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Philosopher and Cognitive Scientist Elizabeth Schechter

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AARON CAIN: Welcome to Profiles from WFIU. I'm Aaron Cain. On Profiles, we talk to notable artists, scholars, and public figures to get to know the stories behind their work. Our guest today is Elizabeth Schechter.


She's an associate professor in the Department of Philosophy and in the Cognitive Science Program at Indiana University, Bloomington. Schechter's work draws on both philosophical ideas about the mind and scientific research on the brain. And since even a normal, healthy human brain is divided into two hemispheres, Schechter's first and biggest questions are about psychological unity. Is the mind unified and to what extent? And if the mind really isn't unified, or if the lines of communication between its hemispheres are cut? How would two brains in one head affect personal identity, self-knowledge, consciousness, and the nature of belief? Schechter takes on these questions and more in her book, Self-Consciousness and Split Brains: The Mind's I. Recently, Elizabeth Schechter joined me for a conversation about all of this in the WFIU studios. Elizabeth Schechter, welcome to Profiles.

ELIZABETH SCHECHTER: Thanks so much, Aaron.

AARON CAIN: If I may, I'd like to start with what I think might be a dumb question. But in light of your work, in light of your book, Self-Consciousness and Split Brains, I'm going to risk asking this dumb question because I think you might provide me with a very non dumb answer. And it's also a variant of the hey, let's start at the beginning, tell me about your childhood kind of question. When you were growing up what do you remember about your own self-consciousness, about your own developing sense of what was governing your perceptions and your actions?

ELIZABETH SCHECHTER: I would not call that a dumb question. I remember very clearly when I was 13 - so this is already in an advanced age - really focusing on the fact that I was a person with her own conscious experiences and that I was kind of like the center of my world and that everyone else was the center of their own world. And that really struck me in a new way when I was 13. And I think when I look back at some of the thoughts I was having at that time, that's like kind of the earliest point in time at which I can really identify with myself. Of course, I have tons of memories from early childhood. But I assume it was just normal developmental growth, you know, puberty or something like that, maybe social changes.

AARON CAIN: Well, because in your book, you're careful to point out - and we should probably unpack this straight away - that self-consciousness itself has at least two definitions to consider: one that's colloquial and one that is kind of a prerequisite for personhood even that word self-consciousness, which I think everyone has their own definition of is something we need to kind of pick up and look at a little bit. So maybe using your own youth as a model, maybe just talking about it.

ELIZABETH SCHECHTER: OK, when philosophers speak about self-consciousness, they're typically talking about the ability to recognize oneself as a psychological being, a being with thoughts and emotions and hopes and dreams and plans and fears. So, again, consciousness of oneself as a psychological being and in particular conscious of oneself as both the thinker and the object of one's own thoughts about oneself. Colloquially, when we refer to self-consciousness, we're actually talking about a particular kind of, like, emotional state, having suddenly a heightened awareness of being the object of other people's evaluation. And presumably self-consciousness in the colloquial sense that is self-consciousness the emotion requires this more basic capacity for psychological self-consciousness, for recognizing oneself as a psychological being.

AARON CAIN: That's more being aware of how you were seen by someone else or how you're registering in someone else's consciousness.

ELIZABETH SCHECHTER: People act differently when no one's watching. And so kind of all the time we have a low-level awareness of the fact that other people can see what we're doing when we're around them and can evaluate us. But when you feel self-conscious, that suddenly surges to the forefront of your awareness and attention rather than just being something that's lurking in the background. And that's why you suddenly are struck by self-consciousness, the emotional sense, the colloquial sense, something you were doing a moment before, totally fluidly and easily just walking down the street, you can suddenly feel incredibly awkward. You're aware of maybe how you look while you walk, then suddenly can seem to you that you don't know how to walk anymore, that you're walking in a strange way.

AARON CAIN: I understand. So someone would say, “gosh, I feel really self-conscious right now.” When they do, they don't mean, “gosh, I really feel like my own individual being with my own individual consciousness.”


AARON CAIN: They're saying, “I feel awkward. I feel aware of myself.” It's more of an emotional response.

ELIZABETH SCHECHTER: Yeah, “aware of myself as someone that other people are seeing and potentially evaluating potentially negatively.”

AARON CAIN: So when did you first take the extra step into thinking of consciousness as something that you want to study and write about and understand more about?

ELIZABETH SCHECHTER: Well, I actually started with the split-brain phenomenon.

AARON CAIN: That's where it began with you.

ELIZABETH SCHECHTER: Yeah, that's where it began with me. And it was - you know, I was trying to resolve what I called a unity puzzle of the split-brain phenomenon. And just eventually I realized that in order to reconcile what I think are these two conflicting intuitions people have about these split-brain subjects, you need to attend to the way that self-consciousness appears to be operating in them. But it actually took me several years to come to that point of realization.

AARON CAIN: Well, let's talk about some of those several years, because we're also going to have to roll up our sleeves and get into some terminology like split-brain phenomenon itself. But, if we can, I'd like to focus a bit on your time at Vassar College. Because you got your undergraduate degree there in English. And over the years when I've spoken with people who have gone into other disciplines after getting degrees in English, I have observed that there are many diverse paths that lead from that particular degree and very few of them are to continue studying English. So looking back, what do you remember about your time at Vassar and your undergraduate studies, your time studying English that directed you into your career in philosophy and cognitive science?

