David Eagleman: The Malleability of the Brain
David Eagleman is a renowned neuroscientist, podcast host, and the author of many bestselling books about consciousness and the brain—along with more than 120 academic publications. Besides his perch as a neuroscientist at Stanford University, David is the co-founder of two venture-backed companies, including Neosensory, which is a pioneering wrist device that enables the deaf to hear. Yep, that’s right.
David is fascinating, and hopefully this conversation lives up to his capacity: We discuss the malleability of the brain to adjust to its inputs, the roots of synesthesia, how those who are born blind and deaf can now use touch to see and hear, and why we dream. Ultimately, we explore just how it happens that a brain trapped in a dark vault can create the vibrancy of our existence.
David is a TED speaker, a Guggenheim Fellow, and serves on several boards, including the American Brain Foundation and the The Long Now Foundation. He is the Chief Scientific Advisor for the Mind Science Foundation, and the winner of Claude Shannon Luminary Award from Bell Labs and the McGovern Award for Excellence in Biomedical Communication.
What’s cooler? He has served as the scientific advisor to several television shows (including Westworld and Perception). Ironically—considering we both host podcasts and David is a neuroscientist—we had some technical difficulties during our conversation, but the hope is that this is not perceptible to you! Let’s turn to our conversation now.
MORE FROM DAVID EAGLEMAN:
Livewired: The Inside Story of the Ever-Changing Brain
Sum: Forty Tales from the Afterlives
David’s Podcast: “Inner Cosmos”
David’s Website
TRANSCRIPT:
(Edited slightly for clarity.)
ELISE LOEHNEN: You're fascinating to me, and we're going to talk about maybe spiky intelligence or the way that the brain adapts itself to its inputs, right? So I was reading Livewired, so that's what I've been steeping my own brain in and in it you write about, for example, musicians and the way that they get the omega or the double omega based on maybe not all musicians, but based on whether they're doing a one or two hand piano versus a violin. When you think about your own brain and so I'm a writer, you're a writer, I have some other skills and talents, but I would say that's where like the spike of my intelligence lives. I'm not a scientist. I'm sorry to tell you, David, I'm sure you're devastated to hear that. But why are you so non spiky and yet so excellent in so many fears?
DAVID EAGLEMAN: Oh, that's very kind, that's a nice compliment. I feel like art and science are actually quite similar in that they're both just trying to get to know the world. They're just trying to understand what is going on around us. They just have slightly different approaches to getting there. So in the laboratory, we have ways of imagining new model of something that no one has ever suggested before. And we think, wait, what if that's right? And then we have very specific ways of trying to get there. You do experiments, you try to prove that's right. And most of the time it's wrong. Most of the time you leap to some island and you try to build a bridge there. And you realize, oh, I guess that, that can't be right. But in art, in writing, you know, you leap to some island and then you can explore around there. And you don't have the same constraints in terms of what you need to do. But they're both trying to do the same thing, which is, hey, what is going on and how can we think about imaginary creative worlds here?
ELISE: Yeah, well, it's interesting to think about the multiple spaces that you occupy, both as a storyteller and storyteller about science and it's almost like you're involved in a dual exploration, one about the brain and one about the mind. And I know that the two theoretically have some sort of shared origin source, but reading your book about the brain is so fascinating because I learned so much and yet, like at the end you talk about maybe someday we'll have a whole new field of science where you'll be able to run a brain like a video projector and understand someone's Life, right?
DAVID: Sort of. So we're infinitely far from that. I mean, maybe that'll be thousands of years from now, but yeah, the argument I was making at the end of the book is simply that everything in your brain, every experience you've had, the language you've learned, the parents you've had, the lovers you've had, the neighbors, everything in your brain is stored in the exact configuration of these 86 billion brain cells, neurons, and their connections between them and the exact strength of the connections between them. And so, in theory, If we found a brain, we could read it out. The entire story of your life is scribbled in there. It's simply that it's in a script that we don't know how to read yet. And, in fact, the computational capacity that would be required to read it would be about a zettabyte of information, which is about a quarter of the computational capacity of the planet right now. So, it's not like this is going to happen anytime soon. But, in theory, everything about Elise is stored in this structure, and we could know it all.
ELISE: And you would be able to sort of understand my history, right? Or like the patterning of my thoughts, or maybe my thoughts, or encoded memories. Do you think that then we really start to understand consciousness, not to go like right off the deep end because we're going to back up a bit too, but...
DAVID: well, let me answer the first part about could we understand your history. The answer is only as well as you understand your history. In other words, everything in your life is not actually written down in your brain. It's not etched into your brain cells and certainly not accurately. So all we would be able to have, and again, I want to emphasize this is theoretical, this is maybe, you know, 1000 or 10, 000 years from now is knowing your version of your life, which of course, memory is a myth making machine and you're constantly reinventing your past to keep it consistent with who you think you are. So it's not like we would have an accurate record of something, but yes, we would know something about you and what things you like and the kind of thoughts you have.
ELISE: it's amazing. Do you have a theory of consciousness? The book is such a beautiful explication of, not the machinery, because it's so much more alive than that, but you mentioned Mother Nature, you capitalized Mother Nature throughout the book, or maybe you can't say, because you're a scientist. Is Mother Nature simply that, like a biological urge to engage with the world in the way that we sort of adapt, evolve, and grow?
DAVID: Yeah, let's back up a few steps. When I talk about mother nature, I'm talking about, you know, nature, which is how we got here. We are natural creatures. We evolved for many millions of years in our species, but billions of years for unicellular and then multicellular life forms. And so we have a planet that is here full of life, teeming with life, screaming with life because it's a natural process. And and in fact, you know, complexity theorists Look at this by saying if you just take a planet and you simmer it at the right distance from a star, you really can't help but have it sprout with life like a chia pet. There's not something so rare about life, it's actually, life's hard to hold down, which is great. But anyway, so when I talk about mother nature and the evolution of the brain, I'm talking about all the forces that got us here and now what we've got is this, Masterpiece of evolution, which is the most complicated thing that we've ever found in the universe.
