WEBVTT - Ep54 "Where do you end and others begin?" 0:00:04.519 --> 0:00:08.360 From the brain's point of view, What is the self? 0:00:08.760 --> 0:00:12.440 How do you put together thirty six trillion cells and 0:00:12.520 --> 0:00:16.279 have it feel like one thing? Does the self of 0:00:16.360 --> 0:00:20.440 a blind person include the tip of the walking stick? 0:00:20.840 --> 0:00:24.000 How flexible is our sense of self? And what does 0:00:24.000 --> 0:00:27.320 any of this have to do with psychedelics or trauma, 0:00:27.760 --> 0:00:33.000 or synchronized swimmers, or religious rituals or cheerleaders, or why 0:00:33.159 --> 0:00:37.760 soldiers across time and place love to march in unison 0:00:37.920 --> 0:00:44.519 in lockstep. Welcome to Inner Cosmos with me David Eagleman. 0:00:45.000 --> 0:00:48.240 I'm a neuroscientist and an author at Stanford and I've 0:00:48.280 --> 0:00:52.160 spent my career at the intersection between how the brain 0:00:52.240 --> 0:01:06.200 works and how we experience life. So I'm going to 0:01:06.240 --> 0:01:09.119 beget in today's episode with a question that I've wondered 0:01:09.160 --> 0:01:12.039 about since i was a kid. Something I've always found 0:01:12.080 --> 0:01:18.480 amazing is watching armies, thousands of soldiers march in perfect lockstep. 0:01:18.920 --> 0:01:21.720 And even as a kid, I noticed that across the world, 0:01:21.880 --> 0:01:24.720 all armies did this and this goes back to the 0:01:24.880 --> 0:01:27.800 earliest days of armies. And I know this because when 0:01:27.840 --> 0:01:31.280 I was younger, I read about how the Romans discovered 0:01:31.319 --> 0:01:35.920 a problem where if they marched in lockstep over a bridge. 0:01:36.240 --> 0:01:39.920 It would sometimes hit the resonance frequency of the bridge 0:01:39.920 --> 0:01:43.720 and then it would collapse. So they learned from their mistakes, 0:01:43.720 --> 0:01:46.760 and whenever they came to a bridge, they would purposely 0:01:47.240 --> 0:01:50.040 go out of sync with one another and they would 0:01:50.080 --> 0:01:52.440 cross the bridge that way. But the point is that 0:01:52.520 --> 0:01:57.880 they normally marched in lockstep. They, like all modern armies, 0:01:58.400 --> 0:02:03.560 loved acting as a mega organism. So why do armies 0:02:03.880 --> 0:02:07.040 love to synchronize? I mean, why not just have all 0:02:07.080 --> 0:02:11.320 the soldiers walk asynchronously however they want to, as long 0:02:11.360 --> 0:02:14.720 as they keep up well. One hypothesis would be that 0:02:15.040 --> 0:02:19.920 an army marching in lockstep is intimidating. You see something 0:02:19.960 --> 0:02:24.840 coming at you. That's like a giant, unified, single minded monster. 0:02:25.639 --> 0:02:29.720 And a related hypothesis could be that an army stepping 0:02:29.840 --> 0:02:35.720 with precision timing represents discipline and training, the way we 0:02:36.160 --> 0:02:41.240 watch dancers or synchronized swimmers, and across sports like ballet 0:02:41.360 --> 0:02:46.280 or cheerleader or whatever, athletes pursue this kind of perfect synchronization. 0:02:47.040 --> 0:02:49.800 In other words, the army does it not just because 0:02:49.800 --> 0:02:53.679 it's scary, but also because it represents discipline and training 0:02:53.720 --> 0:02:57.440 to get there. And these both seem like reasonable hypotheses. 0:02:58.240 --> 0:03:01.200 But I have something else to segest today, something that 0:03:01.240 --> 0:03:05.520 I think you might find quite surprising and hopefully enlightening 0:03:05.600 --> 0:03:08.639 because of all the other things that it sheds light on. 0:03:09.360 --> 0:03:13.640 So what seems like an arbitrary question can sometimes unearth 0:03:13.840 --> 0:03:18.680 a lot. But first, let's start at the beginning. So 0:03:18.800 --> 0:03:22.239 let's step back to sixteen thirty seven, when Renee de 0:03:22.400 --> 0:03:28.640 Kartes famously wrote Japan's don't suis I think? Therefore I am? 0:03:29.040 --> 0:03:33.000 Now when he says I, we all understand what he 0:03:33.120 --> 0:03:37.720 means here, we think, but what exactly is the I 0:03:37.720 --> 0:03:40.839 If you think it's obvious what the self is, get 0:03:40.880 --> 