WEBVTT - Inner Cosmos Inbox 1 0:00:06.720 --> 0:00:08.719 Hi, this is David Eagleman. I've done a couple dozen 0:00:08.760 --> 0:00:11.600 of these podcast episodes so far, and I have been 0:00:11.640 --> 0:00:15.080 so gratified to see all the emails I get at 0:00:15.160 --> 0:00:18.919 podcasts at Eagleman dot com where people have comments or questions, 0:00:18.920 --> 0:00:20.800 and so what I want to do in this short 0:00:20.800 --> 0:00:25.160 episode today was just address a bunch of questions. Okay, 0:00:25.320 --> 0:00:28.320 Laura from Miami asks, is it true that we only 0:00:28.400 --> 0:00:31.200 use ten percent of our brain? Thank you for that question. 0:00:31.240 --> 0:00:33.760 It turns out that is not true. It turns out 0:00:33.760 --> 0:00:37.400 your brain is screaming with activity around the clock all 0:00:37.479 --> 0:00:40.440 the time. All the neurons in your brain are active. 0:00:40.440 --> 0:00:42.879 They're all popping off, even when you're asleep, even when 0:00:42.880 --> 0:00:45.440 you're in a deep sleep, they're popping off. So it 0:00:45.479 --> 0:00:47.120 turns out you do not use just ten percent of 0:00:47.159 --> 0:00:49.120 your brain. You use one hundred percent of your brain 0:00:49.600 --> 0:00:53.560 essentially all the time. Now, the question that's been interesting 0:00:53.560 --> 0:00:56.400 to me is why is it such a sticky myth 0:00:56.600 --> 0:00:58.800 even though it has no basis in the science. Why 0:00:58.800 --> 0:01:01.240 does it stick around? I think it's because it must 0:01:01.320 --> 0:01:04.840 be sort of aspirational or hopeful, which is, if we 0:01:05.160 --> 0:01:06.880 think we're all using ten percent of our brains and 0:01:06.959 --> 0:01:09.200 we think, wow, I could be much smarter than I 0:01:09.240 --> 0:01:12.080 am and do much more than I can do right now, 0:01:12.400 --> 0:01:14.600 But in fact it's a myth. Thank you for the question. 0:01:16.920 --> 0:01:19.360 I did an episode a little while ago about in 0:01:19.400 --> 0:01:22.120 groups and outgroups and the difference that we can measure 0:01:22.360 --> 0:01:26.280 in the brain, and Haroun from Berkeley wrote and asked, 0:01:26.800 --> 0:01:29.880 what if your brain shows a big difference between in 0:01:29.920 --> 0:01:33.119 and out groups, but you don't want that to be true, 0:01:33.600 --> 0:01:36.319 like with your behavior. So that's a great question, Harun. 0:01:36.720 --> 0:01:38.960 Just as a reminder, what we did in the study 0:01:39.080 --> 0:01:42.479 is we had people watch, let's say a hand get 0:01:42.600 --> 0:01:44.960 stabbed with a syringe needle. They see this piece of 0:01:45.000 --> 0:01:47.880 footage and it activates this pain network in the brain, 0:01:48.360 --> 0:01:51.840 and that is essentially a measure of empathy. But what 0:01:51.880 --> 0:01:53.920 we then did is we added a single word to 0:01:54.240 --> 0:01:59.960 each of the six hands. So we had Christian, Jewish, Muslim, Scientologist, Hindu, atheist. 0:01:59.840 --> 0:02:01.880 And now you see a hand get stabbed, and the 0:02:02.000 --> 0:02:05.360 question is which group do you belong to and do 0:02:05.400 --> 0:02:08.040 you have as much of an empathic response when you 0:02:08.080 --> 0:02:11.560 see any member of your outgroup gets stabbed? And generally, 0:02:11.600 --> 0:02:15.040 what we found is that you have a lower empathic 0:02:15.120 --> 0:02:18.000 response when the label is different when it's not your 0:02:18.160 --> 0:02:20.200 in group. So I think this is the heart of 0:02:20.240 --> 0:02:24.280 Harun's question is if you have that big difference in 0:02:24.320 --> 0:02:27.680 your empathic response, does it mean you're a bad person? 