And it is you, it is all your hopes or dreams or aspirations, the agony, the ecstasy, it's all happening in these three pounds in your skull and the way we the reason we know that is because if you let's say hurt your pinky or something, you'd be sad about that. But you wouldn't be any different as a person. You'd still be Elise that we all know and love. But if you damage an equivalent size little chunk of brain tissue that can change you entirely. That can change your decision making, your risk aversion, your capacity to see colors, or understand music, or name animals, or a hundred other things that we see in the clinics every day. And that's how we know that this brain tissue, this three pounds of very delicate pink stuff that Mother Nature keeps protected in the armored bunker plating of the skull, that is you. That's the densest representation of you that there is.
ELISE: So you write about, it's quite miraculous, right, that this brain caged in our heads, in a vault of darkness is responsible for encoding, decoding all of our sensorial experiences. And can map to our body, map to the world in a way that's just stunning. I mean, the book, it's clearly so much of your personal interest, right? A lot of your lab devoted to understanding how to transform sight into touch and to create these sort of belts and bands so that people can see through feeling, is this accurate?
DAVID: It's mostly accurate. What we're concentrating on is sensory substitution for the deaf. So we are translating sound into patterns of vibration on the skin. And then people, for example, who are deaf can come to hear. I don't know if you ever saw this, but in 2015, I gave a talk at Ted about this and halfway through the talk, I ripped my shirt off and I'm wearing this vest underneath and the vest has these vibratory motors with lights on it so you can see what's going on. And I show how this captures sound and it translates sound into patterns on the skin and it demonstrated how people who are deaf can come to hear this way. And in the meantime, what we've done since that time is we've shrunk this down to a wristband. So it has vibratory motors on it on the wrist and we're on wrists all over the world now. So, you know, big company warehouses, some governments, which I can't say, you know, but, some governments for their deaf employees all over the world, deaf schools and so on we capture sound for people who are deaf.
And I just want to mention the only other option for someone who's deaf is what's called a cochlear implant, which is a hundred thousand dollars and it requires an invasive surgery. And our solution is a hundred times cheaper than that. And so it's really revolutionized this, but what we've done more recently actually is come up with a solution to replace hearing aids. So what it's doing is the, it's exactly the same wristband with these vibratory motors, but it's listening using AI in real time, it's listening for the high frequency parts of speech, like a K or an S or a T or a V things like that, and it just buzzes to tell you, Oh, I just heard a K I heard a T I heard a V. When people, as they get older and start losing their hearing, their ears are still doing fine at the medium and low frequencies. They just can't hear the high frequencies anymore. So what we're doing now is just listening to the high frequencies for them and clarifying what got said. And it takes about a week or two for the brain to be able to fuse these signals. And then the brain says, cool, I got it. You said, you know, sheep versus sheik versus sheet, whatever it, you know, it figures out what was just said.
ELISE: And then there are teams working on something similar for vision. Is that accurate?
DAVID: Yes, that's right. There's a group in Wisconsin, for example, that has an electrode grid that sits on the tongue. So it feels like pop rocks in your mouth. And there's a camera on the forehead, let's say, you know, built into your glasses. So the camera is looking out at the world and you're feeling on your tongue the shapes of things and edges in the world. So if there's, let's say, you know, a coffee cup moving from left to right, you will feel that on your tongue. Or if there's, you know, the edges of a doorway, you feel that on your tongue as you're approaching it.
ELISE: So you write about, this girl, Danielle, it's a horrible story. A child not socialized, obviously a highly abusive situation, never developed speech, missed that, is it the first seven years, essentially, when we're developing all these pathways and take, mapping our brains and coordinating our senses? Can you talk a bit about Danielle? And then for people who have never been able to hear or have never been able to see, does this technology still work or is it primarily effective for people who have lost that function but have the original map?
DAVID: So let me do this in reverse order. So it works perfectly well, in fact, exactly as well for people who are born blind or born deaf, as it does for someone who's, who goes deaf later. It takes slightly longer to learn the older you get. But otherwise, everybody can get to the same level, which is remarkable. And you know why this happens is because, as I argue in the book, the brain is what I call live wired, which means it's very fluid. It's moving around. Technically, in the field, we call this neuroplasticity. We call the brain plastic, but I actually don't prefer that term at all, because about a hundred years ago that term was introduced because William James was interested in the way that you can mold plastic and it will hold on to its shape and in the same way when you, you know, have your fifth grade teacher and learn his or her name, there are changes in the structure of your brain such that you remember your teacher.
It's like plastic in the way that you've molded it into some shape and it retains that shape, which is pretty amazing. But we're so far past the point of being impressed with plastic manufacturing now. That's why I use the term live wired, because it's this forest of 86 billion neurons that are changing and reconfiguring every second of your life. So it's a much bigger concept than plasticity. But in any case, brains are very plastic or live wired. And so whatever information is coming in, the brain will just figure out how to use it if it's a useful information source. So in this example, if we're passing in here, if we're passing in auditory information from the world, it doesn't matter if it's coming through your ears or through the skin of your wrist, your brain says, Oh, I see that's correlated with this person's mouth moving and it's socially important to me, or, you know, someone's knocking on the door, someone's saying something to me, or there's a dog barking at me or whatever the issue is, your brain puts together these different senses and says, okay, I got this. And then people actually come to hear through these signals on the skin. I mean, this is what people describe after about six months of wearing this is they say, Oh, I'm just hearing it. I say, when the dog barks, do you feel the buzzing on your wrist? And you look at your wrist, you try to figure out what it was. I said, no, no, I just hear the dog out there.