0:03:43.760 ready for some eye openers, because we're going to see 0:03:43.800 --> 0:03:48.080 how the self emerges from computations in the brain and 0:03:48.120 --> 0:03:52.200 how it can morph in unexpected ways. So let's start 0:03:52.240 --> 0:03:55.680 by noting that nothing seems more obvious than you feel 0:03:55.840 --> 0:04:01.280 like a single entity. But that's strange because you're actually 0:04:01.320 --> 0:04:07.360 built out of thirty six trillion individual cells communicating through 0:04:07.480 --> 0:04:11.280 chemical and electrical signals. But you don't feel like that. 0:04:11.320 --> 0:04:15.400 You don't feel like a swirling bath of seven billion, 0:04:15.480 --> 0:04:19.920 billion billion atoms, not to mention that you're constantly shedding 0:04:20.000 --> 0:04:23.400 atoms and gaining new ones, such that your body is 0:04:23.480 --> 0:04:28.640 composed of entirely new atoms about every seven years. Despite 0:04:28.720 --> 0:04:32.679 all this, you feel like one stable thing. You feel 0:04:32.720 --> 0:04:36.160 like you. You have a name, You have a history 0:04:36.200 --> 0:04:40.320 and a memory, and a personality. You have desires, and 0:04:40.360 --> 0:04:44.560 you are unique personality. You have a self, and that 0:04:44.760 --> 0:04:48.320 self seems to be located right behind your eyeballs. Now 0:04:48.360 --> 0:04:53.040 this is wild, right, because consider other scenarios in which 0:04:53.080 --> 0:04:56.400 there are lots of pieces and parts working together. Let's 0:04:56.400 --> 0:04:58.440 say I go out to some big field and I 0:04:58.480 --> 0:05:02.200 set up a bunch of and pulleys and levers, and 0:05:02.240 --> 0:05:05.480 I start hooking everything up and this turns that, and 0:05:05.520 --> 0:05:09.120 that affects that, and this lever pulls that thing, and 0:05:09.160 --> 0:05:11.360 I start adding more and more parts in this big 0:05:11.480 --> 0:05:16.160 crazy machine gets larger and larger. Here's the question, At 0:05:16.160 --> 0:05:21.040 what point do I add one more lever and I say, ah, 0:05:21.480 --> 0:05:26.920 Now this is no longer a Frankensteinian collection of trillions 0:05:26.960 --> 0:05:32.800 of individual pieces, but suddenly it has the experience of 0:05:32.880 --> 0:05:37.520 a living unity. Or just take your computer. It's made 0:05:37.560 --> 0:05:41.960 of billions of transistors and resistors and capacitors. It's sending 0:05:42.040 --> 0:05:45.839 zeros and ones all around. But the question is does 0:05:45.920 --> 0:05:50.039 your MacBook pro have a sense of itself? Do you 0:05:50.080 --> 0:05:54.440 think it ever aspires to be something greater in its life? 0:05:54.560 --> 0:05:57.920 Or does it feel a sense of embarrassment and its 0:05:57.920 --> 0:06:01.960 performance sometimes, or does it ever desire to be loved 0:06:02.120 --> 0:06:06.120 by another computer? Now, the reason your sense of self 0:06:06.160 --> 0:06:09.040 is so mysterious is because your brain is just made 0:06:09.120 --> 0:06:13.760 up of pieces and parts cells with straightforward properties, each 0:06:13.839 --> 0:06:17.360 cell by itself as just doing basic sell things. So 0:06:17.400 --> 0:06:20.640 why does this giant collection, when hooked up and interacting 0:06:20.720 --> 0:06:24.480 in the right way, have a unified sense of a 0:06:24.560 --> 0:06:28.760 single you interacting with the world through time. You have 0:06:28.839 --> 0:06:31.840 this conscious perception of yourself as a thing such that 0:06:31.880 --> 0:06:36.919 the thirty six trillion cells that comprise you can collaborate 0:06:37.000 --> 0:06:40.120 to go to a dance club tonight, or meet friends 0:06:40.120 --> 0:06:42.720 at the coffee shop, or go to a bookstore, or 0:06:42.800 --> 0:06:45.279 take a road trip across the nation, acting like a 0:06:45.320 --> 0:06:50.000 single thing. So why do you feel like a unified entity? Now? 0:06:50.080 --> 0:06:55.440 The answer, presumably is an evolutionary one. Those cells are 0:06:55.480 --> 0:06:58.200 all hanging together, and this collection has to take the 0:06:58.240 --> 0:07:03.360 whole vast complet space of possibilities and crunch it down 0:07:03.400 --> 0:07:07.839 to a single decision. For example, your