Inner Cosmos Inbox 1

Published Oct 25, 2023, 10:00 AM

Eagleman answers listeners questions.

Hi, this is David Eagleman. I've done a couple dozen of these podcast episodes so far, and I have been so gratified to see all the emails I get at podcasts at Eagleman dot com where people have comments or questions, and so what I want to do in this short episode today was just address a bunch of questions. Okay, Laura from Miami asks, is it true that we only use ten percent of our brain? Thank you for that question. It turns out that is not true. It turns out your brain is screaming with activity around the clock all the time. All the neurons in your brain are active. They're all popping off, even when you're asleep, even when you're in a deep sleep, they're popping off. So it turns out you do not use just ten percent of your brain. You use one hundred percent of your brain essentially all the time. Now, the question that's been interesting to me is why is it such a sticky myth even though it has no basis in the science. Why does it stick around? I think it's because it must be sort of aspirational or hopeful, which is, if we think we're all using ten percent of our brains and we think, wow, I could be much smarter than I am and do much more than I can do right now, But in fact it's a myth. Thank you for the question. I did an episode a little while ago about in groups and outgroups and the difference that we can measure in the brain, and Haroun from Berkeley wrote and asked, what if your brain shows a big difference between in and out groups, but you don't want that to be true, like with your behavior. So that's a great question, Harun. Just as a reminder, what we did in the study is we had people watch, let's say a hand get stabbed with a syringe needle. They see this piece of footage and it activates this pain network in the brain, and that is essentially a measure of empathy. But what we then did is we added a single word to each of the six hands. So we had Christian, Jewish, Muslim, Scientologist, Hindu, atheist. And now you see a hand get stabbed, and the question is which group do you belong to and do you have as much of an empathic response when you see any member of your outgroup gets stabbed? And generally, what we found is that you have a lower empathic response when the label is different when it's not your in group. So I think this is the heart of Harun's question is if you have that big difference in your empathic response, does it mean you're a bad person? Does it mean it has some reflection on how you're going to act? So let me say two things about this. First, it turns out that there is some amount of individual differences in this group outgroup difference. Everyone seems to have this reaction of caring more about their in group, but some show a bigger effect than others. But as far as we can tell, this does not map onto people's behavior. In other words, we can't help what our low level reactions are, what our first response is to something when we see something and there's a label. For example, whenever I see crunchy tortilla chips, my brain fires on all cylinders and tells me to grab those and stick them in my mouth so I can enjoy the crunch. But it doesn't mean that I actually do that. It doesn't mean I actually grab the chips. I have goals at different levels, like I've cut carbs out of my diet because I think that makes me healthier. And this is related to an even longer term issue that for reasons of vanity, I want to be an excellent shape and the chips would sabotage that. So despite this giant low level reaction from my brain when I see the chips, I have the capacity to override that decision with different layers of decision making. I am not slave to my first low level responses. And it's the same thing with these in group and outgroup responses. The effect that people show. That's the first low level thing that exposed how parts of their brain think. And it's massively important because it's different if there's no part of your brain that thinks that way at all. But when you have this first reaction, it has to be either implemented or overridden. In other words, if I didn't like chips at all, it would be a lot less effort to override that, and we wouldn't even be talking about this. So when it comes to a low level response of preferring your in group, no problem, that's just the first offer that your brain is making. But for most of us, we care about societal structure and fairness and equality, and so we override that. And in fact, I have a suspicion with no data to prove this. It's just a suspicion. But I think that perhaps some of the most socially conscious people, the people who fight against religionism or racism or whatever, that at least some of those people are battling some of their own quite powerful internal demons. And that's fine because in the final analysis, actions speak louder than words. Your behavior in the world is the only thing that counts. And I'll just mention one more thing. This is sort of a long answer, but something that's been discussed among the news outlets in the last several years is something called the implicit association's test, and there's a whole flurry of papers about this, and that is, you see things on the screen and you have to react by hitting a button, whether it's a good or a bad thing. So maybe it's a particular religion or a particular race, or a particular sexual orientation or whatever. And the question is, is your reaction time a little bit slowed down when you're seeing some other group and could that mean that you implicitly have some sort of negative association with that group. Now, the question in the media has been could this someday be used in a courtroom. If let's say an employer fires somebody, could you use the implicit associations test to demonstrate, Hey, we think this guy is a racist and that's why he did the firing. From a neuroscience point of view, I think it would be ridiculous to allow that into a courtroom because someone might have a racist or sexist or religious response at an unconscious low level in their brain, and that tells you nothing about how they're going to act in the world, or whether the firing of that employee had anything to do with that low level brain response. As I said, many people actually act better in the world because they're embarrassed by their internal first reaction. It would be like taking me to court and concluding I must be the one who stole the bag of chips because I have the biggest neural response to the site of chips. It doesn't tell you anything about my final behavior, my final decision in a situation. The only thing that can give you a good indication of someone's behavior is their prior behavior, not their brain's knee jerk response. Thanks for that question, okay. Jordan from LA asked a question from my episode about dreams. One of the things I was talking about there is when somebody goes blind, their visual cortex gets taken over by other neighboring territories. And so my hypothesis is that the reason we dream, it's like a screen saver that protects the visual cortex from takeover during the nighttime. So Jordan's question is, what about people who go blind later in life. Well, there's actually a lot of data on this sort of thing. People who become blind after the age of seven have more visual content in their dreams than those who become blind earlier, and that is consistent with the fact that the occipital lobe this part back here your visual cortex. In people who become blind later, that gets less fully taken over by the other senses, and so the activity that you have is experienced more visually. In other words, if you go blind later, your visual cortex is more intact and less likely to get taken over, and so you have more visual dreams. Okay, this next question is from Sampridi in Boston. Why are we so bad at remembering what happened during a dream? Okay, Well, this is because during dreaming you've got these other brain areas like the hippocampus and the prefrontal cortex that are essentially shut down. They are less active during dream sleep than they are during the waking state, and presumably this is what accounts for our difficulty remembering our dreams. Now, why does your brain shut down these areas so that dreams don't get remembered. One possibility is that there's no need to write down memory if the central purpose of dream sleep is just to keep the visual cortex actively fighting off its neighbors. And this is why when you wake up, you say, oh my gosh, I just experienced this wild dream, and you tell it somebody. You try to do it, but it's like gossamer, it just goes away and you can't remember what the dream was after just fifteen minutes. And by the way, I think this is similar to what it is like to have Alzheimer's disease, where you say, okay, i'll be there in five minutes, I'll meet you downstairs, and then it just sort of goes away and you can't remember it. I think, in a sense, we all know what it is like to be a person with Alzheimer's because we have that every morning when we wake up and one possibility about why memory does not get written down during dream sleep is just because there's actually no need to write down memory. It's not supposed to be cataloged for the future. If really the purpose of dream sleep is just to keep the visual cortex defended against takeover at nighttime, keep sending in your questions to podcasts at eagleman dot com and listen to the full episodes of Inner Cosmos wherever you listen to your podcasts, and also on YouTube, where you can leave questions or comments. Until next time. I'm David Eagleman, and this is the Inner Cosmos inbox.

Inner Cosmos with David Eagleman

Neuroscientist and author David Eagleman discusses how our brain interprets the world and what that  
Social links
Follow podcast
Recent clips
Browse 98 clip(s)