Now that sounds crazy, but remember that's what your ears are doing. Your ears are just, you know, these very sophisticated structures made out of cartilage and skin and so on that are directing the sound into the ear canal where you've got a vibrating membrane. So as I'm speaking, your eardrum is vibrating and that goes through several states, the middle ear, then the inner ear. I'll skip all the details except it gets turned into spikes along all these nerves, what we summarize as the auditory nerve. You've got, you know, millions or billions of little spikes that are carrying my voice, the little electrical spikes. And that's all that happens in the silence of your brain are these spikes. But you attribute it to, Oh, I'm hearing Eagleman's voice and it sounds like it's happening out there. But in fact, everything about the hearing of my voice is happening inside your head in the silence and darkness.
ELISE: So stunning. And so Danielle, as a child essentially locked in or shut into her own experience, it's just a closed door?
DAVID: Well, so let me explain. She was severely neglected and her father had mental problems and didn't want any noise at all. And so he kept her locked into her room and wouldn't let her out. And her entire childhood, she was locked in and she was about the closest thing that we have. Unfortunately, these cases are not as rare as we would hope, but, you know, cases like this are the closest thing we have to feral children. Meaning, you know, Children that are raised without the normal social benefits that almost all Children get. And so Mother Nature took a particular gamble with human brains, which is that she made it very flexible and works under the assumption that a human baby's brain will drop into the world and be exposed to language and touch and love and stuff like that.
And in these very rare cases where a child does not get language or touch or love, we see what happens, which is that the brain does not develop correctly. So Danielle, when she was finally discovered, because somebody noticed that occasionally there would be a little face in the window and the neighbors didn't know whose face that was. It didn't make sense to them. And so the police eventually came to investigate and Danielle was discovered, but by the time she was, it was too late for her because there are critical windows to learn language, for example, there was nothing wrong with Danielle's genetics or brain as such. It's just that she didn't get the other half of what she needs. So you come into the world with half of what you need, which is your DNA. And the rest of the brain gets wired up from your experience in the world, your parents, your neighbors, your culture, your language, your friends, all that stuff that wires your brain up. And she didn't have any of that. And so the brain does not wire correctly. And by the way, as you know, cause I mentioned it in the book, but a softer version of this happened in the Romanian orphanages at the fall of Ceausescu. There were tens of thousands of children in these Romanian orphanages and the staff was totally overwhelmed. And so they said, look, you can't you can't talk to the kids or touch the kids because if you do, they will become clingy. And so, our protocol, our rule here is that you don't talk to the kids touch them. You just put the food in the cribs and you, and so on. And these kids all grew up with major, major cognitive limitations as a result. Because that's the other half of what is needed.
ELISE: Yeah, I mean, it certainly makes sense and it's awful. It's fascinating too, this idea that mother nature would recognize and, you know, I sort of knew this only in the sense of, I'd always believed and recognize this as part of it, that babies are born so helpless in part because we wouldn't be able to get them out of our bodies.
DAVID: I should just expand on that for the listeners, which is just that, you know, we've got particularly big brains. And so a baby can't fit out of the vaginal canal if our brain's got any bigger. And so the final secret that Mother Nature came up with is, okay, let's push it out in the world, sort of half baked. And then it figures things out from there.
ELISE: But it seems like there's an extra mechanism to that sort of half formation that then the world can impose on the child, right? And create that responsive environment.
DAVID: Yeah. And this is, by the way, why we are the runaway species. I mean, there are so many animal species on the earth, but we are the only ones that, you know, talk on zoom and have podcasts and get to the moon and invent the internet and invent vaccines and build cities and bridges. I mean, we are the only species on the entire planet doing this. And the reason all comes down to this issue of live wiring. It's just that we have these brains such that you know, if you are a dog, each generation, you're just, you're starting off from zero again and just being a dog or a horse or an alligator. But a human child goes to school and learns essentially everything that humans before them have ever discovered. So my daughter is eight years old and she gets to ride on top of this huge tidal wave of humankind and know, oh, okay, I got it. This is, you know, Newtonian physics, that took a really smart guy, a long time to figure it out. Oh, I got it, that's physics. Oh, here's a phone that I can hold in my hand that has the entirety of humankind's knowledge on it. That's cool. And, yeah, so that's what's made humans so successful is that we are flexible, so we don't have to start from zero every time.
ELISE: Yeah. So is your daughter actually eight?
DAVID: Yes..
ELISE: So I have two boys, 7 and 10. And I have to say that your book was incredibly affirming in your optimistic stance on the internet and education and can you talk a little bit about that? Because I'm going to just misquote your book back to you. But essentially, like when we can learn driven by our own curiosity and we had the Encyclopedia Britannica in the basement and I would go and, you know, get the paragraph entry, but you can't necessarily follow your interest as a child or you couldn't when we were children in the same way.
DAVID: I grew up in the mountains of New Mexico. And so when I wanted to get ahold of the Encyclopedia Britannica, my mother would have to drive me down to the library, which is half an hour away. And, you know, maybe the encyclopedia would have an article, maybe it was 10 years old or something, or I'd go thumbing through the card catalog. You remember that process?
ELISE: Yeah.
DAVID: So the difference now is that children are exposed to all of our knowledge. They have that at their fingertips and the reason that is important is because brain plasticity happens when you are curious about something that is the highest level of brain plasticity because you have the right neurotransmitters kicking around in there and so when you want to know the answer to something and you look it up and you get the answer right away, then you actually remember it. So in our generation we got a lot of just in case knowledge, like, Hey, just in case you need it, the battle of Hastings occurred in 1066, but what the kids are getting now is lots of just in time knowledge. So as soon as they're curious about something, they can find the answer.
