when people first started, started asking, hey, can you push information into the brain in a weird way? So the very first One was in 1880s. They had a little. A little camera lens that would just detect light and dark and it would get translated into a buzzing on your forehead. And for people who were blind, they could tell, okay, well, there's a wall over here and then there's an opening over here, and so on. And then people worked on this. The first major paper was in 1969 in Nature. A guy named Paul Bakirita took blind people and he put them in a dental chair. And he had this thing that would poke them in the back, a grid of 40 by 40 little solenoids that would poke in the back. And he set up a video camera, and whatever the camera saw, you would feel that in your back. So if it's looking at a triangle, you feel that triangle poked in your back. If it's looking at a face, you feel the face. So blind people got pretty good at doing this, especially once he let them control the camera so they could move the camera any way they wanted. People got really good at being able to tell what was going on.

Andrew Huberman (93:11)

So it's following them around as they move through the world.

Dr. David Eagleman (93:13)

No, they were sitting in this dental chair. And that's exactly it. In 1969, the technology was really clunky and heavy and got hot and whatever, and there was no way to make it portable in a meaningful way. But as time has gone on, we've been able to do that now. And so Paul Bakirida's research, he passed away some years ago, but his research has continued with something called the brainport, which is again, for blind people. So with the brainport, the way this works is you're wearing this little camera on your head on glasses, and you've got this little electrical grid on your tongue. And so whatever the camera is seeing, you feel that on your tongue. It feels like pop rocks. So if I'm looking at the coffee cup in front of me, I'm feeling the outline of the coffee cup. And blind people can get so good at this. They can do things like, you know, throw a ball into a basket or navigate a complex obstacle course. Whoa. It sounds crazy, but the thing to remember is the way you normally see is your eyeballs are, you know, these. These devices embedded in your skull here that are capturing photons and turning that into spikes that race into the darkness of your brain.

Andrew Huberman (94:15)

Electrical signals.

Dr. David Eagleman (94:16)

Electrical signals, exactly. And so this is just turning what your tongue is feeling into spikes, these electrical signals that race into the darkness of your brain. And you can figure it out. You can learn how to see that we way. And again, it's with correlation, because you feel something with your fingers, maybe you hear something also. And so you're putting that together, and your brain says, oh, okay, I got it. There's a visual thing out there in the world. And the really wacky part, I'll just mention, is that people using the brain port who, let's say, used to have sight and lost it, they will report it is like sight. They say, I remember seeing, and this is like seeing, even though it's coming through their tongue. And with the neurosensory wristband that we built, I interviewed a guy after he'd been worrying about six months, and I said, look, when you hear a dog bark, do you feel the buzzing on your wrist? And then you think, okay, that must be a dog bark. He said, no, no, I hear the dog bark out there. Which sounds crazy, but obviously that's the same crazy thing happening with our ears. You know, we've got this whole mechanism going on that we're very used to, and so we say, oh, of course the dog is out there, but in fact, it's all happening in here, in the darkness of the skull.

Andrew Huberman (Podcast Host/Announcer) (95:21)

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Andrew Huberman (97:08)

Recently, I've been listening to a book that I read previously, which I love, by the way. I love Livewire.

Dr. David Eagleman (97:13)

Thank you.

Andrew Huberman (97:14)

I'm not just saying. I've read it like three times when it came out. I need to revisit it. I like to reread books. Yeah, I believe in rereading books. Ed Yong wrote a book called An Immense World. He's not a scientist, but he's a science writer. And it's about different sensory modalities that different animals use. And for an animal lover like me, it's. I found it really spectacular. But he says something that I totally agree with, which is that that we shouldn't think so much about whether or not a given animal is good at smell and bad at vision or really good hearing or the valuations of these things are really tough. With visual acuity, we can do it like, you know, an eagle, eagle resolution and versus human resolution. But when it comes to things like smell or touch, the better question, he says, and I agree, is how much does a given organism or person Rely on I, on a given sense will tell you sort of their abilities with that sense. I mean, there's some bounds on that, right? I, I can't echolocate like a bat, but I'm guessing that if I had to in order to navigate an environment, I could learn to echolocate. And I think there are, there are individuals who have learned to echolocate.

Dr. David Eagleman (98:27)

Exactly. In fact, the term was coined in 1930 in a science paper this gentleman wrote called echolocation in Bath. And blind men and blind people since almost 100 years now, can do this thing where they use clicks of their tongue or the tap of their cane or any kind of sound that they make and they listen very carefully for what's bouncing back to them and they can echolocate. It also turns out that seeing people can echolocate if it is relevant to them. You know, if you really want to put the effort into it, you can learn how to do it. Again, this just points to the plasticity of the brain, Brain, how good it is at doing this. Some years ago I suggested this Mr. Potato Head theory about thinking about the brain, which is whatever senses you plug in to a brain, it'll figure out what to do with that information. And so when we look across the animal kingdom, we find all kinds of very weird stuff. Not only eagle eyes and so on, but we find many animals, like let's say snakes, they pick up on infrared range of vision, which is invisible to us us. You've got lots of fish that pick up on perturbations and electrical fields. They have electroreception. You have this animal called the star nosed mole, which has this nose with 22 fingers on it and feels its way through these tunnels with like these 22 fingers, this weird thing. Lots of birds and animals and ins. Birds and cows and insects have magnetoreception so they can pick up on the magnetic field of the earth and they can navigate that way. For years I was staring at this stuff and figuring out how in the world does evolution happen so quickly that you can do all this? And this is what led me to this theory that mother Nature really only had to invent the brain once, figure out the principles of brain operation. And after that she could spend all of her time tweaking the genetics to make all these weird peripheral devices that you plug in and it's all plug and play. Whatever weird thing you come up with, you just say, okay, cool, I'm going to plug the in this in. And I'm sure the brain will figure this out. And it Always does. And that's exactly why we can do sensory substitution and by the way, sensory enhancement or sensory addition, where you can add completely new senses. One example is my colleagues at Osnabruck built this belt that you wear that's got vibratory motors all around it, and it's just a little digital compass on it, so it can tell where north is. So whenever you're, you know, whichever direction north is on your body, you feel that motor buzzing. So. So it might be on my left hip if north is that way, but if I turn around, I'll feel that on my right hip and so on. And people get really good at being able to detect which way north is. Just as one example, it's really easy to add new senses like magnetoreception in this case, and people can figure this stuff out.

