Key Points

From studies of patients with split brains, anosognosia, and Korsakoff’s syndrome comes the the concept of the interpreter, an area in the dominant hemisphere that’s in charge of explaining our own behavior.

As discussed in the prior episode (Subterranean), most of the computations that drive our behavior are walled off from conscious awareness, and from “the interpreter.” Yet, rather than claim ignorance, the interpreter instead invents, or confabulates, its explanations, based on whatever information is at its disposal. It’s goal is not to create an accurate story, just a plausible one.

Thus, the explanations we give to ourselves and others for why we do the things we do can only be incomplete at best, and entirely wrong at worst. Altogether, this updated conception of the drivers of our behavior has profound ramifications for how we understand and assess intelligence, how we attempt to change our behavior, and how we go about creating lives of lasting fulfillment and well being.

Links, etc:

MRI of patient with Posterior Reversible Encephalopathy Syndrome (PRES), showing edema (bright areas) in the occipital lobes
Gabriel Anton’s original case report in 1899 (for those who read German)
Schachter, S., & Singer, J. (1962). Cognitive, social, and physiological determinants of emotional statePsychological Review, 69(5), 379-399.
A. Laird, D. (1932). How the Consumer Estimates Quality by Subconscious Sensory Impressions. Journal of Applied Psychology. 16. 241-246. 10.1037/h0074816.
Related Books
Influence, by Robert Cialdini
Incognito, by David Eagleman
Subliminal, by Laurence Mlodinow
The Brainjo Collective, a community of lifelong learners


Episode Transcript

“Can you help me with a case?

“Sure. What’s up?” I said. The call had come from an obstetrician at the hospital where I worked. Obstetrician’s generally are caring for healthy young women, not a common demographic for neurological disorders. Consults on the OB ward are a bit unusual.

“I’ve got a 23 year old woman, who we induced for preeclampsia yesterday. We’ve got her pressure down and the delivery went fine. Now she’s actually kind of confused. I can’t really put my finger on it, but something just seems off.”

Preeclampsia is a condition that can occur in late pregnancy, where among other things, the blood pressure rises rapidly, a situation that can be dangerous for both mother and baby.

“Okay,” I replied, “I’ll come take a look.”

I arrived in the patient’s room. We’ll call her Jessica. Things seemed pretty unremarkable on the whole. She had some family there with her. Everyone was in the cheery kind of afterglow that ensues after welcoming a new member. I asked Jessica a few, question pertaining to her preeclampsia and the delivery, which she answered with ease. She was alert and didn’t seem disoriented in any way.

She related that she did have a pretty bad headache the night before, but it hadn’t gone away and now she was feeling pretty much her usual self. In speaking with her, I did note something a bit peculiar. She wasn’t making eye contact. She would look towards me, but not right at me. “Are you having any problems seeing Jessica?”

“No. Not at all,” she replied. After gathering the details of her history, I then moved onto the neurological examination, which included an evaluation of her visual fields. Neurologists care about visual fields, because those are the domain of the brain, rather than the eyes. With the left visual cortex receiving light from the right side of the world, and the right visual cortex, receiving light from the left side of the world.

Visual fields are usually assessed by having the patient count fingers in the various quadrants of their vision. Jessica flunked this part of her examination. I then quickly moved my hand towards her right eye, a maneuver that will almost universally illicit a protective blink response in a sighted person. Jessica didn’t blink.

“Jessica. Are you sure you’re not having any trouble seeing?”

“No. Not at all.”

“What color are my eyes,” I asked.

“They’re blue, a pretty blue.” My eyes are not blue. I grabbed a pen from my pocket. “Jessica. What’s this I’m holding in my hand?”

“That’s your glass of water.”

Jessica could not see a thing. Yet, she was holy unaware that she could not see, and moreover, was providing explanations for what she was seeing, explanations that were entirely false, but which she seemed to believe wholeheartedly. Up until this point, neither she nor anyone who come into contact with her, had any idea she was having a problem seeing.

