top of page
  • njikomes

Anil Seth: Consciousness, Perception, Hallucinations, Selfhood, Psychedelics & "Being You"

Full episode transcript below. Beware of typos!

Nick Jikomes

Professor Anil Seth, thank you for joining me.

Anil Seth 2:56

Thank you for having me. It's a pleasure to be here.

Nick Jikomes 2:58

Can you start off by briefly describing for everyone who you are and what you're doing?

Anil Seth 3:03

I'm a professor of cognitive and computational neuroscience. So my main research interest revolves around probably what's one of the oldest questions in the book, which is consciousness, the nature of subjective experience, how do conscious experiences relate to depend on emerge from the wetware the biological stuff inside our brains, and bodies. And for me, this is a, an intrinsically interdisciplinary exercise. So in my research with my colleagues and lab members, we range from philosophy, mathematics, to psychology, brain imaging, virtual reality, lots of different approaches that try to retain as a common focus, how to explain properties of consciousness in terms of the brain and body.

Nick Jikomes 3:54

And so just diving right in, what is consciousness in your view? How would you actually define it? And what is the so called real problem of consciousness that you define in your book,

Anil Seth 4:05

it is worth starting with a definition. And the definition that I like to begin with, and this is in the book, too. It's really very simple. And it's more a way of preventing us talking past each other, rather than an exhaustive, ultimate final endpoint of an explanation. So consciousness for me, is very simple. It's any kind of subjective experience whatsoever. It is what you lose when you fall into a dreamless sleep or go into general anesthesia and it's what returns when you come round again. It is just any kind of experience now that philosopher Thomas Nagel, put it also very simply, and very arrogantly, he said, for a conscious organism. There is something it is like to be that organism. You can think of this in a more intuitive way of saying it feels like something to be a conscious organism. It feels like something to be in may also be you or to be a hippopotamus probably, or an orangutan. But it doesn't feel like anything to be a book, or a table or a chair or an iPhone, there's nothing it is like to be those things. So that's how I would define consciousness. And I think it's important to keep it that simple, because it makes the point that consciousness is not the same thing as intelligence, it's not the same thing as behaving in a particular way. It really is just coextensive with intrinsically private, subjective experience.

Nick Jikomes 5:34

And so you analogize the problem of consciousness, and how it might come to be solved or understood, with a couple of other problems that it took a long time historically for people to to grapple with. One of them is the problem of life, and what is life? And what does it mean for something to be alive? And the other is thermodynamics, just temperature? What does it mean for anything to be hot or cold. So I'm wondering if you could kind of compare and contrast those and give us you know, a very brief history of how those ideas came to be understood, in order to set up how you think the problem of consciousness can be approached?

Anil Seth 6:11

Sure, that's a good way to do it. So there have been these two previous mysteries in science, and they are very different. Both are very different from consciousness. But I think they're both instructive in potentially different ways. So life, at one time was thought to be beyond the remit of physics and chemistry was thought to require some additional special source and add on Vitara spark of life, something that could explain the difference between the living and the nonliving, there was a whole philosophy, espousing this perspective, the philosophy of vitalism, and it seems quite intuitive isn't in fact, it's still intuitive. For young children, even today, this idea that there's something special, something qualitatively different about living systems that exceeds their nature as machines of any sort. Now, the problem of life, our understanding of life in science wasn't arrived that by finding this special source, and the spark of life, as conceived by vitalist, doesn't exist. Our understanding of life progressed by incrementally, accounting for all the diverse properties of living systems, things like metabolism, homeostasis, reproduction, and so on. And as scientists became able to account for these properties, explain them predict when they're going to happen, intervene to control their expression, the apparent mystery of what makes the difference between the living and nonliving just evaporated, there was no need to appeal to a special source anymore. So this hard problem of life was dissolved, it was not solved directly, it went away through incremental understanding of the properties of living systems. That's a useful analogy, I think, for consciousness, because in consciousness now, and certainly this has been the case for a long time, many people, not all people, but many people have a similar perspective about the potential for material systems, whether they're brains, bodies, computers, whatever, to explain, consciousness, consciousness just doesn't seem to be the kind of thing that could be explicable in terms of physical mechanisms. So there must be something that makes the difference, that magics experience out of near mechanism and equivalent to the annovi town to the special source. That's how it seems, but perhaps it's not going to turn out that way. And perhaps by incrementally, explaining, predicting, controlling accounting for the different properties of consciousness, in terms of physical mechanisms in the brain and body, then the apparent sense of mystery that attends consciousness may also evaporate, dissolve, and perhaps eventually disappear completely in some puff of metaphysical smoke. Now, I don't know whether this will happen or not, because we haven't got to the end of this road yet. But that's the pragmatic bet that I'm placing in a science of consciousness. Now, the other analogy is thermodynamics, as you mentioned, heat, and that had a very different resolution. So he was again quite mysterious. At one time, in the history of science, people wondered whether it was this substance that flowed between objects to sort of reach some equilibrium.