Andrew Huberman (101:14)

So cool. As a fan of the X Men in particular, I mean, you mentioned magneto, but that's. But in general, I mean, yeah, different mutations give rise to different abilities. And. And that whole series of the X Men is really about kind of extremes of genetic mutations giving abilities. And there's some social discussion in there too. But let's talk about dreaming, because you mentioned that everything that we perceive as out there, beyond our reach, is occurring by virtue of electrical and chemical events in our brain. It's all vaulted in there. Dreams are. Are a unique situation where typically people's eyes are closed when they sleep and they're often paralyzed during REM sleep. And yet we have very visual dreams. I know you talked about this in Livewire, but please share with us what you think is the origin of the visual component of dreams. And I'm curious if it relates back to the visual imagery continuum that you mentioned earlier. Do some people just tend to have more visual dreams and other people don't?

Dr. David Eagleman (102:21)

Let me answer that second part first. We're not sure about that. I ask people all the time who are aphantasic or hyper fantasic about their dreams. It's hard to tell. I don't see something obvious there, which is to say, when there's dreams, you're getting this activity blasted into your visual cortex, so it's like vision. So. So let me back up to answer the question about. About my new theory about why we dream, because this has everything to do with brain plasticity. So here's where this got started. By about 2013, some of our colleagues at Harvard did this experiment where they put people on the scanner and they blindfolded them tightly, and they were looking at what was going on in the brain, and with touch and with sounds. And it turns out that if you're blindfolded, after about an hour, you start seeing a little bit of activity in the visual cortex when you are touched or when you hear something. Now, this was crazy because we know that if somebody goes blind, you know, hearing and touch will take over that territory. But we thought that was on the scale of years. And here what they were demonstrating is that within 60 to 90 minutes, you start seeing little blips of activity. Why? It's because you've got all this cross modal wiring. In other words, you've got neurons, let's say in the auditory cortex, that actually reach all the way over to the visual cortex. And same with touch neurons and so on. These are normally silent. They don't normally do anything, but they are ready. They're like silent sentinels that say, hey, just in case this territory stops getting used, I'm taking over. Okay, so here's what my student and I realized is that because we live on a planet that rotates into darkness every night, right? The visual system is at a unique disadvantage because when it's dark, you can still hear and smell and touch and taste, but you can't see. And obviously, I'm talking about evolutionary time before the invention of lights, which is the last nanosecond of evolutionary history. It was really dark at night and you can't see. And so, you know, you'd go into the corner of a cave and curl up and go to sleep. But the key is that the visual system was in danger of getting taken over during this long, extended period of dark darkness. So what we hypothesize is that dreams are the brain's way of defending the visual cortex against takeover from the other senses. And when you look at the circuitry, it's this very specific circuitry starts in the midbrain, goes to an area called the lateral geniculate nucleus, and plugs straight into the primary visual cortex. And that's it. Every 90 minutes, you have this volley of activity that just slams into the primary visual cortex. It doesn't go anywhere else in the brain. And so every 90 minutes, you've got this automated way of making activity happen there. And because we are visual creatures, we see that as a dream. We see a whole story. And because the brain is a, you know, a storyteller, we impose plot, meaning, and we have emotion that goes with that. But the key is this is the brain's way of defending territory in the dark. And so what we did then is we examined very carefully, 25 species of primates and looked at their brain plasticity and you can measure this with different proxies, like, you know, when they start to walk and when they get to reproduction, age and so on. And you know, some creatures, like the gray mouse lemur, which is a type of monkey, you know, he, they are born, let's just say pre programmed, you know, they pop out, they're really quick to stop, you know, to wean and reach juvenile age and reproduce and so on. Whereas you look at Homo sapiens, we're super slow, we've got these extended infancies and we take a long time to learn how to walk and so on. Okay? Because we're very plastic, we end up in the world half baked. Okay. Well, it turns out if you plot how much REM sleep each of these animals get, the more plastic the animal, like Homo sapiens, we've got tons of REM sleep. And by the way, this is mostly in infancy. Infants spend 50% of their time time in REM sleep. As you get older and your brain becomes less plastic, you have a drop off in REM sleep. And by the way, when you look across animal species of all types, you find that the animals that are born with extended infancies need to figure out how to do stuff in the world. They all have much more REM sleep, like eight times more REM sleep than animals that are born essentially mature, like cows and giraffes and zebras and whatever. They show up, they start walking in 40 minutes and so on. They have much less REM sleep than we do. So anyway, this is our hypothesis about why we dream. And it's the only hypothesis that makes quantitative predictions across species super interesting.

