1 00:00:05,240 --> 00:00:10,039 Speaker 1: What is a thought? Is it something physical? How can 2 00:00:10,080 --> 00:00:13,160 Speaker 1: you hear a voice in your head? And whose voice 3 00:00:13,240 --> 00:00:15,400 Speaker 1: is it anyway? And what does this have to do 4 00:00:15,520 --> 00:00:19,720 Speaker 1: with a small marine animal who eats its own brain. 5 00:00:23,160 --> 00:00:27,160 Speaker 1: Welcome to Intercosmos with me, David Eagelman. I'm a neuroscientist 6 00:00:27,240 --> 00:00:30,200 Speaker 1: and an author at Stanford and in these episodes we 7 00:00:30,240 --> 00:00:34,159 Speaker 1: sail deeply into our three pound universe to understand some 8 00:00:34,200 --> 00:00:47,519 Speaker 1: of the most surprising aspects of our lives. Today's episode 9 00:00:47,600 --> 00:00:52,280 Speaker 1: is about thoughts. We have them constantly, even for the 10 00:00:52,320 --> 00:00:57,160 Speaker 1: best meditators. It's difficult or impossible to stop the fire 11 00:00:57,240 --> 00:01:01,360 Speaker 1: hose of words and images and ideas. We all talk 12 00:01:01,400 --> 00:01:04,280 Speaker 1: about our thoughts. We sometimes act on our thoughts, we 13 00:01:04,400 --> 00:01:07,959 Speaker 1: draw them with little thought bubbles and cartoons. But what 14 00:01:08,120 --> 00:01:12,640 Speaker 1: in the world is a thought physically? So many years ago, 15 00:01:12,800 --> 00:01:16,119 Speaker 1: a person at a party begged me to watch the 16 00:01:16,160 --> 00:01:20,039 Speaker 1: movie called The Secret. So I watched it for fifteen minutes, 17 00:01:20,080 --> 00:01:22,759 Speaker 1: and I regret to say that I will never get 18 00:01:22,760 --> 00:01:25,640 Speaker 1: those fifteen minutes back. And I knew that this was 19 00:01:25,720 --> 00:01:29,679 Speaker 1: the pinnacle of moronic when the first guy states quote, 20 00:01:30,600 --> 00:01:34,679 Speaker 1: what most people don't understand is a thought has a frequency. 21 00:01:34,760 --> 00:01:38,360 Speaker 1: Every thought has a frequency we can measure a thought, 22 00:01:38,560 --> 00:01:41,880 Speaker 1: and so if you're thinking that thought over and over again, 23 00:01:42,280 --> 00:01:46,880 Speaker 1: you're emitting that frequency on a consistent basis. And then 24 00:01:46,920 --> 00:01:51,520 Speaker 1: the next Schremndrick says, thoughts are sending out that magnetic 25 00:01:51,720 --> 00:01:54,840 Speaker 1: signal that is drawing the parallel back to you. That's 26 00:01:54,920 --> 00:01:58,800 Speaker 1: the signal you're putting out into the universe. And then 27 00:01:58,880 --> 00:02:02,960 Speaker 1: a third genius says, it has now been proven scientifically 28 00:02:03,560 --> 00:02:07,680 Speaker 1: that an affirmative thought is hundreds of times more powerful 29 00:02:07,720 --> 00:02:10,799 Speaker 1: than a negative thought. And every time someone thinks a 30 00:02:10,840 --> 00:02:14,720 Speaker 1: thought in this movie, the graphics show the person having 31 00:02:14,760 --> 00:02:18,120 Speaker 1: a thinking expression on their face, and then an energy 32 00:02:18,160 --> 00:02:20,520 Speaker 1: wave bursts from their head, and then it cuts to 33 00:02:20,600 --> 00:02:23,080 Speaker 1: a wide shot of the planet and you see this 34 00:02:23,320 --> 00:02:29,000 Speaker 1: energy wave transmit across the universe. Now, the most striking 35 00:02:29,040 --> 00:02:32,840 Speaker 1: thing about these statements in the movie is not simply 36 00:02:32,880 --> 00:02:35,480 Speaker 1: that they are incorrect. To me, the shocking thing was 37 00:02:35,960 --> 00:02:38,959 Speaker 1: how these guys looked right at the camera and asserted 38 00:02:39,040 --> 00:02:43,240 Speaker 1: them as though these were not just completely made up, 39 00:02:43,280 --> 00:02:46,800 Speaker 1: and then they used phrases like it has been scientifically proven. 40 00:02:47,160 --> 00:02:49,120 Speaker 1: So in a few weeks, I'm going to do an 41 00:02:49,120 --> 00:02:52,960 Speaker 1: episode about how we judge the value of any scientific 42 00:02:53,000 --> 00:02:55,960 Speaker 1: idea and what it would mean to even say that 43 00:02:56,040 --> 00:02:58,800 Speaker 1: something is scientifically proven. But I'm going to bite my 44 00:02:58,840 --> 00:03:02,320 Speaker 1: tongue for now and put that aside, because for today's episode, 45 00:03:02,360 --> 00:03:08,200 Speaker 1: what I really care about is what really is a thought. 46 00:03:08,800 --> 00:03:11,680 Speaker 1: So to set the table for this, I'm going to 47 00:03:12,200 --> 00:03:15,480 Speaker 1: put thoughts aside for a second and tell a story 48 00:03:15,800 --> 00:03:18,880 Speaker 1: that I originally wrote in my book Incognito, And this 49 00:03:19,200 --> 00:03:23,480 Speaker 1: took place in nineteen forty nine. A guy named Arthur 50 00:03:23,560 --> 00:03:27,519 Speaker 1: Alberts traveled from his home in New York to villages 51 00:03:27,639 --> 00:03:31,160 Speaker 1: between the Gold Coast and Timbuktoo in West Africa. And 52 00:03:31,200 --> 00:03:32,920 Speaker 1: he brought his wife, and he brought a camera and 53 00:03:32,960 --> 00:03:36,480 Speaker 1: a jeep, and because of his love for music, he 54 00:03:36,680 --> 00:03:40,560 Speaker 1: brought a tape recorder. Now he wanted to open the 55 00:03:40,600 --> 00:03:43,960 Speaker 1: ears of the Western world. So what he did was 56 00:03:44,000 --> 00:03:47,200 Speaker 1: record some of the most important music to ever come 57 00:03:47,200 --> 00:03:52,480 Speaker 1: out of Africa. But Alberts ran into social troubles while 58 00:03:52,480 --> 00:03:55,120 Speaker 1: he was using this tape recorder because none of the 59 00:03:55,200 --> 00:03:59,360 Speaker 1: natives had ever seen anything even vaguely like this before. 60 00:04:00,040 --> 00:04:04,040 Speaker 1: So one native heard his voice played back to him 61 00:04:04,600 --> 00:04:09,320 Speaker 1: and he accused Alberts of quote stealing his tongue. And 62 00:04:09,360 --> 00:04:13,840 Speaker 1: according to the biography, Albert's only narrowly averted being pummeled 63 00:04:13,880 --> 00:04:17,200 Speaker 1: by taking out a mirror and convincing the man that 64 00:04:17,279 --> 00:04:21,200 Speaker 1: his tongue was still intact. So it's not difficult to 65 00:04:21,240 --> 00:04:25,760 Speaker 1: see why the natives found the tape recorder so strange 66 00:04:25,800 --> 00:04:30,200 Speaker 1: and counterintuitive. Just imagine that you had never ever seen 67 00:04:30,279 --> 00:04:34,760 Speaker 1: this technology before. The thing is that a voice seems 68 00:04:35,200 --> 00:04:39,360 Speaker 1: ephemeral and ineffable, right. A voice has no weight. You 69 00:04:39,400 --> 00:04:43,080 Speaker 1: can't hold voice in your hand. A voice just exists 70 00:04:43,080 --> 00:04:46,320 Speaker 1: for a moment. It's totally untouchable, and then it's gone. 71 00:04:46,720 --> 00:04:49,800 Speaker 1: There doesn't seem to be any physical trace. So it 72 00:04:49,880 --> 00:04:54,480 Speaker 1: comes as a surprise that a voice is physical. If 73 00:04:54,520 --> 00:04:57,960 Speaker 1: you build a little machine that's sensitive enough to detect 74 00:04:58,200 --> 00:05:01,600 Speaker 1: tiny compressions of the molecule in the air, you can 75 00:05:01,640 --> 00:05:06,200 Speaker 1: then capture those density changes and reproduce them later. We 76 00:05:06,279 --> 00:05:10,400 Speaker 1: call these little machines microphones, and we reproduce the density 77 00:05:10,520 --> 00:05:15,559 Speaker 1: changes on tape or with zeros and ones, And every 78 00:05:15,600 --> 00:05:19,039 Speaker 1: one of the billions of podcasts and playlists on the 79 00:05:19,080 --> 00:05:24,880 Speaker 1: planet is proudly serving up bags of feathers once thought irretrievable. 