0:02:27.840 --> 0:02:29.799 Does it mean it has some reflection on how you're 0:02:29.800 --> 0:02:32.240 going to act? So let me say two things about this. First, 0:02:32.280 --> 0:02:35.480 it turns out that there is some amount of individual 0:02:35.520 --> 0:02:40.560 differences in this group outgroup difference. Everyone seems to have 0:02:40.600 --> 0:02:43.920 this reaction of caring more about their in group, but 0:02:44.040 --> 0:02:46.959 some show a bigger effect than others. But as far 0:02:47.040 --> 0:02:51.280 as we can tell, this does not map onto people's behavior. 0:02:51.800 --> 0:02:55.080 In other words, we can't help what our low level 0:02:55.120 --> 0:02:58.480 reactions are, what our first response is to something when 0:02:58.600 --> 0:03:03.280 we see something and there's a label. For example, whenever 0:03:03.320 --> 0:03:08.280 I see crunchy tortilla chips, my brain fires on all 0:03:08.320 --> 0:03:11.240 cylinders and tells me to grab those and stick them 0:03:11.240 --> 0:03:14.600 in my mouth so I can enjoy the crunch. But 0:03:14.680 --> 0:03:17.880 it doesn't mean that I actually do that. It doesn't 0:03:17.880 --> 0:03:21.519 mean I actually grab the chips. I have goals at 0:03:21.520 --> 0:03:24.720 different levels, like I've cut carbs out of my diet 0:03:24.760 --> 0:03:27.720 because I think that makes me healthier. And this is 0:03:27.800 --> 0:03:31.519 related to an even longer term issue that for reasons 0:03:31.560 --> 0:03:34.240 of vanity, I want to be an excellent shape and 0:03:34.320 --> 0:03:39.400 the chips would sabotage that. So despite this giant low 0:03:39.480 --> 0:03:42.200 level reaction from my brain when I see the chips, 0:03:42.880 --> 0:03:46.280 I have the capacity to override that decision with different 0:03:46.480 --> 0:03:50.560 layers of decision making. I am not slave to my 0:03:50.800 --> 0:03:54.640 first low level responses. And it's the same thing with 0:03:54.720 --> 0:03:59.520 these in group and outgroup responses. The effect that people show. 0:03:59.560 --> 0:04:02.680 That's the first low level thing that exposed how parts 0:04:02.720 --> 0:04:07.520 of their brain think. And it's massively important because it's 0:04:07.600 --> 0:04:09.640 different if there's no part of your brain that thinks 0:04:09.640 --> 0:04:13.120 that way at all. But when you have this first reaction, 0:04:13.840 --> 0:04:17.760 it has to be either implemented or overridden. In other words, 0:04:17.760 --> 0:04:19.080 if I didn't like chips at all, it would be 0:04:19.080 --> 0:04:22.200 a lot less effort to override that, and we wouldn't 0:04:22.200 --> 0:04:25.160 even be talking about this. So when it comes to 0:04:25.200 --> 0:04:30.320 a low level response of preferring your in group, no problem, 0:04:30.400 --> 0:04:33.120 that's just the first offer that your brain is making. 0:04:33.200 --> 0:04:36.520 But for most of us, we care about societal structure 0:04:36.640 --> 0:04:41.480 and fairness and equality, and so we override that. And 0:04:41.640 --> 0:04:44.520 in fact, I have a suspicion with no data to 0:04:44.600 --> 0:04:47.600 prove this. It's just a suspicion. But I think that 0:04:47.839 --> 0:04:50.760 perhaps some of the most socially conscious people, the people 0:04:50.800 --> 0:04:54.960 who fight against religionism or racism or whatever, that at 0:04:55.040 --> 0:04:57.920 least some of those people are battling some of their 0:04:58.000 --> 0:05:03.600 own quite powerful internal demons. And that's fine