Starting in the 1940s, a new surgery was being explored to help people with severe epilepsy which involved severing communication between the two hemispheres of the brain. It worked, but caused some very strange side effects. As researchers began to study these side effects, it led to an entirely new understanding of the brain; including the surprising fact that we really don’t have control over our decisions.
TRANSCRIPT:
What Made You Click?
Hi, thanks so much for clicking on this video. But…
WHY did you click on this video?
Not ten seconds ago, you were just mindlessly scrolling through your YouTube feed but when you saw this title and thumbnail, something in your brain just had to know what that was about. So you clicked. But… what was that something in your brain?
Seriously, tell me, it might get my click rates up.
But for real though, we’ve got a motor cortex, a visual cortex, an auditory cortex. But where do decisions come from?
That question got a lot more complicated in the 1960s when a new surgery started being performed on people with extreme epilepsy. It was called a corpus collosotomy, or split brain surgery.
Try to guess what they do.
Yeah, they split the brain in half, of course the brain is already split in half between the left and right hemispheres, but they’re connected by a bundle of fibers at the bottom, called the corpus collosum.
So they just… cut those fibers.
This made it so the two halves of the brain couldn’t communicate with each other, which sounds like it would be a huge problem, but believe it or not, they went on to live normal lives.
This surgery didn’t change people’s personalities or ability to function. But there were some weird things to come out of it.
Things like, their left hands would start drawing things… And they didn’t know why. It’s like something in their right hemispheres was trying to communicate.
There were kinda two people in there!
So which one is… controlling things?
Who’s In Charge?
The subject of split brain experiments has come up from time to time on this channel but I don’t think I’ve ever done a full video on it. So I decided to do one because this topic is one of those things that really caused a shift in how I think of the world and other people, and even myself.
And it all came from a book that I’ll be sourcing a lot in this video, and I highly suggest you read it if you find this interesting, it’s called Who’s In Charge by the neuroscientist Dr. Michael Gazanniga.
He did pioneering work on split brain patients in the 60s and 70s, he’s written several books about it, done TED talks, I’ll link it all below.
But the reason this book speaks to me is, if I may be personal for just a second, I’ve always had this theory that there are different gnomes in my head.
Obviously I don’t think there are actual garden gnomes living inside my skull… That’s crazy.
But like most people, I imagine, I do have different voices in my head that have thoughts that I don’t even agree with. But they bubble up.
Call it a defense mechanism or a rationalization of bad ideas or whatever but that was my way of explaining why I sometimes had conflicting ideas or had trouble making a decision – or the negative thoughts that take over sometimes, that’s just the negative gnome taking the wheel.
Not much unlike the world they created in Inside Out. Which, I just saw that recently for the first time and I gotta say, the way they structure the world inside her head to explain how memories and emotions work, it was brilliant.
Anyway, the point is this book, and the split brain experiments that he talks about seem to make the argument that my little “gnomes” explanation for how my thoughts work… isn’t too far off the mark.
And that free will and even consciousness is just an illusion. There’s a lot to unpack here.
Split-Brain Surgery
Maybe we could start by asking the obvious question… Why were they cutting people’s brains in half again?
It’s a procedure called a corpus collosotomy, and they first started doing it in the 1940s as kind-of a last resort treatment for severe epilepsy.
Here’s how it works:
When you have a seizure, what happens is there’s a surge of electrical signal that disrupts the normal firing of neurons across the brain.
Depending on where this occurs in the brain, you’ll experience different symptoms, but the worst, of course, are the ones that spread over the entire brain.
These can lead to temporary paralysis and convulsions, vomiting… everything you think of when you hear the word seizure.
And in people who get those multiple times a day, to the point they can’t function normally, and no treatments seem to stop it… well the best option is to just contain it.
So the corpus callosotomy is done to prevent the signals from spreading to the entire brain. So it stays in whatever hemisphere it starts in.
Like a surge protector.