Andrew Huberman (107:03)

And we know that REM associated dreams are much more emotionally elaborate than deep sleep dreams.

Dr. David Eagleman (107:10)

Yeah, and the important part here, of course, is they're more visually elaborate. They're all are dreams that people can have in deep sleep. Obviously the way that this gets studied is, you know, is you rouse the sleeper and you say, hey, what were you just dreaming about? What were you just thinking about? And so if you do that during REM sleep where their eyes are moving around, they'll say, whoa, I was just, you know, riding across a meadow on a camel and this was what was going on. If you wake somebody during other stages of sleep, deep sleep, they'll, you know, they sometimes have something like, well, I was just considering this feeling I had of whatever. But it's not as visual, visual, it's not as rich. By the way, people who Are blind still have dreams, but their dreams are not visual. They have a dream like, oh, I was, you know, feeling my way around the living room, but all the furniture was rearranged. And then I felt in the corner and it was a jaguar and the jaguar started chasing me and I was trying to get away from it and so on. But it's sound, it's touch, it's things like that. Why? Because they're occipital lobe at the back of their head is not visual. It's coming for these other things. So the dreaming circuitry, which is very ancient, is just blasting activity into that area of the occipital lobe. And so they experience whatever that correlates with.

Andrew Huberman (108:19)

So cool. I want to move on to questions that I have about science and the law, but before I do, I just, I was told by a very, very talented magician mentalist recently that there's a guy down in Brazil who does magic tricks for blind people using only the auditory domain. And apparently if you blindfold yourself and you spend a bit of time around him, you can start to hear these magic tricks. And they're not just illusions of sound leaping. And so I said, well, give me an example. He said, you have to just experience this. This is something we should wear. We should meet this person. We should meet this person. Just a complete perceptual bend to try and get one's head around that.

Dr. David Eagleman (109:12)

By the way, counselors who are at these, who deal with these blind students at these blind schools, they're generally encouraged to blindfold themselves for like seven days. And they absolutely start having totally different experiences. Their brain starts changing.

Andrew Huberman (109:28)

I still won't do one of those darkness kids, cave retreats. People have tried to persuade me to do those. I have no interest. I love sunlight. I want to keep my circadian rhythm entrainment intact. I, I, you know, if that's what people want to do. Also I heard about someone going to do it and then they flipped on the lights at the end, they went back into scene and the place was covered with spiders. So clean the place up. Science and the law. Earlier we were talking about how under stressful circumstances, frame rate of perception is not increased, but memory density is higher.

Dr. David Eagleman (110:02)

Yes.

Andrew Huberman (110:02)

Can I therefore take the leap that, let's just say, and these are usually tragic circumstances, if there are two individuals, it's limited to two for sake of example, in a high stress, highly traumatic interaction, but one is more stressed than the other. Maybe they're the victim in that case that their density of memory is higher and therefore Even though there's a perceptual difference, perhaps more accurate than for the person who was calmer? Or is there a threshold at which stress limits memory, and therefore the person who is calmer has a more accurate memory?

Dr. David Eagleman (110:41)

Great question. Well, it turns out, first of all, what victims often have is what's called weapon focus. So if the other person has a knife or a gun, gun. That's all they remember. You know, describe the guy's face. I don't remember the guy's face because I was staring at the gun. So it turns out that what they pay attention to is sort of the wrong thing for forensics purposes. That's number one. But number two is this much deeper issue that even amygdala memories are not necessarily accurate. So, you know, our colleague Elizabeth Phelps did this experiment right after 911 in 2001, shortly after the event happened, she went and interviewed lots of people in downtown and midtown New York about what they saw on September 11th. And she was smart enough to interview them also about what they remembered from September 10th, you know, what they eat for breakfast today and so on. Okay. She then found them three months later. She followed up a year later. She ended up doing that 10 years later as well. What they found is that. That the traumatic memories of 9 11, even though those are amygdala memories, they drifted just as much as the memories of, you know, what they ate for lunch on September 10th. And so an unfortunate fact for the law is that memories are not accurate. They drift. Every time we check in on memories, we're changing them, and it becomes kind of like the operator game, where one person says something in the other person's ear, and the next person repeats that, next person repeats. There's a sense in which we're always playing the operator game with ourselves. You know, each time we pull up a memory, it's changing, and it gets modified and colored by new information that we have. So that's the bad news for the legal system. And so the legal system has gotten really smart about this over the last 30 years and tried to make sure that they take care of things that happen, let's say, with eyewitness identification. So one thing is, you know, police suggestibility. So if I'm. I'm looking at a lineup and I say, gosh, you know, I think that's the guy. And the police officer says, yeah, I think that's the guy. You know, I agree with you on that. Then what happens is when I go to court three months later, I. I say to the judge, yeah, I'm 100 confident, even though at the time of the lineup, I wasn't confident at all. But I come to think I am. There are many, many ways that things get implemented so that we can try to work around how lousy our memories are. Are one thing is separating witnesses right away. Because if you and I witness a crime and then you say, oh, my God, you know, I think the guy had long hair. And I say, no, no, I think it was short hair or whatever. We're influencing each other's memory, and things that we say end up changing what the other believes to be true. One of the classes I teach is the Brain and the law, and I do this thing every year. I sort of hate to give this away on a podcast, but here's what I. I do. I'm teaching the class, and a woman busts into the back of the classroom, starts screaming at me, says, are you Dr. Eagleman? I say, yeah. I say, excuse me, I'm teaching a class. She says, I've been sending you emails and you haven't written back and blah, blah. I say, excuse me, I am teaching a class. I'm happy to talk to you afterwards. I'm sorry, I don't get all my emails. And she says, well, I'm going to wait for you. Okay? So then I keep teaching the class, and then after, you know, 20 minutes or so, I say to the class, look, I'm going to call security, but I don't know what she looked like. I need you guys to write down what you remember about her. I said, all I remember is that she had a big mole on her left cheek. And that's all I was able to really see. And so everyone writes down their stuff. Now, not surprisingly, eyewitness identification is terrible. Everyone comes up with extraordinarily different descriptions of what the woman looked like. One thing they tend to have in common is this mole on left cheek, which I made up. The woman doesn't have that, but it's a demonstration that. That planting something even accidentally in my case on purpose will influence your memory of what you think happened. Obviously, it's an actor that I hire every year, but it demonstrates how poorly we remember things.