We've all had this experience. I mean, it happens multiple times a day to me where I get lost in these mole holes of Wikipedia. And it's such a pleasure where one thing is leading to another thing. And I'm just following my curiosity and I end up on some page. I think, how in the world did I get here? I can't even remember the sequence of pages that got me here. But that is incredibly useful from the brain's point of view. And I've noticed by the way, just a change in the way that dinner conversations go from the time that I was a kid. So, you know, as a kid, we'd have some argument at dinner and it would get stuck because no one actually knew the answer. And so maybe two or three people would assert they know the answer and. And then it was just sort of stuck with no one knowing, but now, you know, everyone's phone gets whipped out. Bang, bang, bang. Oh, here's the answer. Here it is. And then the conversation keeps going. And so it moves at this incredibly fast pace. Everyone learns stuff. So yes, the point is, this is incredibly good for people's brains. I have a lot of colleagues in the neuroscience field who pipe off about things about, Oh, the internet and digital natives and so on. But you know what? They don't know, they're making it up when they have these things to say about the ills of the internet.
And the reason they don't know is because you can't actually do a good experiment on this. In other words, you always need a control group and there are no control groups for this generation that's grown up digitally because you could look at, for example, the Amish or some kid that's growing up in a terribly impoverished environment and use them as a control for someone who's grown up in this era without the Internet. But there are a hundred other differences there. And you can't compare that last generation to the previous generation, because there are lots of other differences there in terms of, you know, education and pollution and politics and whatever, like everything's different. So they don't serve as good control groups. So there's a lot of, there's a lot of piping off about the internet. But in fact, I think from a neuroscience point of view, that the next generation is bound to be much smarter than we are because of this incredible intellectual diet that they're raised on.
ELISE: Not to make you necessarily talk about your parenting, but do you have rules, or how do you inform the use of the internet by your daughter?
DAVID: Yeah. And I also have a son who's 11. So my kids are similar in age to you. You know, Obviously it's tough because they get sucked into these things that, you know, I mean, my daughter is into Taylor Swift now and my son's into any video game, but what I try to do all the time is do things with them online. So we do Dualingo together. We watch YouTube videos on things that we are trying to figure out as a group. And so I just, I try to expose them as much as possible to the amount of knowledge that is out there. And I just try to find the stuff that's fun.
ELISE: Yeah, I mean, I have to say my 10 year old definitely will end up as a neuroscientist, it's just like the only thing that's interesting to him and thank God for YouTube and thank God for Mark Rover.
DAVID: Rover. Yes.
ELISE: Yes. And the amount of stuff that he consumes and retains is stunning. I mean, and then I'm constantly like is that true? And then I check. I mean, he was telling me about Bernie's paradox and he's leap years ahead. When I told you I'm not a scientist, I'm really not a scientist.
DAVID: And here's the thing. We always think, you know, I mean, as proud parents, it was like, Oh, my kid's such a genius. And maybe they are geniuses, but more importantly, they are just growing up in a time where you can learn about these things. It's just, that's the mother's milk that's available. I run into kids all the time who I'm talking to them and they'll say something really smart. I'll say, wow, how did you know that? And they say, Oh, I saw that in a Ted talk. And I realize, you know, I grew up in Albuquerque, New Mexico. You know, you're stuck with whatever homeroom teacher you have who may or may not be more than one page ahead of you in the book. And now kids get to learn on whatever topic they're interested in from the best person in the world, giving the best talk of their life in 15 minutes. It's just a totally different experience.
ELISE: It's amazing. I wish that my youngest son were on as quite a virtuous stream of content. I'm always like, what is that? We need some interference in the stuff that he finds hilarious.
DAVID: One thing to really keep in mind here, is to be honest when we think back on the ways that we wasted time as kids. I mean, we did so much stupid stuff that wasn't meaningful, and everyone has a tendency to do this retrospective romanticization, where we say, well when I was a kid, I sat and read the dictionary or whatever, but it's all bullshit, it's just not true, it's not what people did as kids, we just had different ways of wasting time.
ELISE: Yeah. I mean, I grew up in Montana and similarly like out in the woods and we had a lot of books and that was my primary form of entertainment because my parents were so shaming. And then we got a Mac and I'd play the typing game. So I learned how to type incredibly fast from the only computer game that we had, but it's interesting, I mean, not to go on a total tangent too, but my kids also like video games, some of which are violent. And I don't restrict it, in part because I'm like, I think that this is an actually acceptable way for my kids to experience their shadow and it's funny, I was just listening to a podcast about sort of the way that we moralize around culture with this idea that it's that insistent that it changes human behavior and I have an aversion to this idea that we need to only bathe our children in like the most virtuous activities for fear that they'll be contaminated or ideas will be planted in their heads. I don't know if you have any thoughts about that.
DAVID: sure. I do. And you know, by the way, as parents, this is what we try to do is to bathe them that way, but boy, it is impossible to keep the rest of the stuff out of the bathtub. And so I agree with you. This is part of what I talk about on live wired. And in fact, I've got a long footnote in one place about the number of experiences that you have in one day. Over the course of a full day, you have so many new experiences. And so all of this is rewiring your brain. It is impossible as a parent to ever hope that we can control the trajectory they're on. And by the way, as parents, we know that kids pop out with their own personality from day one anyway. And we're trying to make sure the kid gets piano lessons and swim lessons and this and violin lesson, whatever else they want, you know, we're just here to support that journey.
ELISE: Right. Two things. So you mentioned personality and what's your conception of how personality forms? I agree with you, my kids have completely different sort of base demeanors that I do not think were informed by oh, it's a first child and the second child, things were pretty similar. What do you think is the Genesis of personality?