The first corpus callosotomy was done in 1936 by a neurosurgeon named Walter Dandy, kind-of on accident, he was removing a tumor on a patient’s pineal gland and it required him to cut through the corpus callosum to get to it.
He reported that this had no effect on the patient, which, there had been a debate about what the corpus callosum actually did, like was it involved in processing or was it just structural, just to hold the brain together? This seemed to suggest that latter.
Regardless, in 1940, William P. van Wagenen decided to try a corpus callosotomy on an epilepsy patient, and saw mixed results at first, but they were promising enough to continue experimenting with it.
By the way if this is starting to sound familiar, this all happened about the same time as lobotomies, which I covered fairly recently – this is basically the period of neuroscience when they started paying attention to the white matter and cutting connections to see what would happen.
I should be clear though, while lobotomies were being handed out like candy, split brain surgeries were much more extreme and controversial at the time. This was only for people with a very specific, very debilitating condition. And even then as a last resort.
It really wasn’t until the early 60s that two neuroscientists named Joseph Bogen and Philip Vogel perfected the procedure and it became thought of as an effective, safe treatment.
But not without a few weird side effects.
Like sometimes their two hands didn’t want to work together. One patient talked about how he had trouble buttoning his shirt because he’d be buttoning it up with one hand, but then the other hand would come up behind and unbutton it.
And stories like this kept coming up, patients whose hands would just grab things for no reason, or mess with the other hand, to the point that Joseph Bogen decided someone should research this.
Luckily he knew the perfect someone for this.
A neuropsychologist named Roger Sperry.
Roger Sperry
Roger Sperry was born and raised in Hartford, Connecticut and went to Oberlin College on a scholarship where he originally wanted to major in English, but he took an Intro to Psychology class that sparked an interest in psychology –
Apparently his professor was disabled and he offered to help him get around, so he wound up sitting in on conversations that his professor was having with his peers, talking about their research and arguing over psychological theories and he just found fascinating. He was hooked.
So he got his masters degree in psychology and later a Ph.D from the University of Chicago. And as he went into his career, he became interested in neuronal specificity and brain circuitry. How different parts of the brain work and how they’re connected.
He did experiments on rats and salamanders that involved rewiring the nerves to their legs or their eyes to see if they could adjust – spoiler alert, they didn’t.
But through this research he became known as an expert in how different parts of the brain talk to each other. So of course Bogan thought he would be the right guy to study split brain patients and of course Sperry took him up on it because what an amazing opportunity!
He did also do some experiments on animals before he went into this research, I know nobody likes to hear about animal experiments but he did perform corpus callosotomies on some cats and tested them.
Luckily he didn’t have to do surgery on the split-brain patients because, well, that had already been done.
So Sperry found a group of Bogan’s patients that were willing to volunteer for his tests, which focused on vision, language, and motor skills.
This would involve showing words or images in the left or right visual fields to see how the different hemispheres handle it.
Let me explain.
The Two Hemispheres
As you may know, the hemispheres are contralateral, meaning the left hemisphere controls the right side of the body and right hemisphere controls the left side. Also known by the technical term, criss-cross applesauce.
But your eyes are a little bit weirder.
It’s not quite as simple as just each eye goes to the opposite hemisphere, they go to both hemispheres at the same time.
What happens is the two optic nerves converge at a spot known as the optic chasm. And there they split apart, with one split carrying the left visual field and the other one carrying the right visual field.
And then the left visual field – from both eyes – gets sent to the right hemisphere and the right visual field – from both eyes – gets sent to the left hemisphere.
So it’s still contralateral, but with extra steps.
So if you’re staring at my face right now, Zoe is in your right visual field. You’re seeing her blessing you with both eyes, but it’s the left side of the brain that’s processing that image. Your right hemisphere literally can’t see Zoe right now. But it knows that she’s there because the left side is sharing that information through the corpus callosum.
But what if you don’t have a corpus callosum?
