Why Your Brain Works NOTHING Like You Think

If you type left brain versus right brain into YouTube, you'll fall into a vortex of wild claims. That creative people are right-brained, that analytical people are left-brained. For decades, pop psychology carved the brain into 2 neat categories: logical versus creative, analytical versus emotional. The idea became so oversimplified, so pervasive, that serious scientists abandoned the entire field. One psychiatrist who decided to study the divided brain was warned by his colleagues.

I was told when I got involved in this area, don't touch it, it's toxic. Don't even go there.

He went anyway. And what he found was nothing like the YouTube version. The 2 halves of your brain don't do different things. They do the same things, but in different ways. And that distinction has enormous consequences for how we learn, how we judge right from wrong, how we see reality itself. In this video, I want to show you the real science of the divided brain and why one researcher believes it explains something troubling about the world we've built. Let me explain. Iain McGilchrist is a psychiatrist who spent years studying the brain through case studies and scientific research. His book on the topic, The Master and His Emissary, has been on my radar for years. And it all begins with a question that's much older than pop psychology. Why is the human brain divided into 2 hemispheres? If the brain was simply a processing machine, why split it in half? And yet the division is ancient. It shows up in mammals, reptiles, fish, insects, even nematode worms with just 302 neurons. have brains that work asymmetrically. One of the oldest creatures to have a neural network is a tiny organism called Nematostella vectensis. It lived about 600 million years ago. Its neural network was asymmetrical. Whatever this division does, evolution has been betting on it since long before dinosaurs walked the Earth. Now, whenever we want to understand why the brain is constructed the way it is, It's helpful to start with noticing what the brain does as we go about our lives. Think about a little bird trying to pick up a seed on the ground.

All living creatures need to be able to attend to the world in 2 different ways, which require quite different attention at the same time. And this is simply not possible unless they can work relatively independently. On the one hand, in order to manipulate the world, to get food, to pick up a twig to build a nest, you need a very precise, targeted, attention on a detail in order to be able to achieve that and be ahead of your competition. But if you're only doing that, if you're a bird just concentrating on the little seed, you'll become somebody else's lunch while you're getting your own, because you need at the same time to be paying the precise opposite kind of attention— not piecemeal, fragmented, and entirely detailed, but sustained, broad, and vigilant for predators and for other members of your species.

2 kinds of attention. One narrow and focused, the other wide and watchful, both running at the same time. If you only have the narrow view, you eat the seed but get eaten by the predator. If you only have the wide view, you can see danger coming, but you starve. The brain needs to hold both views of reality at the same time. And this is where the pop psychology version falls apart. The 2 hemispheres don't carve up the work with one handling logic and the other handling creativity. Both hemispheres are involved in everything. The difference is how they approach it.

The reason that we got things wrong, in my view, is that we were looking at simply the functions as we saw them and divided them up in much the way that we would if we thought about a machine. This part of the machine does this, this part of the machine does that. And if you, instead of using the machine model, use the model of this is part of a human being, a person, you would ask a slightly different question, which is not just what does it do, but how does it do it? And that turns out to be a profoundly important question when looking at the hemispheres, because they are both involved in doing everything. But there is a difference. It's that quite consistently, each hemisphere does all these things in a totally different way, with a different kind of spirit towards a different end, if you like to put it that way.

A different spirit. Toward a different end. The right hemisphere takes in the whole picture. The left zeroes in on details. Both are essential, and the way they work together is more fascinating than either one alone.

Imagine you are attracted to a piece of music and you try playing it as a whole and you, you love it, but you realize that there are bits that you are not getting right. So, you know, you need to practice your fingering at bar 18, and when you're taking it apart, you realize, oh, here we move into the subdominant. At this point, we're moving back to the dominant. You, you understand a whole lot of detail. Which are fine. You need to do the work and you need to do the analysis. But when you come to play the piece, you must put all that out of your mind, otherwise you won't be able to play at all. The right hemisphere takes in the whole at the start, the left hemisphere unpacks that and enriches it, but then that work being done, it needs to be taken back into the whole picture, which only the right hemisphere can do.

The whole first, Then the parts, then back to the whole. For this collaboration to work, the hemispheres need to both connect and stay separate. The bundle of nerve fibers that links them, the corpus callosum, has long been described as a bridge passing information freely between the 2 halves. Iain says it's more like a gatekeeper.

In order to collaborate, you need to both work together and work separately. If a surgeon collaborates with the scrub nurse, they don't both try and do the same job. distinct roles. And the corpus callosum enables both separation, mainly, I believe, separation, but also connection.

Mainly separation. Without that boundary, the 2 views of reality would blur into one, and the advantage of having 2 perspectives would be lost. In 1997, PBS aired a documentary about a patient named Joe who had severe epilepsy. His doctors devised a radical treatment. A surgeon sliced Joe's corpus callosum, literally splitting his brain into 2. The surgery stopped the seizures, and it gave researchers a rare window into what each hemisphere could do on its own. What they found is that the differences between the hemispheres run much deeper than just attention. Take language. Both hemispheres process it, but the right hemisphere tracks tone, implication, What's not being said? The left hemisphere is more focused on the literal words.