ELIZABETH SCHECHTER: Yeah. I love reading. And I used to love reading fiction. Although these days I think I read more nonfiction. And I also was a creative writer. And I do still sometimes write creatively. I wanted to write a creative thesis instead of writing some work of literary analysis or in some other discipline. And the requirement for writing a creative thesis and taking this year long creative writing class as a senior was to major in English. So I majored in English for that reason, for my senior year. And again, as I mentioned, you know, I really love reading. I do love writing. I didn't actually enjoy my English classes that much at Vassar. I mean, I have some amazing professors, but the model of teaching in the department was very discussion based. And now as an instructor, I know how valuable this can be pedagogically. But at the time, that wasn't how I saw it. I felt a little frustrated by it. I thought I really wanted to be hearing from the person with the PhD, and I didn't think that the other students or that I myself had much that was very interesting to say. And a lot of ways I didn't actually enjoy the major. I was simultaneously taking a bunch of classes in cognitive science and I really enjoyed those classes. And then I started taking a bunch of classes in philosophy, which I also enjoyed. And then in my senior year, I was simultaneously taking the cognition course like a 400-level course in the cognitive science program. And I finally took philosophy of mind. Up until that point I'd been taking, you know, kind of a sort of philosophy classes, logic, and history of philosophy. And I liked those, but I didn't love them. But suddenly this combination of classes, the cognition class with Gwen Browde and Philosophy of Mind with Jennifer Church and the philosophy department, I really loved both those classes. And at that point I decided, “oh, I want to do …” I didn't actually know whether I wanted to become a cognitive scientist or a philosopher of cognitive science.

AARON CAIN: Well, that's kind of a spoiler because you sort of found a way to do both, didn't you?

ELIZABETH SCHECHTER: Yeah, I did, actually. I mean, I knew that cognitive science was the discipline that I wanted to know more about and that I wanted to read a lot of experimental literature, that I wanted to know a lot of that experimental literature. I wasn't sure whether I wanted to run experiments myself. And I decided ultimately that I didn't have quite the right temperament for it. I think running experiments requires a particular kind of patience. And I have other kinds of patience, but perhaps not that kind of patience in spades. And so that's why I decided to become a philosopher, but who still studied the mind in a way that was empirically informed by looking at actual results of inquiry produced by psychologists and neuroscientists and so on.

AARON CAIN: In light of what you said a moment ago about being interested in writing and reading and creative writing, was part of that decision to take the philosophical route, at least initially - was part of that a creative impulse?

ELIZABETH SCHECHTER: I certainly think that as I began to write articles in graduate school I had less and less of an interest in creative writing, that is, I think there is a creative impulse, I think really in all of us. And I think it expresses itself in different ways. And I certainly feel that writing - I mean, of course, if it's not a novel, you're in some ways much more constrained. But on the other hand, I absolutely do feel that I get my creative energies out in my philosophical writing.

AARON CAIN: Well, I'm going to ask the same question in a different way just because of the nature of your work. It's so interesting, because when I have seen some of these experiments done on split-brain subjects, I think, “who makes this stuff up?” I mean, it seems almost outlandish and creative just to even - the things that are done to get to the bottom of what's happening cognitively in a split-brain. So the same question, then: looking at some early experiments, perhaps more of the psychology side of things, the cognitive science side of things, was that creative impulse within you, as you saw some of those experiments? Did that make you react in a certain way?

ELIZABETH SCHECHTER: Yeah. I mean, I think, originally, I simply admired it and I still very much do. I mean, that's something that scientific training gives you. Maybe it's the central thing that scientific training gives you is that I think people are, to some extent, natural philosophers, right? We - if you look even at little kids, right, they ask a lot of deep questions about the world. But it's very difficult to figure out how to answer those questions through - how to make those questions kind of empirically tractable. That's what scientific training gives you. So I, too, am very impressed by the way scientists managed to take broad abstract questions and break them down a little into pieces that can actually be tackled by particular studies. You know, on the other hand, I will say, there are certainly further studies that I wish scientists had done with split-brain subjects and, perhaps, can still do in the future, your discipline also shapes the kind of questions you tend to ask. And so there are questions about self-consciousness in split-brain subjects that really weren't, to my mind, satisfyingly addressed by any of the current empirical research. I said earlier that I might lack the kind of patience necessary for empirical research. But on the other hand, as the years have passed, I have more and more of a drive, I think, to acquire that kind of patience, to acquire those kinds of skills, because, again, there just are questions, empirical questions about brain psychology that I really do want answered. And might be that the only way for me to get them answered is to actually work on some of this research.


AARON CAIN: Elizabeth Schecther, author of Self-Consciousness and Split Brains: The Mind's I. You're listening to Profiles from WFIU, Elizabeth Schechter is an associate professor in the Department of Philosophy and in the Cognitive Science Program at Indiana University, Bloomington.

Let's talk more about what we're talking about. I'm going to have to rely on you rather heavily for this, because we're going to need some terminology. And we're going to need some scientific practices. We're going to need a bit of an anatomy lesson. We're going to need all that under our belts for this conversation about split brains. So we may as well start with you doing something that's impossible. And that is a simple, basic tour of the brain - in particular, the two hemispheres of the brain. And if you could bring it all together, like the brain itself does with the corpus callosum.

ELIZABETH SCHECHTER: If you look at the just gross structure of the brain; so let's say you're not using any fancy imaging equipment or any of these technologies that are fairly recent and that we're so grateful for. You just, you know, remove a brain from someone's skull. And you look at it, one of the things that strikes you about it is that it is bilaterally symmetric and that it largely consists of paired structures. So, in the same way, if you look at the outside of someone's body, you see we have two arms, right? One on either side. And we have two legs, one on either side, and we have two eyes, one on either side, and so on. The brain looks a lot like that. There are famously, for instance, Rene Descartes who thought that the mind was something that causally interacted with the brain but was distinct from it. He was looking for a particular point on the brain that might be the point of interaction with an immaterial mind. And he thought that since the mind was unified, he wanted just one point. And he looked at the brain and he mostly just saw these paired structures on the right and left. Famously, he saw the pineal gland. And he - you know, it wasn't a big part of his theory, but he tentatively hypothesized that the pineal gland might be the point of attraction. And that's because it's an unpaired structure. And this is quite rare. So if you look at the brain, you see, yes. The two cerebral hemispheres - there are, you know, two hemispheres of the cerebellum as well. There's a right thalamus and a left thalamus, right hippocampus, a left hippocampus, a right amygdala, left amygdala and so on and so forth. But, certainly, what would strike you first, as you looked at the brain, are the cerebral hemispheres because they're very large and they're right on the surface of the brain. And, actually, in the 19th century there were debates amongst intellectuals interested in psychology and in neurology about materialism versus immaterialism, right? So there were those like Descartes, who thought that the mind was somehow separate from the brain. And there were those, on the other hand, who - you know, materialists who thought that the mind must, in fact, be the brain somehow. And one of the arguments that the immaterialists had was they said, well, if you look at the brain, the brain is visibly dual. Again, it's divided into these paired structures on the right, in the left of the midline, whereas the mind is unified. So, therefore, the mind cannot be the brain. And materialists responded in several different ways to this argument. What one popular response was to say, “aha, but the brain is not dual because although there are these two cerebral hemispheres - and at the time it was believed that the hemispheres were the seat of really every interesting and certainly uniquely human psychological trait - they said, nonetheless, the brain is not dual because the two hemispheres are connected by this giant band of white fibers called the corpus callosum. And this is the largest white matter fiber tract enabling fast communication in the human brain, connecting these two cerebral hemispheres.

