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In this episode, Richie and Cort continue their conversation on brain asymmetry by revisiting one of the most popular neuroscience ideas of the 1990s: the divide between the “left brain” and the “right brain.” Was the right hemisphere really the creative side of the brain, and the left hemisphere the logical one? Richie explains where that idea came from, what it got right, and why it was taken too far. Along the way, he explores language, visual-spatial processing, the 200 million neurons connecting the hemispheres, and why real creativity may depend less on one side of the brain than on the coordination between both.
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CHECK OUT EPISODE COMPANION FLASHCARDS below!
This is the second part of our conversation on hemispheric specialization with Dr. Richard Davidson and Dr. Cortland Dahl. For the first part, see Your Brain Is a Storyteller, where we explore what split-brain research reveals about consciousness and emotion. For more on the popular science misreadings Richie warns about here, see our recent episode on Why dopamine isn't your problem. Dr. Richard Davidson is the William James and Vilas Research Professor of Psychology and Psychiatry at the University of Wisconsin–Madison and founder of the Center for Healthy Minds and the Healthy Minds App. His new book with Dr. Cortland Dahl, Born to Flourish, was published by Simon & Schuster in March 2026.
Podcast Chapter List
00:00:00 – Intro clip: Creativity requires both hemispheres
00:01:30 – Welcome to Dharma Lab
00:02:47 – Left brain/right brain ideas in popular culture
00:04:00 – Where did these ideas come from?
00:05:11 – Language, handedness, and hemisphere differences
00:07:36 – The myth of the creative right brain
00:08:50 – The 200 million neurons connecting both hemispheres
00:10:38 – Split-brain patients and the corpus callosum
00:11:57 – What surprised Richie in the early asymmetry research?
00:13:10 – The resting brain data they almost threw away
00:15:15 – Stable patterns in the resting brain
00:16:04 – From “noise” to emotional style
00:18:23 – The prefrontal cortex and emotion
00:19:58 – Could you choose to use one side of the brain?
00:21:52 – A grain of truth, taken too far
00:22:55 – Sequential vs. parallel processing
00:23:50 – Why real creativity requires both hemispheres
00:24:51 – Interhemispheric coordination and creativity
00:26:08 – Tibetan mudras and two-handed movement
00:27:31 – Visualization, imagination, and creativity
00:28:34 – Closing
Earlier Post on Brain Asymmetry (Part 1)
Written transcript for those who prefer to read
Lightly edited for clarity and readability.
Intro clip: Creativity requires both hemispheres
00:00
Richard Davidson:
One of the things that’s true about language, and especially about speech, is that it’s sequential. We can’t say six words at the same time. Just can’t do it.
Cortland Dahl:
I’m pretty sure my son could when he was really young, but in any case, it’s usually true.
Richard Davidson:
Usually true. But if you have pictures of those six words — let’s say there are six animals and you present a picture — you can see all six at the same time.
That difference is what we call sequential versus parallel processing. There are certain kinds of visual-spatial skills that can be done more in parallel, and other kinds of skills and tasks that require more sequential activity.
And of course, real human creativity, I think, requires both.
This is why we have this massive fiber bundle that connects the two hemispheres together so they can work in an integrated way. I think it’s really an oversimplification to think that the right hemisphere is creative and the left is not.
Every human being has the potential to be creative. When humans are the most creative, we’re harnessing the full capabilities of our brain. It’s not just the right hemisphere or the left hemisphere. It’s both.
Welcome to Dharma Lab
00:01:30
Cortland Dahl:
Hello everyone. Welcome back to another episode of Dharma Lab. I’m Cortland Dahl. I’m here with Dr. Richard Davidson, who we all affectionately call Richie, one of the great living neuroscientists on the planet.
Today we’re going to continue a discussion we’ve had previously about some of Richie’s most important early work.
Richie, I’m excited to ask you about this, partly because I myself have always wanted to geek out and hear more about these things. We always have a million things to talk about, but I never get to talk to you about this.
In a previous episode, we talked about your very early research when you were just at Harvard, coming out of grad school, and your early work that showed differences between the different hemispheres of the brain — what is most simply referred to as asymmetry between these different hemispheres.
We talked a lot about that, and we can put a link to that previous discussion.