DAVID: So this is one of the oldest debates in neuroscience and in the literature is nature versus nurture. Which one has more influence? Is it the genes you come to the table with, or is it the experiences you have? And the answer is so clearly both, the nature versus nurture debate is totally dead, because these things are intertwined. So you drop into the world with a particular set of genes and that dictates where you can or can't go. Just as an example, I would like to be a great swimmer like Michael Phelps, but I just don't have wingspan that he does. So I'm just never going to be there. I don't have the genetics for it. So I think of it like a cone where you start off at the base, you know, at the, like the ice cream cone, you start off at the sharp point and then depending on your experiences in the world, you can, you know, move through time up the cone, but you can go all these directions, but it's constrained, you can't be anything, but your experiences determine the directions that you do end up taking. Anyway, personality, a lot of that you drop into the world with, you refine the rest when you're growing up, but we all know as parents, what it's like to see certain aspects of our children, where we think, okay, this kid is more like Michael Phelps in the sense that he's really competitive and this kid over here is more like, you know, Mozart and that he loves the music. And this kid over here is more like whatever, Marie Curie, who loves science.
ELISE: The discovery of DNA wasn't obviously a dead end, but it didn't pan out, right, in terms of offering us all the answers about who we are in the world. Do you think that we'll ever have a more intimate understanding of that essential imprint, I would call it the spirit or the daimon to quote Jung, like that animating impulse. Will we find that do you think someday or do we just not quite have the right lens yet to understand that?
DAVID: We do have the right lens, and the answer's pretty clear, which is, it is the structure of your brain, which comes about as a function of your genetics that you came to the table with and all of your experiences. And so we can do, you know, whole genome mapping quite easily now, but you're exactly right, there was so much excitement in the year 2000, when the human genome project was coming to completion, we all thought, wow, this is going to tell us everything. And in fact, it certainly didn't answer many of the questions that we would like to know because if somebody was born 3000 years ago with exactly your DNA, they would be totally different.
They wouldn't be Elise in any meaningful way that we recognize, except they might look a bit like you. But, you know, first of all, they'd speak a different language. They'd be part of a different culture. They'd have had a different diet. They'd be exposed to all kinds of different things. Their thoughts, the deities they believe in, the whatever, would all be so different from even your way of thinking. So, experience in the world matters a lot. DNA is just a piece of the puzzle. In answer to your question of could we ever, you know, measure that better? Obviously, we can measure your DNA just fine now, but the weird answer is maybe in a hundred years from now, we'll all be wearing full time cameras, the way that police officers wear cameras on their vests. People are working on this sort of thing. There's a new company coming out called humane, for example, where instead of carrying around a cell phone, you've just got this camera attached to you. That's just records everything in your life and can do all kinds of interesting things. This is all still in the very, very earliest stages, but I can imagine in a hundred years, maybe we actually record everything and then we'd have a better sense of what's going on and we'd say, Oh, you know, at least actually this thing happened when she was seven, that kind of influenced her. And when she was 13, she had a crush on this boy and that didn't work out and that hurt her and changed her behavior a little bit and blah, blah, whatever. And so we could put together a whole life story. Obviously, we would need chat GPT, it'll be, you know, GPT 397 at that point or whatever, and we'll have to have some massive technology to summarize a life story, but that will certainly get us closer if we could know everything about a person's life experiences.
ELISE: It's just interesting to imagine, like understanding there are however many people who are dropped in with an almost essentially identical blueprint and then here's the variation as they've gone through their lives versus like how similar are we?
DAVID: Yeah, I mean, look, there are at least a million genetic differences between me and you, just what are called single nucleotide polymorphisms, or maybe I have a T and you have an A or I have a C and you have a G, you know, whatever, like the protein meant for doing whatever still works just as well, but just slightly different anyway, between any human and any other human, there's at least a million differences. But of course, it's even more than a you drift farther and farther from people that you're genetically related to, it's even more. And so the differences between people is enormous. And in fact, this has been a giant part of what I study in my career is obviously we can all point to things like the big things like, oh, that person has schizophrenia or that person has psychopathy, let's say, and we say, okay, so I'm different than that person, but it's way more subtle than that. The differences between one person and another can be extremely subtle. Just as one example, do you know what synesthesia is?
ELISE: Oh, yeah. This is fascinating. Yeah.
DAVID: Yeah, so for anyone who doesn't know, you know, some of synesthesia might look at letters on a page and that triggers a color experience, or they might hear something and it triggers a visual for them, or they hear something and it puts a taste in their mouth, or they taste something and it puts a feeling on their fingertips. There are all these different forms of synesthesia and the point is, this is not a disease or a disorder. It's just an alternative perceptual reality. And we now know that you know, a not insignificant portion of the population has this, probably 3 percent of the population has some form of synesthesia, maybe more than that. But there are a million things. Have you ever heard of aphantasia and hyperphantasia?
ELISE: I don't think...
DAVID: this is something I've been studying for 16 years now and I'm obsessed with it. Okay, so let's say I asked you to picture a brown and white cat sitting on a picnic table eating cereal and looking at you suspiciously.
So my question to you is, when you picture that, do you have it like a clear image in your head like a movie or is it, you're not picturing anything, but it's just conceptual.
ELISE: I can picture components of it and like hold it for a minute as a freeze frame but then I would need to rebuild it if I sort of try to keep my attention on it.
DAVID: Okay, cool. So it turns out across the population, you've got this whole spectrum where some people immediately see it like a movie. I mean, they see it in detail. It's like they're looking at it and other people all the way at the other end of the spectrum don't see anything in their heads. There is no picture in their heads, they're just conceptualizing it. And so at the first end, we call that hyperphantasia. And at the other end, we call that aphantasia. And it turns out, you know, my colleagues, I've been studying this for years, cross population, everyone's different. There are all kinds of surprises, just as one example, I've been working with Ed Catmull on this for some years. He is the guy who started Pixar and, you know, has all the patents on ray tracing and all this stuff. Turns out he's aphantasic. He doesn't see anything in his head. And what he found out is that most of the great animators and directors at Pixar are aphantasic. They're not seeing anything in their head, which, you know, came as a surprise.
But my new view on this, my hypothesis on this is that people who grow up aphantasic better artists, because if you are hyperfantastic, if you see everything so clearly in your head, then when it comes time for you to draw a horse, you already think you know what a horse looks like, and it's not going to be, you know, right or accurate, but if you're aphantasic , you really have to look at what the heck's out there and you have to have a dialogue with the page and pencil and make corrections and really pay attention to what you're seeing out there. So I think it's more likely for aphantasia people to become artists.