AARON CAIN: And so that's how they talk to each other, for want of a better term, the two halves of the brain.

ELIZABETH SCHECHTER: Sometimes some of this literature would refer to the corpus callosum is the seat of the soul, because the idea was that it provided the basis for what was widely regarded as existing, the unity of mind. By connecting these two hemispheres in which we're located, all the uniquely human psychological capacities, the capacity for language, the capacity for moral reasoning, for consciousness, probably love of country.

AARON CAIN: Well, but also just from a gross anatomical standpoint, if you bisect a brain, you take a look at it, there's one of them. There is one corpus callosum when there's two of just about everything else.

ELIZABETH SCHECHTER: That's right. And there are other commissures, but the corpus callosum is just so big. There are even other white-matter commissures connecting the two cerebral hemispheres. But none of them seem to have the functional significance, especially in human beings, that the corpus callosum does. By far and away, it seems to be the major source of right left integration in the brain.

AARON CAIN: Over the years, especially since the last century, folks would sever the corpus callosum. That membrane that contains the largest fiber tracts connecting the two hemispheres would be severed, if not completely, at least partially. Why do that, before we talk about what the results of that are?

ELIZABETH SCHECHTER: Yeah. So in the second half of the 20th century, a number of so-called split-brain surgeries were performed in which this corpus callosum was severed in adult human beings. And it was severed as a treatment for severe cases of epilepsy that had not responded to other kinds of intervention. These were patients who were having generalized seizures that couldn't really be localized to a particular point of the brain. They would start typically in one hemisphere, spread to affect the other hemisphere as well with the resulting loss of consciousness, typically. So patients would just collapse where they were. And many of them were having so many seizures that they were having seizures every day, sometimes so frequently that the seizure would feel as though it lasted a whole day. So these were severely impairing not just a quality of life, but they were also causing progressive brain damage. And the theory was that the corpus callosum might be acting as the bridge through which this wildfire, electrical activity was passing from one hemisphere to the other. And if that hypothesis were right, then if you cut the bridge, you could at least confine the seizure activity to one hemisphere. And that would allow the subject to retain consciousness, for instance. And, actually, for reasons that I'm still not sure are totally well understood, cutting the corpus callosum appears to reduce seizure frequency as well as severity. So these surgeries were performed on human beings for strictly medical reasons. Though I will note that most split-brain surgeries have actually been performed on non-human animals for experimental purposes.

AARON CAIN: Now, wait a minute, though, this radical solution of severing the corpus callosum, did I hear you correctly in that you said that it seems to have worked even though it might not have worked?

ELIZABETH SCHECHTER: No, it worked some ways even better than they were hoping. I mean, on the one hand, they weren't sure what the side effects will be. And I'm sure we're going to talk a lot about those side effects, because the side effects are, in a sense, the split-brain phenomenon. But they had just hoped, well, they'll still have seizures, but they'll be confined to one hemisphere instead of affecting the whole brain. But my understanding is that, actually, it seemed to reduce the number of seizures, period, as well as reducing the severity.

AARON CAIN: I see. But we just don't really know for sure exactly why it works. I get it.


AARON CAIN: Then once you have a brain that is thus bifurcated, that has the corpus callosum severed, there were a lot of really remarkable side effects.

ELIZABETH SCHECHTER: Yeah, that's right. There were. I mean, the standard line has always been that these side effects, the consequence of the surgery are visible really only under experimental conditions. Although this is something that I dispute in the book. But certainly the really striking, gripping effects of this surgery are most visible under experimental conditions. I mean, unsurprisingly, these same materialists in the 19th century who thought that the corpus callosum was the seat of the soul, that it was the corpus callosum that unified what would be two brains into one. They predicted that if the corpus callosum were cut, then someone would have two minds. And it was only in the 20th century when split-brain surgery or callosotomy emerged as a medical treatment, that this hypothesis was able to be tested. Unsurprisingly, after they are no longer connected via this really large white matter pathway, the two hemispheres of the brain begin to operate independently of each other, not totally, but to an unusual degree in the realms of perception, cognition and the control of action.

AARON CAIN: Those three main areas, perception - how you perceive things, there's the way that you think - cognition, and also how your brain continues to control the body. So, changes in all three of those areas. So what were some of them?