80 00:05:25,600 --> 00:05:28,560 Speaker 1: When Alberts played the music, back from the tape recorder. 81 00:05:28,640 --> 00:05:35,320 Speaker 1: One tribesman described the feat as tremendous magic. And so 82 00:05:35,440 --> 00:05:39,120 Speaker 1: it goes with thoughts. What exactly is a thought? It 83 00:05:39,120 --> 00:05:44,120 Speaker 1: doesn't seem to weigh anything. It feels ephemeral and ineffable. 84 00:05:44,600 --> 00:05:47,279 Speaker 1: You wouldn't think that a thought has any shape or 85 00:05:47,320 --> 00:05:51,920 Speaker 1: smell or any sort of physical instantiation. Thoughts seem to 86 00:05:51,920 --> 00:05:56,120 Speaker 1: be a kind of tremendous magic. So it comes as 87 00:05:56,120 --> 00:06:00,320 Speaker 1: a surprise that a thought is physical, just like voice is. 88 00:06:00,920 --> 00:06:06,560 Speaker 1: Thoughts are underpinned by biological stuff. We know this because 89 00:06:06,640 --> 00:06:10,359 Speaker 1: alterations to the brain change the kinds of thoughts we 90 00:06:10,440 --> 00:06:14,200 Speaker 1: can think. In a state of deep sleep, there are 91 00:06:14,240 --> 00:06:19,200 Speaker 1: no thoughts. When the brain transitions into dream sleep, there 92 00:06:19,240 --> 00:06:23,680 Speaker 1: are unbidden, bizarre thoughts. During the day, we enjoy our normal, 93 00:06:23,800 --> 00:06:29,560 Speaker 1: well accepted thoughts, which people enthusiastically modulate by spiking the 94 00:06:29,640 --> 00:06:33,800 Speaker 1: chemical cocktails of the brain with alcohol or narcotics, or 95 00:06:34,160 --> 00:06:38,760 Speaker 1: exercise or coffee. So the state of the physical material 96 00:06:39,240 --> 00:06:43,840 Speaker 1: determines the state of the thoughts, and issues like obsessive 97 00:06:43,880 --> 00:06:48,719 Speaker 1: compulsive disorder or schizophrenia tell us that when certain networks 98 00:06:48,720 --> 00:06:53,279 Speaker 1: in the brain become overactive or miscalibrated, the character of 99 00:06:53,400 --> 00:06:57,400 Speaker 1: thinking changes. It's this kind of thing that tells us 100 00:06:57,400 --> 00:07:01,920 Speaker 1: that the physical stuff is irreversible, tied to the thinking. 101 00:07:01,960 --> 00:07:04,520 Speaker 1: And we know this also because when people get even 102 00:07:04,640 --> 00:07:08,160 Speaker 1: small bits of brain damage, let's say, because of a 103 00:07:08,200 --> 00:07:12,480 Speaker 1: stroke or a tumor, that can change their capacity to 104 00:07:12,600 --> 00:07:16,960 Speaker 1: understand music, or name animals or see colors, or judge risk, 105 00:07:17,080 --> 00:07:20,960 Speaker 1: or make decisions, or read signals from their bodies, or 106 00:07:21,040 --> 00:07:24,560 Speaker 1: understand the concept of a mirror, or hundreds of other 107 00:07:24,760 --> 00:07:28,400 Speaker 1: changes in thinking that we can witness in the clinics 108 00:07:28,440 --> 00:07:32,360 Speaker 1: every day, and the consequences of injury is a big 109 00:07:32,400 --> 00:07:36,160 Speaker 1: part of how brain science has mapped out the general 110 00:07:36,320 --> 00:07:39,840 Speaker 1: blueprints of the brain. So the bottom line lesson which 111 00:07:39,840 --> 00:07:45,040 Speaker 1: has emerged over centuries is that our internal thoughts about 112 00:07:45,080 --> 00:07:48,960 Speaker 1: hopes or fears or desires, they all emerge from this 113 00:07:49,600 --> 00:07:53,720 Speaker 1: strange three pound organ and when the brain changes, so 114 00:07:53,880 --> 00:07:57,440 Speaker 1: do our thoughts. So although it's easy to intuit that 115 00:07:57,640 --> 00:08:01,360 Speaker 1: thoughts don't have a physical basis, that there are something 116 00:08:01,400 --> 00:08:04,760 Speaker 1: like feathers on the wind, they in fact depend directly 117 00:08:04,880 --> 00:08:09,920 Speaker 1: on what's happening in this small, enigmatic mission control center 118 00:08:10,400 --> 00:08:15,080 Speaker 1: locked in the silent vault of the skull. So what 119 00:08:15,440 --> 00:08:19,120 Speaker 1: is a thought. It's the result of billions of neurons 120 00:08:19,240 --> 00:08:23,720 Speaker 1: firing and coordinated patterns. As we've talked about in other episodes, 121 00:08:23,800 --> 00:08:28,200 Speaker 1: the neurons communicate using electrical impulses and chemical signals, and 122 00:08:28,240 --> 00:08:32,560 Speaker 1: they form vast networks that operate together, such that at 123 00:08:32,640 --> 00:08:37,640 Speaker 1: any moment you have some millions of neurons doing something coordinated, 124 00:08:37,679 --> 00:08:40,080 Speaker 1: and in the next moment it's a different collection of 125 00:08:40,120 --> 00:08:43,800 Speaker 1: neurons that are working together. Now, it may not surprise 126 00:08:43,880 --> 00:08:46,160 Speaker 1: you to know that a thought is not located in 127 00:08:46,200 --> 00:08:49,839 Speaker 1: one place in the brain. It's an emergent property. It's 128 00:08:49,880 --> 00:08:54,880 Speaker 1: a collaboration between these millions or billions of neurons. When 129 00:08:54,920 --> 00:08:58,800 Speaker 1: you have a thought, it's like a symphony playing inside 130 00:08:58,840 --> 00:09:02,920 Speaker 1: your head. Every neuron involved is an instrument in the orchestra, 131 00:09:03,360 --> 00:09:06,800 Speaker 1: and no single part can create the music by itself. 132 00:09:07,320 --> 00:09:09,319 Speaker 1: So we're gonna come back to the brain in a moment, 133 00:09:09,360 --> 00:09:11,880 Speaker 1: but before we do, I want us to really zoom 134 00:09:11,920 --> 00:09:16,640 Speaker 1: in on the subjective experience. How would you describe the 135 00:09:16,880 --> 00:09:21,040 Speaker 1: experience of a thought. When you try to capture what 136 00:09:21,120 --> 00:09:25,320 Speaker 1: a thought is, the most commonplace to go is your 137 00:09:25,840 --> 00:09:29,520 Speaker 1: inner monologue. This is the voice in your head that 138 00:09:29,559 --> 00:09:33,800 Speaker 1: you use to problem solve, or criticize, or plan or reflect. 