Language has many components. One of them is attending to the tone of voice in which I say something. For example, I can say yes, or I can say yes. I can intone that in probably a dozen different ways with quite different meanings. So, for example, I say it's a bit hot in here. You using your right hemisphere know that what I mean is, could we have the door open? Could we put on the air conditioning? But your left hemisphere is wondering meanwhile, I'm supplying this quite unnecessary meteorological information.

The right hemisphere understands context. The left hemisphere is more literal. It's the weather report. This extends to everything implied, everything unspoken. Humor, for instance, requires you to hold multiple meanings at once, to grasp what isn't being said. People with right hemisphere damage can find it difficult to understand why something is funny. The same split shows up in moral reasoning. Ian describes a wonderfully vivid experiment. Picture 2 scenarios. A woman is having coffee with her friend. She puts what she thinks is sugar in her friend's cup, but it's actually poison. Her friend dies. Second scenario. A woman is having coffee with someone she hates. She puts what she thinks is poison in the coffee, It's actually sugar. The other person lives. Which scenario is morally worse? Most of us would unhesitatingly say the second. Intent is what matters. She tried to kill someone. But when the researchers temporarily disabled part of the right hemisphere—

The right temporoparietal junction, which you can do with a painless procedure, and ask people to solve moral problems, they give quite bizarre answers to them. Based on entirely utilitarian understanding of them.

To the left hemisphere, what matters is that in one case, someone is dead on the floor. It's the worst outcome. It justifies the harsher punishment. The fact that it was unintentional requires seeing the bigger picture. When someone steps on your toe in a crowded elevator, your left hemisphere and your right hemisphere have a conversation. Your left hemisphere says, This person stepped on my toe. I need justice, maybe vengeance. Hang on a second, your right hemisphere says. The elevator is crowded. The person who stepped on your toe wasn't looking. It was an accident. Chill out. Language, humor, moral reasoning— 3 things that make us most human, and the left hemisphere struggles with all of them. But here's where the story gets darker. The left hemisphere cannot see the big picture, but because it believes that what it can see is all there is to see, it doesn't know that it's missing the big picture. If a person suffers a stroke in the left hemisphere, the right hemisphere remains functional. The person knows that something is wrong. They're aware of their deficits. But when the stroke hits the right hemisphere, something disturbing happens. The person can have no idea that anything has changed. Iain describes an exchange between a doctor and a patient who had right hemisphere damage. Again, that means her ability to see the big picture has been diminished. Her arm was paralyzed, but she wasn't aware of it because her left hemisphere believed that what it can see is all there is to see. Producers from our show performed the exchange that Iain described. The physician asks the patient, About her non-working arm. Whose arm is this? It's not mine.

Whose is it?

It's my mother's. How on earth does it happen to be here? I don't know. I found it in my bed. How long has it been there? Since the first day. Feel, it's warmer than mine. The other day too, when the weather was colder, it was warmer than mine. Her own arm Attached to her body. And her left hemisphere, working alone, came up with a self-contained story that her arm was fine, but her mother's defective arm happened to find itself in her bed.

Well, what we're seeing is a phenomenon called denial, which is a feature of the way the left hemisphere works. So if you have a left hemisphere stroke, so your right hemisphere is still functioning, you're very aware of what deficits you have. If you have a right hemisphere stroke, you are completely unaware of there being anything wrong. So if you have a paralyzed left arm, which is often a consequence of right hemisphere stroke, more often than not, you will deny that there's any problem with it. If asked to move it, you will say, there, but it didn't move. If, on the other hand, I bring it in front of you and say, whose arm is this? Can you move it? They say, oh, that's not mine. That belongs to you, doctor, or to the patient in the next bed, or as in this cut, My mother. It's extraordinary because these are not people who are in any way mad. They, they, they don't have a psychosis, but they're simply incapable of understanding that there is something wrong here that involves them.

The left hemisphere doesn't just see a narrow view of the world. When evidence contradicts its view, it confabulates. It invents a story that fits what it already believes. The right hemisphere, meanwhile, can see what both hemispheres are doing. It recognizes the value of the left. It understands its own limitations. Think about this as you watch this video. To process what I'm saying, you need your left hemisphere. It hears the words, makes out the meaning in them. But I'm not just spewing words. I'm trying to paint a picture, to tell you a story. If you're a writer or a creator yourself, perhaps you're noticing the way this narrative is unfolding. But to see this, you need to look beyond the words and sentences. You need to go from processing to understanding. Iain offers an analogy that brings this idea to life.

And I sometimes give the analogy of, you know, a scientific approach to what is music. And a conventional scientific approach would be, well, let's drill down and see what it's made of. And after years of expensive electron microscopy, I can inform you that music is made up of notes. What is a note? A note is a simple tone. What does it mean? Actually, it means nothing. Well, let's take another one. That was an A-flat. Let's take a B. Doesn't mean anything. Now, if you put 35,000 of these together, you've got the Bach B Minor Mass. Where does it come from? Well, it can't come from the notes because we've established that they don't mean anything. So, it must be something else, but all the rest is gaps. It's the gaps between the notes, the gaps that make melody, the gaps that make harmony, and so on. But the gaps are just, as it were, silence. They don't mean anything either. So if you put lots of things together that don't mean anything with lots of gaps that don't mean anything, you get something that means everything.