body can go 0:07:07.960 --> 0:07:09.960 to the left or go to the right to get 0:07:10.000 --> 0:07:13.400 around the tree, but you can't do both, and that's 0:07:13.400 --> 0:07:16.760 why you have to squeeze down all the chattering of 0:07:16.880 --> 0:07:22.000 billions of neurons to a single choice and control your 0:07:22.120 --> 0:07:25.200 trillions of cells to do something that makes sense in 0:07:25.240 --> 0:07:28.720 the outside world. I've mentioned before that the brain is 0:07:28.800 --> 0:07:33.360 typically celebrated for its parallel processing, but in fact, just 0:07:33.400 --> 0:07:38.320 as importantly it should be celebrated for its serialization. In 0:07:38.360 --> 0:07:42.640 other words, its ability to conclude something, to decide something 0:07:43.040 --> 0:07:46.680 from the vast space of possibilities, to take all the 0:07:47.160 --> 0:07:51.440 rumbling trillions of cells and get to a single conclusion 0:07:51.720 --> 0:07:56.160 about what to do next. So that's presumably why you 0:07:56.440 --> 0:08:01.320 have a unified sense. But the story gets stranger from 0:08:01.320 --> 0:08:05.280 here because the sense of self is not fixed, it's 0:08:05.320 --> 0:08:09.520 not nailed into place. Instead, it's quite fluid, and in 0:08:09.560 --> 0:08:14.520 many scenarios what we find is a dissolution of the self. 0:08:14.760 --> 0:08:19.360 For example, various drugs can have profound effects on an 0:08:19.400 --> 0:08:24.360 individual's sense of self. They lead to an alteration of 0:08:24.400 --> 0:08:27.720 one's identity. And this is amazing, right, because these are 0:08:28.080 --> 0:08:32.920 invisibly small molecules with particular shapes, and when they enter 0:08:33.000 --> 0:08:36.760 your system and bind to particular receptors in your brain 0:08:37.200 --> 0:08:41.080 and change the activity just a little bit, then this 0:08:41.480 --> 0:08:47.320 neural technology that builds selfness breaks down. For example, a 0:08:47.320 --> 0:08:51.000 lot of psychedelic drugs do this. They bind to particular 0:08:51.080 --> 0:08:55.320 receptors here and there, and they cause profound alterations in 0:08:55.400 --> 0:09:01.800 the feeling of self. Think of LSD or SILAS or DMT. 0:09:02.320 --> 0:09:04.960 What happens when people take this is they report a 0:09:05.440 --> 0:09:10.720 dissolving of their ego boundaries, leading to experiences of what's 0:09:10.720 --> 0:09:16.440 sometimes called an ego death, meaning the loss of self identity. 0:09:16.480 --> 0:09:20.960 You also have substances like ketamine or PCP or some 0:09:21.240 --> 0:09:27.359 synthetic cannabinoids, and these can trigger feelings of depersonalization and dissociation. 0:09:27.520 --> 0:09:30.079 In other words, people on these drugs get a sense 0:09:30.160 --> 0:09:35.080 of detachment from their own body, or their emotions or 0:09:35.080 --> 0:09:40.360 their surroundings, so they have a distorted perception of self. 0:09:40.840 --> 0:09:44.120 And you sometimes see this with certain psychiatric medications when 0:09:44.120 --> 0:09:48.560 they're misused or taken in appropriately. They can alter cognition 0:09:48.760 --> 0:09:52.839 and emotion and often lead to a feeling of disconnection 0:09:53.400 --> 0:09:57.079 from a person's identity or sense of self, and all 0:09:57.120 --> 0:10:00.480 throughout the drug world, you find people mixing different drugs 0:10:00.520 --> 0:10:04.640 together and getting all kinds of severe things like dissociation 0:10:04.840 --> 0:10:10.319 and confusion and a loss of coherent self awareness. So 0:10:10.440 --> 0:10:14.160 what does this tell us? In all these situations, we 0:10:14.320 --> 0:10:20.400 see how invisibly small molecules can disrupt the normal, very 0:10:20.440 --> 0:10:25.400 delicate functioning of the brain, and that busts up the 0:10:25.559 --> 0:10:29.760 computation of the self. And you can find the same 0:10:29.800 --> 0:10:33.000 thing not just from the influence of molecules, but also 0:10:33.000 --> 0:10:37.240 from the influence of experiences. Just look at something like 0:10:37.640 --> 0:10:41.920 post traumatic stress disorder. Beyond the emotional challenges that we 0:10:42.000 --> 0:10:46.960 find there, we also