WEBVTT - Ep75 "How do you decide?" (Part 1) 0:00:05.040 --> 0:00:08.080 When you're trying to choose which ice cream flavor to get, 0:00:08.280 --> 0:00:12.000 what's actually happening in your brain? How do you decide? 0:00:12.560 --> 0:00:15.160 It seems pretty easy, but that's only if you don't 0:00:15.200 --> 0:00:19.319 see the storms of activity lighting up the brain. And 0:00:19.360 --> 0:00:22.400 how do you make long term decisions like that You're 0:00:22.400 --> 0:00:24.040 not going to eat the ice cream at all, but 0:00:24.079 --> 0:00:27.080 instead you're going to eat some broccoli. And what does 0:00:27.120 --> 0:00:30.240 any of this have to do with the ancient Greeks, 0:00:30.360 --> 0:00:35.040 or what alien hand syndrome is, or what the rules 0:00:35.040 --> 0:00:39.479 should be around how the president can launch the nuclear bomb. 0:00:42.720 --> 0:00:45.640 Welcome to Inner Cosmos with me David Eagleman. I'm a 0:00:45.760 --> 0:00:49.560 neuroscientist and author at Stanford and in these episodes we 0:00:49.680 --> 0:00:53.040 dive deeply into our three pound universe to uncover some 0:00:53.120 --> 0:00:57.080 of the most surprising aspects of our lives. Today's episode 0:00:57.080 --> 0:01:07.480 and next week's is about decision making. Although you generally 0:01:07.480 --> 0:01:10.959 feel like you're just moving through a day, decision making 0:01:11.080 --> 0:01:15.000 lies at the heart of everything we do. The complexity 0:01:15.040 --> 0:01:17.920 of the world presents itself to us, and we are 0:01:18.040 --> 0:01:23.240 constantly weighing alternatives. If you couldn't do that, you couldn't 0:01:23.360 --> 0:01:27.040 navigate the now, and you couldn't plan out your future. 0:01:27.560 --> 0:01:31.360 So by having a richer understanding of how choices battle 0:01:31.400 --> 0:01:33.840 it out in the brain, we can learn how to 0:01:33.920 --> 0:01:36.840 make better decisions for ourselves. And, as we're going to 0:01:36.880 --> 0:01:39.600 see next week, because this is a two partern, we'll 0:01:39.640 --> 0:01:41.840 even see how we can use this to build a 0:01:41.880 --> 0:01:45.680 better criminal justice system. So let's start at the very beginning. 0:01:45.959 --> 0:01:49.480 Should you choose the taco or the brito? Should you 0:01:49.520 --> 0:01:52.800 go for that T shirt or a more formal shirt. 0:01:53.120 --> 0:01:55.680 Should you take care of this email first or that 0:01:55.800 --> 0:01:59.480 bill payment first? Do you feel like the mint, chocolate 0:01:59.560 --> 0:02:02.840 chip or cookies and cream? On any day, you're making 0:02:02.880 --> 0:02:07.040 one thousand little decisions, which phone calls to make, which 0:02:07.120 --> 0:02:10.519 shooes to wear, whether to take the shorter path or 0:02:10.560 --> 0:02:14.040 the faster path, how exactly you should answer a question, 0:02:14.600 --> 0:02:17.919 what you should agree to on your schedule tomorrow. This, 0:02:17.960 --> 0:02:20.520 it turns out, is one of the most central things 0:02:20.560 --> 0:02:24.720 the brain does, make decisions. Your brain is a decision 0:02:24.800 --> 0:02:28.280 making machine. It takes the complexity of the world and 0:02:28.320 --> 0:02:32.880 it squeezes things down to single decisions. So how do 0:02:33.080 --> 0:02:38.520 brains do this? Now? When economists and psychologists first started 0:02:38.520 --> 0:02:42.960 looking at this question, they assumed that we humans act rationally. 0:02:43.040 --> 0:02:45.799 The idea is we look at our options, we add 0:02:45.880 --> 0:02:49.480 up the pros and cons, and we make the optimal decision. 