ELIZABETH SCHECHTER: Well, so maybe the simplest example is: suppose you blindfolded a split-brain subject so that they can't see their hands and you put an object, an unfamiliar object - let's say first you put an unfamiliar object in the right hands, like, you put a pen in the right hand and you ask the subject what he's holding. And the subject feels it for a second and then says, you know, he feels a pen. Now, you put another familiar object, say a pipe, in the left hand. And you ask him what he's holding and he will say he doesn't know, possibly that he can't feel the object. Well, he can't feel the left hand. This is because each hand sends tactile information, kind of fine-grained touch information directly to the opposite hemisphere. So the right hand to the left hemisphere and the left hand the right hemisphere. This is actually true in all brains. It's true in your brain. It's true in my brain. But your brain, I assume, is one in which the two hemispheres are connected by a corpus callosum. So that allows either hemisphere to gain access to this information that only a single hemisphere initially received. But in a split-brain subject in whom the corpus callosum is missing, this information more or less stays put. So when you put the pipe in the subject's left hand, tactile information about the pipe has been sent to the right hemisphere. And in the majority of the population, including the split-brain population, the right hemisphere is mute, lacks a capacity for spoken language. So when the subject has said, “I don't know what's in the left hand, I can't feel it that well,” there's a verbal report is coming from - it's the product of left hemisphere speech centers. And the left hemisphere didn't receive this tactile information from the left hand that tactile information was sent only to the right hemisphere. But if you now, say, you take the pipe out of the subject's left hand and you put it in a box of objects and you ask him a minute later to reach into that box with the left hand and select the object he was holding a minute ago, he easily selects the pipe. If you give him a piece of paper and a pencil to hold in his left hand, he may draw a picture of a pipe. He might even be able to write the word pipe, but he can't speak it.

AARON CAIN: That's extraordinary. So that's the tactile sense. What sorts of things did experiments reveal on the split-brain phenomenon in terms of what we can see?

ELIZABETH SCHECHTER: All the split-brain experiments exploit the fact that various perceptual modalities and various forms of motor control are to some extent lateralized - that neither hemisphere’s, like, totally equivalent to the other in terms of the kinds of sensory perceptual information it receives from the body and world, or the kind of motor control it has. So in the case of vision, let's say you're staring at a point in a wall. Everything to the right of that point in your right visual field will be received by your left hemisphere. Everything to the left at that point will be received by your right hemisphere. And, again, in your brain, it doesn't make a difference because the information is ultimately shared between both hemispheres.

AARON CAIN: Can I butt in for some anatomical clarification? That's because the optic nerve - they criss-cross – like, the optic nerve from the right eye goes into the left hemisphere and the corpus callosum connecting the hemispheres is not involved in that.

ELIZABETH SCHECHTER: It's actually a little more complicated than that because, setting aside the corpus callosum, there's a point called the optic chiasm at which information from - I mean, effectively one half of each eye crosses. So, then, your left hemisphere is actually getting information from - I guess it would be the left side of your retinal field, but in both eyes. So, actually, in non-human animals, you could just cut the optic chiasm, right? Because you can do things to non-human animals  for experimental purposes. And then it's very easy to work with them. Once you cut the optic chiasm, the right eye sends information only to the right hemisphere and the left eye only to the left hemisphere. But humans, but brain subjects. You can't cut the optic chiasm just because it makes experiments easier. And so, you end up getting information from one half of each eye in each hemisphere. And, again, what that means effectively is that, you know, information from the left side of space to the left of wherever you're looking from both eyes goes to the right hemisphere, and information from the right side of space to the left hemisphere.


AARON CAIN: You're listening to Profiles from WFIU. I'm Aaron Cain. I'm speaking with philosopher and cognitive scientist Elizabeth Schechter, author of Self-Consciousness and Split Brains: The Mind's I.

You mentioned that we know what we know about the split-brain phenomenon because of this radical surgical procedure to curtail epileptic seizures in humans. And we know what we know from experiments performed on non-human animals. Apart from those who have their corpus callosum severed in this way, what are some examples of other subjects with compromised communication between the hemispheres of the brain and how, if at all, do their experiences differ?

ELIZABETH SCHECHTER: Yeah. That's a great question. I mean, there are a lot of different conditions like this, but I think some of the most interesting studies I found were with a series of patients in Japan who had suffered organic, callosal damage and they had suffered damage to the more frontal or anterior regions of the corpus callosum, so those regions that are closer to your forehead than to the back of your head. The regions of the corpus callosum towards the back of their head were still intact. This is interesting only because, you know, as you mentioned before, for surgical purposes, sometimes only part of the corpus callosum is sectioned. And in those cases, when they do the section, they section the reverse. So they section the back parts of the corpus callosum, but they leave the front parts intact. So I was really excited to find these patients who had suffered damage to the front parts of the corpus callosum, between the back half, was intact. And the author wasn't familiar with some of the early split-brain studies. And so he coined a term for what he saw as kind of a new set of symptoms that hadn't been seen before in these patients. He called it “conflict of intentions.” So patients with damage in these regions of the corpus callosum - it's kind of funny to describe, but they would form an intention to do something like go upstairs and grab a particular book. And then they would also be struck by a contrary intention, intention to do something different that couldn't be combined with that action. And they would not really see a way of resolving that conflict. So, of course, this happens to all of...

AARON CAIN: I'm terrified. That happens to me every day.

ELIZABETH SCHECHTER: I've had people say that. So, of course, it often happens that “this happens to me a million times a day. I decide to do something and then I realize, oh, no, wait, I really need to do whatever.” But I resolve that, right? I make a quick decision about which one to do first. These patients would see no way of resolving the conflict. So you know...

AARON CAIN: They're stuck in that moment.

ELIZABETH SCHECHTER: Yeah, I mean, for really unusual periods of time, right? So, someone might be halfway up the staircase then they're struck by the intention to get something downstairs instead. And they stop on the staircase for 20 minutes because they don't see how to decide which one to do first, or they would try to combine the actions in ways that would be obviously unsuccessful. So on the one hand, wanting to go into the bathroom to wash their face and then thinking that they should water the flowers and they'd be bringing the - what's it called?

AARON CAIN: The watering can.