Left brain/right brain ideas in popular culture
00:02:47
This was back in the late seventies and into the eighties. Then something very interesting happened in the nineties.
I graduated from high school in 1992 and was just starting college. There was a book at that time, and there was all sorts of stuff in the popular media about asymmetry, although that word probably wasn’t used. I remember a lot of things about the left side and right side of the brain.
There was a book that I think was something like Drawing on the Right Side of the Brain. It was pointing, in many ways, to your work, which you were very much at the forefront of and had been for many years at that point.
But I imagine, like many things, there was probably a lot of oversimplification and perhaps even misunderstanding about what the science really says and what’s really going on in the brain.
So maybe we could start there, going back to this discussion about asymmetry and what your research and other researchers were really finding about the different hemispheres of the brain — and how that relates to things like creativity, being more logical, and all the stuff that was at work in our popular conversations about the brain at that time.
Where did these ideas come from?
00:04:00
Richard Davidson:
Thank you for that great introduction. There’s so much to say. Just being primed with that brings back intense memories from that period. I was very much living this.
I published more than 100 papers on brain asymmetry in one way or another, and edited two books on brain asymmetry that were published by MIT Press. They were major compendiums at the time, with a scientist in Norway named Kenneth Hugdahl, one of my early collaborators.
So yes, there’s so much to say.
Let’s begin by asking where these ideas may have come from.
In the previous episode of Dharma Lab, where we began to introduce this topic, one of the things we talked about is that the left hemisphere can speak and has language much more so than the right hemisphere — at least in most people.
Language, handedness, and hemisphere differences
00:05:11
I should say that these broad generalizations about the left and right hemisphere are roughly true for right-handed people only. They are not necessarily true for people who write with their left hand.
That itself is a whole topic of really interesting conversation, and we’ll bracket it. We can come back to it today briefly. But for now — and I apologize to all you lefties out there — since the majority of people are right-handed, roughly 85%, we’ll just stick with that for now.
One of the questions scientists posed is this: if the left hemisphere can speak and really is the primary province of language, what is the right hemisphere doing?
It’s presumably not just an appendage. It’s not just there to structurally latch on to the left hemisphere and hold it in place. It has to be doing something.
Does it have some specialized role? If the left hemisphere is specialized more for language, is there some set of functions for which the right hemisphere may be better than the left hemisphere?
Scientists discovered that there are certain kinds of visual and spatial tasks that the right hemisphere seems to be better at.
Now, when we say “better,” what we mean is typically a little bit better. It’s not like there are absolute differences. It’s not like the right hemisphere can do this and the left hemisphere can’t do this.
Similarly for language, although for language, the lateralization seems to be more definitive, particularly for speaking. For right-handed people, it’s pretty much the case that the left hemisphere can speak and the right hemisphere cannot speak. That’s pretty clear, and there are various ways in which that has been demonstrated.
The myth of the creative right brain
00:07:36
Let me get back to the title of this popular book, Drawing on the Right Side of the Brain. There was a lot of hype that the right hemisphere is the creative hemisphere and the left hemisphere is the analytic hemisphere.
When it got overgeneralized, it became something like: the right hemisphere is more interesting and the left hemisphere is boring.
Those kinds of generalizations, in my view, were taken way too far.
The other really important thing to keep in mind is that within a hemisphere, there is a lot of specialization as well. The anterior portions of the cerebral cortex, the prefrontal region, are doing something quite different from the back of the brain.
The visual areas and the parietal area are doing different things. The parietal area is where visual information, auditory information, and kinesthetic information are all integrated. It’s kind of a multi-sensory melting pot.
So these characterizations may apply to certain specific regions within a hemisphere, and not necessarily to the whole hemisphere.
The 200 million neurons connecting both hemispheres
00:08:50
The other thing that is so important to keep in mind is that in most of us who are neurologically “normal,” meaning we have basically intact brains, there are roughly 200 million neurons connecting one side of the brain to the other.
It’s a huge number. It’s the largest white matter fiber bundle in the brain. White matter refers to the axons that connect neurons together.
There are 200 million neurons connecting many different parts of the two hemispheres, virtually from the front to the back of the brain.