Andrew Huberman (114:39)

How does the legal system deal with forget eyewitness account, just of potential perpetrators, but just like recollection in general.

Dr. David Eagleman (114:50)

Yeah, well, this spent all the way up to the Supreme Court because some guy was accused from a. You know, he got sent to jail based on the eyewitness testimony of a woman who was up on the second floor seeing him from There and it was dark out. And he said, look, that can't be reliable eyewitness testimony. So this went to the Supreme Court and they said, look, sorry, but we can't guarantee reliable eyewitness testimony. And if we were to ever try to legislate that, that would ruin most court cases because most things are predicated on eyewitness test testimony. So what the legal system tries to do is just educate jurors about this, about how seriously to take it. Because, and by the way, I should mention, unfortunately, people are very swayed by this. Jurors are meaning, you know, a scientist might get up and say, look, there's this information or that, but then some, some eyewitness test, you know, eyewitness comes up on the stand and says, look, I don't know about all that science stuff, but I know what I saw. And the jury is swayed by, by that. So it's not easy to educate jurors on this because people fundamentally, even after education, feel like, okay, but I know that my memory is like a video camera. So anyway, but that's, that's one thing that the legal system tries to do and tries not to take it as, as gospel.

Andrew Huberman (116:05)

Are kids versus adults more prone to making up stories under these circumstances?

Dr. David Eagleman (116:13)

Exactly.

Andrew Huberman (116:13)

I, I think that I like most, most, perhaps I'm not going to speak for most people. I assume that kids tell the truth. I mean, kids don't always tell the truth, but that they don't understand all the incentives systems around lying that some adults do. And so I think we tend to believe what kids say.

Dr. David Eagleman (116:31)

Oh, but kids are actually more susceptible to memory manipulation. So Elizabeth Loftus at Irvine ran these studies years ago where she. Well, here's. Sorry, this is slightly different, but what she's doing in these cases is she says to someone, hey, I talked to your parents. She actually did talk to the person and she says, I found out a story from when you were younger about the time you got lost in the mall and you were found by this woman in a red hat who then, you know, found your parents and so on. And it turns out she can make these stories completely up and people will come to believe these. And when she interviews them a week later, they, that is just part of the fact of their life resume is that they were lost in the mall and found this woman in the red hat and so on.

Andrew Huberman (117:11)

I mean, that has huge implications for therapy to unearth, you know, repressed memories and so called repressed memories.

Dr. David Eagleman (117:19)

Exactly.

Andrew Huberman (117:19)

Maybe we need dogs to just, you know, who are completely unbiased to evaluate the veracity of some of these claims.

Dr. David Eagleman (117:29)

Well, here's what I think. Look, you and I grew up in a slightly different world where if I count the number of childhood photos that I have that I see, you know, I've got like little landmarks every couple of years. Oh, that was me at 8 years old standing in front of my house in Albuquerque, and that was me at 10 years old and so on. But now, you know, we have an Alexa in our kitchen and it's constantly cycling through the pictures of my kids who see that every day. They say, oh, that was me a few years ago, that was me last month, and so on. I think kids are now much more tightly tied to their memory in a way that might prove very useful. Unuseful in the sense that maybe you can't get away from your childhood, but useful in the sense of sense that at least your memory is going to be slightly more accurate because you're getting, you know, repetition, you're getting spaced repetition on it.

Andrew Huberman (118:11)

A previous guest hypothesized, I don't think this was based on real data, hypothesized that, you know, like if you go to a concert now everyone's taking photos of the concert as opposed to just experiencing the concert. They hypothesized that perhaps people have more memory of the photo taking experience and the photo than the actual experience, which is a kind of an interesting divergence like, of like the perceptual window that you're taking in information through. I'm not telling people not to take photos, but it is. Or videos. But it is sort of interesting that you're at a concert that, you know, thousands of people are at and everyone's taping it and projecting them. Maybe it's because people want to project themselves into the concert for their friends and followers to see.

Dr. David Eagleman (118:54)

I suspect it's a social issue. Yeah, everyone wants to prove that they were there. You know, I went and saw the Mona Lisa at the Louvre recently and every person there was just taking a picture of it instead of standing there looking at the damn Mona Lisa. But here's my suspicion is that they might have a slightly less present experience at the moment, but maybe it also lasts longer in the sense that every once in a while they see that picture themselves at the concert and they remember it. So maybe the area under the curve is the same.