0:02:50.040 --> 0:02:52.840 That's not necessarily how it goes with our brains. And 0:02:52.960 --> 0:02:55.160 in this episode and the next one, we're going to 0:02:55.200 --> 0:02:58.560 get a really good understanding why. So let's get going 0:02:58.600 --> 0:03:02.480 with these drawing where there are two ways to interpret 0:03:02.560 --> 0:03:05.400 the same image. You've probably seen these things. If you 0:03:05.840 --> 0:03:08.520 look at the picture one way, it looks like a rabbit, 0:03:08.560 --> 0:03:11.360 and if you keep staring at it you can see 0:03:11.400 --> 0:03:14.440 that suddenly it looks like a duck. So you probably 0:03:14.440 --> 0:03:15.960 saw this when you were a kid, But just in 0:03:16.000 --> 0:03:18.120 case you didn't, I'm putting it on the show notes 0:03:18.160 --> 0:03:22.200 at eagleman dot com slash podcast. The point is the 0:03:22.400 --> 0:03:26.680 image is what we call perceptually by stable, which is 0:03:26.720 --> 0:03:28.720 just a way of saying that when you stare at 0:03:28.720 --> 0:03:31.760 the picture, your brain can make one interpretation of what 0:03:31.760 --> 0:03:35.839 you're seeing or the other interpretation, and it switches back 0:03:35.880 --> 0:03:38.600 and forth. You see the rabbit and then the duck, 0:03:38.880 --> 0:03:41.200 and then the rabbit and then the duck. The critical 0:03:41.200 --> 0:03:44.800 thing to appreciate is that nothing on the page changes, 0:03:44.960 --> 0:03:49.240 so the only thing that's changing is something inside your brain. 0:03:49.680 --> 0:03:53.000 So some years ago I collaborated with my neurosurgery colleagues 0:03:53.040 --> 0:03:56.240 to study this sort of thing. Now, neuroscience, what I 0:03:56.280 --> 0:03:59.360 do is pretty different from brain surgery what a neurosurgeon does, 0:03:59.520 --> 0:04:01.360 but happily we tend to be friends and we can 0:04:01.360 --> 0:04:05.320 often help each other. So I accompanied surgeries while my 0:04:05.400 --> 0:04:08.600 colleagues were operating on people's brains. And you may know, 0:04:08.640 --> 0:04:11.040 one of the incredible things about neurosurgery is that you 0:04:11.080 --> 0:04:14.320 can do this while a patient is awake and talking 0:04:14.360 --> 0:04:17.320 to you. And this is because you can put little 0:04:17.480 --> 0:04:21.960 electrodes these are small metal wires into the brain and 0:04:22.000 --> 0:04:25.520 the brain has no pain receptors, so it doesn't hurt. 0:04:25.600 --> 0:04:28.120 The patient can't feel that. Now, why does the brain 0:04:28.160 --> 0:04:31.400 have no pain receptors. It's generally because nothing ever touches 0:04:31.440 --> 0:04:34.919 your brain. Your brain, which is about the consistency of jello, 0:04:35.200 --> 0:04:38.520 is well protected in the thick plates of the skull, 0:04:38.800 --> 0:04:42.360 so evolutionarily, there was no point in developing pain receptors 0:04:42.360 --> 0:04:47.080 in the brain anyway. As a consequence, a neurosurgeon only 0:04:47.120 --> 0:04:50.359 needs to use local anesthesia when making a cut on 0:04:50.440 --> 0:04:53.480 the scalp, and then they drill a burhole into the skull, 0:04:53.960 --> 0:04:56.960 and once the brain is exposed, you can poke things 0:04:56.960 --> 0:04:59.680 into the tissue while you and the patient are having 0:04:59.760 --> 0:05:02.920 a conversation about what it's like and what you find 0:05:03.000 --> 0:05:07.720 there is that this empire of eighty six billion neurons 0:05:08.120 --> 0:05:12.200 is constantly storming with activity. Every neuron in your head 0:05:12.279 --> 0:05:16.000 is having these little spikes of electrical voltage known as 0:05:16.200 --> 0:05:20.240 action potentials, and every neuron is firing off some tens 0:05:20.400 --> 0:05:22.920 or hundreds of these spikes every second of your life. 0:05:23.560 --> 0:05:28.520 Every idea you've ever had, every memory you can ever recollect, 0:05:28.560 --> 0:05:32.479 every choice that you've ever contemplated, is written in the 0:05:32.600 --> 0:05:37.920 language of these tiny, mysterious spikes. And using a very 0:05:38.000 --> 0:05:41.400 very tiny electrode think of a super small wire that 0:05:41.440 --> 0:05:44.560 you just push into the brain, you can eavesdrop on 0:05:44.720 --> 0:05:48.400 these spikes. Now, let's call the patient on the table, Marcia. 