because in 0:05:03.640 --> 0:05:08.799 the final analysis, actions speak louder than words. Your behavior 0:05:08.839 --> 0:05:12.640 in the world is the only thing that counts. And 0:05:12.680 --> 0:05:14.600 I'll just mention one more thing. This is sort of 0:05:14.640 --> 0:05:18.359 a long answer, but something that's been discussed among the 0:05:18.400 --> 0:05:21.200 news outlets in the last several years is something called 0:05:21.240 --> 0:05:25.520 the implicit association's test, and there's a whole flurry of 0:05:25.640 --> 0:05:29.320 papers about this, and that is, you see things on 0:05:29.360 --> 0:05:31.919 the screen and you have to react by hitting a button, 0:05:32.440 --> 0:05:35.840 whether it's a good or a bad thing. So maybe 0:05:35.880 --> 0:05:39.240 it's a particular religion or a particular race, or a 0:05:39.240 --> 0:05:43.520 particular sexual orientation or whatever. And the question is, is 0:05:43.560 --> 0:05:46.440 your reaction time a little bit slowed down when you're 0:05:46.440 --> 0:05:49.280 seeing some other group and could that mean that you 0:05:49.440 --> 0:05:54.080 implicitly have some sort of negative association with that group. Now, 0:05:54.120 --> 0:05:57.200 the question in the media has been could this someday 0:05:57.600 --> 0:06:01.920 be used in a courtroom. If let's say an employer 0:06:02.160 --> 0:06:07.760 fires somebody, could you use the implicit associations test to demonstrate, Hey, 0:06:08.080 --> 0:06:10.359 we think this guy is a racist and that's why 0:06:10.400 --> 0:06:14.440 he did the firing. From a neuroscience point of view, 0:06:14.920 --> 0:06:17.159 I think it would be ridiculous to allow that into 0:06:17.160 --> 0:06:21.719 a courtroom because someone might have a racist or sexist 0:06:21.839 --> 0:06:26.679 or religious response at an unconscious low level in their brain, 0:06:27.400 --> 0:06:30.560 and that tells you nothing about how they're going to 0:06:30.680 --> 0:06:33.480 act in the world, or whether the firing of that 0:06:33.600 --> 0:06:37.000 employee had anything to do with that low level brain response. 0:06:37.800 --> 0:06:41.400 As I said, many people actually act better in the 0:06:41.440 --> 0:06:45.440 world because they're embarrassed by their internal first reaction. It 0:06:45.480 --> 0:06:47.680 would be like taking me to court and concluding I 0:06:47.839 --> 0:06:50.159 must be the one who stole the bag of chips 0:06:50.480 --> 0:06:53.159 because I have the biggest neural response to the site 0:06:53.160 --> 0:06:56.280 of chips. It doesn't tell you anything about my final behavior, 0:06:56.800 --> 0:07:00.240 my final decision in a situation. The only thing that 0:07:00.320 --> 0:07:03.279 can give you a good indication of someone's behavior is 0:07:03.320 --> 0:07:08.520 their prior behavior, not their brain's knee jerk response. Thanks 0:07:08.560 --> 0:07:25.360 for that question, okay. Jordan from LA asked a question 0:07:25.760 --> 0:07:28.680 from my episode about dreams. One of the things I 0:07:28.720 --> 0:07:31.920 was talking about there is when somebody goes blind, their 0:07:32.080 --> 0:07:36.800 visual cortex gets taken over by other neighboring territories. And 0:07:36.840 --> 0:07:40.240 so my hypothesis is that the reason we dream, it's 0:07:40.320 --> 0:07:43.720 like a screen saver that protects the visual cortex from 0:07:43.720 --> 0:07:46.760 takeover during the nighttime. So Jordan's question is, what about 0:07:46.760 --> 0:07:50.480 people who go blind later in life. Well, there's actually 0:07:50.520 --> 0:07:52.040 a lot of data on this sort of