ELIZABETH SCHECHTER: The watering can into the bathroom, holding it in one hand, and now they can't wash their face because they only have one hand. This is really interesting because I think that split-brain subjects also suffer from a kind of conflict of intentions since they've lost this portion of the corpus callosum, too. But these patients in Japan haven't lost the entirety of their corpus callosum. And so they were aware of the conflict between the intentions. So my hypothesis is that different intentions actually were formed in the two hemispheres. The corpus callosum, which would normally serve as a medium through which these intentions could be integrated, or in which one could be prioritized and the other deprioritized, it's missing there. So, they're just stuck with these two intentions. But they are aware of having both intentions. And that's different from in the split-brain case. So I think in the split-rain case, there's a lot of experimental literature that shows that each hemisphere does form its own intentions and can use these to guide intelligent behavior. But because the split between the two hemispheres is more complete, there's no awareness of the existence of both intentions at once. So, in particular, when you ask the subject what they wanted to do, you get a report from the left hemisphere system. And it's a report of its own intention with no mention of - because no awareness of - a conflicting right hemisphere intention, one that experimenter's nonetheless must posit to explain some of these subjects' right hemisphere-controlled behavior.

AARON CAIN: You mentioned that the vast majority of things that we know about the split-brain phenomenon, we know because of controlled experimental conditions. Has anybody ever made a concerted effort to study how split-brain subjects get through life outside of these controlled experimental conditions?

ELIZABETH SCHECHTER: Yeah, that's a great question, too, because normally what you hear, the kind of standard line on these subjects is that, well, under experimental conditions like the pipe experiment that I described before, yes, they can be observed to behave in these very strange ways that are kind of eerily suggestive of two centers of consciousness in one body into conscious agents, but outside of experimental conditions they behave perfectly normally and they seem just like everybody else. That's what a lot of neuropsychologists who worked with the subject said. And it's what philosophers reading that work said as well. But, actually, they said this without really having made any attempt to systematically observe how the subjects behaved in their normal life. I found one study that was done like this. One. Ferguson, Rayport, and Corrie, where three neuropsychologists who reached out to six brain subjects and asked if they could follow them around for a couple of days -see how they got on at home, out running errands, also interview their family members. In one case, employers and all six subjects said yes. And these researchers found that in all six of the subjects they observed, their behavior was not normal. And it was, you might call it, disunified. It was certainly kind of disruptive. They had a lot of problems with daily living that were apparently caused by the surgery. These are problems that they hadn't been having prior to the surgery. By the way, I hasten to add that I don't mean this as a criticism of the surgery because all these patients nonetheless said that they were extremely glad to have had the surgery because even though they had these new difficulties that they hadn't had before, the benefits of seizure reduction are just enormous.


AARON CAIN: Elizabeth Schechter, author of Self-Consciousness and Split Brains: The Mind's I, you're listening to Profiles from WFIU.

  1. So at this point, we have some terminology under our belts, and we know a little bit more about the split-brain phenomenon and what subjects we've had this done go through some of the cognitive results. So now I'm going to ask once again if we could go back to Vassar.


AARON CAIN: If we could go back to when you were first taking your courses in philosophy in the cognitive sciences, because you'd mentioned that pretty much from the jump, it was all about the split-brain phenomenon for you. Now that we know what you're talking about, what was it that lit that fire? What did you absolutely have to know about this that made you dedicate your studies to it?

ELIZABETH SCHECHTER: Yeah. I mean, this is what I called the unity puzzle of the split-brain cases that,  although I think I'm the first one to have formulated it explicitly, I think that a lot of people have intuited it. And that this is why the split-brain cases are so gripping to people, not just to specialists, but to really pretty much everyone who might have described it. And you introduce intro cog sci, like 100-level students in philosophy or in cognitive science to the split-brain phenomenon and they're interested too. So this unity puzzle is that, on the one hand, the subjects, like, under these experimental conditions, again, their behavior just seems to be the product of these two distinct conscious intelligences, right? I mean, almost everyone has that impression when you describe the experimental results. On the other hand, it's very difficult to see split-brain subjects as being, at the end of the day, anything more than one of us. Each of them seems like one person rather than being like, you know, two of us glued together; two of us trapped in one body. And so these are these two conflicting intuitions. And they're conflicting because we think, “well, each of us has just one mind,” right? You know, we're inclined to think, I think, that, you know, each person has exactly one mind, that each person is a single thinking thing. And so then these two intuitions we have about split-brain subjects are in conflict. Something has to give there. It can't be true both that a split-brain subject has two minds, a split-brain subject is one person. If it's also true that a person necessarily has just one mind, and I think that although it took me years to kind of formulate that puzzle explicitly, I think my question about the split-brain cases is the question that everyone has. How many of us is a split-brain subject anyway?

AARON CAIN: Well, and I could be wrong about this, but I'm struck by how long that question has been sitting out there, really, because you mentioned how in the 19th century there were people who were trying to figure out how can a mind be unified when the brain is dual, a non-split brain? How can we have a singular consciousness when you have this symmetrical thing that has two parts, two halves.

ELIZABETH SCHECHTER: The philosopher Thomas Nagel, who first kind of introduced the split-brain phenomenon to the philosophical world, he said there's something deeper there. Still, he says, you know, we have these, I don't know, more humanistic or just theoretical, as you said, are pre-scientific ways of looking at ourselves or just these more personal ways of looking at ourselves, right? We have to kind of assume some sort of unified psychological being in our interactions with others. I just want to note, I think he takes this point too far. But, you know, it's definitely true that if you tell me you'll do something and then you don't do it, I assume that you broke a promise. I don't assume that the person who said he would do something is distinct from the person who didn't do it. So we posit just a certain kind of unified or unitary psychological being just in our ordinary interactions with each other. On the other hand, Nagel said, you look at the sciences and they're reductive and there's a picture of the human being that emerges from the physical sciences that’s just, you know, a collection of parts. I mean, I don't mean to say - these are parts that are obviously, like, incredibly richly integrated and attractive with each other and so on. But he felt that the split-brain cases highlight a kind of broader tension between our ordinary ways of thinking about ourselves as psychological and social beings and the picture of human beings that is emerging from the sciences, the physical sciences, as a complicated mechanism with a ton of different parts.