This is what Roger Sperry wanted to figure out. So he came up with a series of tests along with his graduate student, Michael Gazzaniga – the guy who wrote this book.
Sorry, just have to clarify one more thing before I get to the results of those tests, a lot of the basic functioning of the body takes place at the base of the brain, which is kind-of a shared space they call the subcortical region.
These include structures like the thalamus, hippocampus, amygdala and lots of other things you’ve probably never heard of.
But these kind-of handle the basic stuff, like motor control, sensory information, and what they call proprioceptive functioning, basically our body’s understanding of its position in space. So there’s no one hemisphere controlling that stuff.
It also includes what Dr. Gazzaniga calls an integrated spatial attention system that directs where the brain’s attention is focused. And this controls both halves of the brain so you can’t have like one half of the brain doing homework while the other half is gaming, doesn’t work that way.
Would be great though.
WJ Story
I know all that was a lot of exposition but it’s all stuff you kinda need to know before we get into the good stuff. So here comes the good stuff.
One of their first patients that they studied was a man named WJ. They kept their names anonymous for obvious reasons.
WJ’s test started out simple. They showed pictures and words to his right visual field, and he was able to respond. A dog. A car. A spoon. Easy.
But when they showed an image in his left visual field, he didn’t see it. He claimed that there was nothing there.
Now this really was a big moment because up to this point there was still a bit of a debate about how much the corpus callosum controlled the flow of information between the two hemispheres and this seemed to be indisputable proof because it wasn’t that the right hemisphere couldn’t actually see the object, it’s that the language center of the brain is in the left hemisphere. So it literally didn’t have the words to describe it.
Based off of this, they tried a new experiment, this time with a simple flashing light.
They put his hands under a barrier so his eyes couldn’t see them, and gave each hand a button. And they told him whenever he saw a flash of light, to click the button and confirm it verbally by saying, “light.”
So they signaled his left hemisphere, and he clicked the button. And said, “light.”
Then they signaled his right hemisphere. He clicked the button, and then said, “Hey, why did I click that button?”
He didn’t see the light. But the right hemisphere did. And it was able to communicate that it did, it just couldn’t do it with language.
It’s kind of like the left hemisphere has a voice and the right doesn’t. But now they were figuring out how to talk to it. And things got a lot more interesting.
More Experiments
These kind of results bore themselves out with the other split brain patients as well, with some of the other experiments they did.
In one experiment, the left hand was placed in a box with a handful of objects in it, and then they flashed an image of the object at the right hemisphere and the left hand was able to feel around and pick out the object.
When asked why they grabbed the object, of course, they had no idea.
And sometimes the patient could just draw the image, for example they flashed a picture of a bike at the right hemisphere of one patient and then his left hand drew a bike.
But think about the experience the patient is having, he’s just sitting there. He’s got a pencil in her left hand and he’s waiting for them to flash an image at him…
And he’s waiting…
And then, his left hand draws a bike.
The experiments would continue to get more complex and over time they began to understand how different the right and left brains really are.
The Differences In The Hemispheres
You know how we always talk about left-brained people being more analytical and right-brained people are more creative? That whole thing? Well here’s how they’re actually different.
The right hemisphere was better with visual and spatial skills. And the left hemisphere was good with language.
Like he described an experiment where the patient was flashed a picture of a pattern of colored blocks and then had to recreate it. When they flashed the right hemisphere, the left hand was able to recreate it easily. But when they did that with the left brain, the right hand really struggled with it.
In fact, there’s one story of a patient who was struggling to put it together with his right hand and his left hand kept trying to help, he had to actually sit on his left hand to keep his right brain from solving the problem for the left brain.
According to Dr. Gazzaniga, “The right hemisphere turned out to be specialized for such tasks as recognizing upright faces, focusing attention, and making perceptual distinctions. The left hemisphere was the intellectual. It specialized in language, speech, and intelligent behavior.”