ELISE: Is that like an auditory cortex disorder? Is it like dyslexia?
DAVID: So it's a visual cortex issue and what we were able to measure in brain scanning is that the more activity you have in visual cortex when you're imagining something, the clearer it is. You're essentially just running that machinery without information from the eyeballs, but instead with, you know, feedback information.
ELISE: So interesting, because aren't so many amazing filmmakers dyslexic? Like Spielberg is, I know, I think there is a high correlation. I'm not completely sure. My son has an auditory processing disorder, which I had never heard of, it's passing the information back and forth from language to visual back to language. So he will give me, this is why he loves science, a part of probably why, he gives me 90 successive facts. Not so much a story.
DAVID: Yeah, what's interesting, actually, sorry, this is just a one second tangent, but you know, one of the classes I teach at Stanford is called literature and the brain. And that's because I actually majored in British and American literature as an undergraduate, because that's what I love. And one of the things that got me interested once I became a neuroscientist was this issue about story, about how story is the right mechanism to get anything from brain to brain. In other words, if I gave you a list of facts, you're going to forget it. It doesn't mean much to you, but if I wrap it in a story, it has meaning to you. For example, you read my book Livewired and you, one of the first things you remembered was the story of Danielle, which I, you know, presented as a story at the beginning of the chapter. And then I go into the details that you need to know about the brain, but start with the story. And you know, I'm running this podcast, inner cosmos and it's a monologue podcast. So every week I do 45 minutes to an hour monologue and it's stories where by the end of it, the listener has really learned some stuff about the brain.
ELISE: No, I love that podcast and so does my son. Finally, this idea of neuroplasticity, obviously it fades with age, but I want you to tell us about the nuns because I think that's so promising. And then if you can segue there, do you like how I give you three, three things to do in one?
DAVID: I can hold it in mind. Yep.
ELISE: Okay. Your conversation about dreaming was It's fascinating. I had no idea that that was a mechanism for the visual cortex to preserve its real estate in the brain. But this idea that I guess in some ways like working out your brain and its impact, I think we all know this, right? That first stroke victims that sort of getting them reengaged, will rewire the part of the brain that's still accessible or I guess in available. But can you talk about the real estate of the brain and how it can be re rewired? Reapplied?
DAVID: Yeah. Okay. So let me address points three and one first. So the point is that as you grow older, your brain is able to keep rewiring all the time. And so we have this impression that the flexibility of the brain decreases as you get older. But in fact, it's just because your brain's job is just to figure out how to get by in the world and do a good job in the world. And once you've figured most things out, like, oh, these are different kinds of personalities, and this is how I need to do something at work, and this is how I use email and phone and whatever, then your brain does less changing only because it has successfully done its job, and it doesn't need to keep changing. The brain changes when there's surprise, when there's something that happened that it wasn't expecting, then it changes up. So, you still have plenty of plasticity even when you're 90 years old. It's just that most people aren't using it at that point because they say, Oh, I got it. I know how things work.
I know how politics work. I know everything I need to know. The point is you need to always seek novelty and seek challenge. Cognitively, emotionally, everything. And that's what keeps your brain young and healthy and moving around and making changes. So I do all kinds of things to try to, you know, keep my brain always on its toes and surprised. You know, it's really easy to rearrange things in your house, you know, push things around, find the part of your house that's been there the longest, like, oh, the desk has always been against this wall, and this painting's always been on that wall, whatever, just, you know, switch things around, it's easy to do, it takes five minutes, it's worth doing, I try to drive a different route home from work every day so that I can just see new things. It doesn't make me live longer, but it makes it seem as though I've lived longer. So, when it comes to something like a stroke patient, when a person has had a stroke, typically what happens is for the first X number of days, there's a lot of swelling and stuff like that. And so you're not sure how things are going to turn out. But once the swelling goes down, then you can really tell what skills have been lost, usually because a chunk of brain tissue is gone and not coming back.
The good news is you can rewire the remaining tissue to cover a lot of that ground. And so the whole key, once somebody has had a stroke, is to make sure that they are working hard to recover, to regain those skills. Sometimes it's like being an infant again and relearning skills from scratch, but that's how you rewire your brain. And people can have remarkable recoveries, just because they're totally rewiring things. So that's why it's important when there's any kind of brain damage. Going to the question about the nuns, there was a study, an ongoing study where a whole bunch of nuns and priests in Chicago, agreed to donate their brain upon their death for research. And so the researchers were examining an autopsy all these brains of nuns. And what they found was something that really surprised them, which was that some fraction of these nuns actually had Alzheimer's disease, but nobody knew it when they were alive. No one had detected that because they weren't showing it cognitively. Even though the brain tissue was getting chewed up by the ravages of the disease, they weren't having any of the cognitive problems. And it's because they lived in these convents till the day they died and they had social responsibilities and they were playing games and they had chores and they were driving places and they had a million conversations with people. And, you know, this is how you keep the brain healthy, by running the motor of it. In contrast, what happens often, a lot of people will retire and then their lives will shrink and they'll end up just sitting on their couch watching television and that is really the worst thing that you can do for your brain, having a shrunken social life, not challenging yourself to do new things, that kind of thing.
ELISE: Hmm, such a fascinating study. I was just talking to Ellen Langer and you probably encountered her at Harvard. She's one of the mothers of mindfulness and she did that counterclockwise study where she took, this is an old study, but famous, where they took, I think it was men and put them in a setting that took them back 20 years, and everything looked... You know, like they were 20 years younger and they were sort of forced to carry their own bags and move as though they had the mobility of, let's say, a 60 year old, not an 80 year old, and they all, within five days, I think, they started to show the impact of this in their blood work. And so you also have to wonder, the nuns, the fact that they're in, in some ways, maybe a time capsule, or there's so little maybe variation in how they dress or what they're eating. I've never been a nun, so I can't necessarily speak to it, but it's interesting to think if they also aren't a little bit in a bit of a counterclockwise study.