0:05:48.800 --> 0:05:52.039 So Marcia is wide awake and talking to me, and 0:05:52.120 --> 0:05:55.280 I can show her this bistable picture of the rabbit 0:05:55.400 --> 0:05:59.160 duck and ask her to tell me what she sees. Now, 0:05:59.200 --> 0:06:03.520 the moment that Marcia switches to rabbit or duck, her 0:06:03.560 --> 0:06:07.520 brain has made a decision. A decision doesn't have to 0:06:07.520 --> 0:06:11.479 be conscious in this case, it's a perceptual decision by 0:06:11.480 --> 0:06:16.080 her visual system, and the mechanics of this switchover are 0:06:16.120 --> 0:06:19.599 totally hidden under the hood. Now, what's interesting is that 0:06:19.960 --> 0:06:23.200 in theory, a brain should be able to see both 0:06:23.240 --> 0:06:25.000 the rabbit and the duck at the same time, but 0:06:25.040 --> 0:06:28.960 in reality, brains don't do that. What brains do is 0:06:29.000 --> 0:06:33.200 they take ambiguous data and they make a choice. In 0:06:33.240 --> 0:06:35.600 this case, it eventually remakes the choice, and it might 0:06:35.640 --> 0:06:38.200 switch back and forth over and over. But the point 0:06:38.320 --> 0:06:42.320 is that our brains are always crushing ambiguity down to 0:06:42.640 --> 0:06:46.560 a choice. So when Marsha's brain lands on the interpretation 0:06:46.720 --> 0:06:49.520 that the drawing is of a duck or a rabbit, 0:06:49.960 --> 0:06:53.560 we can listen through the electrode to the responses from 0:06:53.640 --> 0:06:56.960 a small number of neurons these cells in her brain. 0:06:57.400 --> 0:07:06.800 Some neurons shift to a higher rate of activity while 0:07:06.880 --> 0:07:15.520 other neurons slow down their activity. And that happens right 0:07:15.560 --> 0:07:18.560 when Marcia says, oh, now I see it as a duck, 0:07:19.040 --> 0:07:21.360 and then when she says, oh, now it's a rabbit again, 0:07:21.440 --> 0:07:24.920 the neurons are changing their activity. Now, the neurons we 0:07:25.000 --> 0:07:29.320 happen to be eavesdropping on are not by themselves responsible 0:07:29.360 --> 0:07:33.920 for the perceptual change. Instead, they're operating in concert with 0:07:34.040 --> 0:07:37.240 billions of other neurons. So the changes we're listening to 0:07:37.840 --> 0:07:43.320 are just pieces of this massive changing pattern taking hold 0:07:43.360 --> 0:07:47.080 across large swaths of brain territory. But the idea is 0:07:47.120 --> 0:07:50.640 that when one pattern wins out over the other in 0:07:50.760 --> 0:07:55.440 Marcia's brain, a decision has been landed upon. Now it's 0:07:55.480 --> 0:07:58.520 a rabbit. Now it's a duck. Now. Just as a 0:07:58.560 --> 0:08:01.120 side note, it's not always about the neurons speeding up 0:08:01.200 --> 0:08:04.960 or slowing down their spikes. Sometimes neurons change their pattern 0:08:04.960 --> 0:08:08.520 of activity in more subtle ways. They become synchronized or 0:08:08.600 --> 0:08:12.760 desynchronized with other neurons even while they're maintaining their original pace. 0:08:13.080 --> 0:08:16.160 Now here's the thing. Although we can look at this 0:08:16.240 --> 0:08:20.720 in Marsha's brain and correlate the changes with seeing the 0:08:20.840 --> 0:08:24.200 rabbit or the duck, the thing to appreciate is that 0:08:24.240 --> 0:08:27.840 your brain makes thousands of decisions every day of your life, 0:08:28.200 --> 0:08:31.200 and that dictates your experience of the world. What are 0:08:31.240 --> 0:08:33.800 you gonna wear today, who are you going to text today, 0:08:34.160 --> 0:08:36.400 How are you going to interpret what was meant by 0:08:36.440 --> 0:08:39.200 that email? Are you going to exercise today? Or are 0:08:39.240 --> 0:08:41.480 you gonna eat that bag of chips or pass it up. 0:08:41.840 --> 0:08:44.960 We don't typically chew on it, but these small decisions 0:08:45.080 --> 0:08:50.400 underlie every action we take. Who you are emerges from 0:08:50.480 --> 0:08:54.800 the brain wide battles for dominance that rage in your 0:08:54.880 --> 0:08:59.200 skull every moment of your life. So listening to that 0:08:59.640 --> 0:09:08.760 neural activity in Marsha's head, it's impossible not to be 0:09:09.080 --> 0:09:13.520 in awe because this is what every decision in the 0:09:13.600 --> 0:09:19.000 history of our species sounded like. Every marriage proposal, every 0:09:19.160 --> 0:09:23.840 declaration of war, every leap of imagination, every mission launched 0:09:23.880 --> 0:09:28.960 into the unknown, every act of kindness, every lie, every breakthrough, 0:09:29.000 --> 0:09:33.480 every decisive moment. It all happened right here in the 0:09:33.600 --> 0:09:38.800 darkness of the