There are also differences in logic and problem-solving between the hemispheres
Like they would show the right hemisphere a picture of water, and the guy would point to a picture of water. They’d show a picture of a pan, the guy would point to a picture of a pan. But when they asked what they could do with those two items, the right hemisphere just couldn’t figure that out. Where the left hemisphere understood you put the water in the pan.
The right hemisphere also couldn’t draw inferences, like another experiment showed a match and a woodpile and they couldn’t figure out that the next image in that series should be a burning woodpile.
And in another experiment, the patient was shown the letter U and asked to turn it into a square using a choice of shapes. The right brain couldn’t do it. But the left brain had no problem.
The right brain is very literal. Things are what they are. He uses the example in the book of a box of candy. If someone gives you a box of candy, your right brain is like, yes, that’s a box of candy. But your left brain will try to figure out the meaning of this gift.
This means that both halves of the brain are experiencing consciousness, but very different kinds of consciousness.
As Dr. Gazanigga puts it:
”It was becoming apparent that the right hemisphere had its own rich mental life, quite different from that of the left.”
So right away, we can see that there’s not just one consciousness going on inside our minds, there’s two. But it actually gets crazier.
Turns out there’s multiple modules inside each of the hemispheres that can display a kind of consciousness. And they have their own things to say.
The Interpreter Module
So you remember earlier how I was imagining what it must be like for these split-brain patients when their left hand just kinda randomly does something beyond their control? How weird that must be? Well Gazzaniga and Sperry were wondering the same thing, and began developing tests to see how the patients explain these actions.
Like the left brain normally has a gigabit internet connection with the right, they’re sharing everything. But now it can only get information by seeing what that brain does externally, the pictures that it points to and words it writes and whatnot. If the left brain is more interpretive and wired to find patterns, what would it interpret from this?
Turns out, a lot.
So in one experiment, a patient was shown a chicken claw to his left hemisphere and a snow scene to his right. He was then asked to choose a picture that related to what he was shown. His right hand pointed to a picture of a chicken, which obviously made sense because the guy saw a chicken foot. But his left hand pointed at a shovel. Which makes sense because the original picture was a snow scene but he didn’t consciously see it, so when they asked why he selected the shovel, he said, “Oh, that’s simple. The chicken claw goes with the chicken and you need a shovel to clean out the chicken shed.”
The left hemisphere, without hesitation, came up with a justification for what the right hemisphere chose. It didn’t say, “I don’t know” – which would be the correct answer. It didn’t say, “Maybe it’s this, I’m just guessing…” It confidently declared chicken poop.
And this was a result that repeated itself over and over and over again.
In another example, the word “music” was flashed to the left brain and a photo of a bell was flashed at the right brain. He was then given several images to choose from, and these images were all musical instruments, including the bell.
So the patient acknowledged that he’d read the word music, with his speaking left brain and then his left hand – controlled by the right brain – picked the bell image.
When asked why he picked the bell over all the other musical instruments, the patient said,
“Well, the last time I heard any music was the bells banging outside here”
There was a church across the street.
Again, the left brain, having no idea that the right brain had seen a bell, confidently came up with a justification.
One more example of this was an experiment where they flashed the word, “red” to the left hemisphere and the image of a banana to his right hemisphere. He was then asked to draw a picture with his left hand out of an assortment of different colored pencils. He picked the red pen and drew a banana. But when asked why he drew a banana, he said, “It is the easiest to draw with his hand because this hand can pull down easier”
Which, by the way, makes no sense. But that’s what the interpreter came up with.
And this was the name that they gave it by the way, they call it the Interpreter module.
They also found the Interpreter module hard at work explaining emotional triggers.
For example in one experiment they showed the right hemisphere a scene from a fire safety video where a guy gets pushed into a fire. The patient reported that she just saw a white flash, but afterward, she noticed a change in her mood.