An MRI revealed swelling in the back of the brain on both sides, in both visual cortices, a condition known as posterior reversible encephalopathy syndrome, or PRES for short. It’s something known to happen with sudden changes in blood pressure, as is the case with preeclampsia. Clinically, that edema had led to Anton Syndrome, which is named after Gabriel Anton, the Austrian neurologist who first described it back in 1899.

In Anton Syndrome, which is caused by damage to the occipital lobe, which houses the visual cortex, patients are blind, but unaware of their blindness. In neurology, this lack of awareness for a neurological problem, is referred to ask Anosognosia. Furthermore, patient’s with Anton’s also confabulate, meaning that they invent false stories about what they’re seeing. They’re blind, but unaware of their blindness and still speak as if they are sighted. Anton Syndrome is rare.

This was the first case of it I’d seen. I’d heard of it before. As an undergraduate in neuroscience, I’d written a paper about it, largely because I found it so incredibly bizarre, and at the time I half, doubted whether it had been made up altogether. Jessica had just put those doubts to rest. Fortunately, PRES, the condition causing the swelling in her brain, has an excellent prognosis. In almost all cases, the swelling resolves after the blood pressure normalizes, and the neurological problems reverse. When I saw Jessica in the office eight weeks later, her brain and her vision were entirely back to normal.

Hi. I’m Doctor Josh Turknett, founder of Brainjo and the Brainjo Center for Neurology and Cognitive Enhancement. An this is the Intelligence Unshackled Podcast.

Join me as we take a tour through the human brain, to explore and understand the true nature and scope of human intelligence, and to unlock the secrets of optimizing brain help and function. In the last episode, where we introduced the mental model subterranean, I discussed the idea of subconscious or non-conscious neural networks. These are brain networks that are walled off entirely, or nearly entirely from the networks that mediate our conscious mind.

There’s strong evidence that these subterranean networks do most of the heavy lifting when it comes to our cognition, accounting for up to 95% of our cognitive abilities. It’s in these networks, where our intellectual horsepower lies, which is at odds with our traditional notions about cognition. In other words, most of our intelligence then, is not consciously mediated, nor do we have access to, it’s workings.

If we think about it, this kind of thing is abundantly obvious, when we do things like speak or read, and convey or extract meaning. Here we have two extraordinarily complex acts of information processing, happening in a fraction of a second, with near instantaneous transmission of meaning and understanding. In spite of the fact that so much of what drives our behavior is inaccessible to our conscious mind, we still almost always have an explanation for why we do the things we do. How can that be? How do are those explanations? These questions get right to the heart of this episode’s mental model, confabulation.

The human brain consists of two symmetric hemispheres, referred to as the left and the right. Those two hemispheres send signals back and forth, through a structure known as the corpus callosum, a large bundle of nerve fibers. That bundle of fibers also carries the electrical activity that spreads from one hemisphere to the other, during a gran mal seizure. One last resort treatment that’s been used in the past for patient’s who had unrelenting grand mal seizures that didn’t respond to any other treatments is to cut the corpus callosum. It’s a drastic procedure, but it works.

Patient’s who have had this procedure done are said to have had their brains split, as in the two hemispheres are now split from each other. They can’t communicate.

One thing that’s surprising is that when you cut the corpus callosum, it can be difficult to tell if it’s caused any problems. People with a severed corpus callosum, can appear almost entirely normal. The specific problems that result from it, require more detailed investigation. In the mid 20th century, a series of landmark experiments were done in the lab of Doctor Roger Sperry and his colleagues, ones that directly bear on the question of the accuracy of the explanations we provide, for our behaviors. The subjects of these experiments were folks who had had their corpus callosum cut.