139 00:09:34,280 --> 00:09:37,200 Speaker 1: So take just a second to pay attention to the 140 00:09:37,320 --> 00:09:42,400 Speaker 1: voice inside your head, that constant stream of chatter. Now 141 00:09:42,559 --> 00:09:46,839 Speaker 1: you might think, what voice inside my head? That's the voice? Now. 142 00:09:46,960 --> 00:09:51,320 Speaker 1: Your internal voice can involve deliberate problem solving, like what 143 00:09:51,360 --> 00:09:55,160 Speaker 1: should I do next here? Or it can involve involuntary 144 00:09:55,360 --> 00:09:58,040 Speaker 1: commentary like oh so stupid to me, why did I 145 00:09:58,080 --> 00:10:03,120 Speaker 1: do that? Or it can be whole imagined conversations like Okay, 146 00:10:03,200 --> 00:10:04,920 Speaker 1: I say this, and then she says that, and then 147 00:10:04,920 --> 00:10:07,319 Speaker 1: I respond like this. It can be helpful for things 148 00:10:07,400 --> 00:10:11,439 Speaker 1: like working memory. So for example, you're trying to log 149 00:10:11,480 --> 00:10:14,640 Speaker 1: into a website and you get texted some six digit 150 00:10:14,760 --> 00:10:17,600 Speaker 1: pass code, and you need to remember that code while 151 00:10:17,600 --> 00:10:21,680 Speaker 1: you switch windows, So you internally say the numbers over 152 00:10:21,720 --> 00:10:24,880 Speaker 1: and over. So you're using the internal voice to keep 153 00:10:24,920 --> 00:10:27,600 Speaker 1: the information in mind as part of your working memory. 154 00:10:27,920 --> 00:10:30,440 Speaker 1: There's so many places where the internal voice comes in. 155 00:10:30,520 --> 00:10:34,160 Speaker 1: We tend to talk to ourselves when we're planning something, 156 00:10:34,200 --> 00:10:38,560 Speaker 1: when we're weighing options. The internal dialogue seems to be 157 00:10:38,640 --> 00:10:43,240 Speaker 1: really helpful in simulating different scenarios. So you're running your 158 00:10:43,240 --> 00:10:46,960 Speaker 1: internal voice all the time and subjectively, it seems to 159 00:10:47,000 --> 00:10:51,320 Speaker 1: be a mental space that can seem almost as vivid 160 00:10:51,400 --> 00:10:55,120 Speaker 1: as external speech. It follows all the rules of grammar 161 00:10:55,240 --> 00:10:59,480 Speaker 1: and syntax, and it can be emotionally laden with encouragement 162 00:10:59,600 --> 00:11:05,080 Speaker 1: or or anywhere in between. Now, how does this happen? 163 00:11:05,160 --> 00:11:09,240 Speaker 1: How can you generate a voice internally and hear it well? 164 00:11:09,280 --> 00:11:12,640 Speaker 1: When we eavesdrop on the brain, let's say, using brain 165 00:11:12,760 --> 00:11:16,320 Speaker 1: imaging like fMRI, what we find is a network of 166 00:11:16,520 --> 00:11:22,040 Speaker 1: areas involved in speech production, like Broca's area, which is 167 00:11:22,040 --> 00:11:25,200 Speaker 1: a key region involved in talking out loud. And we 168 00:11:25,240 --> 00:11:30,520 Speaker 1: find areas involved in language comprehension like Wernicke's area and 169 00:11:30,559 --> 00:11:34,000 Speaker 1: the auditory cortex more generally, as though you're listening to 170 00:11:34,120 --> 00:11:38,080 Speaker 1: spoken language from somebody else talking. And also what we 171 00:11:38,160 --> 00:11:43,640 Speaker 1: see is a network that we summarizes the default mode network, 172 00:11:43,800 --> 00:11:46,320 Speaker 1: and this is a network that becomes active when you're 173 00:11:46,360 --> 00:11:50,199 Speaker 1: not focused on monitoring the outside world, but instead when 174 00:11:50,240 --> 00:11:53,680 Speaker 1: you think about yourself, where you daydream, or you reflect 175 00:11:53,760 --> 00:11:57,240 Speaker 1: on your past, or you imagine your future. So all 176 00:11:57,280 --> 00:11:59,840 Speaker 1: these networks are cranked up when you're talking to yourself. 177 00:11:59,840 --> 00:12:02,840 Speaker 1: And one really important point when you're generating your own 178 00:12:02,880 --> 00:12:07,160 Speaker 1: speech is that you have something called corollary discharge, which 179 00:12:07,320 --> 00:12:10,200 Speaker 1: just means that when your brain generates internal speech, it 180 00:12:10,320 --> 00:12:13,360 Speaker 1: sends a copy of what it's doing to other parts 181 00:12:13,360 --> 00:12:16,000 Speaker 1: of the brain to let them know this is coming. 182 00:12:16,040 --> 00:12:18,320 Speaker 1: I'm the one who did this. That's how the rest 183 00:12:18,320 --> 00:12:21,360 Speaker 1: of the brain knows that the inner voice is self 184 00:12:21,480 --> 00:12:26,480 Speaker 1: generated instead of confusing it with external speech. As a 185 00:12:26,520 --> 00:12:29,559 Speaker 1: side note, if you're a regular listener to this podcast, 186 00:12:29,600 --> 00:12:31,800 Speaker 1: you know that I've been publishing on the topic of 187 00:12:31,880 --> 00:12:36,720 Speaker 1: schizophrenia for many years, and my hypothesis is that auditory 188 00:12:36,760 --> 00:12:41,880 Speaker 1: hallucinations in schizophrenia might have to do with a miscalibration 189 00:12:42,080 --> 00:12:46,000 Speaker 1: of the timing of signals, such that the internal voice 190 00:12:46,559 --> 00:12:51,079 Speaker 1: gets misinterpreted as someone else's voice. In other words, when 191 00:12:51,160 --> 00:12:54,800 Speaker 1: you're talking to yourself under normal conditions, you generate the voice, 192 00:12:55,080 --> 00:12:58,240 Speaker 1: then you hear the voice, and the corollary discharge tells 193 00:12:58,280 --> 00:13:00,560 Speaker 1: you that it was your own. But if there's something 194 00:13:00,600 --> 00:13:03,880 Speaker 1: wrong with the timing of the corollary discharge, then it 195 00:13:03,880 --> 00:13:06,240 Speaker 1: doesn't seem like you're the one who generated the voice, 196 00:13:06,320 --> 00:13:09,199 Speaker 1: and you have to attribute the voice to someone else. 197 00:13:09,520 --> 00:13:13,719 Speaker 1: The internal voice feels like it must be external. If 198 00:13:13,720 --> 00:13:17,720 Speaker 1: you're interested in more on this, hypothesis about schizophrenia. Check 199 00:13:17,760 --> 00:13:21,720 Speaker 1: out episodes thirty three and forty four. Okay, so back 200 00:13:21,760 --> 00:13:25,400 Speaker 1: to the internal voice, which in normal circumstances we understand 201 00:13:25,480 --> 00:13:29,280 Speaker 1: as our voice in our heads. Here's my question, is 202 00:13:29,320 --> 00:13:33,560 Speaker 1: this inner monologue really the main way that we think? 203 00:13:33,800 --> 00:13:36,600 Speaker 1: What if some of our thoughts don't come with words 204 00:13:36,800 --> 00:13:41,119 Speaker 1: at all? So that's the question that psychologist Russell Hurlbert 205 00:13:41,120 --> 00:13:43,599 Speaker 1: set out to answer with a set of experiments in 206 00:13:43,640 --> 00:13:47,640 Speaker 1: the nineteen nineties. And here's how it works. Imagine that 207 00:13:47,720 --> 00:13:51,400 Speaker 1: you are given a beeper that beeps off at random 208 00:13:51,480 --> 00:13:56,160 Speaker 1: times during your day, and the instant it beeps, your 209 00:13:56,320 --> 00:14:00,679 Speaker 1: job is to write down whatever was just in your mind. Beep, 210 00:14:00,880 --> 00:14:04,720 Speaker 1: what are you thinking about right now? So when Hurlbert 211 00:14:04,840 --> 00:14:08,280 Speaker 1: analyzed the data, he found that only about twenty six 212 00:14:08,360 --> 00:14:12,160 Speaker 1: percent of people's thoughts were verbal, meaning that they involved 213 00:14:12,240 --> 00:14:16,000 Speaker 1: actual words or inner speech. The other seventy four percent 214 00:14:16,720 --> 00:14:23,080 Speaker 1: completely nonverbal. So what does nonverbal thought mean? Well, when 215 00:14:23,120 --> 00:14:26,560 Speaker 1: your thoughts are suddenly probed, lots of people find that 216 00:14:26,600 --> 00:14:31,160 Speaker 1: they were just thinking about, for example, vivid mental images 217 00:14:31,280 --> 00:14:35,840 Speaker 1: like picturing a beach or remembering somebody's face, or thinking 218 00:14:35,840 --> 00:14:38,320 Speaker 1: about some moment they just saw at the restaurant, and 219 00:14:38,360 --> 00:14:40,960 Speaker 1: that's all their thought was at that moment. It was visual. 