skull, emerging from patterns of activity in 0:09:38.960 --> 0:09:43.480 networks of biological cells. So let's take a closer look 0:09:43.480 --> 0:09:46.480 at what's happening behind the scenes during a decision. So 0:09:46.520 --> 0:09:49.600 imagine you're making a simple choice. You're standing in the 0:09:50.080 --> 0:09:53.800 drinksisle at the store, and you're trying to decide between 0:09:53.840 --> 0:09:56.839 two flavors of sports strength that you like equally. So 0:09:57.160 --> 0:10:00.920 you're looking at lemon and blueberry. Now from on the outside, 0:10:01.080 --> 0:10:03.600 someone's looking at you standing in the aisle. It doesn't 0:10:03.600 --> 0:10:06.040 look like you're doing much. You're simply stuck there in 0:10:06.080 --> 0:10:09.080 the aisle, looking back and forth between these two options. 0:10:09.720 --> 0:10:13.640 But inside your brain, a simple choice like this has 0:10:13.760 --> 0:10:17.319 unleashed a hurricane of activity. Now keep in mind that 0:10:17.400 --> 0:10:21.360 by itself, no single neuron has much influence. But each 0:10:21.480 --> 0:10:24.680 neuron is connected to thousands of others, and they in 0:10:24.720 --> 0:10:27.320 turn connect to thousands of others and so on. In 0:10:27.360 --> 0:10:32.920 this massive, loopy, intertwining network, they're all releasing chemicals that 0:10:33.080 --> 0:10:37.839 excite or depress each other. Within this web, a particular 0:10:37.920 --> 0:10:42.120 constellation of neurons represents the Lemon drink, and this pattern 0:10:42.200 --> 0:10:46.160 is formed from neurons that mutually excite each other. Now 0:10:46.160 --> 0:10:49.439 they're not necessarily next to each other. They might span 0:10:50.080 --> 0:10:54.000 distant brain regions involved in smell and taste, and vision 0:10:54.440 --> 0:10:58.600 and your unique history of memories involving lemons sports strengths. 0:10:58.920 --> 0:11:01.760 Each of these neurons by itself has very little to 0:11:01.760 --> 0:11:05.320 do with lemon. In fact, each neuron plays many different 0:11:05.400 --> 0:11:10.199 roles at different times in ever shifting coalitions. But when 0:11:10.240 --> 0:11:14.040 these neurons all become active collectively at the same time 0:11:14.120 --> 0:11:18.280 in this particular arrangement, that's the Lemons sports drink. To 0:11:18.320 --> 0:11:21.319 your brain. So as you're standing in front of the drinks, 0:11:21.480 --> 0:11:26.280 this federation of neurons eagerly communicates with one another, like 0:11:26.360 --> 0:11:30.320 the way that dispersed individuals link online. Now, these neurons 0:11:30.360 --> 0:11:34.120 aren't acting alone in their electioneering. At the same time, 0:11:34.640 --> 0:11:39.240 the competing possibility the blueberry flavored drink is represented by 0:11:39.240 --> 0:11:43.400 its own neural coalition, and thousands or millions of neurons 0:11:43.400 --> 0:11:46.320 there are talking with each other and trying to get 0:11:46.360 --> 0:11:50.400 the vote out. Now, each coalition lemon and blueberry, tries 0:11:50.440 --> 0:11:54.040 to gain the upper hand by intensifying its own activity 0:11:54.080 --> 0:11:59.240 and suppressing the others. Neural populations compete against one another, 0:11:59.400 --> 0:12:03.360 just like police parties struggle for dominance. They fight it 0:12:03.360 --> 0:12:07.040 out until one of them triumphs in this winner take 0:12:07.080 --> 0:12:28.240 all competition, and whichever network wins defines what you do next. Now, 0:12:28.280 --> 0:12:30.959 this is what is so cool about brains as compared 0:12:31.000 --> 0:12:33.840 to let's say, are digital computers. The brain is a 0:12:33.880 --> 0:12:39.360 machine that runs on conflict between different possibilities, and all 0:12:39.400 --> 0:12:43.240 these possibilities are always trying to outcompete the others, and 0:12:43.320 --> 0:12:48.040 there are always multiple options. Even after you've selected the 0:12:48.320 --> 0:12:50.880 lemon or the blueberry drink, you find yourself in a 0:12:50.920 --> 0:12:54.320 new conflict. Should I drink the whole thing right now? 0:12:54.840 --> 0:12:56.720 Part of you feels like it's a good idea to 0:12:56.760 --> 0:12:59.160 