If I were to present information to one hemisphere — and you can do this by doing certain tricks — it would be presented initially to one hemisphere. If you are focusing straight ahead and information is presented on the left side of that fixation point, that information will be projected initially to the right side of the brain. The pathways are crossed.
Similarly, if you are focusing straight ahead and information is presented to the right of that fixation point, it goes to the left hemisphere of the brain.
But the moment it gets to one hemisphere, it is automatically transferred to the other hemisphere, so both hemispheres become recipients — unless, for some reason, there is damage to the fiber bundle connecting the two hemispheres.
Split-brain patients and the corpus callosum
00:10:38
In the previous episode of Dharma Lab, Cort, you brought up the case of split-brain patients whose corpus callosum — the main fiber bundle that connects the two hemispheres of the brain — has been surgically severed.
That is not done very much anymore, but in patients who have very severe epilepsy that originates in one hemisphere and spreads to the other hemisphere, producing a huge grand mal seizure, it was found that if you surgically separate the hemispheres, you can dramatically reduce the severity of the epilepsy.
So that has been done. It’s not done very much anymore, but there was a time when that kind of neurosurgery was done.
There are patients walking around with two hemispheres that are relatively independent because the fiber bundle was severed. But in most of us, that’s not true.
Our two hemispheres are talking together all the time. Whatever specialization might exist, and it does exist to some extent, the two hemispheres are typically cooperating and sending information rapidly back and forth.
What surprised Richie in the early asymmetry research?
00:11:57
Cortland Dahl:
I’m curious. There are two big questions I want to ask. One goes back to the book and the stuff in popular culture, but maybe let’s set that aside for a moment.
You had been researching this for a long time. You started back in the seventies, and this was clearly a huge focus of yours in the eighties.
Amidst these hundreds of papers that you studied, plus hundreds more in the broader field with other colleagues and researchers, what were the things that were surprising?
When was your mind blown? When were you surprised? What were the big breakthroughs where you thought, “Whoa, I didn’t see that coming,” or that really shifted the understanding in some way?
Richard Davidson:
I would say the biggest breakthrough was that these were the days before MRI was available, before functional MRI was available.
Cortland Dahl:
So most of this was EEG, looking at electrical patterns in the brain?
Richard Davidson:
Exactly. We were looking at EEG, electrical patterns from scalp electrodes that were non-invasive. You’ve had that done to yourself. And we can make some inferences about how activation patterns are shifting and occurring using that method.
The resting brain data they almost threw away
00:13:10
The thing that was most mind-blowing to us from all this work is that when you put these electrodes on people and just ask them to sit and rest — before we gave them tasks — we would collect eight minutes of resting data.
They would alternate between one minute of eyes open and one minute of eyes closed. We would collect eight minutes of “resting” data.
Cortland Dahl:
So you were doing, as we do in brain imaging all the time now, an early resting-state analysis, essentially.
Richard Davidson:
Exactly. But we typically did very little with that in the early days. Actually, in the very early days, the honest truth is we did nothing with it.
It was just a time to make sure our recordings were accurate. If there were any tweaks in calibration, or if an electrode was not making good contact, we would fix it at that time.
But we would throw out the data, because we were interested in what happens when we give people tasks and look at changes in the brain.
It turns out that we were throwing out the most interesting data.
What people were showing when they were just sitting and resting and not doing anything turned out to be fascinating. Some people had greater activation on the left side of their brain when they were sitting and resting. Other people had greater activation on the right side.
That differed depending on whether the electrodes were in the back of the head or the front of the head, so it wasn’t the same across the hemispheres.
Stable patterns in the resting brain
00:15:15
When we first started seeing this and paying attention to it, we thought, “It can’t really be stable. It can’t be a characteristic of people.”
So we brought people back a week later, a month later.
Cortland Dahl:
So you thought it was just random shifting. If you looked long enough, you would see that everybody was all over the place. You just got a snapshot, but you didn’t want to draw any conclusions.
Richard Davidson:
Exactly.
Then we brought people back several weeks later, several months later. Unbelievably, it was super stable.
If a person was showing left-sided activation today, if we tested them three months from now, we would almost certainly see a very similar pattern three months later.
Cortland Dahl:
So this is like a neural disposition, basically.