220 00:14:41,000 --> 00:14:59,920 Speaker 1: There were no words involved, just pictures. So what's go 221 00:15:00,000 --> 00:15:02,080 Speaker 1: going on in the brain when you have these kind 222 00:15:02,120 --> 00:15:06,440 Speaker 1: of vivid mental images. Well, if I were to ask 223 00:15:06,520 --> 00:15:11,000 Speaker 1: you to think about a Siberian tiger, your prefrontal cortex 224 00:15:11,120 --> 00:15:14,200 Speaker 1: right behind the forehead takes on the task and starts 225 00:15:14,280 --> 00:15:18,360 Speaker 1: broadcasting to see who can fulfill the request. So your 226 00:15:18,440 --> 00:15:22,760 Speaker 1: memory systems chug into place to determine what a Siberian 227 00:15:22,800 --> 00:15:27,360 Speaker 1: tiger is, combining all the different examples of Siberian tigers 228 00:15:27,360 --> 00:15:31,119 Speaker 1: that you've seen before, and your visual cortex is recruited 229 00:15:31,640 --> 00:15:36,400 Speaker 1: to generate a picture. Your emotion centers might even contribute, 230 00:15:36,520 --> 00:15:41,320 Speaker 1: shading this thought with feelings of alertness or awe or fear. 231 00:15:41,880 --> 00:15:45,800 Speaker 1: So when you think about that Siberian tiger, hundreds of 232 00:15:45,920 --> 00:15:49,360 Speaker 1: millions of neurons across different areas of your brain are 233 00:15:49,440 --> 00:15:54,480 Speaker 1: lighting up, working together to create something that feels whole 234 00:15:54,720 --> 00:15:58,120 Speaker 1: and immediate. And of course, if you're a musician and 235 00:15:58,320 --> 00:16:01,160 Speaker 1: the pager beeps, you might find that you're thinking about 236 00:16:01,160 --> 00:16:05,360 Speaker 1: something auditory. You're thinking about which notes would sound great. 237 00:16:05,480 --> 00:16:07,960 Speaker 1: Right after this transition from this cord to this court. 238 00:16:08,280 --> 00:16:11,240 Speaker 1: But there's no words involved in that. And in the 239 00:16:11,240 --> 00:16:14,920 Speaker 1: brain we can measure activity in your auditory cortex while 240 00:16:14,960 --> 00:16:18,720 Speaker 1: you're doing that, And if you're a perfumer, you might 241 00:16:18,760 --> 00:16:22,920 Speaker 1: be doing smell imagery. You're thinking about the way that 242 00:16:22,960 --> 00:16:25,200 Speaker 1: this other perfume smell than how you're trying to get 243 00:16:25,200 --> 00:16:29,920 Speaker 1: a little closer to that. But as you are internally smelling, 244 00:16:30,440 --> 00:16:34,960 Speaker 1: there are no words associated with that. It's just olfactory imagery. 245 00:16:35,480 --> 00:16:38,680 Speaker 1: And this sort of sensory thinking can come in all 246 00:16:38,800 --> 00:16:42,520 Speaker 1: kinds of flavors, like feeling the warmth from the sun 247 00:16:42,600 --> 00:16:46,520 Speaker 1: on your face or the tightness of your chest during stress. 248 00:16:47,280 --> 00:16:51,240 Speaker 1: So that's what Hurlbert found people were thinking about quite 249 00:16:51,320 --> 00:16:56,520 Speaker 1: often when you probe them at random, sensory imagery without language. 250 00:16:56,840 --> 00:16:58,760 Speaker 1: But that was just the beginning. The kind of thoughts 251 00:16:58,760 --> 00:17:03,520 Speaker 1: that people were thing went beyond just sensory imagery. Lots 252 00:17:03,560 --> 00:17:07,280 Speaker 1: of other times people described they were thinking about how 253 00:17:07,320 --> 00:17:10,960 Speaker 1: to do something physical, like how to position their hands 254 00:17:11,000 --> 00:17:13,960 Speaker 1: for reaching into the oven, or how to remove the 255 00:17:14,040 --> 00:17:16,520 Speaker 1: cover off the printer, or how far to turn the 256 00:17:16,560 --> 00:17:19,120 Speaker 1: steering wheel to get their car into the parking spot. 257 00:17:19,480 --> 00:17:22,840 Speaker 1: But they were thinking about how to do these moves, 258 00:17:23,160 --> 00:17:26,159 Speaker 1: and there were no words involved. It was a physical 259 00:17:26,280 --> 00:17:30,960 Speaker 1: activity they were simulating. This is called motoric imagery. Their 260 00:17:31,000 --> 00:17:35,160 Speaker 1: brains were thinking their way through something. And other thoughts 261 00:17:35,200 --> 00:17:39,040 Speaker 1: are even more difficult to pin down than imagining senses 262 00:17:39,200 --> 00:17:44,360 Speaker 1: or imagining movement because they're more abstract, like a vague 263 00:17:44,560 --> 00:17:49,359 Speaker 1: sense of unease with no clear words or pictures attached. 264 00:17:50,119 --> 00:17:52,760 Speaker 1: So thoughts come in many flavors, and I'll just make 265 00:17:52,760 --> 00:17:55,560 Speaker 1: a thirty second side note here about whether it makes 266 00:17:55,600 --> 00:17:59,840 Speaker 1: sense to call the activity in the unconscious brain think. 267 00:18:00,400 --> 00:18:03,480 Speaker 1: For example, you're trying to remember the name of that 268 00:18:03,640 --> 00:18:05,439 Speaker 1: song and it's on the tip of your tongue, but 269 00:18:05,480 --> 00:18:09,320 Speaker 1: you just can't remember it. And then hours later, when 270 00:18:09,359 --> 00:18:13,080 Speaker 1: you're not even thinking about it, the answer suddenly pops 271 00:18:13,080 --> 00:18:16,520 Speaker 1: into your mind. Your unconscious mind has been working on 272 00:18:16,560 --> 00:18:19,320 Speaker 1: it in the background, even though you had no awareness 273 00:18:19,320 --> 00:18:22,720 Speaker 1: of it. So should we call that thinking even when 274 00:18:22,760 --> 00:18:26,600 Speaker 1: it happens unconsciously. Just for the purposes of having a 275 00:18:26,640 --> 00:18:29,320 Speaker 1: clear definition, it's probably going to make the most sense 276 00:18:29,359 --> 00:18:32,760 Speaker 1: to call that something like processing, and will reserve the 277 00:18:32,800 --> 00:18:37,480 Speaker 1: word thought for the conscious conclusion of that behind the 278 00:18:37,480 --> 00:18:40,280 Speaker 1: scenes activity, so at least for the moment I'm not 279 00:18:40,400 --> 00:18:46,040 Speaker 1: going to call the unconscious activity thought. So this simple 280 00:18:46,119 --> 00:18:49,159 Speaker 1: experiment of pinging people at random to ask them what 281 00:18:49,200 --> 00:18:51,919 Speaker 1: they're thinking, what's in their minds at this exact moment, 282 00:18:52,760 --> 00:18:55,920 Speaker 1: This experiment tells us something important, which is that thinking 283 00:18:56,480 --> 00:18:59,920 Speaker 1: is not just talking to ourselves. It's broader than that. 284 00:19:00,520 --> 00:19:03,720 Speaker 1: We have different kinds of thoughts in different formats. We 285 00:19:03,800 --> 00:19:07,280 Speaker 1: have inner speech, but we also have mental imagery, like 286 00:19:07,760 --> 00:19:10,760 Speaker 1: when you're visualizing what your kitchen reed design could look like, 287 00:19:11,040 --> 00:19:16,040 Speaker 1: and you have abstract thinking like when you're contemplating infinity 288 00:19:16,280 --> 00:19:19,720 Speaker 1: or justice or love. And possibly there are still other 289 00:19:19,800 --> 00:19:22,840 Speaker 1: things which could fall under the umbrella of thought. So 290 00:19:23,400 --> 00:19:27,760 Speaker 1: thinking is a rich, multi dimensional experience. Okay, so here's 291 00:19:27,760 --> 00:19:30,280 Speaker 1: where we are. So far. We talked about the internal 292 00:19:30,400 --> 00:19:34,400 Speaker 1: voice and visualization and imagining sound or smell or bodily feelings, 293 00:19:34,440 --> 00:19:38,080 Speaker 1: and imagining motor movement, and even abstract sorts of thoughts. 294 00:19:38,359 --> 00:19:40,520 Speaker 1: But if you've been listening to these episodes for a while, 295 00:19:40,640 --> 00:19:44,959 Speaker 1: you know that I'm obsessed with the difference between people's 296 00:19:45,040 --> 00:19:49,160 Speaker 1: internal experiences and thinking is no exception. When we look 297 00:19:49,200 --> 00:19:53,640 Speaker 1: at the diversity of thought, some people seem to lean 298 00:19:53,760 --> 00:19:57,879 Speaker 1: more towards verbal thinking, they talk things out in their heads. 299 00:19:58,280 --> 00:20:02,920 Speaker 1: Others are visual things, seeing vivid mental images as their 300 00:20:03,320 --> 00:20:07,600 Speaker 1: primary mode of thinking. And some people experience thoughts more 301 00:20:07,680 --> 00:20:11,439 Speaker 1: like abstract concepts without the voice or the images. And 302 00:20:11,480 --> 00:20:13,840 Speaker 1: this goes hand in hand with something I've talked about 303 00:20:14,000 --> 00:20:16,399 Speaker 1: in many episodes, which is that, as far as we 304 00:20:16,440 --> 00:20:22,480 Speaker 1: can tell, subjective experiences exist on a spectrum. So let's 305 00:20:22,560 --> 00:20:25,080 Speaker 1: zoom in on the inner voice. Some people report having 306 00:20:25,280 --> 00:20:29,560 Speaker 1: constant chatter in their heads, while other people have little 307 00:20:29,720 --> 00:20:36,080 Speaker 1: or no inner verbalization. That's called an endophasia no internal voice. 308 00:20:36,119 --> 00:20:39,160 Speaker 1: As an example, when it comes to the inner monologue, 309 00:20:39,320 --> 00:20:42,640 Speaker 1: my wife's internal radio is very loud, she says, she's 310 00:20:42,680 --> 00:20:46,000 Speaker 1: always hearing it at full volume. For me, it happens 311 00:20:46,040 --> 00:20:48,960 Speaker 1: to be pretty quiet most of the time. I'm going 312 00:20:49,000 --> 00:20:51,959 Speaker 1: to link some papers in the show notes about studies 313 00:20:52,080 --> 00:20:55,840 Speaker 1: on the variation of the internal voice. And when it 314 00:20:55,880 --> 00:20:59,600 Speaker 1: comes to visualization, I've talked in other episodes about this, 315 00:21:00,800 --> 00:21:04,800 Speaker 1: from a fantasia to hyperfantasia. In other words, the spread 316 00:21:04,840 --> 00:21:08,679 Speaker 1: from not really picturing anything visually in your mind to 317 00:21:08,800 --> 00:21:14,639 Speaker 1: having very rich, colorful, movie like visualizations, and everyone is 318 00:21:14,720 --> 00:21:18,920 Speaker 1: somewhere along that spectrum. Now we haven't really measured this yet, 319 00:21:18,960 --> 00:21:22,640 Speaker 1: But when it comes to more subtle issues of abstract thinking, 320 00:21:23,359 --> 00:21:27,040 Speaker 1: like contemplating infinity or justice or love, it may be 321 00:21:27,119 --> 00:21:31,560 Speaker 1: that people are having very different experiences of how strongly 322 00:21:31,720 --> 00:21:36,000 Speaker 1: or intensely they're feeling that. Now, it's a little difficult 323 00:21:36,040 --> 00:21:39,359 Speaker 1: to design an experiment to probe this, because it's purely 324 00:21:39,440 --> 00:21:43,320 Speaker 1: an issue of somebody's subjective report, and it's not always 325 00:21:43,359 --> 00:21:47,440 Speaker 1: easy to know if people are reporting accurately. But if 326 00:21:47,520 --> 00:21:51,840 Speaker 1: this subjective experience of abstract thought is like everything else 327 00:21:51,840 --> 00:21:55,320 Speaker 1: we've measured so far, it is surely going to differ 328 00:21:55,720 --> 00:21:58,880 Speaker 1: from person to person. So it seems to me there's 329 00:21:58,920 --> 00:22:03,359 Speaker 1: probably massive of divergence in what we mean from person 330 00:22:03,400 --> 00:22:08,160 Speaker 1: to person when we talk about the experience of thought. 331 00:22:08,560 --> 00:22:11,840 Speaker 1: If we can only know what the experience is inside 332 00:22:11,840 --> 00:22:17,199 Speaker 1: another head, we might suddenly understand why Susan immediately sees 333 00:22:17,240 --> 00:22:20,960 Speaker 1: the solution to the math problem, and why Amy keeps 334 00:22:20,960 --> 00:22:24,440 Speaker 1: in mind so well what everyone else's emotion is, and 335 00:22:24,480 --> 00:22:28,240 Speaker 1: why Steve is so interested in fixing broken radios, and 336 00:22:28,280 --> 00:22:32,040 Speaker 1: why Tim spends all his intellectual efforts figuring out how 337 00:22:32,040 --> 00:22:34,200 Speaker 1: to get other people to do work for him, and 338 00:22:34,240 --> 00:22:37,359 Speaker 1: so on with the differences between every person you know, 339 00:22:37,760 --> 00:22:40,520 Speaker 1: and by the way this diversity in the inner experience, 340 00:22:40,560 --> 00:22:44,040 Speaker 1: this has real world implications. So just think about how 341 00:22:44,119 --> 00:22:50,160 Speaker 1: people learn or solve problems. Schools and workplaces often prioritize 342 00:22:50,520 --> 00:22:54,399 Speaker 1: verbal reasoning. But what if somebody's thoughts arrive more like 343 00:22:54,480 --> 00:22:57,960 Speaker 1: pictures or more like physical sensations. What if their best 344 00:22:58,000 --> 00:23:02,040 Speaker 1: ideas can't be put into words immediately? I think as 345 00:23:02,080 --> 00:23:06,720 Speaker 1: we bring the individual differences in thinking into focus, we'll 346 00:23:06,760 --> 00:23:11,440 Speaker 1: be able to increasingly build education to take advantage of 347 00:23:11,480 --> 00:23:16,200 Speaker 1: the full spectrum of human cognition and understanding this diversity 348 00:23:16,240 --> 00:23:20,600 Speaker 1: of thought. This also has implications for mental health. Verbal thoughts, 349 00:23:20,600 --> 00:23:24,840 Speaker 1: for example, are strongly linked to rumination, which is the 350 00:23:24,960 --> 00:23:29,480 Speaker 1: endless loops of self talk that fuel anxiety or depression. 