DAVID: Well, I can speak from my experience as a nun. Just kidding, so I don't know. Yeah, that's a really interesting observation though about about all the things that don't change for them, even despite all the stuff that is held constant, they are constantly dealing with the other nuns. And it turns out that other people is the hardest thing that your brain does. Because you're constantly having to assume what they mean and guess, and how do I say this so that I can get the other person to do this, or understand what I mean or whatever. And it's just tons of cognitive work for your brain. And so having an active social life is everything. That's a major part of it. So you can imagine someone who has a big house and wears different clothes every day and stuff like that, but if they don't have any social life because they're just older and they're for whatever reason they've allowed their life to shrink like that, then that's the thing that causes their brain to degenerate. Or I should say the lack of the cognitive exercise is what causes their brain to degenerate.
So I'll come back to this thing that you asked about dreams. So, the reason you had never seen that before, by the way, is because this is the new theoretical framework that I've built to explain dreams. And what's funny is some people have asked me and said, wait, don't we already know why we dream? But the answer is no, there, there actually is not a good explanation for why we dream. People say, thing, just general things like, Oh, well, you know, it allows you to practice things that you wouldn't normally get to practice. Or, you know, it helps with memory consolidation, things like that, but no one has any proof for any of this stuff. And I ended up with my student deriving a theory that we can prove quantitatively across species. So here it is, so I was talking about the plasticity of the brain. Here's the thing, if you go blind, your visual system at the back of your brain will get taken over eventually by hearing, by touch, by other things.
And so this is why blind people have this extraordinary sense of hearing and of touch and they can tell things at a much finer resolution than you can because they have more brain real estate devoted to it. Okay, the surprise in neuroscience was how fast this takeover could happen, and nobody expected this to be fast, but some colleagues of mine at Harvard figured out that if you blindfold people and put them in the scanner, in the brain scanner, you can see after an hour of being blindfolded, when you make a sound or you touch somebody, You start seeing activity in their visual system. So that means the encroachment is starting after this incredibly short amount of time. So what my student and I realized is, you know, look, we live on this planet that rotates into darkness away from its star, you know, for half the time. And obviously, you know, we're all used to electricity, but our entire evolutionary history, it was really dark when the planet rotated.
And so you can still hear and smell and touch and taste in the dark, but you can't see. And that puts the visual system at a big disadvantage compared to the other senses. And so there are all kinds of hypotheses about why we sleep. One of the main ones is that it's, you know, to keep us out of trouble in the dark. And so, you know, you go into the corner of the cave and you essentially shut off. But the point is your visual system is not getting any input, whereas all the other systems are still getting, you know, you can still hear and touch and stuff like that. So, what we realized is that it needs some way to defend itself against takeover. And that's what dreams are. Every 90 minutes, you've got these very ancient circuits in your midbrain that just generate random activity and blast this activity into the primary visual cortex. That's the only place it goes. It doesn't go brain wide. It just goes into your visual cortex, just the first stage of it. And every 90 minutes, just blast this random activity in there. And because we are visual creatures, we see, we say, Oh, I'm having, you know, I'm in a meadow and I'm approaching a castle and I'm whatever. And but essentially the whole thing is just a screensaver. It's just protecting it against takeover from the other senses.
ELISE: God, dream analysts must hate you. I've had some prophetic dreams, though. I've had some, like, pretty magical dreams. I don't mind as science evolves that some of the magic is taken over by science. That's exciting. I do think there's just so much we don't understand.
DAVID: it is, of course, the case that there's so much we don't understand, when it comes to prophetic dreams, there doesn't actually seem to be any prophecy happening in dreams. But what does happen obviously is I mean, look at this way. Let's say that you dream about a big earthquake and then you turn on the news in the morning and you see that there's some big earthquake in Brazil or something and you'll say, God, that was prophetic. You know, think about it this way, there are probably, I don't know, 500 million hours of dreaming every night in America. And the real statistical aberration would be if nobody dreamt of an earthquake, right? That would be the surprising part. So worth keeping in mind.
ELISE: Okay. I can't let you go without asking you about ai. You seem quite optimistic that a computer will never be able to understand what's relevant to humans. Do you still feel optimistic?
DAVID: Well, I'm so glad you asked that question. So I wrote this book live wired in 2020 or that's, that's when it was published. I wrote it really in 2018 and 19 and everything has changed so rapidly in the AI space. We're all, you know, holding on to this fast wave that we're surfing and trying to understand what's going on with it. I would say AI At the moment, even the best large language models and all that stuff doesn't have a model of what it is to be a human. What it does have is it's read every single thing humans have read, and so it's able to do these statistical games and tell you the most likely next word and so on. And so it's able to tell you things that seem quite extraordinary, but it's not because it has a model of being a human. And in fact, there are, despite the incredible advances in the things that we've all been seeing with it, you know, there are ways in which it suddenly has its pants fall down all the time, you know, just as an example, it's not very good at getting jokes or making jokes because to make a joke, you have to think of the punchline first, and then you work backwards the way these large language models work is everything is going in the four direction. They're just asking what word do I put next? AI always has not had a good model of the physical world. So if I say, Hey, when president Biden walks into the room, does his head come with him? That's obvious for you. It's not obvious for an LLM. So we can see ways in which we think, Oh yeah, it's not quite like a human, but it may be that it is becoming intelligent, just sort of a different sort of intelligent, not the way that, that humans are. This is yet to be seen. I mean, I'm doing experiments on this every day about whether it actually has something like theory of mind, which is, you know, what is it like to be in your shoes?