Richard Davidson:
A neural disposition.
It didn’t matter who the people were putting on the electrodes, who was testing them, or what day of the week it was. They were showing a very stable pattern. Remarkably stable.
That really blew our minds. We were not expecting that at all.
From “noise” to emotional style
00:16:04
Once we started discovering that, we thought: if this is really a stable characteristic, then it must be associated with some behavioral differences or experiential differences.
That’s when we started our whole journey into this domain of affective style, or emotional style, which refers to enduring ways in which people respond differently to emotional challenges.
We discovered a whole bunch of interesting things with that.
This is a great case of something we first thought of as noise turning out to be the most interesting part of our experiment. Fortunately, we were paying enough attention that it enabled us to discover something novel.
Cortland Dahl:
It’s funny that there’s such a parallel with how the default mode network was discovered later with imaging research. It was almost the exact same thing: accidentally noticing something in resting-state periods.
That seems like a natural segue into what eventually became this popular meme around the brain, the left side and right side. It’s funny how it becomes almost a caricature of the brain. We’ve talked elsewhere about dopamine or the amygdala. There may be some legitimate, genuine scientific insight, but then we draw all sorts of conclusions. It becomes good and bad, overly simplistic, and we lose the nuance.
The prefrontal cortex and emotion
00:18:23
If we translate that into what you actually learned, in this case it sounds like a lot about emotion. At some point we’re going to talk about the whole field of affective neuroscience, because I’m imagining that in those early days you weren’t necessarily thinking about emotion as a guiding principle, but it sounds like it led you into that realm.
Richard Davidson:
We were thinking about emotion early on. That was part of what we were trying to do. We were thinking particularly about what role the prefrontal cortex was playing in emotion.
In the last episode of Dharma Lab, I mentioned this obscure paper written by a very famous neuroanatomist at MIT.
Cortland Dahl:
The cult classic of scientific research, I remember.
Richard Davidson:
Right. This was a guy I studied neuroanatomy with, Walle Nauta. He wrote a paper published in the Journal of Psychiatric Research, where he speculated for the first time, really by a mainstream scientist, about the role of the prefrontal cortex in emotion.
That is what got me started on this path to look at the prefrontal cortex and emotion.
But the hype about brain asymmetry was focused on the specializations in the back of the brain, not the front of the brain. We were really the first to introduce the notion of asymmetries in the front of the brain that may be related to emotion.
There was earlier work on asymmetries having to do with language and visual-spatial processes, more focused on what is going on in the back of the brain. The right-brain coloring book is really alluding to work focused on specialization of the two hemispheres in the back, not in the front.
Could you choose to use one side of the brain?
00:19:58
Cortland Dahl:
A lot of the stuff in popular culture gave the impression that you could kind of choose. Even the title of that book suggests, “I want to draw from the right side of my brain,” and somehow I’m going to shut off the left side.
To what degree is this under volitional control? I’m guessing some function or activity might be, but maybe not. To what degree is there any control?
Richard Davidson:
One of the very early papers I published — which I haven’t thought about in literally decades — was a biofeedback study where we gave people feedback, not based on activation in one hemisphere or the other, but based on the difference in activation.
We were giving them feedback to change their asymmetry. We found that people were able to do that to some extent with very little training, just using this kind of neurofeedback.
Cortland Dahl:
On the one hand, that makes sense to me. You could learn quite quickly what you’re doing that makes something go up or down.
But it’s a different thing to say that a given function, like drawing, can be shifted in that way. Language, for example, probably isn’t something you’re going to shift to the right side of the brain. Certain functions, processes, and activities are going to fall more to one side or the other.
When it came to all the stuff in popular culture, did that make sense to you? Did it feel like it was drawing on something legitimate, or did it feel like we were in hand-wavy territory?
A grain of truth, taken too far
00:21:52
Richard Davidson:
There was a grain of truth, but it was way overgeneralized.
To the extent that it is grounded, it is referring to what may be going on in posterior parts of the cortex, mostly the parietal and temporal regions of the brain.
It’s interesting to ask what fundamental dimension might actually be the basis of this lateralization. That was a question asked early on.
Why is language more specialized to the left hemisphere? Is there something about the left hemisphere in those regions that is more conducive or preferential for language? And what is going on in the right hemisphere that may be more conducive to certain kinds of visual and spatial functions?