find cognitive impacts like a pervasive 0:10:47.080 --> 0:10:51.560 sense of disconnection from one's identity and a loss of 0:10:52.000 --> 0:10:57.440 coherence in self perception. For example, sometimes people report feeling 0:10:57.559 --> 0:11:01.079 like an object rather than a person. Now, what happens 0:11:01.120 --> 0:11:04.320 when we measure the effects of post traumatic stress disorder 0:11:04.440 --> 0:11:08.240 in the brain. While there's a network called the default 0:11:08.320 --> 0:11:12.720 mode network, and this network is critical for constructing one 0:11:12.840 --> 0:11:16.920 sense of self, and in post traumatic stress disorder, for example, 0:11:17.400 --> 0:11:23.000 you can find in neuroimaging that the connectivity gets disrupted, 0:11:23.360 --> 0:11:27.200 and this appears to correlate with problems with one's perceived 0:11:27.559 --> 0:11:32.040 sense of self. This feeling that people sometimes have in 0:11:32.080 --> 0:11:35.160 post traumatic stress disorder, where they say they don't know 0:11:35.200 --> 0:11:38.520 who they are, where they feel like they've stopped existing. 0:11:38.880 --> 0:11:42.960 What this reflects is a disruption in their networks that 0:11:43.040 --> 0:11:47.480 are critical to computing the self, and we see disruptions 0:11:47.520 --> 0:11:51.600 of the self in closely related clinical settings also, for example, 0:11:51.679 --> 0:11:56.720 in dissociative identity disorder. This is where people usually who 0:11:56.760 --> 0:12:00.560 have been through some trauma, will have a fragment of 0:12:00.600 --> 0:12:05.640 their self into different identities. They switch personalities. They can 0:12:05.679 --> 0:12:09.599 have these sudden changes in mood and in their behavior, 0:12:10.200 --> 0:12:13.760 and family members can usually tell when a person switches 0:12:13.920 --> 0:12:17.439 their personality. And by the way, they often get amnesia. 0:12:17.480 --> 0:12:20.240 They can't remember what they said just a few minutes 0:12:20.280 --> 0:12:23.800 ago when they were speaking as one of their other personalities. 0:12:24.360 --> 0:12:27.920 I'll just note that often people with dissociative identity disorder 0:12:28.320 --> 0:12:33.240 are misdiagnosed as having schizophrenia because their beliefs are interpreted 0:12:33.400 --> 0:12:37.880 as a delusion. But I think more properly this could 0:12:37.920 --> 0:12:41.600 be interpreted as yet another demonstration that the brain has 0:12:41.679 --> 0:12:45.640 to go through an enormous amount of very delicate work 0:12:45.720 --> 0:12:50.160 to construct the self, and there are lots of ways 0:12:50.160 --> 0:12:53.080 this can be disrupted. Now, how can we study this? 0:12:53.320 --> 0:12:57.120 In the lab, one of my colleagues at Stanford, Joseph Parvizi, 0:12:57.679 --> 0:13:01.920 was studying patients with epilep see people who have electrical 0:13:02.000 --> 0:13:04.520 seizures in the brain. So one day one of his 0:13:04.640 --> 0:13:07.920 patients with APLEPSI tells him every time I have a seizure, 0:13:08.280 --> 0:13:14.360 I have a sense of depersonalization and dissociation. Everything's unreal, 0:13:14.440 --> 0:13:18.440 It's like it's not happening to me. And Parvez finds 0:13:18.440 --> 0:13:22.600 out that this patient's seizures started in a tiny brain 0:13:22.760 --> 0:13:27.559 area right in the brain's midline, called the anterior precuneus. 0:13:27.880 --> 0:13:30.360 And there was something very interesting about this area because 0:13:30.400 --> 0:13:33.840 it's not part of the default mode network, which I 0:13:33.880 --> 0:13:36.640 mentioned a moment ago, but instead it's a node at 0:13:36.679 --> 0:13:40.160 the center of a different network consisting of different areas. 