David Eagleman

The fact is, if you felt good at some moment in your life and you sat around and tried to reproduce that, I think you'd do just as well thinking about that moment and trying to put yourself in that state rather than trying to match a squiggly line.

I think that's right. I mean, there's also this very deep question about what kind of feedback is useful for you. Most of the action in your brain is happening unconsciously. It's happening well below the surface of your awareness or your ability to access it. And the fact is that your brain works much better that way. Do you play tennis, for example? Not well. Or golf? Golf I play. Okay, good.

So if I ask you, hey, Stephen, tell me exactly how you swing that golf club. The more you start thinking about it, the worse you're going to be at it. Because consciousness, when it starts poking around in areas that it doesn't belong, it's only going to make things worse. And so it is an interesting question. about the kind of things that we want to be more conscious of.

I'm trying some of these experiments now, actually using my wristband, wearing EEG and getting a summarized feedback on the wrist. So I don't have to stare at a screen, but as I'm walking around during the day, I have a sense of what's going on with this. Or with the smartwatch, having a sense of what's going on with my physiology.

I'm not sure yet whether it's useful or whether those things are unconscious because... Mother Nature figured out a long time ago that it's just as well if it remains unconscious. One thing I'm doing, which is just a wacky experiment, just to try it. The smartwatch is measuring all these things.

We have that data going out, but the key is you have someone else wear the wristband, like your spouse wear the smartwatch, and you're feeling her physiology. And I'm trying to figure out, is this useful to be tapped into someone else's physiology? I don't know if this is good or bad for marriages. What a nightmare.

But I'm just trying to really get at this question of these unconscious signals that we experience. Is it better if they're exposed or better to not expose them? What have you found empirically? Empirically, what I found is that married couples don't want to wear it.

In my book, Incognito, the way I cast the whole thing is that the right way to think about the brain is like a team of rivals. You know, Lincoln, when he set up his presidential cabinet, he set up several rivals in it and they were all functioning as a team. That's really what's going on under the hood in your head is you've got all these drives that want different things all the time. So

If I put a slice of chocolate cake in front of you, Steven, part of your brain says, oh, that's a good energy source. Let's eat it. Part of your brain says, no, don't eat it. It'll make me overweight. Part of your brain says, okay, I'll eat it, but I'll go to the gym tonight. And the question is, who is talking with whom here? It's all you, but it's different parts of you.

All these drives are constantly arguing it out. It's, by the way, generating activity in the same parts of the brain as listening and speaking that you would normally do. It's just internal before anything comes out.

Well, this might be a good reason for you to keep pursuing possible ways to tap into your brain data. And by the way, it turns out that the internal voice is on a big spectrum across the population, which is to say some people like you have a very loud internal radio. I happen to be at the other end of the spectrum where I have no internal radio at all. I never hear anything in my head.

That's called anendophagia. But everyone is somewhere along this spectrum. One of the points that I've always really concentrated on in neuroscience is what are the actual differences between people traditionally that's been looked at in terms of disease states? But the question is, from person to person who are in the normal part of the distribution, what are the differences between us?

It turns out those are manifold. So take something like how clearly you visualize when you imagine something. So if I ask you to imagine a dog running across a flowery meadow towards a cat, you might have something like a movie in your head. Other people have no image at all. They understand it conceptually, but they don't have any image in their head.

And it turns out when you carefully study this, the whole population is smeared across the spectrum. So our internal lives from person to person can be quite different.

So I've spent about 25 years now studying synesthesia, and that has to do with some percentage of the population has a mixture of the senses. They might look at letters on a page, and that triggers a color experience for them, where they hear music and that causes them to see some visual, or they... put some taste in their mouth and it causes them to have a feeling on their fingertips.

There are dozens and dozens of forms of synesthesia, but what they all have to do with is a cross blending of things that are normally separate in the rest of the population. And what share of the population has these patterns? So it's about 3% of the population that has colored letters or colored weekdays or months or numbers. It's big. It's interesting. I wouldn't have thought it was so big.

The crazy part is that if you have synesthesia, it probably has never struck you that 97% of the population does not see the world the way that you see it. Everyone's got their own story going on inside, and it's rare that we stop to consider the possibility that other people do not have the same reality that we do. And what's going on in the brain?

In the case of synesthesia, it's just a little bit of crosstalk between two areas that in the rest of the population tend to be separate but neighboring. So it's like porous borders between two countries. They just get a little bit of data leakage, and that's what causes them to have a joint sensation of something.

I suspect it's the latter, which is to say everyone loves pointing out synesthetic musicians, but no one has done a study on how many deep sea divers have synesthesia or how many accountants have synesthesia. And so we don't really know if it's disproportionate among musicians.

So typically, as you said, it's totally idiosyncratic. Each synesthete has... his or her own colors for letters. So my A might be yellow, your A is purple, and so on. And then what happened is, with two colleagues of mine at Stanford, we found in this database of tens of thousands of synesthetes that I've collected over the years, we found that starting in the late 60s,