Sequential vs. parallel processing
00:22:55
One of the core dimensions that has been studied — though I would not say it is definitive — is that language, especially speech, is sequential.
We can’t say six words at the same time. Just can’t do it.
Cortland Dahl:
I’m pretty sure my son could when he was really young, but in any case, it’s usually true.
Richard Davidson:
Usually true.
But if you have pictures of those six words — let’s say there are six animals and you present a picture — you can see all six at the same time.
That difference is what we call sequential versus parallel processing. There are certain kinds of visual-spatial skills that can be done more in parallel, and other kinds of skills and tasks that require more sequential activity.
Why real creativity requires both hemispheres
00:23:50
Of course, real human creativity, I think, requires both.
This is why we have this massive fiber bundle that connects the two hemispheres together, so they can work in an integrated way and utilize whatever specialization might be in each hemisphere together, in a synergistic way, to accomplish something that may be greater than either hemisphere alone can accomplish.
I think it’s really an oversimplification to think that the right hemisphere is creative and the left is not.
Every human being has the potential to be creative. When humans are the most creative, we’re harnessing the full capabilities of our brain.
It’s not just the right hemisphere or the left hemisphere. It’s both.
That is one of the really important take-home messages.
Interhemispheric coordination and creativity
00:24:51
One of the speculations that is super interesting — although there really has not been very much science around this — is that what may really stimulate creativity are tasks that require a lot of interhemispheric coordination.
One class of tasks that require a lot of interhemispheric coordination are certain kinds of motor tasks. For example, jugglers.
Juggling requires a lot of interhemispheric coordination. It’s not just hand-eye coordination, but coordinating what’s happening between the two hands.
One of the things we know is that pretty much the control of the right hand is in the left motor region of the brain, and the left hand is pretty much controlled by the right side of the brain.
If the hands are working together, it requires interaction between them. So one really interesting, untested hypothesis is whether exercises that facilitate this kind of interhemispheric coordination may be beneficial for certain kinds of creative activities that may have nothing to do with those motor tasks.
Tibetan mudras and two-handed movement
00:26:08
Cortland Dahl:
We talked about this Tibetan practice of mudras, where you’re doing things with your hands, but what’s going on with one hand is totally different from what’s going on with the other hand.
It’s like the whole thing where you pat your head and circle your stomach, but on steroids. They almost have to operate completely independently, but it goes against some biological wiring. You have to retrain something deep to do that.
That would be an example of something where you’re doing it physically, but the idea is that perhaps it is opening something up in the creative space, or in some other way.
Richard Davidson:
Yes. This was something that Cort and I talked about just before we started recording.
There are these mudras in the Tibetan Buddhist tradition. They are hand gestures, and they can be very complex and quite different. They involve different motions of each hand, all occurring simultaneously in a kind of beautiful orchestration when done by an accomplished practitioner.
There may be some real side benefits that Tibetan yogis thousands of years ago had some experiential insight about, which may potentially be revealed in some future science.
Visualization, imagination, and creativity
00:27:31
Cortland Dahl:
There are so many interesting things there. That’s another little rabbit hole.
It’s interesting that at the time you do those physical gestures, you’re also doing very elaborate movements with your imagination. You’re visualizing whole worlds, essentially. It’s like you’re dreaming something into existence, but you’re doing these physical movements at the same time.
It really is all about creativity in some respect.
I’ve already cataloged a whole range of things to talk about. In a subsequent episode, I really want to dig deeper into the hemispheric differences in the resting state — not only that you found those hemispheric differences, but what they mapped onto in terms of experiential qualities.
What was different about those people aside from the electrical activity in their brain? Maybe that’s something we can dig into in a future episode.
Closing
00:28:34
Richard Davidson:
I’d love to do that.
Cortland Dahl:
Yet another great window into all the amazing work you’ve done, Richie. Thank you for sharing this.
And for everybody joining, thank you for sticking around and spending a little time with us. I can promise many more discussions like this. So if you found this interesting, there will be much more to come.
Thank you, Richie, and thank you everybody for tuning in.
Richard Davidson:
Thank you, Cort. Thank you all.