0:13:40.320 --> 0:13:45.040 And this network integrates data about where you are and 0:13:45.080 --> 0:13:48.679 how you're moving, and where your muscles and joints are, 0:13:49.080 --> 0:13:52.800 so it's involved in building a mental map of your 0:13:52.920 --> 0:13:56.240 physical self. Now, just before I tell you more about this, 0:13:56.280 --> 0:13:58.680 one of the things I think is interesting is how 0:13:58.760 --> 0:14:05.080 parvs this ditinguishes between the I and the me. He says, Look, 0:14:05.120 --> 0:14:08.440 for every action we take, even during dreams, there's always 0:14:08.520 --> 0:14:12.880 an agent behind it. We call that agent I. But 0:14:13.480 --> 0:14:18.040 me is everything we have stored in our memories about 0:14:18.160 --> 0:14:21.040 the I. In other words, the eye has to do 0:14:21.520 --> 0:14:24.920 with your sense of your body in the immediate here 0:14:25.000 --> 0:14:27.880 and now, with a particular point of view, a first 0:14:27.920 --> 0:14:31.440 person perspective that belongs to only you. But the me, 0:14:31.800 --> 0:14:35.000 that's the narrative self, that has to do with actively 0:14:35.120 --> 0:14:39.160 or passively thinking about your past life or planning your future, 0:14:39.680 --> 0:14:45.720 things like memory and habits and personality, emotions, feelings for others, 0:14:45.760 --> 0:14:49.080 what lies ahead, and so on. Okay, now here's the 0:14:49.160 --> 0:14:51.720 key point from the brain's point of view. These two 0:14:51.920 --> 0:14:55.280 functions of the eye and the me, they're actually underpinned 0:14:55.320 --> 0:15:00.240 by separate networks of brain areas. These networks interact, they're 0:15:00.280 --> 0:15:04.560 not the same. So the me involving my memory, inhabits 0:15:04.560 --> 0:15:09.400 and personality and emotions, that mostly involves the default mode network. 0:15:09.880 --> 0:15:14.040 But the eye, which gives my sense of my particular 0:15:14.080 --> 0:15:17.680 point of view right now, that involves this other network 0:15:17.720 --> 0:15:21.720 where the anterior precunius sits at the center. And what 0:15:21.800 --> 0:15:25.480 Parvizi found is when that network becomes disrupted, let's say 0:15:25.480 --> 0:15:29.680 by an epileptic seizure that disrupts your self in the 0:15:29.760 --> 0:15:34.640 here and now. So he stuck electrodes into the anterior 0:15:34.680 --> 0:15:39.960 precuneus and zaps with electricity, and people say that something 0:15:40.040 --> 0:15:43.520 weird happens to their sense of physical self. They get 0:15:43.520 --> 0:15:47.800 a depersonalization, similar to what happens with psychedelics. It's not 0:15:48.200 --> 0:15:51.040 an out of body experience. People still feel like they're 0:15:51.040 --> 0:15:53.800 in their bodies, but they generally feel like there's a 0:15:53.920 --> 0:15:57.920 change in their orientation or their location, depending on where 0:15:57.920 --> 0:16:00.840 the stimulation happens. They feel like they're floating, your sinking, 0:16:01.440 --> 0:16:03.720 and it doesn't make any sense when they look around 0:16:03.720 --> 0:16:07.080 and they see where they are. And so their report 0:16:07.320 --> 0:16:28.760 was that the world around them seemed unreal. So again 0:16:28.880 --> 0:16:34.120 I want to be clear that you require this extraordinarily specific, 0:16:34.320 --> 0:16:38.240 delicate operation of multiple networks in the brain to make 0:16:38.320 --> 0:16:42.440 you feel a particular way, to give you an eye 0:16:42.720 --> 0:16:45.280 that's anchored in space with a point of view, and 0:16:45.320 --> 0:16:49.000 a me with a stable sense of who you are, 0:16:49.480 --> 0:16:51.880 and a connection to your memories and your sense as 0:16:51.920 --> 0:16:55.680 an individual. Now, assuming you have average good luck, then 0:16:55.720 --> 0:17:00.360 you'll never even be conscious of this perspective on the world. 0:17:00.720 --> 0:17:04.640 But if your brain gets disrupted from drugs or trauma 0:17:04.760 --> 0:17:08.119 or epilepsy, you're suddenly going to see it. Your world 0:17:08.160 --> 0:17:12.760 will seem unreal, and you'll come to understand that the 0:17:12.880 --> 0:17:16.720 self is a construction of the brain and needs all 0:17:16.800 --> 0:17:20.719 the pieces and parts to be running just right. Okay, 0:17:20.760 --> 0:17:23.600 so what we've talked about so far is the way 0:17:23.720 --> 0:17:27.800 the self can get disrupted. But now I want to 0:17:27.880 --> 0:17:32.040 switch gears to a less studied area. Instead of the 0:17:32.480 --> 0:17:36.600 dissolution of the self, I want to consider the expansion 0:17:36.880 --> 0:17:39.760 of the self. Now. I started thinking about