Andrew Huberman (119:23)

We live in a polarized world right now. I think it was always polarized, but it seems increasingly so is it more polarized? And you've done some interesting work on the neuroscience around polarization. And I think it's just important for us to be aware of the fact that we're all prone to this.

Dr. David Eagleman (119:46)

Yeah.

Andrew Huberman (119:46)

And perhaps also, I would hope to also push back on it. I also feel like people like to be in the echo chamber that there might be some dopamine reward or other neuromodulator reward for kind of verifying what we think to be true.

Dr. David Eagleman (120:03)

I also think this is a social thing. I think you can't even talk about beliefs that we hold without talking about what that means for our identity and for what team we're on. Okay, so let me back up. I think we're not any more polarized than ever before. Just as an example, look at the 20th century. You've got, you know, if you look really what happened with Nazism in Europe, in Germany, or fascism in Italy, or what happened in Cambodia with Pol Pot, or in Rwanda, or the Chinese and the Chinese and Russian communist revolutions, all these things were extraordinarily polarized moments where people took up arms and killed their neighbors. And that was all pre social media. So I don't think that has much to do with it, except that I do think maybe we're more. More aware because it used to be that everyone was in their echo chambers also. Nothing new there. But all of your friends and neighbors and whatever all believed in whatever. And so you didn't realize there were other people who believed other things. But I think now we're just much more exposed to that. Okay, so polarization. Nothing really new about that. But it's very important for us to understand this. So one of the experiments we did in my lab was the following. We put people in the brain scanner, fmri. They see six hands on the screen. All the hands look pretty much alike. And the computer goes around, doot, doot, doot, doot, doot. And it picks one of the hands. And then you see that hand get stabbed with a syringe needle. What happens is you have this empathic response, specifically this network of areas that we summarize as the pain matrix comes online. It's not your hand getting stabbed. Nonetheless, you're watching a hand getting stabbed and you. This is the neural basis of empathy you're feeling. What would it feel like if that were my hand? Great. Okay. Now what we do is we put a one word label on each hand. Christian, Jewish, Muslim, Scientologist, Hindu, atheist. Computer goes around, picks a hand, you see that hand gets stabbed. And the question is, does your brain care as much if it's a Member of one of your out groups versus your in group. Turns out the answer to pressing is that your brain cares much less. So the size of the empathic response, if it's your in group is enhanced from what it was. And if it's any one of your out groups, it's diminished. By the way, this is not a criticism of religion because we find exactly the same thing with atheists. People who profess themselves as atheists really care when they see the atheist hand get stabbed.

Andrew Huberman (122:22)

Really, they're.

Dr. David Eagleman (122:23)

Yeah, it's everything about in groups and out groups. So it turns out this is such a low level response. Now happily this doesn't necessarily map onto how you act as a person. This is just your first response. You care more more about your in groups. Other labs like Tanya Singer and others have shown very similar versions of this with even things like sports teams. In fact, one of the experiments we did was we brought fresh people in and we said, hey, I want you to toss a coin. If it's heads, you're a Justinian, if it's tails, you're an Augustinian. So they toss the coin, they find out what they are, we give them a wristband that reminds them that they're Justinian or Augustinian. Then they go in the scanner and they see Justinian or Augustinian hands getting stuck, stabbed. And it turns out they have a bigger response predicated on their team. Completely arbitrary label. It doesn't mean anything. But this is how we are wired very much, very strongly for in groups and out groups. Obviously this is a real problem for everything we're witnessing around us.

Andrew Huberman (123:20)

Can I ask you a question? I have a theory, unsubstantiated by any laboratory data, that we all naturally feel some degree of empathy for both in group or common group and other group, except for groups that we really despise. Okay. I think there are some people who don't, provided that the other person is being tortured or killed. They're so like, oh well, dislike them anyway. But I think we tend to feel we know how we feel about someone or a group when something good happens for them. To me it's a much stronger indicator. So has the reverse experiment ever been done where instead of the hand getting stabbed with a syringe, the person of same group or outside group is being given something that is of value.

Dr. David Eagleman (124:07)

That's interesting. I don't know. I don't think anyone's run that experiment to my knowledge.

Andrew Huberman (124:10)

Because if I tell you like, okay, if I were to have access to your thoughts and I could Find like a hundred people that you like on arrange or that you know in your mind and arrange them on the continuum of really, really adore this person all the way to, to like actually really, I'm not going to use the word hate, but like really, really dislike this person. And I tell you, you know, and give any one of them stage three pancreatic cancer. I imagine as an empathic person you're gonna be like, ah, that sucks. But if I instead flip it and say, okay, you know, this person you really, you really like, they had something spectacular happen to them versus somebody that you dislike, something spectacular. There's a little bit of a, of a, of a twist on the feeling of happiness for somebody that you don't like receiving something that maybe you think they didn't deserve or, And I think we are all wired this way to some extent.