People also really struggled to struggle to figure out how to measure it. And we didn't always have accurate thermometers. And there was a kind of circular problem here. Because in order to develop an accurate thermometer, we have this intuitive idea that things are hot or cold, but in order to put numbers to that to have an accurate thermometer We needed a scale of temperature. But in order to get a scale, you need some sort of fixed point or some pre existing confidence in some measurements. And how do you do that without that a thermometer and so on. So it's a very arduous process by which accurate thermometers, bootstrap themselves into existence. But when they did, then we were able, or scientists at the time were able people like Boltzmann, and so on, were able to develop a theory of thermodynamics. And this had quite a different character to how theories of life ultimately developed in thermodynamics, we now understand heat to actually be something else. Heat simply is the mean molecular kinetic energy of the molecules in a substance, roughly how fast the molecules moving around bumping into each other. And so and this is a very reductive explanation, heat turns out to be identical with some other lower level property. Could consciousness be like that? Could it be not something that's a constellation of different properties like life, we don't measure life in the same way, there's no single scale upon which you measure how alive a creature is. different properties get expressed to different degrees in different living systems, and there are gray areas. But with temperature, there is a scale, it's one thing and we can measure it and the ability to measure it meant that we really understood what it was. So you could take that perspective on consciousness to that it's going to turn out to be identical to some other thing that we could potentially put a number or a series of numbers to. And I think, My My bet is that consciousness turns out to be something a bit more like life than like temperature. But I do find it fascinating to hold these two possibilities in mind. And certainly, from where I sit, the science of consciousness in general, could go either way, it's there. There are people, indeed, who are putting forward theories that are more aligned with the temperature view, and others, like me, that are putting forward ideas more in line with the life view. But of course, consciousness is different from both of these things. So I don't want to overextend these parallels. The biggest difference is that consciousness is intrinsically subjective, you can't put a conscious experience on the table. And everybody look at it and observe the same thing. It's a very problematic thing to study methodologically. But there are these two different ways in which science has dealt with previous mysteries. And I think it's worth bearing in mind that even though something seems mysterious now, with the tools that we have now, doesn't mean that it will always seem mysterious, and there are these different potential ways in which the apparent sense of mystery can go away.

Nick Jikomes 12:57

Yeah, I do think that these analogies work really well. Because, you know, in the case of life, even if you don't know, the history of biology there, you know, it wasn't like one day, some scientists published Nature paper, and it was like, Alright, we've we figured it out, it really did just sort of incrementally evaporate as we came to understand a lot of the complexity that is associated with living things as opposed to nonliving things. And then the other thing that strikes me about the thermodynamic analogy is, you know, we have equations for thermodynamics, we really do understand heat and you know, heat, as as we as we know, it is identical with with the movement of atoms. And no one says, Well, yes, but the movement of atoms is merely a correlate of temperature, a very close correlate, but no one sort of asks the equivalent question asked for consciousness, which which is, well, yes, you appear to have the equations and and these tight correlations and observations of the physical world. But these but But why, but why is it the mean movement like that, you just simply stop asking that question at some point, when, when the level of precision is high enough, I suppose where this breaks down is that all of these things are happening within the domain of experience, right? The only thing that can be taken a priori is that there is conscious experience. So even the notion that I think all thinkers on this topic today, although not historically, agree that there's like one, one kind of thing in the universe. You and most people scientifically would say, well, it's all it's all matter and mind emerges from matter. But the converse view, which I think is the minority view, is no no, you've got it backwards. And anything that you can say about the material world is actually an inference you're making from your own conscious experience, which which is prior to that.