AARON CAIN: This gets to another piece of terminology we should perhaps unearth and examine a bit, and that's neuromania.

ELIZABETH SCHECHTER: So this is a term for a kind of popular obsession with the brain and a belief that neuroscience and the kind of level at which neuroscientists pitch their explanations - and neuroscience is itself an incredibly diverse discipline - the view that every interesting facet of not just human psychology but human social life, arts and government and so on can be fully understood and explained just by looking at the brain and the operations of the brain. And one of the problems with - and I love neuroscience, so this isn't meant to knock neuroscience - but one of the problems with neuromania is that it tends to take certain questions that are asked from other sorts of perspectives and try to offer answers to those questions by actually implicitly changing the question.

AARON CAIN: Do you ever feel like you're walking kind of a fine line, though, because in order to avoid the homunculus fallacy – which, as fallacies go has probably the best name ever - are you getting dangerously close to your own work? Because, if I understand your hypothesis of your book correctly, you're essentially arguing that a split brain can be two independent consciousnesses, and yet they're not, at the same time. That's sounding a little bit like a homunculus to me.

ELIZABETH SCHECHTER: Yeah. No, that's a great question. I do defend in the book two minds or two thinkers claim that there are two distinct thinking things, two distinct consciousness things, two distinct conscious agents after split-brain surgery. And there has always been a kind of anthropomorphism concern about that claim. And that's because typically there's been a lot of debate about whether or not there are these two distinct thinking things after brain surgery. And, typically, those who have argued that a split-brain subject remains a unitary mind or a unitary thinker have been arguing that it's the human being as a whole that thinks and feels and chooses and sees and acts, and so on. And then those who've argued that a split-brain subject is or contains or is composed of two thinking things have been arguing that it's the right and the left hemisphere that think and choose and feel and act and see, and so on. And that two thinkers claim, therefore, has been plagued by this kind of anthropomorphism worry. Are mere hemispheres of the brain, really even the kinds of things that can think or feel or choose? One move I make in the book is to say that although I argue that there are these two thinkers after split-brain surgery – Righty and Lefty, or R and L - they aren't mere hemispheres. They're much larger things. Things that there's independent evidence to show are capable of thought and consciousness and action. And what I draw on there to introduce, you know, you to another kind of surgery, what I drawn, there are cases of hemispherectomy, which is an even more radical surgical procedure. That's the removal or functional incapacitation of an entire cerebral hemisphere. And these are, again, very radical surgeries. You definitely don't want to have them done if you can avoid it. But there have been cases of hemispherectomy - right or left hemispherectomy done on adults following normal development - and it is clear that after removing an entire cerebral hemisphere, you are nonetheless left with a being that can think and decide and feel and see and act. People who have undergone hemispherectomy, even if they've lost their left or language-dominant hemispheres so that they initially can't speak at all, they nonetheless are conscious. They make socially appropriate decisions to the extent that it can be judged. They don't appear to have radically different personalities. They experience emotions. They appear to experience self-conscious emotions as well, like embarrassment. In context, that makes sense. So what hemispherectomy shows is that you don't need two hemispheres to have a mind. And then the question about the split-brain case becomes, OK, so if a split-brain subject does have two hemispheres, but they are no longer connected by this corpus callosum, are they nonetheless parts of one thinker just because they're both still present and functioning in one body, or is a split-brain subject kind of like a right-hemispherectomy subject co-embodied with the left-hemispherectomy subject? These two thinkers that I identify after split-brain surgery - Righty and Lefty - Righty is, as I'm thinking about it, the entire human being minus the left hemisphere, like,  excluding the left hemisphere and its contributions to the human being’s psycho-behavioral functioning. And then Lefty is the entire split-brain human being minus the right hemisphere, excluding the right hemisphere and its contributions to psycho-behavioral function. And note that, in terms of their intrinsic structure and capacities, Righty is intrinsically equivalent to someone who's undergone left hemispherectomy and Lefty is intrinsically equivalent to someone who has undergone right hemispherectomy. And we know that those things - right and left, each of which is almost an entire animal -we know that they are the sorts of things that can think and be conscious and make choices, because people who have undergone right hemispherectomy or left hemispherectomy can think and be conscious and make choices. So that's how I think I avoid this anthropomorphism worry. It may be true that no mere hemisphere of the brain could think or make choices, but things as big and sophisticated as Righty and Lefty can.

AARON CAIN: At this point, I'm afraid that I'm going to have to ask you to assuage my fears here, because - I might sound frustrated. I'm not. I'm fascinated, but it seems to me as if we're kind of back where we started in terms of answering this one question: If you don't necessarily need two communicating hemispheres for a mind, what do you need? So I'm going to have to ask you, Elizabeth Shechter, since Descartes, since the debates about the mind in the 19th century, what have we learned about what does make a mind, in terms of the body of scientific literature in general and, more importantly, your assertions?

ELIZABETH SCHECHTER: So, do you mean what do we need to have any mind at all or what do we need to have one mind rather than two?

AARON CAIN: Wow. They're both questions I want to know the answer to. So let's take them, maybe, one at a time if we can remember. What we need for a mind at all?