thing. People 0:07:52.040 --> 0:07:56.440 who become blind after the age of seven have more 0:07:56.560 --> 0:08:00.960 visual content in their dreams than those who become blind earlier, 0:08:01.200 --> 0:08:04.280 and that is consistent with the fact that the occipital 0:08:04.320 --> 0:08:07.400 lobe this part back here your visual cortex. In people 0:08:07.400 --> 0:08:11.680 who become blind later, that gets less fully taken over 0:08:11.760 --> 0:08:14.520 by the other senses, and so the activity that you 0:08:14.640 --> 0:08:18.760 have is experienced more visually. In other words, if you 0:08:18.920 --> 0:08:22.680 go blind later, your visual cortex is more intact and 0:08:22.760 --> 0:08:24.960 less likely to get taken over, and so you have 0:08:25.040 --> 0:08:31.760 more visual dreams. Okay, this next question is from Sampridi 0:08:31.920 --> 0:08:35.360 in Boston. Why are we so bad at remembering what 0:08:35.520 --> 0:08:39.760 happened during a dream? Okay, Well, this is because during 0:08:39.880 --> 0:08:43.439 dreaming you've got these other brain areas like the hippocampus 0:08:43.480 --> 0:08:46.600 and the prefrontal cortex that are essentially shut down. They 0:08:46.640 --> 0:08:49.680 are less active during dream sleep than they are during 0:08:49.720 --> 0:08:53.360 the waking state, and presumably this is what accounts for 0:08:53.600 --> 0:08:59.360 our difficulty remembering our dreams. Now, why does your brain 0:08:59.640 --> 0:09:02.280 shut down these areas so that dreams don't get remembered. 0:09:02.720 --> 0:09:06.520 One possibility is that there's no need to write down 0:09:06.600 --> 0:09:10.000 memory if the central purpose of dream sleep is just 0:09:10.040 --> 0:09:14.760 to keep the visual cortex actively fighting off its neighbors. 0:09:15.320 --> 0:09:17.320 And this is why when you wake up, you say, 0:09:17.360 --> 0:09:19.720 oh my gosh, I just experienced this wild dream, and 0:09:19.760 --> 0:09:21.880 you tell it somebody. You try to do it, but 0:09:22.160 --> 0:09:26.360 it's like gossamer, it just goes away and you can't 0:09:26.400 --> 0:09:30.440 remember what the dream was after just fifteen minutes. And 0:09:30.480 --> 0:09:34.240 by the way, I think this is similar to what 0:09:34.360 --> 0:09:38.439 it is like to have Alzheimer's disease, where you say, okay, 0:09:38.760 --> 0:09:42.079 i'll be there in five minutes, I'll meet you downstairs, 0:09:42.200 --> 0:09:44.520 and then it just sort of goes away and you 0:09:44.559 --> 0:09:46.800 can't remember it. I think, in a sense, we all 0:09:47.280 --> 0:09:49.080 know what it is like to be a person with 0:09:49.080 --> 0:09:52.840 Alzheimer's because we have that every morning when we wake 0:09:52.920 --> 0:09:57.400 up and one possibility about why memory does not get 0:09:57.440 --> 0:10:00.360 written down during dream sleep is just because there's actually 0:10:00.360 --> 0:10:03.440 no need to write down memory. It's not supposed to 0:10:03.480 --> 0:10:07.599 be cataloged for the future. If really the purpose of 0:10:07.679 --> 0:10:11.240 dream sleep is just to keep the visual cortex defended 0:10:11.400 --> 0:10:15.520 against takeover at nighttime, keep sending in your questions to 0:10:15.760 --> 0:10:18.680 podcasts at eagleman dot com and listen to the full 0:10:18.720 --> 0:10:22.160 episodes of Inner Cosmos wherever you listen to your podcasts, 0:10:22.200 --> 0:10:25.280 and also on YouTube, where you can leave questions or comments. 0:10:25.840 --> 0:10:28.679 Until next time. I'm David Eagleman, and this is the 0:10:28.720 --> 0:10:30.560 Inner Cosmos inbox.