this many 0:17:39.800 --> 0:17:41.520 years ago, even when I was a kid. I noticed 0:17:41.520 --> 0:17:44.960 that when you ride a bicycle, and maybe you accidentally, 0:17:45.040 --> 0:17:48.240 without meaning to, you run over a little worm that's 0:17:48.280 --> 0:17:51.480 crawled onto the sidewalk, and you recoil as though you'd 0:17:51.520 --> 0:17:54.560 physically stepped on the worm yourself with your bare feet, 0:17:54.600 --> 0:17:57.880 even though it was only the bicycle that touched the worm. 0:17:58.200 --> 0:18:01.879 So I started wondering if the bicycle becomes essentially a 0:18:02.119 --> 0:18:06.680 part of you, an extension of the self of some sort. 0:18:06.920 --> 0:18:08.560 And then when I got to college, I ended up 0:18:08.600 --> 0:18:13.920 reading some philosophers like Maurice Merleau Ponti and Gregory Bateson 0:18:14.160 --> 0:18:17.960 who posed a question like this about a blind man 0:18:18.080 --> 0:18:21.760 with a stick. The question was where does the blind 0:18:21.880 --> 0:18:25.240 man's self end and the rest of the world begin. 0:18:25.760 --> 0:18:28.720 You can think of the stick as like an extended 0:18:29.160 --> 0:18:32.520 cognitive system that pulls in information from the world. So 0:18:32.600 --> 0:18:35.879 does the blind man end at the handle of the 0:18:35.920 --> 0:18:39.120 stick or at the tip of the stick? Or does 0:18:39.119 --> 0:18:44.120 his self end somewhere in between? As Merleau Ponti wrote, quote, 0:18:44.440 --> 0:18:48.040 the blind man's cane has ceased to be an object 0:18:48.119 --> 0:18:51.840 for him. It's no longer perceived for itself. Rather, the 0:18:52.000 --> 0:18:58.000 caine's furthest point is transformed into a sensitive zone end quote. 0:18:58.000 --> 0:19:00.920 In other words, since the world is a deserved through 0:19:00.960 --> 0:19:05.639 the stick, it becomes part of the man's self. So 0:19:05.800 --> 0:19:09.119 humans alter the borders of their self all the time 0:19:09.200 --> 0:19:13.920 by using new instruments. I talked way back in episode 0:19:13.920 --> 0:19:18.040 two about dogs who learn how to ride skateboards, and 0:19:18.119 --> 0:19:21.920 even though wheels are not a part of the evolutionary 0:19:22.040 --> 0:19:25.520 history of canines, it becomes part of the dog. They 0:19:25.560 --> 0:19:30.000 become one with the skateboard, and I talked about surfing 0:19:30.160 --> 0:19:33.639 dogs even though the dog skeleton didn't evolve to be 0:19:33.800 --> 0:19:36.480 big and long and flat. The dog has no trouble 0:19:37.040 --> 0:19:42.800 incorporating the surfboard into its body plan into itsself. So 0:19:43.280 --> 0:19:46.840 we're not limited by the borders of our skin, but 0:19:46.960 --> 0:19:51.600 instead these self can expand. And I've also previously mentioned 0:19:51.640 --> 0:19:54.680 some experiments that were done years ago where a monkey 0:19:55.240 --> 0:19:57.919 learns to use a little rake to get some food 0:19:58.000 --> 0:20:01.880 that he couldn't otherwise reach. And once the monkey becomes 0:20:01.960 --> 0:20:05.679 proficient at this, there are cells in its brains sells 0:20:05.720 --> 0:20:08.600 that command actions and sells that sense what's going on. 0:20:09.080 --> 0:20:13.560 These cells change to include the rake in the space 0:20:13.640 --> 0:20:16.960 that they care about, what's known as their receptive field. 0:20:17.520 --> 0:20:22.440 In other words, the rake literally becomes part of the monkey. 0:20:23.080 --> 0:20:26.640 So whether we're talking about bicycle tires or walking canes 0:20:26.680 --> 0:20:29.400 for the blind, or the monkey and the rake, we 0:20:29.520 --> 0:20:32.480 see that the notion of the self has flexibility. It's 0:20:32.560 --> 0:20:37.399 not something that's just genetically pre programmed and fixed into place. 0:20:38.160 --> 0:20:42.320 So how does the body decide what to include what 0:20:42.920 --> 0:20:46.679 makes up the self? Well, in my last book, Live Wired, 0:20:46.760 --> 0:20:51.159 I proposed an answer to this. In part, it's about control. 