ELIZABETH SCHECHTER: There has been a bunch of at least philosophical work on this, what are the kind of minimal capacities that are being needs to have in order to have a mind? So, for instance, do insects have minds? And human beings obviously don't just have minds, but of much more sophisticated minds that there are some - I don't know any scientists who would say this - but there are some philosophers who set the bar pretty high, right? - and are going to require actual natural language for a mind. I don't set the bar nearly that high. I think you need to be capable of having informational states that kind of represent the world in a somewhat flexible way: beliefs, motivational states. These need to be able to interact with each other so as to produce intentions, to perform actions. That's pretty minimal. Obviously, human minds have a bunch of further additional capacities. And, again, that's true even of people who have undergone removal of their language-dominant hemisphere, although they can't speak. And, again, if you were going to set the bar very high, you might require speech for a mind. Again, I wouldn't set it anywhere near that high. And they do have a bunch of further psychological capacities that are more complex. For instance, people who have undergone left hemispherectomy appear to experience self-conscious emotions like embarrassment. Presumably, they are psychologically self-conscious. Presumably, they are capable of thinking of themselves both as a thinker and object of their own thoughts and an objects of other people's thoughts as well. While there's been a lot of philosophical work on that question, what are the minimal capacities that a being needs to have in order to have a mind? There hasn't been much philosophical work on the kind of subtler question of what it is to be the thing that has those capacities in the relevant sense. And that's what's really necessary to answering the question of how many minds a split-brain subject has. And I say that because everyone agrees that if the left hemisphere weren't there, if a split-brain subject first underwent split-brain surgery and then left hemispherectomy, everyone agrees that there would still be a being with a mind there, that the right hemisphere intrinsically has what it takes to form a mind, at least in conjunction with the rest of the nervous system and the body. But the question is about what it is to be something that thinks, or to be something that chooses, rather than just to be something that serves the capacity for thinking or that provides the mechanism for choice. If you think that after brain surgery, a split-brain subject still has one mind, what you're going to say is that the two hemispheres of a split-brain subject's brain, they provide the basis for various capacities of the split-brain subject as a whole, but it is that subject that remains that thinker and the chooser, not the mere hemispheres. Those provide the kind of mechanistic basis for thought or for choice, but they aren't the thinkers or the choosers themselves. So this question about what it is to be the thing that has the capacities in the relevant sense is very subtle. And, actually, I really only found one philosopher who’d addressed that, the great philosopher Sydney Shoemaker. He argues - and I agree, and I draw on this in the book - that to be a thinker is to be a certain kind of causal system within which certain kinds of activities operate; activities like thinking, choosing, feeling, carrying out actions, and so on, and that these activities are themselves causally defined. Drawing on this, I argue that what makes it true that a split-brain subject is composed of two thinkers, Righty or Lefty, is that these processes, these causal processes of judgment forming and decision making and so on, these processes are still happening after split-brain surgery, but they are happening within the boundaries of one hemisphere system and the other rather than across them. You asked early on for an example of some of the behavior you might see after a split-brain surgery. And I gave the example of a split-brain subject, who’s holding a pipe in the left hand, verbally says that they don't know what they're holding because they can't feel that hand, but if you take the pipe away and put a pencil in that hand, might be able to write the word pipe. OK, this is a kind of behavior which is -  note that, among other things, there is such a thing as unconscious perception. But so far as I know, there's no reason to think unconscious perception can lead to that kind of behavior. That is, when asked to identify an object that you were holding a minute ago, leads you to actually write down what it was. But on the other hand, here's something else that's true of conscious perception. If you consciously perceive something and if you're capable of speech, you can verbally identify through spoken language what it was that you held. So it looks as though there was an act of conscious perception here, but it was conscious only relative to other events of the right hemisphere. That's why it can direct left-hand writing, each hand being predominantly controlled by the opposite hemisphere. But, again, that this conscious perception of the pipe wasn't conscious relative to the left hemisphere activities, the left hemisphere activities that resulted in the subject saying, “well, I didn't feel anything.”


AARON CAIN: You're listening to Profiles from WFIU. Our guest today is philosopher and cognitive scientist Elizabeth Schechter, author of Self-Consciousness and Split Brains: The Mind's I.

Let's talk a little bit more about self-consciousness itself as a concept, because you point out that there are two ways of defining that term. One is colloquial and one is a social capacity that's required for personhood. So if people read your book, they'll know more about this. But this isn't the book. This is us just talking. If you had just a few minutes in which to make people understand something about self-consciousness, what would you like them to understand that you suspect they might not?

ELIZABETH SCHECHTER: I suppose…it's a tough question. I found it very interesting to reflect on what human life would look like if we weren't self-conscious. And I guess I always think about my dog, who I assume is not self-conscious, we always joke about the dog, who we love very much, but she has no dignity. I mean, she - it's interesting to think about if you had no awareness of - you know, I will note that self-consciousness has these twin aspects that are deeply intertwined. I mean, on the one hand, again, there is the ability to think about yourself as a psychological being and that gives us powers of agency that non self-conscious beings don't have. For instance, you can decide to do something, but you can immediately scrutinize your motives and ask whether you're doing this for the right reason. Or you can scrutinize the intention that you've formed and say, “is this really wise?” Your access to yourself isn't solely kind of observational or based on observing your behavior. You can reflect on your mental states before they result in action. And, of course, after all, so you can think about how to make a better decision next time. Another really interesting aspect of self-consciousness is this ability to think about yourself as an object of other people's thoughts. And if you imagine losing that, well, it's the difference between a small child, right, and an adult, the self-consciousness with which children will sing and do various things that they do. And adults, we have our dignity. We have a firm sense of the distinction between private and public behavior. We have different ways of acting alone versus in front of others. There was a funny Onion article a few years ago that said something like, “Study Finds that 84” - it was something like, “80 Percent of Americans Begin Exhibiting Symptoms of Psychosis after 15 Minutes Alone.” And it was talking about people, like, making funny faces at themselves in the mirror and so on. And just, like, and obviously, you know, people might walk around naked in their own house and it's not something they would ever do in public. That sense of dignity, the sense of, like, “I'm not going to lower myself in someone else's eyes,” right? Which my dog lacks. I hadn't thought about it much, but think about what human social life would look like without that, without that sense of the difference between public and private, without any sense of how other people are looking at you, what they're thinking about you and so on. Again, it can be taken to unhealthy extremes. That's what colloquial self-consciousness is, when you're suddenly too aware of how other people are looking at you. But when it's in the background of your consciousness all the time, that's just being kind of socially normal as a human being and that's foundational to human social life.