The left hemisphere hears the individual notes, notices the gaps between the notes. The right hemisphere hears Bach, feels the glory in a piece of music written more than 200 years ago. Now, you can draw the wrong conclusion from what Iain is saying. He is not saying that the left hemisphere is unimportant. You wouldn't be able to raise your spoon to your mouth without your left hemisphere. What he is saying is that the left and right hemispheres of the brain both have important roles to play. But in an increasingly busy and deadline-driven world, we have come to prioritize the left hemisphere. And we have come to devalue the right hemisphere. We celebrate accomplishment and achievement, but we fall short when it comes to understanding and meaning. Iain's book is called The Master and His Emissary. The title comes from a parable about power, knowledge, and the danger of not knowing what you don't know. The parable comes from Nietzsche. A wise spiritual master rules over the land, He cannot be everywhere at once, so he appoints an emissary, a bright messenger, to carry his instructions to the far corners of the kingdom.

And this emissary was bright enough, but not quite bright enough to know what it was he didn't know. And he thought, I know everything. And he thought, what does the master know, sitting back there seraphically smiling while I do all the hard work? And so he adopted the master's cloak, pretended to be the master, and because he didn't know what he didn't know, the result was that the community fell apart, essentially.

The master in Iain's analogy is the right hemisphere. It sees the whole picture, understands context, holds the meaning. The left hemisphere, it handles the details, executes the tasks, breaks problems into pieces. The emissary is essential. Without it, nothing gets done. But the emissary Cannot see what the master sees. And because it doesn't see the big picture, it assumes there's no big picture to see. Iain believes this parable describes what has happened to modern Western society. He argues that we have built a world that listens almost exclusively to the left hemisphere and dismisses what the right hemisphere has to offer. So I asked him, what would a world that only had a left hemisphere Well, obviously we would lose sight of the big picture.

That's the thing I've emphasized throughout. There'd be an emphasis on, on the details instead. There would be a great emphasis on predictability, organizability, anonymity, categorization, loss of the unique, and an ability to break things down into parts but not really see what the whole is like. There'd be a need for total control. Control, because the left hemisphere is somewhat paranoid. And that's because one can't understand quite what's going on, and one needs therefore to control it. Anger would become the keynote in public discourse. Everything would become black and white. The left hemisphere needs to be decisive, because don't forget, it's the one that's catching the prey. It's no good going, well, yeah, it could be a rabbit, but it might not be. It's got to go, I'm going to go for it. So it likes black and white. It doesn't like shades of meaning. So in this world, we would lose the capacity to see grades of difference. We would misunderstand everything that is implicit and metaphorical and have to make rules about how to achieve it.

Black-and-white thinking, putting algorithmic calculations on a pedestal, forgetting nuance and curiosity— does any of that sound familiar? Look around you. Do you see examples of people racing around without knowing where they're going? Building things but not understanding what they're building or why?

I think what I observe is an overemphasis on predetermined systems of algorithms, the sense of social alienation, the way in which we live divorced from the natural world, which is a very new phenomenon, the insistence on extreme positions, which is what the left hemisphere understands, not a nuanced argument about the pros and cons of Extremism instead of judgment.

Life divorced from the natural world. Rules for everything. Hmm. I wonder where we can spot those things these days.

Meaning comes out of living in a consistent culture where there is a sense of connection with one's past and, and not just one's own past, but the past of the people who made you who you are. With the other people in the society to which you belong and to the world at large, the natural world, and things that are just simply beyond our ken, the transcendental. These are very important things that the right hemisphere is much better equipped to understand, and I feel that the loss of them in modern life is grievous.

Iain is careful to point out that this is not an argument against science or reason. He loves science. He depends on it. The argument is about balance. The hemispheres need each other. The problem comes when one of them forgets that the other one exists. He ended our conversation with a line sometimes misattributed to Albert Einstein.

The right hemisphere sees the need of the left. That's in the image of the master and the emissary. The master knowing the need for the emissary, the emissary not knowing the value of the master. And if I may use a quotation from Einstein, I think this gives us the full picture. He said that the rational mind is a faithful servant. The intuitive mind is a precious gift. We live in a society that honors the servant but has forgotten the gift.

We have forgotten the gift. That line has stayed with me since my conversation with Iain, because the story of the divided brain is not about one half being good and the other being bad. We need the emissary. We need its precision, its focus, its ability to break things into parts. But the master, the part of us that sees the whole picture, that understands context and meaning and what is not being said, that part has been pushed aside. And most of us don't even realize it's gone. Because as Iain's research shows, when the left hemisphere loses something, It doesn't mourn the loss. It denies there was ever anything there to lose. Thank you for watching this video. If you've come this far, you are someone who is fascinated by the mind. You're curious and interested in learning more about ideas. Check out the Hidden Brain podcast on your favorite audio podcast app. Each week, I'll teach you something new about your own hidden brain. I'm Shankar Vedantam. See you soon.