Dr. David Eagleman (124:59)

Yeah, that's a really interesting point. To my knowledge, no one has done that experiment. And it's, in a sense it's because this issue of when something bad happens to someone, we naturally have an empathic response. If it's a stranger, look at the issue of, I don't know, let's say some older gentleman gets, you know, know, his nose broken because someone attacks him outdoors at a park. You would feel empathy for that. But now if I tell you, oh, look, he was at a Democrat rally or a Republican rally, depending on your perspective on the world, you might have differential empathy predicated on how strongly you feel on one team or the other. Here's the thing, even with pancreatic cancer, there's a whole lot of experiments from my lab and other labs that shows that sometimes when something happens to someone that we don't like, the reward system actually comes on. This was Tanya Singh, had a Nature paper on this showing that you actually show reward system activation when something happens, which is awful. But one thing I have always noticed in the movies is that you're watching the James Bond movie or whatever and the bad guy, you know, falls from a 500 foot building and splats on the ground and you like, you know, eat your popcorn, you don't care at all that something awful happened to somebody. Whereas if James Bond, you know, gets grazed by a bullet, if you're like, oh, ow, poor guy, it's weird how much we can dial this around where we simply don't care when bad things happen to other people.

Andrew Huberman (126:26)

And what you're describing provides a very useful filter for what we see out there in the media. And you know, just recently there was this event that's being debated, treated very intensely from both sides. Someone was shot, whose fault was it at? What were they were in their rights to shoot her, etc? I mean it's, it's like, it's, it's immediate polarization around, you know, same collection of videos, two totally different interpretations. Right.

Dr. David Eagleman (126:50)

Because was that woman your protagonist or your antagonist? And just like in the movies, we have a completely different empathic response based on, on that.

Andrew Huberman (127:00)

In the sort of hypothetical example of an experiment where people that are either same group or different group are rewarded. I feel like it gets to an issue that's a little bit more subtle than when people are harmed because it gets to the zero. This notion of zero sum, like if somebody else gets something, does that mean anything was taken from you? Not necessarily. Right. But there are some people who go through life seeing people get things and they feel the pain of what they didn't get by virtue of someone else getting something. And it's got to be a very difficult place to live. And yet I've known people like that. They, they, you know, there are people who hate rich people.

Dr. David Eagleman (127:34)

Yeah.

Andrew Huberman (127:35)

If. And they hate them for a number of reasons. Maybe they were treated poorly. Etc. They hate famous people, they hate beautiful people. They hate you. You can see this, right? And what aspect of, of self, other in group, out, group does that relate to? Because it gets to this notion of how much resource there is to go around something for someone else is something taken from us is a very different perspective.

Dr. David Eagleman (128:00)

Yeah, that's right. I don't know the answer to that. Except that people clearly are wired differently on that in terms of whether they think it's a zero sum game or there's, you know, infinite resources.

Andrew Huberman (Podcast Host/Announcer) (128:08)

Do we see it in animals?

Dr. David Eagleman (128:09)

Yes, actually there are experiments on, on capuchin monkeys where the monkey does something and then gets a piece of banana. Banana. And then the other monkey does something in the neighboring cage and gets a piece of banana. And so they're doing this, but then the other monkey doing it gets a grape, which is a big treat for the monkey. And the first monkey goes nuts and is shaking the bar. He's so angry that the other monkey got a better reward. There's this sense of fairness that's actually quite deep in our evolution about what's unfair and so on. But I want to come back to this issue about rewarding people versus punching punishing. To my mind, the reason I care so much about this issue of harm happening to people and when we don't care is because of when we look at what happens around the world? I'm not even talking right now. Let's just take the 20th century. We constantly see people murdering their neighbors for all kinds of reasons, for religious reasons, for atheist, communist, you know, secular reasons, for all kinds of reasons. People are perfectly willing to, willing to take their friends and neighbors. Look at the Hutu and Tutsi in Rwanda. They had lived together with friends, there was intermarriage, and then the Hutu raised up their machetes and slaughtered Tutsi at a rate faster than the Germans were able to do with gas chambers and Jews. How these things happen, it's so important for us to understand what are the elements that lead to in group and out group stuff. One of the things I've been very interested in is propaganda. And it turns out across place and time, all governments do propaganda in exactly the same way, which is you simply dehumanize the other group by calling them an animal or any like a virus, you know, a pestilence, rats. Nowadays you can even call them robots, whatever, anything that's not human that turns off these networks that we have in the prefrontal lobe that care about other humans and how to interact with other humans. Humans. Our colleague Lassana Harris has studied this stuff. And what happens is when you're dealing with an object now like, oh, the Tutsi, the famous thing that happened in Rwanda is the Tutsi were described as cockroaches. And the radio was blaring that all the time, the Tutsi are cockroaches. So, you know, killing a cockroach isn't so hard to do. So you grab your machete and you go do that. And that's the kind of thing I am essentially dedicating my life to. This kind of thing is an education about this, such that when the next generation hears propaganda about any group, they say, wait a minute, I've heard that trick before. I know what this is. This is just calling the other group, oh, they're not like us, they're not human. And so on dialing down these networks that care about other humans, therefore I don't care about them as much, I don't have empathy for them as much, and I'm willing to take up arms against them.

Andrew Huberman (130:54)

Many years ago, I was at a meeting and one of our colleagues, I'll let them remain anonymous for soon to be obvious reasons, stood up and made a really strong case for not referring to the mice. And at that time, experiments were still done on cats and non human primates. Those are still used, but To a lesser extent now, but still to not refer to them as animal models because he felt that it was de, not dehumanizing them, it was removing the sense that they were real beings. And you know, as someone who has worked on a number of species, including humans and, and frankly, I'm, I'll say this proudly, I'm relieved to not do experiments on animals anymore. I really did not like that aspect. I, I did like working with humans. We say not on humans because they can sign up and consent and that sort of thing. I think every profession has the, this, you know, they, my friends who are psychologists. You said your dad was a psychiatrist. I always ask people, psychologists and psychiatry, do you refer to your, the people that you treat as clients or as patients? Like the, the language doesn't always matter so much. But I think when it comes to animal experimentation, when it comes to people and professional relationships, it actually does matter because I think as you pointed out out, certain circuits in the brain get turned off or on, depending on how we refer to people.