She said, “I don’t really know why, but I’m kind of scared. I feel jumpy. I think maybe I don’t like this room or maybe it’s you – you’re getting me nervous”
In another experiment with a female patient they flashed a picture of a pinup girl to her right hemisphere. And then without knowing why, she snickered a little. When they asked what she was laughing about, she said that they had a funny machine.
Have you ever had your mood change, suddenly get sad or angry, and you don’t know why?
In case you haven’t noticed, in every one of these examples, the interpreter module got it wrong. Often confidently wrong. It got a limited about of information and assumed it knew everything about it. Might as well call it the Dunning-Krueger module.
Multiple Modules
And yet, this module is kind-of running the brain. Or at least navigating our thoughts.
Because further testing revealed that the interpreter module is just one of multiple modules in the brain, all of them kind-of black boxes, we don’t really know how they make their choices, but they make choices, and then the Interpreter module justifies it.
For example, fMRI tests showed that different areas of the brain would light up before a conscious decision was made – to say take an action or say something. That was a decision being made… before the decision was made.
This is basically how we live our lives, just walking around, justifying the decisions and thoughts that pop into our heads from various random semi-conscious modules in our skull.
This fact has been such a revelation for me because I don’t really think of my thoughts and actions as “me” doing it. I mean, yes it is me – I’ll get into the theory of mind around it in a second – but it’s a lot easier to look at your thoughts and beliefs objectively if you don’t think of them as “part of you.”
Like when I have a thought that comes up, I don’t know where it came from, so I can ignore it if I don’t like it. It’s not tied in to my sense of self, my ideas aren’t my identity. And it’s a lot easier to change your mind on something if don’t have it tied to your identity.
Also, once I understood that our brains are just justification machines, I find myself often asking myself, “what am I justifying right now?”
It’s usually when I’m procrastinating on work.
Have you ever felt anger or annoyance at someone after you’ve hurt them in some way? I mean we’ve all done it, we’ve hurt people’s feelings or failed to live up to a promise; betrayed someone, it happens. But there’s this psychological phenomenon that happens where we know we hurt someone, and we feel bad about it, but then that justification module kicks in and just sees that you feel bad and it it has to do with that guy. Well they must have done something wrong!
And then you wind up feeling resentment toward the person you hurt.
We’re constantly justifying bad behavior and bad habits in the service of comfort or protection or a little dopamine reward. That’s normal, it makes us human. But the awareness of that fact can help you see it more clearly.
The Question of Free Will
But the other mind-blowing part gets into the very nature of free will. Like… what is actually making our decisions?
There are some that make the argument that this disproves free will, that our decisions are made by patterns of neurons firing in a predetermined manner that we’re not even consciously aware of. These guys call themselves determinists.
Taken to an extreme, one might make the argument that nobody can be held accountable for their actions because “they” weren’t the ones who made the decision to take that action.
But seriously, try that in a court of law, it just doesn’t work.
This can also be used by people to justify bad behavior because, well, “I’m not the one who chose to do it…”
Obviously this is a bit of a philosophical slippery slope. How do you have justice and accountability in the world if there is no free will? But also how can you have free will when your decisions aren’t your own?
Emergence Theory
In Dr. Gazzaniga’s book, he talks about how the quantum world operates on vastly different rules than the macro world, we’ve talked about it here on this channel a million times.
But these atoms and subatomic particles that don’t play by the Newtonian or even Einsteinian rules that we experience – in fact, they exist mostly in probability states – they manage to come together and combine to make physical matter. The air you’re breathing, the chair you’re sitting on, the building around you, even you yourself.
This is emergence theory, the idea that objects in one system can combine to create something entirely different in another system. And Gazzaniga talks about two forms of emergence, strong and weak emergence.
He explains:
“There are two schools of thought on emergence. In weak emergence, the new properties arise as a result of the interactions at an elemental level and the emergent property is reducible to its individual components, that is, you can figure out the steps from one level to the next, which would be the deterministic view.
Whereas, in strong emergence, the new property is irreducible, is more than the sum of its parts, and because of the amplification of random events, the laws cannot be predicted by an underlying fundamental theory or form an understanding of the laws of another level of organization.”