0:20:51.800 --> 0:20:56.000 If the brain can control something, it becomes part of 0:20:56.040 --> 0:20:59.960 the self. So, for example, when my brain sends out 0:21:00.160 --> 0:21:04.119 signals to move my arm. My arm follows the commands, 0:21:04.160 --> 0:21:08.480 and therefore it becomes part of my self. The monkey's 0:21:08.560 --> 0:21:11.520 rake becomes part of what it can use and command 0:21:11.640 --> 0:21:14.440 in the world, so it becomes in a sense, part 0:21:14.480 --> 0:21:17.959 of its body. Now. Fundamentally, remember the brain is locked 0:21:17.960 --> 0:21:22.120 in silence and darkness, and so what does command mean 0:21:22.200 --> 0:21:27.720 to it? Fundamentally, it's all about prediction. Now. In an 0:21:27.760 --> 0:21:32.080 earlier episode forty four, we dove into the issue about 0:21:32.080 --> 0:21:36.480 the brain being a prediction machine. That's all it's trying 0:21:36.520 --> 0:21:39.199 to do. Locked in silence and darkness, It's trying to 0:21:39.240 --> 0:21:42.639 figure out what's happening in the world out there, And 0:21:42.680 --> 0:21:46.359 for really sophisticated brains like ours, it's not just about 0:21:46.720 --> 0:21:50.800 reacting to what happened, but instead having a model of 0:21:50.840 --> 0:21:55.600 the world that makes predictions about what will happen. So 0:21:55.960 --> 0:21:59.920 given this, what else can become a part of the cell. 0:22:00.000 --> 0:22:04.440 We are used to our brains controlling just our limbs, 0:22:04.520 --> 0:22:07.879 and this is because evolution has built us with muscle 0:22:07.960 --> 0:22:11.880 and tendons and nerves. But evolution never came up with 0:22:12.480 --> 0:22:16.960 controlling distant limbs via bluetooth. So in theory, if you 0:22:17.000 --> 0:22:20.879 could control a robotic arm with your brain, or a 0:22:21.040 --> 0:22:24.760 metal avatar that's all the way across town. This would 0:22:24.800 --> 0:22:28.480 become part of your self. And one question is what 0:22:28.640 --> 0:22:33.560 consequence would this have for your conscious experience. The answer 0:22:33.640 --> 0:22:36.919 is that the robot or the avatar would be perceived 0:22:37.320 --> 0:22:41.040 as a part of you. It would be another limb. 0:22:41.560 --> 0:22:43.879 It would be an unusual limb because of the physical 0:22:43.960 --> 0:22:47.560 gap between you and it, but it would nonetheless qualify 0:22:47.720 --> 0:22:51.960 as an extension of you. Think of the Avatar movies. 0:22:52.480 --> 0:22:56.719 The protagonist Jake Sully thinks of something he wants to 0:22:56.760 --> 0:23:00.280 do with his limited body, and the eight foot all 0:23:00.480 --> 0:23:06.760 avatar moves accordingly, and therefore the avatar becomes an extension 0:23:06.920 --> 0:23:10.000 of his self. By the way, you see this all 0:23:10.000 --> 0:23:14.760 the time. In the military. A soldier is in charge 0:23:14.760 --> 0:23:19.159 of driving a bomb sniffing robot, and everything the soldier 0:23:19.240 --> 0:23:23.359 commands with his joystick, the robot does. And at some point, 0:23:23.400 --> 0:23:27.639 if the robot gets blown up, it's not unusual to 0:23:27.680 --> 0:23:30.960 see one of these soldiers crying and heartbroken. It's like 0:23:31.040 --> 0:23:35.360 a part of them physically has been lost. Now, if 0:23:35.359 --> 0:23:39.480 this kind of extension of the self seems strange, just 0:23:39.560 --> 0:23:43.520 remember that you have everyday experience with this. Whenever you 0:23:43.600 --> 0:23:47.119 look in a mirror and move your body around, you 0:23:47.160 --> 0:23:51.640 see a distant object move in perfect synchrony with your 0:23:51.680 --> 0:23:55.320 motor commands. Your brain says, lift your arm, and you 0:23:55.359 --> 0:23:58.880 see this thing across the room, lift its arm. It's 0:23:58.920 --> 0:24:02.000 a perfect prediction. And so when you do that, you 0:24:02.160 --> 0:24:06.840 understand the reflection as your self. You don't feel any 0:24:07.240 --> 0:24:11.480 direct sensation from the distant limbs, but your brain registers 0:24:11.560 --> 0:24:15.159 the prediction. Every time I send out a command for X, 0:24:15.680 --> 0:24:20.399 that body over there does X, and that's enough for 0:24:20.560 --> 0:24:25.160 your reflection to become a member of the selfhood tribe. 