Dr. David Eagleman (132:24)

Yeah, exactly.

Andrew Huberman (132:25)

Yeah, I know it's, I'm starting to sound a little bit like, like this is some like, political statement, but it's not, it's just like, I think that words matter. They, they really do.

Dr. David Eagleman (132:34)

Yeah. Oh, I totally agree. I think this political statement does matter because when the society reaches a point where some group of people is referred to essentially as non human human, that's when things get really dangerous really fast. The Tutsi's cockroaches, the Jews as pestilence, and Germany and what, you know, all these things make a difference. And by the way, you know, in Germany, in The Reichstag in 1934, all the people elected the Reichstag that year were either far right Nazi party or far left Communist Party. It was like a really polarized time. And the part that's so scary about polarization of that extreme is that it just takes a moment in for one party to eat the other. It just, it goes really fast. And suddenly, you know, when Hitler took power, when the president von Hindenburg died, Hitler declared himself the Fuhrer and rounded up all the communists and put him in jail, in concentration camps right away. And so that's why polarization, if there are things we can do as a society to work on that, to try to get better models of the other person, to have, have meaningful debates and listen to the other side, it doesn't mean coming to agree with them or whatever, but it means saying, okay, I'm going to assume the other person is Speaking genuinely, what is their reason for holding this political position? Also, by the way, having a better notion of our own internal models, which is that we are extraordinarily limited. This is actually what my next next book is about. It's called Empire of the Invisible and it's about why we all believe our own internal models. We've all taken very thin trajectories through space and time.

Andrew Huberman (134:07)

Time.

Dr. David Eagleman (134:09)

And we've collected up our little scraps of data and we think, oh, I know the truth. I know how to think about the world and these political issues. And if I could just shout in all capital letters on X loudly enough, everyone would come to agree with me. Essentially everyone thinks this deep down, irrespective of what their political position is. And that's weird that we can't see the fence lines of our own internal models. So I think it's really important, important that this gets built all the way down into our education system at the high school level, maybe even junior high, where we understand the limitations of our own model. We understand how to try to understand other people's models. We understand when it's appropriate to blind our biases in the way that, for example, symphony orchestras have been doing this for decades now where they do a blind audition of musician behind a curtain. So you, you can't have the opportunity for discrimination based on gender or race or anything else. You're just hearing, oh, that was a great oboe player. And so you. Things like that. And I also think that there's another technique that might be super useful here, which is, and this is, I've been exploring this a lot lately, what I'm calling the complexification of relationships. Meaning if you have something in common with someone and. And then you find out later that that person has a very different opinion than you do on some hot button political issue. You're more willing to listen to them because you're already pals on the. You go surfing together, whatever you like, the same sports team or whatever, you're more willing to listen. My example for this is the Iroquois Native Americans who were up in sort of northern Wisconsin area. Five tribes, they all killed each other for years and years. They had a new leader come in, this guy Denegaw, who came to be known as the Great Peacemaker. What he did is he said, look, you've got these five tribes. I'm going to assign each person membership in a clan. So let's say we're in the same tribe, but you're a member of the Beaver Clan. I'm a member of the Eagle Clan and so on. And these clan memberships are cross cutting such that now you say, hey, let's go invade that tribe over the hill. And I say, oh, you know, I don't know, that guy's a member of the Eagle Clan and so am I. I've got these cross cutting relationships now and I'm less likely, I'm less willing to do that. And this ties back to the experiments we did that I mentioned with the hand stabbing. What we now do is we say the year is 2029 and these three religions have teamed up against these three religions. And now you see the different hands get stabbed, but the ones who I just told you in one sentence are your allies. Now you care more about them them just because I arbitrarily told you that they're your allies. And so when things get complexified like this, we suddenly care more about certain groups and so on. Anyway, I think this is a really important thing to do. So I've patented a new social media algorithm which essentially works simply by surfacing what people have in common. So if you and I are both on this algorithm, it, oh, we've got this in common, that in common, and all those things get surfaced and we come to know each other and like each other and, and only later temporally down the line do we hear, oh, wow, I didn't realize you felt so differently about gun control or abortion or whatever. We learned that later and then we're more willing to lean in and talk.

Andrew Huberman (137:25)

Fascinating. I thought for a while that the solution to polarization was going to be. It sounds like a laboratory experiment, but the interbreeding across first genetic, but also, and geographic, but also, you know, racial and cultural and ethnic boundaries. Right. And when you have people mixing and having children that are mixed, you can no longer assign identity in a way that allows people to continue to hurt and harm one another. Because I do think that the one thing that runs very deep in our species is this evolutionary drive. And there are other sources of this, of course, but to make more of ourselves and to protect our young, young, and if those young are, are, you know, of, of several different races, religions, etc, you know, then you really don't have any, anywhere to go. Oh, you know, in terms of violence and, and, and, and of course I, I started thinking about this in the way that when I grew up, it wasn't that long ago I was born 75, but it was 50 years ago that you saw less in marriage across races. You just did. Right. You, it was, it happened, but far less frequently than it does now across religions, even across cultures. And. And now things are quite different. But the polarization continues.