In these so called split brain experiments, subjects were presented visual information that only one side of the brain could see. The visual cortex in the left hemisphere of the brain only receives input from the right side of our world. The right hemisphere of the brain only receives input from the left side of the world. In order for information that’s seen by the left side of the brain to be sent to the right side of the brain and vice versa. That information must be passed across the corpus callosum. When visual information is presented to the right hemisphere of a split brain patient, with a severed corpus callosum, that information stays in the right hemisphere. The left hemisphere can’t access it.

Perhaps one of the most famous of these experiments, subjects were shown a picture of a chicken in their right visual field, which again was processed by the left side of the brain. They were shown a picture of a snow scene in the left visual field. The left hemisphere sees a chicken claw and the right hemisphere sees a snow scene. Because of the severed corpus callosum, neither hemisphere knows what the other hemisphere has seen. The subjects were then shown a collection of pictures, again separately, to each visual field, and asked to point to the one, best matched to the original picture. The left hand controlled by the right hemisphere, would correctly point to a shovel, to go with the snow scene. The right hand, controlled by the left hemisphere, would correctly point to a chicken to go with the chicken claw.

Here’s the astonishing thing: when the subjects were asked why they chose the items they did, they would provide a correct explanation for what the right hand had chosen. They would fabricate an explanation for what the left hand had chosen. For example, one subject correctly stated that he’d chosen the chicken claw, because that goes with a chicken, but stated that he’d chosen the shovel, because that’s what you’d use, to clean out a chicken shed. The left side of the brain, the one that mediates language, had only seen the picture of the chicken claw, but not the picture of the snow scene. It didn’t have access to why the left hand controlled by the other side of the brain, had pointed at the shovel.

Rather than say, “I have no idea why I chose the shovel,” the left side of the brain created or confabulated, an explanation based on the only information that it did have. These split brain experiments would go on to show this sort of thing time and again, that, rather than saying, “I don’t know,” when the left hemisphere didn’t have access to information, it would instead invent and explanation based on whatever information was available to it.

Earlier I posed two questions. One of which was, if our conscious mind only has access to a small sliver of the processing that drives our behaviors, how is it that we are still almost always able to give ourselves and other an explanation of our behavior? Well, these split brain experiments gave rise to the notion of part of the brain that’s been referred to as the interpreter. Anatomically, the interpreter part of the brain, sits in the dominant hemisphere, which is the left hemisphere in most folks. Appropriately alongside the networks that mediate language. What does it do? It makes up stories. Only the stories, it makes up are about us, or about itself. Its job seems to be to take our behavior and create an explanation, one that’s consistent without other behaviors, or one that’s consistent with our self concept.

Now, perhaps the idea that we have a part of the brain that helps us explain ourselves to ourselves, isn’t that surprising. What is surprising, is that those explanations don’t have to be rooted in fact at all. This was what was so remarkable about the split brain experiments. In these cases, the interpreter in the left hemisphere was entirely cut off, from what was happening in the right hemisphere. I didn’t know why the left hand had pointed to the shovel, for example. That was irrelevant. The goal of the interpreter is simply to provide a sensible explanation, regardless of its grounded in the truth. And so, in the absence of information from the right hemisphere, we simply made up its own explanation.

In clinical neurology, the phenomenon of confabulation is most commonly associated with a condition known as Korsakoff Syndrome. Korsakoff Syndrome arises from a severe deficiency of vitamin B1 or thiamin, which is most commonly seen in people who drink heavily. It affects a particular part of the brain, known as the Mammillary Bodies. The Mammillary Bodies are structures that are intimately involved in the encoding of memory. Those with Korsakoff’s often demonstrate profound Anterograde amnesia, or the inability to form new memories. Yet, when those with Korsakoff Syndrome are asked about recent events, rather than saying that they don’t remember what happened, they’ll invest stories or confabulate.

Now, it’s important to note here that once again, they’re entirely unaware that their stories aren’t grounded in truth. This is as it was with Jessica, the woman with Anton Syndrome, who I described earlier. She’d been rendered entirely blind, due to the swelling and the visual cortex of both parts of the brain. Yet, not only was she unaware of any problem seeing, she confabulated seeing things that she wasn’t seeing, again, with no awareness that her statements were false. Once again, for the interpreter, who is driven to provide a story no matter what, facts aren’t necessary.