Anil Seth 14:46

Right? Those are two opposite poles that have defined the philosophy of mind for centuries now, right? You have sort of physicalism materialism, empiricism, if you want to give it its own sort of philosophical context. So what we know about the world comes through our sensory organs. But the VAT is this idea that this goes back to David Hume, and so on. And knowledge comes ultimately through our senses. But that's itself premised on this idea that there is a physical world out there. And we just have indirect access to it. And this is a line of thought that goes from Hume from Plato, really to Hume to Canton and into the present day. And the question there, as you put it, is, indeed, how do conscious experiences relate to or emerge from this material world, that we only have a reverse kind of indirect access to through our sensations of it? The other perspective is idealism. Bishop George Berkeley, you know, there's, there's many traditions that espouse this in one way or the other. The problem isn't how you get mind from matter. It's how you get matter from mind so that the mental stuff is primary now. And that I think that yeah, it's this is not the common starting point for science and or for neuroscience either. But there are lots of other options out there, too. It's not just those two dualism, of course, is the obvious one made famous by Descartes, that there are two modes of existence, there's a physical mode of existence and a mental mode of existence. And the problem there is how do these two domains interact? And dualism I think, is really interesting, because it still seems quite intuitive. So if you ask people, you haven't spent years thinking about consciousness, which of the available metaphysical perspectives wouldn't describe it as available metaphysical perspectives, which way of thinking about the relation between mind and matter seems most appealing? For many, it's dualism, because it just seems as though conscious experiences are immaterial. Now, the fact that it seems that way, of course, is not a good guide to how it's actually going to turn out. But there are still then other perspectives like pan psychism, that consciousness is fundamental and ubiquitous, and it has the same sort of status as mass or energy or charge in physics. This is neither idealism, nor materialism, it's just building consciousness in as an additional components of matter if you'd like. So you can think of it maybe as a kind of materialism, but it's, it's a very atypical one. And in the landscape today, I think you'll find people that adopt all sorts of these perspectives. But the majority of neuroscience, my view, at least implicitly assumes a kind of physicalism, a kind of materialism. But you can still, you can still go about your business as a neuroscientist. Figuring out how the brain relates to consciousness without necessarily buying wholesale into materialism, because you might just say, well, there's perhaps some limits on what this perspective can account for. But the way I see it, it's not really the question I asked myself is not which of these positions is a priori, the right one, or one of these are going to be the answer. For me, they're all just sort of starting points for how we conceptualize the challenge. And this is why I think I'm a kind of modest, slightly agnostic, physicalist, that this is a perspective that's been very successful in science, there are good reasons to think that consciousness is different, more challenging. But there are also good reasons to think that by following the physicalist perspective, but taking conscious experiences seriously, taking seriously they exist, and they have properties of different sorts, that we will make a lot of progress, whether we'll get all the way or not, I think is still an open question.

Nick Jikomes 19:00

So running with this physicalist frame, let's talk about the gradations of consciousness that people are all intuitively familiar with. And the analogy here with heat would be you know, you can stick a thermometer in something and read out what the temperature is, no matter what it is, is there an equivalent for consciousness? Is there some way we can measure the level of consciousness that appears to be there and that we all intuitively experience right, we've all fallen asleep and woken up drowsy, and then become more alert later in the day. But is there actually a way scientifically to measure the level of consciousness someone has?