351 00:23:30,080 --> 00:23:33,919 Speaker 1: And meanwhile, nonverbal sensations like a tight chest or a 352 00:23:34,080 --> 00:23:37,840 Speaker 1: racing heart, these are the things that dominate panic attacks. 353 00:23:38,040 --> 00:23:41,359 Speaker 1: So really understanding how differently people think and how to 354 00:23:41,440 --> 00:23:44,960 Speaker 1: measure that could help us to manage these mental states 355 00:23:45,040 --> 00:23:49,680 Speaker 1: more effectively. Okay, so we've been talking about our private 356 00:23:49,840 --> 00:23:52,680 Speaker 1: internal experience of thoughts, but we still have a nailed 357 00:23:52,720 --> 00:23:55,879 Speaker 1: down what a thought is exactly and what could this 358 00:23:56,080 --> 00:24:00,760 Speaker 1: possibly have to do with a c squirt finding its home, 359 00:24:01,200 --> 00:24:05,080 Speaker 1: So let's start there. The sea squirt is a small 360 00:24:05,240 --> 00:24:09,600 Speaker 1: marine creature that begins life as a free swimming larva. 361 00:24:10,119 --> 00:24:12,520 Speaker 1: It has a little brain and a nervous system that 362 00:24:12,760 --> 00:24:17,960 Speaker 1: helps it navigate and search for a suitable place to settle. Now, 363 00:24:18,000 --> 00:24:22,080 Speaker 1: once it finds its permanent spot, it attaches itself to 364 00:24:22,160 --> 00:24:26,159 Speaker 1: a surface like a barnacle, and then it undergoes a 365 00:24:26,320 --> 00:24:31,800 Speaker 1: dramatic transformation because in this phase, once it's docked, it 366 00:24:32,000 --> 00:24:36,640 Speaker 1: no longer needs its brain for movement or navigation, so 367 00:24:36,720 --> 00:24:41,080 Speaker 1: it eats its brain for nutrition. It digests its own brain, 368 00:24:41,640 --> 00:24:45,119 Speaker 1: and it uses that as nutrients for other bodily functions. 369 00:24:45,440 --> 00:24:49,119 Speaker 1: So this illustrates two things. First, how incredible it is 370 00:24:49,160 --> 00:24:53,800 Speaker 1: that some organisms can radically adapt their anatomy to fit 371 00:24:53,840 --> 00:24:57,320 Speaker 1: their new role. But more importantly, for today's purpose, the 372 00:24:57,359 --> 00:24:59,920 Speaker 1: main lesson from the sea squirt is that you only 373 00:25:00,200 --> 00:25:05,000 Speaker 1: need a brain for one purpose, and that is to move. 374 00:25:05,760 --> 00:25:09,439 Speaker 1: If you've stopped moving, a brain serves only as a 375 00:25:09,440 --> 00:25:13,560 Speaker 1: little snack for nutrition, and that's an idea that's been 376 00:25:13,600 --> 00:25:16,720 Speaker 1: floating around in neuroscience for well over a century. The 377 00:25:16,760 --> 00:25:21,439 Speaker 1: reason for the brain's evolution is movement control. The need 378 00:25:21,480 --> 00:25:25,240 Speaker 1: to move and interact with the environment is the driving 379 00:25:25,440 --> 00:25:29,399 Speaker 1: force behind the development of the nervous system. In other words, 380 00:25:29,400 --> 00:25:32,280 Speaker 1: brains exist for one purpose, and that is to get around. 381 00:25:33,280 --> 00:25:37,240 Speaker 1: So now let's return to thinking. The big idea for 382 00:25:37,320 --> 00:25:43,240 Speaker 1: today is that thinking is like a physical movement. You're 383 00:25:43,359 --> 00:25:47,600 Speaker 1: moving stuff around on the inside, but nothing on the outside. 384 00:25:47,720 --> 00:25:51,960 Speaker 1: You are moving concepts instead of limbs. In other words, 385 00:25:52,280 --> 00:25:56,680 Speaker 1: thinking is simply an outgrowth of the same brain mechanisms 386 00:25:57,160 --> 00:26:01,720 Speaker 1: that govern moving. This idea reach way back into the 387 00:26:01,720 --> 00:26:04,679 Speaker 1: scientific literature, but the most complete version of the argument 388 00:26:04,720 --> 00:26:08,080 Speaker 1: that I know comes from the neuroscientist Rudolfo Ginas in 389 00:26:08,160 --> 00:26:11,439 Speaker 1: his book called Eye of the Vortex. The key is 390 00:26:11,440 --> 00:26:14,560 Speaker 1: that to get good at movements, your brain works to 391 00:26:15,040 --> 00:26:19,400 Speaker 1: predict the outcome of possible actions. So as brains grew 392 00:26:19,480 --> 00:26:24,400 Speaker 1: more sophisticated, they could run simulations that didn't necessarily result 393 00:26:24,440 --> 00:26:29,280 Speaker 1: in overt behavior. So the brain generates predictions about the environment, 394 00:26:29,600 --> 00:26:32,200 Speaker 1: and then it tries things out and it adjusts things 395 00:26:32,240 --> 00:26:36,119 Speaker 1: based on the feedback, and that's how it refines future predictions. 396 00:26:36,800 --> 00:26:40,199 Speaker 1: The key idea is that this predictive function of the 397 00:26:40,240 --> 00:26:45,119 Speaker 1: brain eventually extended into the realm of cognition. So a 398 00:26:45,200 --> 00:26:50,960 Speaker 1: thought is like an internalized movement simulations of possible actions 399 00:26:51,000 --> 00:27:12,400 Speaker 1: or scenarios that don't necessarily result in overt behavior. When 400 00:27:12,440 --> 00:27:16,400 Speaker 1: we think, the brain is doing a kind of mental rehearsal, 401 00:27:16,640 --> 00:27:22,600 Speaker 1: like motor planning. It generates and navigates through thoughts by 402 00:27:22,680 --> 00:27:27,320 Speaker 1: simulating potential outcomes, but all without the body physically moving, 403 00:27:27,480 --> 00:27:32,480 Speaker 1: just the way that athletes mentally practice movements before performing them. 404 00:27:32,840 --> 00:27:36,120 Speaker 1: In other words, thought can be viewed as the brain's 405 00:27:36,160 --> 00:27:41,000 Speaker 1: way of moving through abstract mental landscapes, just as it 406 00:27:41,040 --> 00:27:44,000 Speaker 1: would move through physical space. And what this means is 407 00:27:44,040 --> 00:27:49,320 Speaker 1: that the mind is inseparable from the body's motor control systems. 