There are all these tests in psychology about theory of mind. Little children can't do it very well. Children with autism can't do it very well. You know, like if I ask you a question, Bob comes into his room and puts his baseball under his bed. Then he leaves. Then his mother comes in the room, sees the baseball there, and she puts it away in the closet. Now Bob comes back in the room. Where does he look for the baseball? So any adult will know that Bob's gonna look under the bed 'cause that's where he thinks it is. But in order to answer that correctly, you have to ignore the fact that, you know, the baseball is in the closet. You have to be in Bob's shoes. You have to have to have a theory of what it is like to be Bob. And so little kids can't do this well, they'll say closet, you know, kid with autism will say closet.
And the question is chat GPT able to really understand what it is to be in someone else's head? And there's some sparks of that where it seems like, my gosh, it's not bad at doing that. And let me just say one more thing about this, because I've been obsessed, obviously, for the last year with AI, like everyone has, so I published a paper some months ago about how we could actually test for intelligence in AI and, you know, we have things like the Turing test, which is, could a machine impersonate a human and fool somebody, and the answer is totally, like, that's already, that's old news already, it's easy to fool somebody into thinking they're talking with a human.
So that's not really the right measure for intelligence. So I propose that it's scientific discovery. When it can actually discover new things in science, then we've got something to contend with. Then we have something that is smart in the way that humans are smart. And I'm not talking about just piecing together facts in the literature, which is obviously very useful, but I'm talking about the next level. Like when Einstein says, what if I were riding on a beam of light, what would the world look like? What would it be if I were moving at that speed? And he developed the special theory of relativity and, you know, or Darwin figuring out evolution, natural selection by thinking, okay, what about all the animals I'm not seeing here? What if there were a bunch of animals that also existed, but they didn't make it, that kind of stuff. You know, putting yourself in a theoretical world, like I said earlier about jumping to some island and seeing if you can build a bridge there. This is what humans are so good at doing all the time. And so the question is, when is AI going to get there? And by the way, it might be very soon.
ELISE: I know, it seems quite rapid. I mean, isn't the idea that AI will be able to start coding or programming itself?
DAVID: This is what we're all worried about. Yes. When that happens, yeah, we might as well...
ELISE: oh God.
DAVID: The part, let me just say one last thing about this. The part that has remained fascinating to me is what this means for human creativity. And, I think, Perhaps surprisingly that this actually means very little in terms of damaging human creativity, people are still going to write, people are still going to perform, do art, things like that. Even if AI can do it better, just look at something like chess. I mean, it was years ago that AI proved definitively that it could crush humans at chess. Nobody can play as well as an AI, but you know what? Chess is more popular than ever. There are more humans playing chess now than ever before. Why? Because they enjoy it. And by the way, you can get trained, you know, you can do these good training programs where you're using AI to train you so you don't make stupid mistakes. But humans enjoy doing this stuff. And by the way, when, you know, visual painters were, you know, painting their canvases and the camera was invented, they thought we're dead. No one's ever going to paint anymore. Cause you can capture a scene. Perfectly in just one click, but you know what? Painting never went away. It just flowered on a neighboring field to photography. So I think it'll only enhance things and it's not going to make any of our human endeavors go away.
ELISE: Yeah. No, I hope you're right. I was talking to Baratunde Thurston about this, and he was saying, and we were just laughing, and I mean, it's not funny, but that the things that AI seems to be going after out of the gate are the creative endeavors, right? Like taking the jobs, theoretically of photographers, writers, and it's like, well, no, that's the provenance, like do the programming or do the things that don't require, I guess, programming requires a lot of creativity, but they're sacred to humans, but maybe I'm just biased.
DAVID: yeah, that's right. I mean, just as a side note, that's not all they're going after. It's all the high level jobs. I mean, just as an example, you know, the whole legal profession. You know, the idea of a paralegal looking up case law and spending a month looking up case, you just don't need that anymore. You know, radiologists, this has actually been an interesting one, because many years ago it was predicted that radiologists would be gone by now, but in fact they're not, they're doing fine, because AI can... Actually, examine an image better than a human radiologist, and yet you need the human radiologist to understand that in context and talk to the patient and see what the patient's choices are and all that kind of stuff. These things will evolve and flower rapidly, but I don't think it's going to be a wholesale replacement.
ELISE: Yeah, I do think I can write better than chat GPT, for now.
DAVID: Exactly. By the way. I mean, I try this sometimes, you know, as I'm doing stuff, I think, Oh, maybe I can just get it to spit out this paragraph for me. And it writes it about the level of a really intelligent, you know, sophomore in high school or something. And it doesn't ever reach to the standard that professional writers need to do.
ELISE: Yeah. No, certainly. Well, thank you, such a pleasure. We'll do this again someday. I want to talk to you about consciousness. I want to talk to you about all the woo so that you can ground it into scientific probability.
DAVID: All right. Great. Okay. Well, it's such a pleasure. I can't wait till next time.
ELISE: All right. Thank you.
At the end of Livewired, David Eagleman writes: “At some point we might perhaps be able to read the rough details of someone’s life—what he did and what was important to him—from the exact molding of his neural resources. If feasible, this would amount to a new kind of science. By looking at how the brain shaped itself, could we know what a person was exposed to, and perhaps what he cared about? Which hand did this person use for fine motor skills? What were the relevant signals in his environment? What was the structure of his language? And all the rest of the questions that we cannot answer by looking simply at guts and hair and knees and fingernails.” I want to have another conversation with Eagleman at some point because I want to talk about psychic phenomena and other energies that are perceptible to some people and not to others and whether he thinks we will ever have the science to understand what’s at play, or whether he thinks we can already explain that phenomena. I believe that the realm of “woo” (which isn’t such a nice word but we’re going to go with it) will ultimately be something we’ll have language for that will live within science, maybe not all of it but certainly some of it. He seems to be one of the people who’s exploring all those big questions—a magic, really, that keeps us all engage, entertained, inspired. Alright, I’ll see you next week.