An example that’s always used of emergence is how millions of individual ants with very basic programming can come together to build giant ant colonies that are basically superorganisms, with organization and structures that would be impossible for any one ant to conceptualize.
One could draw the same conclusion about people forming cities, or people forming the internet.
But our brains work the same way. Actually, we have a few different levels of emergence, we have the atoms coming together to make the organic molecules that comprise the neurons, you have the neurons firing in patterns that create the subconscious modules, and you have the multiple modules coordinating to create our lived experience of consciousness
Actually, it’s funny, I’ve talked about octopuses on here and how they have this seemingly alien form of intelligence where they essentially have 9 brains, because each arm has a mini-brain controlling it, with an executive brain that sort-of manages all of it. It’s a hierarchy of brains that I’ve always thought was fascinating because it’s hard for us to even conceptualize that.
But it turns out in a lot of ways, our brains work pretty similarly. We have multiple semi-conscious modules that coordinate at times and jockey for position at times, with an executive “justifier” module that takes in their signals and tries to make sense of it.
And again, determinists would look at this and say it’s all pre-wiring, we have no conscious control over it, we are basically that guy from Men in Black with the Christopher Walken-looking alien its head.
The fact is, our conscious experience follows our actions, it’s something that happens after the fact.
He uses the example of touching your nose. Go ahead, touch your finger to your nose. You feel the sensation on your nose and the tip of your finger at the same time, which, of course you do, that makes sense, it’s happening at the same time.
But… the distance that signal travels between your nose and your brain is just a few inches, where the distance between the tip of your finger and your brain is a few feet. And those signals travel at the same speed.
There’s actually about a half-second difference between when those signals reach your brain, but your brain does a little trick on you. It can reason that the action took place at a specific time and syncs up those signals so you experience it simultaneously.
Top-Down and Bottom-Up
So our feeling of free choice and agency is a bit of an illusion…
But hold on, that doesn’t make sense, does it?
If our thoughts and actions are hard-wired and controlled by some wizard behind the curtain, how do we explain neuroplasticity? How do we learn new skills and get better with practice?
The fact is, consciousness is a result of both bottom-up and top-down causation.
We are simultaneously making decisions on a subconscious level but also shaping those decisions at a conscious level.
It is possible – it’s not easy, but it’s possible – to change a pattern of negative thinking by being aware of it and replacing negative thoughts with positive thoughts. We do have, to various degrees, conscious control over our emotions and thoughts.
In Dr. Gazzaniga’s words:
”Action is made up of complementary components arising from within and without. That is how the machine (brain) works. Thus the idea of downward causation may be confusing our understanding. What is going on is the match between ever present multiple mental states and the impinging contextual forces within which it functions. Our interpreter, then claims we freely made a choice.”
To put the question of whether we have upward or downward causation in simpler terms…
So… do we have free will?
Yes and no.
A lot of our decisions it seems are hard-wired and out of our control, but ultimately we have conscious control over our actions. We do have agency. This isn’t a get out of jail free card.
Sadly, if you want to commit a crime and get away with it, you’re going to have to do it the old fashioned way – be rich.
Anyway, there’s a lot more in this book that I couldn’t fit in this video, it goes into how our brains operate socially – things like mirror neurons that cause us to mimic other people subconsciously – it’s a fascinating book and definitely worth a read. I’ll put a link down in the description.
But again, for me, there’s really something freeing about the idea that there’s a lot going on up here that I don’t really have control of. I don’t beat myself up for my thoughts, I’m able to allow myself some grace when I mess up. It’s just a much better headspace for me.
Ironically, knowing that I’m not totally in control is kind-of freeing. It gives me objectivity and makes me a lot less reactive.
I feel like my life has been made better by having this understanding. And that’s why I talk about it a lot, that’s why I made this video, because I genuinely think it can help you, too.
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