0:24:25.480 --> 0:24:27.679 And one of the things I've written about recently is 0:24:27.800 --> 0:24:33.520 expanding oneself using virtual reality. You're in a virtual world 0:24:33.560 --> 0:24:36.760 and you raise your arm and you see your virtual 0:24:36.840 --> 0:24:40.960 avatar and the virtual mirror raise its arm. You tilt 0:24:41.000 --> 0:24:44.080 your head and it tilts its head. Now, interestingly, people 0:24:44.080 --> 0:24:47.800 are studying this in the context of empathy, because you 0:24:47.840 --> 0:24:51.760 can put someone else's face on the virtual avatar. Let's 0:24:51.800 --> 0:24:54.359 say someone of a different gender and a different race, 0:24:54.840 --> 0:24:58.159 and the question is how do you feel after having 0:24:58.240 --> 0:25:01.520 them be a part of you for a while. And 0:25:01.560 --> 0:25:05.359 you can experiment with very different kinds of bodies in VR. 0:25:05.840 --> 0:25:09.480 What if in a VR world you're one hundred feet tall, 0:25:09.560 --> 0:25:12.960 or you have eight legs or three arms. In all 0:25:13.000 --> 0:25:16.560 of these cases, you can learn to control that body, 0:25:16.880 --> 0:25:21.199 to predict what's happening, and then that body becomes you. 0:25:21.920 --> 0:25:27.879 The identity of the self is surprisingly flexible. So what 0:25:28.000 --> 0:25:31.960 I've proposed is that what the body can control becomes 0:25:32.040 --> 0:25:36.439 the self. And this all pivots on predictability, and so 0:25:36.720 --> 0:25:39.880 one tragic lesson we can glean from this is what 0:25:40.040 --> 0:25:44.000 happens when a person gets damage to their peripheral nerves 0:25:44.280 --> 0:25:47.639 so they can no longer control their limb. And what 0:25:47.800 --> 0:25:52.320 happens is they can get a disorder called asomatic nosea, 0:25:52.880 --> 0:25:56.800 which means they now deny ownership of the limb that 0:25:56.840 --> 0:26:01.320 they can't control. So as somatic nosia means not knowing 0:26:01.359 --> 0:26:04.520 one's body. And in the clinics you'll find the strangest 0:26:04.560 --> 0:26:08.119 things where somebody will say this leg does not belong 0:26:08.240 --> 0:26:11.680 to me, and sometimes they'll insist that the limb belongs 0:26:11.760 --> 0:26:16.360 to somebody else. They'll attribute the leg to, say a 0:26:16.480 --> 0:26:20.719 dead friend or a relative, or a phantasm or a devil, 0:26:21.160 --> 0:26:23.640 or one of the doctors taking care of them. They'll 0:26:23.680 --> 0:26:28.120 say the leg was sewn onto her, but it's not hers. 0:26:28.800 --> 0:26:33.639 She'll explain that her own real limb was stolen or 0:26:33.800 --> 0:26:37.760 is simply missing. And in variance of this disorder, people 0:26:37.760 --> 0:26:41.000 will sometimes construe the limb as an animal, perhaps like 0:26:41.040 --> 0:26:44.800 a snake, with its own independent life force and intentions. 0:26:45.160 --> 0:26:48.040 But the point is it's no longer a part of 0:26:48.119 --> 0:26:51.200 their self. So I was surprised when I found there 0:26:51.240 --> 0:26:54.639 was no gold standard explanation for this in the literature. 0:26:55.200 --> 0:26:59.040 But you'll have no trouble guessing my proposal, which is 0:26:59.040 --> 0:27:02.480 that the brain can no longer control the limb, and 0:27:02.520 --> 0:27:06.679 so the limb falls from the brotherhood of the self. 0:27:07.200 --> 0:27:09.920 By the way, sometimes these patients have a small window 0:27:09.960 --> 0:27:14.040 of lucidity in which they re recognize their limb as 0:27:14.119 --> 0:27:18.800 their own, but it doesn't last long. I hypothesize that 0:27:18.840 --> 0:27:22.720 this might result when the leg happens to move the 0:27:22.760 --> 0:27:27.119 way that they had intended accidental predictability. That might be 0:27:27.160 --> 0:27:30.240 a feeling of wanting to move the foot to the left, 0:27:30.280 --> 0:27:33.439 and then the foot happens to move that way, which 0:27:33.600 --> 0:27:37.200 leads the owner to take credit for the action. And 0:27:37.480 --> 0:27:42.000 given a person's lifelong experience of controlling her leg It 0:27:42.000 --> 0:27:45.840 should come as no surprise that even a temporary impression 0:27:45.880 --> 0:27:49.879 of control can snap it back into alignment with the self, 0:27:50.320 --> 0:27:53.720