make sure you have plenty of hydration, And at the 0:12:59.160 --> 0:13:01.880 same time, part of you he recognizes that it's very 0:13:01.920 --> 0:13:04.200 sugary and you don't want to do too much of that. 0:13:04.559 --> 0:13:07.320 And part of you also knows you're going to have 0:13:07.400 --> 0:13:09.040 to go to the bathroom soon if you drink the 0:13:09.080 --> 0:13:11.679 whole thing. So whether you polish off the whole drink 0:13:11.679 --> 0:13:14.559 now or save some for later is simply a matter 0:13:14.640 --> 0:13:17.560 of the way that the infighting goes as a result 0:13:17.640 --> 0:13:21.440 of the ongoing conflict in the brain. You can argue 0:13:21.440 --> 0:13:25.040 with yourself, you can curse it yourself, you can cajole yourself. 0:13:25.520 --> 0:13:29.080 But who exactly is talking with whom? It's all you, 0:13:29.520 --> 0:13:32.120 but it's different parts of you now. As I said, 0:13:32.120 --> 0:13:36.080 we're not usually aware of these internal conflicts, but sometimes 0:13:36.120 --> 0:13:39.280 we can use simple tasks to bring this to the surface. 0:13:39.840 --> 0:13:44.080 For example, there was a simple psychological task introduced in 0:13:44.080 --> 0:13:47.120 the nineteen thirties, which we call the Stroop task, and 0:13:47.160 --> 0:13:49.640 it's very easy. All you do is you look at 0:13:49.640 --> 0:13:52.160 a word printed on a page, and the word might 0:13:52.200 --> 0:13:55.640 be in red ink or blue, or green or yellow, 0:13:55.840 --> 0:13:57.920 and all you need to do is say the color 0:13:58.000 --> 0:14:00.280 of the ink. So if I show you the word 0:14:00.679 --> 0:14:03.280 garage and the ink is yellow, all you do is 0:14:03.320 --> 0:14:06.000 you say yellow. Now that sounds very easy to do, 0:14:06.120 --> 0:14:08.959 But the trick is that the words I show you 0:14:09.040 --> 0:14:12.880 might themselves be color words. Like I show you the 0:14:12.960 --> 0:14:17.160 letters R, E, D, but the ink is in green. 0:14:17.720 --> 0:14:20.320 So when you see this, you're supposed to shout out green, 0:14:20.680 --> 0:14:23.440 but it proves very difficult. Or I show you the 0:14:23.480 --> 0:14:27.520 word purple written in yellow ink, or the word blue 0:14:28.040 --> 0:14:31.080 written in red ink. Check out some examples on the 0:14:31.120 --> 0:14:34.160 show notes. Now, the instructions are very easy. All you're 0:14:34.160 --> 0:14:36.360 supposed to do is say the color of the ink. 0:14:36.720 --> 0:14:40.320 So why is the stroop task so hard? It's because 0:14:40.360 --> 0:14:43.120 one network in your brain has the task of identifying 0:14:43.240 --> 0:14:45.120 the color of the ink and putting a name to it. 0:14:45.360 --> 0:14:48.360 But at the same time, you have competing networks in 0:14:48.400 --> 0:14:51.720 your brain that are responsible for reading words. And these 0:14:51.760 --> 0:14:56.320 are so proficient that word reading has become a deeply 0:14:56.560 --> 0:14:59.960 ingrained automatic process. And so you can feel the strugg 0:15:00.200 --> 0:15:03.440 as these systems contend with each other and to get 0:15:03.480 --> 0:15:07.520 the right answer. You have to actively suppress the strong 0:15:07.640 --> 0:15:11.320 impulse to read the word in favor of really concentrating 0:15:11.360 --> 0:15:13.880 on the ink color. So with a simple task like this, 0:15:13.960 --> 0:15:18.360 you can directly experience the conflict. But most of the 0:15:18.440 --> 0:15:21.440 time things are running so smoothly under the hood that 0:15:21.480 --> 0:15:24.360 you don't even realize that you have all these competing networks. 