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We have multiple lines of evidence from split brain patients, to those with anosognosia, to those with Korsakoff Syndrome, that show that cutting off the interpreter from certain parts of the brain doesn’t cause it to stop explaining our behavior, it just makes those explanations entirely wrong. Now, in these instances, part of the brain that normally are in communication with the conscious mind, are disconnected by pathology of various kind.

The somewhat disturbing reality is that this process is happening all the time in anatomically normal brains. While pathological situations like I’ve described, can cut off the interpreter from parts of the brain that it normally does communicate with, in the last episode, we learned that in anatomically normal brains, it is still cut off from most of our cognition, given the significant involvement of subterranean networks in our cognitive function. In all of us, in the course of normal operation, not just pathological scenarios, we are always creating explanations for why we do the things we do in the face of incomplete information.

There will always be influences on our behavior, that are hidden to the interpreter. Those hidden influences can be in either our external or our internal environment. Not surprisingly, people who sell things are very much interested in understanding all the factors that play into our purchasing decisions, so there’s a lot of research along these lines, with the overarching theme again being that the reasons we give, for buying a certain thing, often have little to do with why we actually bought it.

For example, in one of the earliest studies of this kind, it was published in 1932, women were sent pairs of stockings and asked to rate them based on their quality. There were four different pairs, but they were actually all identical. Three of the pairs had a faint, but different scent. One had a slightly rancid scent. The ones with the pleasing scent were consistently rated of higher quality than the ones with the less pleasing scent. One scent in particular was consistently rated as the highest quality.

Now, at first, you might not think this is that surprising, until you know that only six of the 250 women in the study, reported noticing any scent at all. The smell of the stockings, had clearly influenced their choice of perceived quality. It was a factor that was entirely hidden to almost all of them. Now, of course, it won’t surprise you to know that they didn’t claim to have no idea why they preferred one pair over the others, they could provide a rational and convincing explanation. It’s just that the explanation failed to include the primary driver of their decision. That’s an example of a hidden external factor shaping our decision.

In another famous study, conducted in 1962, Stanley Schachter and Jerome Singer published an experiment that looked at how our physiology and the perceptions of our internal state that arises from that, influences the explanations that we give for our behaviors. In this study, subjects were injected with a drug called epinephrine, or a placebo, or inert drug. Epinephrine is a chemical that the body normally makes and it’s involved in our arousal response. It increases the heart rate and the blood pressure. Our skin gets flushed. It’s released normally in any situation where there’s heightened emotion, including when we’re really excited, or when we’re really angry.

In this experiment, subjects were divided into different groups. One group who received the drug, were told about its effects. Another group was told that the drug would have certain effects, not the actual effects that the drug have. They were misled into believing they would experience something different. Another group wasn’t told of any possible effects at all. Lastly, the placebo group was not told of any potential effects either. After the subjects were injected with either the epinephrine or placebo, someone then came into their room and acted in a funny or silly way, to try to get them to laugh or smile, or did things to try to annoy them.
In these types of experiments, a person who does this kind of thing is referred to as a stooge.

What they found is, that the people who reported feeling happiest in the presence of the stooge doing funny things, were the one who’d received epinephrine with the false explanation of its effects. The least happy people were those who were told of the effects of the epinephrine. What appears to have happened is that the happiest people had misattributed their physical sensations to being entirely produced by the stooge, while those who knew the effects of the drug had factored that into their explanation.

Similarly, the people who reported feeling most annoyed by the stooge, were the ones who’d been given false information about the drug. Again, we’re attributing everything about the way they felt, to the effects of the stooge. There are many other fun studies that have been published since then, where these kinds of manipulations of our physiology are misattributed to something else. Who knows. Those heart palpitations that you felt when you first laid eyes on your future wife may not have been from her warm smile, or soothing demeanor after all, but from the jalapeno you’d eaten for lunch.