408 00:27:49,520 --> 00:27:51,400 Speaker 1: And I just want to note that this framework has 409 00:27:51,840 --> 00:27:56,720 Speaker 1: far reaching implications for how we understand brains and brain disorders, 410 00:27:57,000 --> 00:28:02,480 Speaker 1: because conditions that affect movement, like Parkinson's disease or motor 411 00:28:02,560 --> 00:28:06,680 Speaker 1: neuron disease, might also give us insights into disorders of 412 00:28:07,080 --> 00:28:11,240 Speaker 1: thought and consciousness and things that we lump into cognitive 413 00:28:11,280 --> 00:28:16,640 Speaker 1: disorders like schizophrenia or obsessive compulsive disorder. These could perhaps 414 00:28:16,680 --> 00:28:22,320 Speaker 1: be viewed through the lens of disrupted internal movements, the 415 00:28:22,359 --> 00:28:24,600 Speaker 1: way to understand all of this is that the brain 416 00:28:25,240 --> 00:28:29,440 Speaker 1: is loopy. Very primitive brains have inputs that lead to outputs, 417 00:28:29,800 --> 00:28:34,160 Speaker 1: but our brains became more sophisticated such that you find 418 00:28:34,240 --> 00:28:38,560 Speaker 1: all kinds of internal loops. One piece of brain anatomy 419 00:28:38,600 --> 00:28:41,520 Speaker 1: worth mentioning here is a structure deep inside the brain 420 00:28:41,600 --> 00:28:44,720 Speaker 1: called the thalamus. All the inputs and outputs of the 421 00:28:44,760 --> 00:28:49,160 Speaker 1: brain stop in the thalamus like a trainway station, and 422 00:28:49,200 --> 00:28:51,520 Speaker 1: what you get are these very sophisticated loops called the 423 00:28:51,560 --> 00:28:56,080 Speaker 1: lamo cortical loops, which allows information to move around internally 424 00:28:56,280 --> 00:28:59,520 Speaker 1: as though things are moving in the world, but without 425 00:28:59,640 --> 00:29:02,720 Speaker 1: actually moving them. In this way, instead of the brain 426 00:29:03,240 --> 00:29:07,240 Speaker 1: generating a movement and it happens right away, instead the 427 00:29:07,280 --> 00:29:12,080 Speaker 1: brain can run a simulation internally to see what would 428 00:29:12,120 --> 00:29:15,160 Speaker 1: be predicted to happen if the movement were to be made, 429 00:29:15,440 --> 00:29:18,280 Speaker 1: and then eventually the simulations can be not just about 430 00:29:18,560 --> 00:29:21,800 Speaker 1: pushing this button or lifting this coffee cup, but more abstract, 431 00:29:22,000 --> 00:29:24,480 Speaker 1: like what would it be like if I got that 432 00:29:24,600 --> 00:29:27,680 Speaker 1: job promotion, or how should I break this news to 433 00:29:27,720 --> 00:29:31,880 Speaker 1: my friend? Or what is the optimal path to build 434 00:29:31,880 --> 00:29:36,280 Speaker 1: a society for peace and justice? Now, with new data 435 00:29:36,320 --> 00:29:38,800 Speaker 1: about the brain. We can go even deeper to see 436 00:29:38,800 --> 00:29:41,720 Speaker 1: how this would work. For example, in a recent episode, 437 00:29:41,760 --> 00:29:46,040 Speaker 1: I talked with neuroscientist Jeff Hawkins on his theory about 438 00:29:46,120 --> 00:29:50,600 Speaker 1: cortical columns. Think of cortical columns like little rice grain 439 00:29:50,800 --> 00:29:53,760 Speaker 1: sized units that are all packed together in the cortex, 440 00:29:53,960 --> 00:29:56,640 Speaker 1: and you have hundreds of thousands of them, and each 441 00:29:56,680 --> 00:30:00,520 Speaker 1: one takes care of little overlapping aspects of the world, 442 00:30:00,560 --> 00:30:05,600 Speaker 1: and together they communicate and collaborate to build a larger 443 00:30:05,760 --> 00:30:09,240 Speaker 1: internal model of the world. So here's a clip from 444 00:30:09,240 --> 00:30:12,040 Speaker 1: that interview which I didn't include in the original cut, 445 00:30:12,480 --> 00:30:16,040 Speaker 1: on the topic of what the columns are coding for. 446 00:30:16,880 --> 00:30:19,280 Speaker 1: And Jeff points out that the cells that you find 447 00:30:19,640 --> 00:30:22,720 Speaker 1: in mammals called grid cells, seem to be coding for 448 00:30:22,800 --> 00:30:25,640 Speaker 1: two dimensional space, but they can also code for three 449 00:30:25,680 --> 00:30:30,440 Speaker 1: dimensional space. And once you have these mechanisms for coding 450 00:30:30,840 --> 00:30:35,280 Speaker 1: for movement in space, maybe those cells can do something more. 451 00:30:35,840 --> 00:30:36,560 Speaker 1: Here's Jeff. 452 00:30:41,280 --> 00:30:43,280 Speaker 2: It looks like the neurons. It's a speculative, but it 453 00:30:43,280 --> 00:30:46,120 Speaker 2: looks like the neurons can learn whatever is the proper 454 00:30:47,000 --> 00:30:51,680 Speaker 2: space for a particular problem. Yeah, so math may have 455 00:30:51,760 --> 00:30:55,320 Speaker 2: a different sort of space than what you learn for 456 00:30:56,040 --> 00:31:00,600 Speaker 2: cups and it could be n dimensional. It's a little 457 00:31:00,600 --> 00:31:01,680 Speaker 2: hard to think about this. 458 00:31:01,760 --> 00:31:03,960 Speaker 1: But here's the way that we maybe can think about 459 00:31:03,960 --> 00:31:07,040 Speaker 1: this is people have done this in VR, where they 460 00:31:07,080 --> 00:31:10,520 Speaker 1: put people in let's say a four dimensional world, so 461 00:31:10,680 --> 00:31:12,520 Speaker 1: it doesn't follow the normal three You know, if I 462 00:31:12,600 --> 00:31:14,640 Speaker 1: go to the right and the right and the right again, 463 00:31:14,680 --> 00:31:16,120 Speaker 1: I'm not gonna end up in the same space. I 464 00:31:16,160 --> 00:31:18,200 Speaker 1: end up in a different space. And people are quite 465 00:31:18,200 --> 00:31:22,560 Speaker 1: good at learning know exactly this is not that hard 466 00:31:22,560 --> 00:31:22,840 Speaker 1: for them. 467 00:31:23,360 --> 00:31:25,040 Speaker 2: Initially it's very disoriented. 468 00:31:24,720 --> 00:31:27,320 Speaker 1: Exactly right exactly, but they are able to learn it, 469 00:31:27,360 --> 00:31:29,600 Speaker 1: which is consistent with your idea. If I understanding that 470 00:31:31,160 --> 00:31:33,320 Speaker 1: the neurons are flexible about which dimension. 471 00:31:33,360 --> 00:31:36,360 Speaker 2: The neurals don't know what they're representing. They don't know 472 00:31:36,760 --> 00:31:38,800 Speaker 2: what where they're getting input from. They don't know what 473 00:31:38,800 --> 00:31:41,400 Speaker 2: the input represents. It's just some pattern that's coming in 474 00:31:41,440 --> 00:31:44,440 Speaker 2: from something that's moving, and in the movement could be 475 00:31:44,600 --> 00:31:47,800 Speaker 2: can be expressed as a set of one dimensional vectors, 476 00:31:47,840 --> 00:31:50,600 Speaker 2: and you're some intersection of those. So we could learn anything. 477 00:31:51,120 --> 00:31:53,120 Speaker 2: It could learn fourth dimensional space. Now I would think 478 00:31:53,120 --> 00:31:54,880 Speaker 2: it would be hard to learn these things because you 479 00:31:55,000 --> 00:31:57,120 Speaker 2: have to practice a lot, but this is why a 480 00:31:57,160 --> 00:32:00,239 Speaker 2: mathematician might be really good and a non mathematician look 481 00:32:00,280 --> 00:32:02,280 Speaker 2: at some math and say this is all gobbledgook to me. 482 00:32:02,320 --> 00:32:04,520 Speaker 2: I can't And a mathematicians look at ah, these are 483 00:32:04,520 --> 00:32:06,720 Speaker 2: like friends. These numbers are friends, these equations are friends. 484 00:32:06,720 --> 00:32:08,200 Speaker 2: I know where they are, I know the relationship. I 485 00:32:08,240 --> 00:32:09,520 Speaker 2: know how to move from here to here. I know 486 00:32:09,600 --> 00:32:11,920 Speaker 2: what action I have to take to get this equation 487 00:32:12,000 --> 00:32:14,560 Speaker 2: to look like that equation. And so they've developed this 488 00:32:14,680 --> 00:32:19,240 Speaker 2: sort of movement centro motor space for mathematics that if 489 00:32:19,240 --> 00:32:23,520 Speaker 2: you haven't spent years doing it, it's like mystery, just goblbook, right. 