0:15:24.680 --> 0:15:28.240 And it's only under very special circumstances that it can 0:15:28.280 --> 0:15:31.680 become easy for us to witness in another person the 0:15:31.800 --> 0:15:36.360 internal conflict between the different parts of the brain. So 0:15:36.520 --> 0:15:39.240 this can happen when a person has a particular kind 0:15:39.320 --> 0:15:44.280 of epilepsy, where the epileptic seizures spread from one hemisphere 0:15:44.280 --> 0:15:47.760 to the other. In these cases, some patients have undergone 0:15:48.080 --> 0:15:51.080 what is called a split brain surgery, which the brain's 0:15:51.160 --> 0:15:56.120 two hemispheres get surgically disconnected from each other. So normally 0:15:56.480 --> 0:16:00.080 your two hemispheres are connected by a super highway of 0:16:00.160 --> 0:16:04.000 nerves called the corpus colosum, and this allows the right 0:16:04.040 --> 0:16:07.480 and left halves to coordinate and to work in concert. So, 0:16:07.600 --> 0:16:11.000 for example, if you are feeling chilly, both of your 0:16:11.000 --> 0:16:14.840 hands cooperate. One holds your jacket hem while the other 0:16:14.960 --> 0:16:19.040 tugs up the zipper. But When the corpus closum gets cut, 0:16:19.480 --> 0:16:23.120 the two hemispheres aren't talking anymore, and you can get 0:16:23.160 --> 0:16:28.120 a very wild and haunting clinical condition that's called alien 0:16:28.400 --> 0:16:31.920 hand syndrome. So the two hands can act with totally 0:16:31.920 --> 0:16:36.960 different intentions. So a person with a severed corpus colosum 0:16:37.360 --> 0:16:39.920 begins to zip up a jacket with one hand and 0:16:39.960 --> 0:16:43.840 the other hand the alien hand suddenly grabs the zipper 0:16:43.920 --> 0:16:47.760 and pulls it back down. Or the person might reach 0:16:47.840 --> 0:16:50.160 for a piece of pizza with one hand and their 0:16:50.200 --> 0:16:52.920 other hand leaps into action to slap the first hand. 0:16:53.640 --> 0:16:57.320 The normal conflict running in the brain now comes to 0:16:57.360 --> 0:17:01.400 the surface because the two hemispheres are now acting independently 0:17:01.440 --> 0:17:04.439 of one another. They're not working things out under the 0:17:04.440 --> 0:17:09.399 hood anymore. Alien hand syndrome typically fades in the weeks 0:17:09.440 --> 0:17:12.520 after surgery, as the two halves of the brain take 0:17:12.520 --> 0:17:16.439 advantage of any remaining connections to start coordinating again. But 0:17:16.520 --> 0:17:19.800 what it reminds us is that even when we think 0:17:19.840 --> 0:17:24.119 we're being single minded, our actions result from these immense 0:17:24.400 --> 0:17:29.719 battles that continually rise and fall in the darkness of 0:17:29.880 --> 0:17:33.879 the cranium. Now to appreciate some of the major competing 0:17:33.960 --> 0:17:38.680 systems in your brain. Consider a philosophy experiment known as 0:17:38.760 --> 0:17:42.280 the trolley dilemma. I spoke about this once about sixty 0:17:42.320 --> 0:17:45.199 episodes ago, but if you haven't heard this one, it 0:17:45.320 --> 0:17:47.879 paints an important point. So here's how it goes. A 0:17:48.080 --> 0:17:51.240 trolley is barreling down a train track and you are 0:17:51.280 --> 0:17:54.960 a bystander, and you notice that there are four workers 0:17:55.000 --> 0:17:58.840 who are doing repairs down the track, and you realize 0:17:58.880 --> 0:18:01.600 that they are going to get it and killed by 0:18:01.680 --> 0:18:04.840 this trolley. Then you notice that there's a lever right 0:18:04.960 --> 0:18:07.960 near you, and if you pull this lever, that'll divert 0:18:08.040 --> 0:18:11.600 the trolley onto a parallel track. But wait a minute. 0:18:11.640 --> 0:18:14.480 You realize that there's one worker on that track, and 0:18:14.520 --> 0:18:18.080 if you pull the lever, that one worker will get killed. 0:18:18.119 --> 0:18:20.680 So here's the question. Do you let four people get 0:18:20.760 --> 0:18:23.280 killed or do you pull the lever so that only 0:18:23.359 --> 0:18:26.080 one person is killed. When people are asked what they 0:18:26.080 --> 0:18:29.480 would do in this scenario, almost everyone pulls the lever. 0:18:29.680 --> 0:18:32.440 After all, it's better than only one person gets killed 0:18:32.560 --> 0:18:37.400 rather than four, right, But now consider a slightly different scenario. 0:18:38.119 --> 0:18:41.000 In the second scenario begins with the same premise that 0:18:41.040 --> 0:18:44.040 trolley is barreling down the track and four workers are 0:18:44.040 --> 0:18:46.520 going to get killed. But this time you're standing on 0:18:46.560 --> 0:18:50.040 a bridge that goes over the tracks, and you notice 0:18:50.040 --> 0:18:53.240 that there's a large man standing on the bridge watching 0:18:53.240 --> 0:18:56.959 the birds. And you realize that if you push him off, 0:18:57.480 --> 0:19:00.840 he'll land right on the track and his body will 0:19:00.920 --> 0:19:05.160 be sufficient to stop the trolley and save the four workers. 