All-in-all, there’s a large body of evidence that shows this to be the case, that our behavior is heavily influenced by factors we are unaware of, including a huge amount of social behaviors. These factors we fail to account for, in the explanations we give for our behavior, a fact that experts of sales and marketing use to great advantage. Just as a sampling, here are some other examples.

Increasing the size of snack food container, causes you to eat more. The pitch of someone’s voice influences how trustworthy you think they are. The same wine is rated as better tasting if you pay more for it. Foods that are described with flowery language are rated as tasting better, than the same food that’s described blandly. Encountering someone of the opposite sex after you’ve just crossed a rickety bridge will make you feel more attracted to them. If you’re a waiter or waitress, touching a customer at some point, during the meal, leads to a greater tip, and on, and on, and on.

Again, all of these things influence our behavior, yet they don’t make it into our personal narrative of why we did the thing we did. This topic is also discussed at length in [inaudible 00:19:32] classic book, Influence. I’ll put links to that as well as to a couple of other great books on this topic in the show notes. These non conscious influences on our behavior have been known for some time. Now we understand that they are readily explained by what we’ve learned about the architecture of cognition in the brain, from computational processes that are running beneath our awareness to our moment to moment biological state.

Again, a little reflection will reveal this to be true. I’m sure you’ve had the experience of being introduced to someone and shortly after talking to them, get a sense that they can’t be trusted, and only after the fact, give an explanation about why you feel that way, or you may find yourself liking somebody, and then later on inventing a story as to why. The reality being, that most of that perception and the influences on how you felt, was happening in non conscious parts of the brain.

Now, what are we to make of all this, and how does this model help us in improving our brain health and function and in helping us to promote our desired brain states? On the one hand, this updated conception of the roots of our behavior, provide some significant challenge. What are we to do in the face of this incomplete knowledge about ourselves? It also explains why changing behavior is so notoriously hard, even for people who’s profession it is to help other people change their behaviors. Efforts along these lines are often targeted towards the explanations that we provide for our behaviors.

How can we expect to hope to do this sort of thing, if our explanations of why we behave a certain way in the first place are wrong? This doesn’t mean we can’t change our behavior. It just changes how we approach doing so. We already knew that we were terrible at this. Having a more robust understanding of our own behavior, provides an opportunity to actually get it right. There’s traditionally been so much wheel spinning in this area, due to our incomplete explanations of behavior that ignored the real drivers of why we do what we do and focused instead on our fabrications.

What that has also done is led us to ignore or overlook some of the most powerful levers that we have for changing our behavior, including the cultures and environments that our brains are in day-in and day-out, as well as the underlying biological function to the brain. What this entire body of evidence shows, is that those two things have an enormous influence on everybody’s behavior. The nature of that influence and how we can use it to our advantage are topics that will continue to cover in-depth in this podcast.

I think there’s no better way to create rapid behavioral change, than to understand the role of context and environment in our behavior and by improving the biological foundations of our cognitive function, which I discussed in the second episode. Needless to say then, this is relevant for anyone in the business of helping others change their behaviors, whether it’s doctors, counselors, psychologists, executive coaches and so on. We can’t hope to be successful if we don’t understand why we do the things we do.

All together, this has enormous ramifications for how we understand and assess intelligence, how we attempt to change our behavior and how we would go about creating lives of lasting fulfillment and wellbeing. All right. That concludes this episode of the podcast. Remember that you can find the show notes along with links to things that I mentioned in the episode by going to
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Lastly, if you are enjoying this podcast and you would like to help others discover it, it would be fantastic if you would leave a rating in iTunes. It really makes a difference. I will be traveling next week for the Thanksgiving holiday. I will be coming to you again with a new episode in two weeks. See you then.

Episode 4: Confabulation

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