AARON CAIN: So your book is about the split-brain phenomenon. I would like to ask you about another weird hypothetical thing, the split career phenomenon. Elizabeth Schechter, before coming to Bloomington, before joining the faculty of Indiana University, you were in the philosophy department and the Philosophy Neuroscience Psychology Program, the PSP program, at Washington University in St. Louis, which is an innovative interdisciplinary program. If I could get you to speak for a moment about what scientists and humanists can learn from each other, because the split career phenomenon I'm asking you to contemplate is what would have happened if you, Elizabeth Schechter, would have just gone down the path of philosophy alone or the path of cognitive science alone. Could you have done this in one discipline?

ELIZABETH SCHECHTER: Yeah, that's a great question. And, by the way, I just want to give a shout out to the cognitive science program here, which I'm also a member of, which is also just a fantastic interdisciplinary program. That really one of the things I really appreciate about the cognitive science program here is that - and this is not always true - but I think they really do value philosophy and the contribution that philosophers can bring to cognitive science. It's pretty difficult work because each discipline does develop its own language. I mean, anyone who's engaged in interdisciplinary work will notice each discipline does have its own language; its own methods and standards of evaluation. And so you kind of have to master two languages and two sets of standards, and you need to constantly be translating. I really tried in the book to do justice to some of the messiness and complexity of the actual split-brain empirical literature. There has been a lot of philosophical literature on the split-brain phenomenon, but there hasn't been as in-depth an exploration that really does try to do justice to the empirical literature as well. So if I had been writing the book just as purely a philosopher of mind and not a philosopher of psychology and cognitive science, it would just be a radically different book; a fictionalized version of the split-brain brain studies. And fiction is great, and you can learn a lot from thought experiments, from just kind of constructing hypothetical scenarios and thinking through what would be true in them. But on the other hand, I think the nice thing about real life is that real life actually is more surprising than fantasy. You've heard the expression, it's something like, you know, “this is so crazy it had to be true.” I think you see this a lot in cognitive neuropsychology, in the study of the psychological consequences of brain damage. Certain psychological phenomena that people would have thought were impossible, that couldn't possibly happen, certain capacities that people might have thought couldn't possibly come apart, they happen. They come apart. One of the, kind of, insights I tried to develop in the second half of the book where I'm arguing that, despite containing two thinkers, a split-brain subject is one person, the basis of that argument is that these two thinkers lack the capacity to distinguish themselves from each other. I see it as a part of the capacity for self-consciousness, but it's a much, much simpler part of that capacity. I mean, even an incredibly simple organism has the ability to distinguish itself from things that aren't itself. That's how organisms can tell when they're being grasped by, you know, a predator and struggle to remove their own body from the predator's mouth. Split brain subjects - you have these two thinkers that are capable of recognizing themselves as psychological beings, but they can't tell each other apart because they share one body. That enabled me to then look at, OK, so what does the capacity for self-destruction alone get you? Suppose you have two beings that have the capacity for psychological self-consciousness, self-consciousness in the philosophical sense, but what they lack is the capacity for self-distinction. This might be the only case in the world that would have allowed me to kind of formulate that question and try to explore it, because, again, normally a lot of beings lack the capacity for self-consciousness, but they all have the capacity for self-distinction. Split-brain phenomenon is unique because you have these two psychological beings that are co-embodied. That really do share a body. I never would have arrived at even that distinction between self-consciousness and self-distinction if I had not been diving pretty deep into the empirical literature. Meanwhile, I think if I had tried to explore it from - if I had just been a cognitive scientist trying to work from - I mean, first of all, I don't even think I would have had the professional liberty, necessarily, right? I mean, I would have still, at this point in my career, really been trying to prove my experimental chops rather than being able to try to synthesize a lot of existing empirical literature on the split-brain studies and philosophical literature as well. I always hugely appreciate running into neuroscientists and psychologists who do appreciate philosophy and find philosophical questions interesting. I think the reason everyone is so gripped by the split-brain cases are because of certain philosophical questions the studies raise. And I think it was only coming from the background of philosophy that I could address precisely those questions, precisely that puzzle that makes the split-brain phenomenon such a fascinating topic to everyone, to experts and laymen.


AARON CAIN: I think I just figured it out. You're the corpus callosum.

ELIZABETH SCHECHTER: [laughter] That's right.

AARON CAIN: The two halves wouldn't make sense…


AARON CAIN: …the philosophy and the cognitive science couldn't come together without you linking them up and getting them to talk to each other.

ELIZABETH SCHECHTER: Yes, I love it. I'm putting that on my website.

AARON CAIN: Elizabeth Shechter, this has been fascinating for my entire brain, both halves of it. Thank you so much for speaking with me today.

ELIZABETH SCHECHTER: Thank you, Aaron. Thanks for inviting me.

AARON CAIN: Elizabeth Schechter, author of Self-Consciousness and Split Brains: The Mind's I. Elizabeth Shechter is an associate professor in the Department of Philosophy and in the Cognitive Science Program at Indiana University, Bloomington. I'm Aaron Cain. Thanks for listening.

For more information about Profiles including archives of past shows, go to Profiles is a production of WFIU and comes from the studios of Indiana University. The producer is Jillian Burley. The studio engineer is Michael Paskash. The executive producer is John Bailey. Please join us again next week for another edition of Profiles.


Elizabeth Schechter

Elizabeth Schechter (Photo Courtesy of Ron Jautz)

Elizabeth Schechter is an associate professor in the Department of Philosophy and in the Cognitive Science Program at Indiana University, Bloomington.

Much of her work centers on issues of psychological unity, including personal identity, self-knowledge, the unity of consciousness, and the nature of belief. Schechter takes on these questions and more in her book, Self-Consciousness and Split-Brains: The Minds’ I.

Before coming to Bloomington, Elizabeth Schechter was in the Philosophy Department and the Philosophy-Neuroscience-Psychology (PNP) Program at Washington University in St. Louis. Prior to that she was a Mellon Postdoctoral Fellow at Oxford University. Schechter earned her Ph.D. at the University of Maryland and her B.A. at Vassar College.

She spoke with host Aaron Cain in the WFIU studios.



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