0:19:05.720 --> 0:19:09.600 So do you push him off? In this second scenario? 0:19:09.760 --> 0:19:12.000 Almost no one I talk with is willing to push 0:19:12.080 --> 0:19:14.760 the man. Why not? Well, when I ask them, they 0:19:14.760 --> 0:19:16.840 give answers like that would be murder and that would 0:19:16.840 --> 0:19:20.480 just be wrong. But wait, isn't it the same equation? 0:19:20.800 --> 0:19:24.520 In both cases? The question is would you trade one 0:19:24.640 --> 0:19:27.960 life for four? So why do the results come out 0:19:28.160 --> 0:19:32.879 so differently in the second scenario. Ethicists have addressed this 0:19:32.960 --> 0:19:36.040 problem from many angles, but brain imaging has been able 0:19:36.080 --> 0:19:40.600 to provide a fairly straightforward answer to the brain. The 0:19:40.640 --> 0:19:44.440 first scenario about pulling the lever, that's just a math problem. 0:19:44.760 --> 0:19:49.679 The dilemma activates regions that are involved in solving logical problems. 0:19:50.160 --> 0:19:53.520 But in the second scenario, where you have to physically 0:19:53.560 --> 0:19:56.160 interact with the man and push him to his death, 0:19:56.400 --> 0:20:00.560 that recruits additional networks. Into the decision. Now you have 0:20:00.640 --> 0:20:04.959 the involvement of brain regions involved in emotion. In this 0:20:05.160 --> 0:20:09.159 second scenario, you're caught in a conflict between two systems 0:20:09.480 --> 0:20:12.840 that have very different opinions. Your rational networks tell you 0:20:12.880 --> 0:20:16.159 that one death is better than four, but your emotional 0:20:16.160 --> 0:20:21.439 networks trigger this gut feeling that murdering a bystander is wrong. 0:20:21.840 --> 0:20:24.760 You're now dealing with these competing drives, with the end 0:20:24.800 --> 0:20:29.040 result that your decision is likely to change entirely from 0:20:29.400 --> 0:20:48.760 the first scenario. Now, the trolley dilemma sheds light on 0:20:48.880 --> 0:20:53.480 real world situations. Just think of modern warfare, which has 0:20:53.520 --> 0:20:57.000 become more like pulling the lever rather than pushing the 0:20:57.040 --> 0:21:00.240 man off the bridge. When a person pushed which is 0:21:00.320 --> 0:21:03.640 the button to launch a long range missile, it involves 0:21:03.720 --> 0:21:08.680 only the networks involved in logical problems. Operating a drone 0:21:09.200 --> 0:21:13.800 can become like a video game. Cyber attacks reconsequences at 0:21:13.880 --> 0:21:17.200 a distance, So the rational networks are at work here, 0:21:17.680 --> 0:21:22.159 but not necessarily the emotional networks. The detached nature of 0:21:22.320 --> 0:21:27.760 distance warfare reduces internal conflict, and it makes this easier 0:21:27.800 --> 0:21:30.240 to wage. So in the nineteen sixties there was a 0:21:30.280 --> 0:21:34.560 military thinker who suggested that the button to launch nuclear 0:21:34.600 --> 0:21:39.560 missiles should be implanted in the chest of the president's 0:21:39.640 --> 0:21:44.880 best friend. That way, if the president chooses to launch nukes, 0:21:45.359 --> 0:21:48.760 he'd have to inflict physical violence on his friend first, 0:21:48.840 --> 0:21:52.000 he'd have to tear him open, and that consideration would 0:21:52.080 --> 0:21:57.040 recruit emotional networks into the decision. After all, the world 0:21:57.200 --> 0:21:59.960 would not be better if we all behaved like row 0:22:00.040 --> 0:22:05.200 robots when making life and death decisions. Unchecked reason can 0:22:05.240 --> 0:22:09.679 be dangerous. Our emotions are actually a powerful and often 0:22:09.840 --> 0:22:14.920 insightful constituency, and we'd be remiss to exclude them from 0:22:14.920 --> 0:22:19.800 the parliamentary voting. Although the neuroscience is new, this intuition 0:22:19.920 --> 0:22:23.760 about having different drives has a long history. The ancient 0:22:23.880 --> 0:22:27.520 Greeks suggested that we should think of our lives like 0:22:27.600 --> 0:22:31.400 we are charioteers trying to hold on to two horses. 