Dr. David Eagleman (138:44)

Yeah, I. I wish I shared that optimism on that, on that front. But, you know, the fact is, in Rwanda, Hutu and Tutsi had been intermarrying for a long time. In Germany, Jews and Christians had been intermarrying there for a long time. But when stuff hits the fan, none of that matters. And people will still make dividing lines and say, hey, if you've got some of this in you, you're on the other side. I wish I had a more optimistic note there, but.

Andrew Huberman (139:11)

No, I think. Well, it sounds like the, the projects you're involved in to try and reduce polarization are. Are. Well, I'll say, certainly they're very important and. And they sound very promising. Look, you're. I feel like we could go another six hours. We have to have you back. Of course, you have your own podcast. Amazing podcast. So tell us about. Just for folks. We'll put links in the show, note captions. But you're right, you're writing, what, 10 books now? You got a podcast.

Andrew Huberman (Podcast Host/Announcer) (139:38)

You're involved in movie.

Andrew Huberman (139:39)

Movie scripts. But give us the highlights. What are you up to these days when you're not teaching three different classes at Stanford?

Dr. David Eagleman (139:46)

So I'm running the podcast Inner Cosmos.

Andrew Huberman (139:48)

Which is awesome podcast. I listen to it.

Dr. David Eagleman (139:50)

Thank you. Thanks. And that's a really wonderful way for me to put out lots of ideas. Often I do mostly it's monologue, but I do have guests as well, and I get to just tackle big philosophical questions about time, about polarization, about whatever. I just signed my next two books. One is the Ulysses contract, and one I mentioned is called Empire the Invisible. And then, yeah, I'm also doing a lot in the realm of movie production stuff. We're making a documentary film right now with the comedian Craig Ferguson where we're asking the question, question, can AI be funny? So we've built a robot that Craig is going to go on the road with and do this comedy with, you know, like, in the middle of the country. And the reason we're starting there is because that allows us to ask all these deeper questions about AI but in a way that draws people into the movie, because you can't just make, like, a doomy, gloomy movie about AI and expect anybody to watch it. But. But this is sort of a really fun, funny movie that allows us to really ask, what's it going to be mean for our lives?

Andrew Huberman (140:51)

Awesome. And when you're not doing that you're fixing door knobs and stuff in your, in your home and raising a family.

Dr. David Eagleman (140:56)

Yeah.

Andrew Huberman (140:57)

David, thanks so much for coming here today. Great to see Andrew, as everyone now sees and many already knew coming into this, you're a world class educator and storyteller and most importantly, a scientist who ran experiments. I think it really helps to have, you know, no diss on science communicators that haven't run labs and things like that. But I think when one has done experiments, you get a real deep sense for how data comes together and what it does and doesn't mean and you're a virtuoso. So thanks for coming here today and sharing just so many pearls of wisdom and some practical takeaways that I know myself and other people are really going to, going to work with.

Dr. David Eagleman (141:36)

Great. Thanks Andrew. It's a blast being here.

Andrew Huberman (141:38)

Awesome. Come back.

Andrew Huberman (Podcast Host/Announcer) (141:39)

Thank you for joining me for Today's discussion with Dr. David Eagle. To learn more about his work and to find links to his various books, please see the links in the show. Note Captions if you're learning from and or enjoying this podcast, please subscribe to our YouTube channel. That's a terrific zero cost way to support us. In addition, please follow the podcast by clicking the follow button on both Spotify and Apple. And on both Spotify and Apple you can leave us up to a five star review and you can now leave us comments at both Spotify and Apple. Please also check out the sponsors mentioned at the beginning and throughout today's episode. That's the best way to support this podcast. If you have questions for me or comments about the podcasts or guests or topics that you'd like me to consider for the Huberman Lab podcast, please put those in the comments section on YouTube. I do read all the comments. For those of you that haven't heard, I have a new book coming out. It's my very first book. It's entitled An Operating Manual for the Human Body. This is a book that I've been working on for more than five years and that's based on more than 30.

Andrew Huberman (142:34)

Years of research, research and experience. And it covers protocols for everything from.

Andrew Huberman (Podcast Host/Announcer) (142:39)

Sleep to exercise to stress control, protocols related to focus and motivation, and of course I provide the scientific substantiation for the protocols that are included. The book is now available by pre sale@protographsbook.com there you can find links to various vendors. You can pick the one that you like best. Again, the book is called Protocols An Operating Manual for the Human Human Body. And if you're not already following me on social media. I am Huberman Lab on all social media platforms. So that's Instagram, X threads, Facebook and LinkedIn. And on all those platforms I discuss science and science related tools, some of which overlaps with the content of the Huberman Lab podcast, but much of which is distinct from the information on the Huberman Lab podcast. Again, it's Huberman Lab on all social media platforms and if you haven't already subscribed to our Neural Network Newsletter, the Neural Network Newsletter is a zero cost monthly, monthly newsletter that includes podcast summaries as well as what we call protocols in the form of one to three page PDFs that cover everything from how to optimize your sleep, how to optimize dopamine, deliberate cold exposure. We have a foundational fitness protocol that covers cardiovascular training and resistance training. All of that is available completely zero cost. You Simply go to hubermanlab.com, go to the menu tab in the top right corner, scroll down to newsletter and enter your email. And I should emphasize that we do not share your email with anybody. Thank you once again for joining me for Today's discussion with Dr. David Eagleman. And last but certainly not least, thank you for your interest in science.