490 00:32:24,560 --> 00:32:25,640 Speaker 1: So it takes. 491 00:32:25,440 --> 00:32:29,000 Speaker 2: Time, and I certainly think we would be we would 492 00:32:29,000 --> 00:32:32,120 Speaker 2: be really in trouble if all of our dimensional reference 493 00:32:32,200 --> 00:32:34,200 Speaker 2: names and their brain changed over night, because nothing would 494 00:32:34,280 --> 00:32:36,480 Speaker 2: make any sense. So but you could take some and 495 00:32:36,520 --> 00:32:38,560 Speaker 2: movement of certain different directions. So a lot of practice 496 00:32:38,600 --> 00:32:41,800 Speaker 2: you could become a mathematician potentially, or another lot of 497 00:32:41,800 --> 00:32:44,520 Speaker 2: practice you might be good at whatever it is, you know, 498 00:32:44,720 --> 00:32:48,520 Speaker 2: understanding computer code, which is a totally different set of problems. 499 00:32:47,920 --> 00:32:50,520 Speaker 1: That's a really it's a really cool answer to that, 500 00:32:50,600 --> 00:32:55,080 Speaker 1: because one would think we have a three dimensional reference 501 00:32:55,120 --> 00:32:57,360 Speaker 1: frame because that's the physical world we live in. But 502 00:32:57,440 --> 00:33:00,160 Speaker 1: your point is these norms are actually flexible enough that 503 00:33:00,240 --> 00:33:02,840 Speaker 1: you could get higher dimensionality when useful. 504 00:33:02,960 --> 00:33:05,360 Speaker 2: Right, it looks like we look at evolutionary point of view, 505 00:33:06,160 --> 00:33:09,240 Speaker 2: The first reference ang you needed were two dimensional, right, 506 00:33:09,280 --> 00:33:12,000 Speaker 2: if you're moving on the surface of the of the 507 00:33:12,080 --> 00:33:15,600 Speaker 2: of the ground, or you're moving along the floor the floor, right. 508 00:33:16,240 --> 00:33:19,200 Speaker 2: And so these early reference systems, the grid cells and 509 00:33:19,240 --> 00:33:21,800 Speaker 2: the play cells, and the ant Ronald cortex and the hippocampus, 510 00:33:22,160 --> 00:33:26,200 Speaker 2: they seem to be predominantly two dimensional. And one could 511 00:33:26,280 --> 00:33:28,720 Speaker 2: argue back a little bit, argue that that makes sense 512 00:33:28,720 --> 00:33:30,720 Speaker 2: because that's the older system, that's what animals had to 513 00:33:30,720 --> 00:33:33,920 Speaker 2: start with. And maybe what happened was in the neocortex 514 00:33:35,440 --> 00:33:39,760 Speaker 2: they generalized the system right. Right, So it's so that 515 00:33:39,960 --> 00:33:41,720 Speaker 2: it looks like the grid cells and the ant hinod 516 00:33:41,720 --> 00:33:44,840 Speaker 2: projects can represent three D structure because bats can do it. 517 00:33:44,880 --> 00:33:47,400 Speaker 2: But there's really wonky, there's all this research trying to 518 00:33:47,400 --> 00:33:49,040 Speaker 2: figure out what's going on. They don't really inderstand it. 519 00:33:49,120 --> 00:33:52,800 Speaker 2: But it's clearly two dimensional. But it's possible that in 520 00:33:52,840 --> 00:33:55,360 Speaker 2: the cortext it says, okay, we can rempresent any dimensionality 521 00:33:55,360 --> 00:33:59,000 Speaker 2: we've generalized this thing now beyond just navigating on the 522 00:33:59,000 --> 00:34:01,719 Speaker 2: ocean floor on the Earth, And maybe first I had 523 00:34:01,760 --> 00:34:04,160 Speaker 2: to do for flying or climbing in trees, but now 524 00:34:04,840 --> 00:34:07,960 Speaker 2: humans could do it for math and that history, and 525 00:34:08,280 --> 00:34:10,400 Speaker 2: you know, we can build reference frames for everything. 526 00:34:15,160 --> 00:34:17,239 Speaker 1: So that was my interview with Jeff Hawkins from a 527 00:34:17,280 --> 00:34:20,320 Speaker 1: couple of months ago, and I include that to illustrate 528 00:34:20,360 --> 00:34:23,760 Speaker 1: the degree to which different scientists are scratching at different 529 00:34:23,840 --> 00:34:28,320 Speaker 1: versions of this idea that brains evolve to move through space. 530 00:34:28,360 --> 00:34:32,960 Speaker 1: But once you've got that solved, the mechanisms can generalize 531 00:34:33,239 --> 00:34:38,160 Speaker 1: to represent higher order concepts. So let's wrap today's episode. 532 00:34:38,239 --> 00:34:41,960 Speaker 1: We saw two main lessons. The first is that thoughts 533 00:34:42,040 --> 00:34:46,000 Speaker 1: are much more than words. Thinking comes in many formats, 534 00:34:46,480 --> 00:34:49,839 Speaker 1: and the second is that to the brain, thinking may 535 00:34:49,880 --> 00:34:55,000 Speaker 1: be just like moving, but it's internal moving through a 536 00:34:55,400 --> 00:34:59,280 Speaker 1: cognitive landscape. In other words, the brain's capacity to control 537 00:34:59,360 --> 00:35:03,960 Speaker 1: the body extends to its ability to simulate and navigate 538 00:35:04,320 --> 00:35:09,000 Speaker 1: mental spaces. Through this lens, thinking is mental motion, and 539 00:35:09,120 --> 00:35:14,960 Speaker 1: consciousness arises as the brain's continuous orchestration of movements both 540 00:35:15,040 --> 00:35:20,319 Speaker 1: real and imagined. Understanding how we think can enrich how 541 00:35:20,360 --> 00:35:25,160 Speaker 1: we see ourselves. So here's a challenge. Spend today paying 542 00:35:25,200 --> 00:35:30,160 Speaker 1: attention to your thoughts. Notice how often they're verbal, or visual, 543 00:35:30,440 --> 00:35:34,000 Speaker 1: or emotional or something else entirely. If you get a chance, 544 00:35:34,239 --> 00:35:38,200 Speaker 1: download an app that randomly beeps your phone throughout the 545 00:35:38,320 --> 00:35:43,600 Speaker 1: day and jot down exactly what you were thinking. What 546 00:35:43,640 --> 00:35:46,200 Speaker 1: were you thinking about right then? Was it words? Was 547 00:35:46,200 --> 00:35:50,440 Speaker 1: it a feeling, a picture, something else. Our thoughts aren't 548 00:35:50,480 --> 00:35:54,359 Speaker 1: always what we naively expect, and if most of our 549 00:35:54,440 --> 00:35:57,480 Speaker 1: thoughts don't come in words, what does that say about 550 00:35:57,640 --> 00:36:00,840 Speaker 1: who we are? How much of your identity is tied 551 00:36:00,880 --> 00:36:03,360 Speaker 1: to the words in your head, and how much of 552 00:36:03,400 --> 00:36:09,200 Speaker 1: it lies in the massive nonverbal undercurrents of your mind. 553 00:36:14,960 --> 00:36:18,040 Speaker 1: Go to Eagleman dot com slash podcast for more information 554 00:36:18,160 --> 00:36:21,120 Speaker 1: and to find further reading. Send me an email at 555 00:36:21,200 --> 00:36:24,640 Speaker 1: podcasts at eagleman dot com with questions or discussion, and 556 00:36:24,760 --> 00:36:27,880 Speaker 1: check out and subscribe to Inner Cosmos on YouTube for 557 00:36:28,080 --> 00:36:33,479 Speaker 1: videos of each episode and to leave comments until next time. 558 00:36:33,600 --> 00:36:36,799 Speaker 1: I'm David Eagleman, and this is Inner Cosmos.