0:22:31.640 --> 0:22:34.400 We've got the horse of reason and the horse of passion, 0:22:34.800 --> 0:22:38.560 and each horse pulls slightly off center in opposite directions, 0:22:38.800 --> 0:22:42.440 and your job is to keep control of both horses, 0:22:42.840 --> 0:22:46.439 keeping yourself moving down the middle of the road. So 0:22:46.640 --> 0:22:49.920 I've asserted that emotions are really important and we shouldn't 0:22:50.000 --> 0:22:52.440 try to be like mister Spock. But I want to 0:22:52.480 --> 0:22:54.879 double click on that claim, and the way we can 0:22:54.960 --> 0:22:58.080 do that is by seeing what happens when a person 0:22:58.480 --> 0:23:03.639 loses the capacity to include emotions in decision making. So 0:23:03.760 --> 0:23:07.040 let's take someone like Hammy Myers, who I filmed in 0:23:07.080 --> 0:23:10.880 my television show called The Brain. Cammy is a former 0:23:11.040 --> 0:23:14.000 engineer and some years ago she got into a motorcycle 0:23:14.040 --> 0:23:17.840 accident and the consequence was damaged to her orbitofrontal cortex, 0:23:17.880 --> 0:23:21.600 which is the region just above the orbits of the eyes. Now, 0:23:21.720 --> 0:23:26.640 this is a critical region to integrate signals streaming in 0:23:26.680 --> 0:23:29.919 from the body, Signals that tell the rest of the 0:23:29.960 --> 0:23:34.400 brain what state her body is in. Is she hungry, 0:23:34.560 --> 0:23:38.119 is she nervous? Is she excited? Is she embarrassed? Is 0:23:38.160 --> 0:23:42.359 she thirsty? Is she joyful? Now? The interesting thing is 0:23:42.400 --> 0:23:45.639 that Cammy doesn't look like someone who has suffered a 0:23:45.720 --> 0:23:48.680 traumatic brain injury. But if you were to spend even 0:23:48.800 --> 0:23:52.080 five minutes with her, you would detect there's a problem 0:23:52.480 --> 0:23:56.280 with her ability to deal with decision making. So let's 0:23:56.280 --> 0:23:59.280 say you say, hey, do you want the lemon drinker 0:23:59.359 --> 0:24:02.760 the blueberry? And she can describe all the pros and 0:24:02.800 --> 0:24:05.399 the cons while the lemon drinks a little more sour, 0:24:05.800 --> 0:24:08.800 but the blueberry has more sugar, and so on. But 0:24:08.840 --> 0:24:14.600 she can't actually decide. She can't finalize a choice. Even 0:24:14.640 --> 0:24:19.720 the simplest situations leave her mired and indecision why. It's 0:24:19.760 --> 0:24:24.320 because she can no longer read her body's emotional summaries, 0:24:24.960 --> 0:24:28.160 and as a result, decisions become incredibly difficult for her. 0:24:28.440 --> 0:24:32.760 In other words, because of her brain injury, no particular 0:24:32.880 --> 0:24:37.000 choice is now tangibly different from any other choice, and 0:24:37.040 --> 0:24:40.800 without decision making, very little gets done. Tammy reports she 0:24:40.880 --> 0:24:44.920 often spends all day on the sofa, So her brain 0:24:44.960 --> 0:24:48.879 injury tells us something crucial about decision making. It's easy 0:24:49.200 --> 0:24:52.560 to think about the brain commanding the body from on high, 0:24:52.560 --> 0:24:55.879 but in fact, the brain is in constant feedback with 0:24:56.040 --> 0:24:59.600 the body. The physical signals from the body give a 0:24:59.680 --> 0:25:02.600 quick summary of what's going on and what to do 0:25:02.680 --> 0:25:06.560 about it. To land on a choice, the body and 0:25:06.640 --> 0:25:10.240 the brain have to be in close communication, and for 0:25:10.320 --> 0:25:12.840 that you need the orbit or frontal cortex. Now you can, 0:25:12.880 --> 0:25:15.760 of course understand this in your own life. Consider a 0:25:15.920 --> 0:25:19.680 situation like this. You get a package misdelivered to your door, 0:25:19.720 --> 0:25:22.040 but it belongs to your next door neighbors. So you 0:25:22.160 --> 0:25:24.679 go over to deliver it to them, But as you 0:25:24.720 --> 0:25:29.200 approach their gate, their dog growls and bares its teeth. 0:25:29.240 --> 0:25:32.359 So do you open the gate and press on to 0:25:32.440 --> 0:25:37.800