Anil Seth 19:35

There is, but it's unclear whether it's going to really play out along the lines of the temperature story. I think the temperature story gives us a nice if you like historical ideal for how these things play out, but it's unlikely that everything will play out this way. So to what extent do we have that already? Well, we have various ways of putting a number to the level of consciousness in humans, exhibited by human beings or human brains. There's this there's this particular measure called the perturbation complexity index developed by my chair, Massey meany and Giulio Tononi quite a few years ago now. And this is still I think the closest we have. And what it involves is injecting a pulse of energy directly into the brain using a method called transcranial magnetic stimulation, or TMS. And then using electroencephalography, EEG, to record the echoes of the pulse throughout the brains, energy goes in bounces around the brain in some way. And you measure that bouncing with EEG. And you can put a number to how complex that bouncing is, if you if it's very simple, if you just stimulate the brain, and you get a single pulse that just just spreads out in the brain, like throwing a stone into a still pond of water. It's a very simple echo, so very simple number that you put to that. But if the echo bounces around a lot, then it's more complicated. And you put a higher number to it in a very quantitative way. That's the perturbation complexity index, it's indexing the complexity of a perturbation to the brain. And it turns out, if you do this in the right way, and use the right kind of mathematics and so on, you get a number that is very useful even in clinics to tell whether somebody is conscious, even if they might not be able to express it in behavior, there are a number of clinical conditions like the vegetative states, where, from the outside, it looks as though the person is completely unconscious, even though they go through sleep and wake cycles. So they may wake up, but they show no sign of orienting to their environment or responding to command or making voluntary action. But that might just be because the brain is unable to control these kinds of behaviors. It's usually assumed that if they can't exhibit any of these behaviors associated with consciousness, then they're unconscious. But using methods like the perturbation complexity index, the PCI clinician is now able to detect cases of residual consciousness. These are patients who appear unconscious from the outside, but show these complex brain responses when you examine their brain dynamics in this way. And what turns out to happen is that people who look like that tend to be the ones that recover. Okay, so for you for your talk. It's an agnostic, it has proven it has diagnostic and prognostic value. It's not a treatment, but but it has some some validation in the clinic for sure. But the thing is, this is not the same as the full temperature story, right? And I think there's two reasons for that. One is that consciousness, even conscious level, even the scale between awake, aware and anesthesia, and calm and whatever, it's not going to be a one dimensional thing. There are many different aspects of being conscious at all, it's not going to reduce to a single number. And the second thing is, it doesn't really

go as far as these wholly reductive stories that that we were telling about temperature, where we know that it's equivalent to the that heat is equivalent to the mean molecular and kinetic energy of the molecules or atoms. This is still fairly indirect. So in practice, it means it's quite hard to generalize. Like if I took this TMS thing and applied it to, I don't know, Dolphin brain or something or or a B brain, it would be very hard to interpret the answer what the number would mean. But where we are with heat, for instance, it makes perfect sense to talk about the temperature at the surface of the sun, or out in instant interstellar space. Now we know what that means, because the story runs all the way through to fundamental physics. And there are some theories in consciousness research, like Giulio Tononi is integrated information theory, which attempt to make it run all the way through. So that it would make sense to talk about the level of consciousness exhibited by any system, whether it's another human, or another animal, or some sort of cloud of interacting atoms somewhere out there in the void. The problem is, it's very, very difficult. Well, it's kind of infeasible to actually make those measurements in practice, so that remains rather speculative.

Nick Jikomes 24:44

So it's really intuitive to think about levels of consciousness, just given our everyday experience, right. You know, if you tell someone that when you're drowsy that we can consider that a lower level of consciousness than when you're alert and awake. That make that feels correct. That makes perfect sense. You're doing additionally saying that neuroscientists have ways of measuring brain activity that seem to map to this. Even if it's imperfect, it's not going to reduce to one and only one variable. It's more complex than that. But the quote unquote level of consciousness one has has something to do with the complexity of the brain activity that one can measure, if we take it in the other direction. So if we start from the normal waking state, there's many people who claim to have reached higher states of consciousness, either through a contemplative practice, or through psychedelics or something like this. And I know you've done some collaborations with people who study the effect of psychedelics on the brain, I'm wondering if you could talk about those non ordinary states of awakened consciousness and how you think about them in this context,

Anil Seth 25:46

right, good. It's tempting to use this colloquial language of higher states of consciousness. But I think it's also quite dangerous or certainly misleading. The use of these terms in describing psychedelic or spiritual experiences, it's very freighted with sort of social meaning that it's somehow more valuable or seeing more, experiencing more widening, opening the filter, all these sorts of things. And they, for me, they're interestingly different, they're not higher or lower, or less or more, they really me underpin this, this notion that even conscious level is multi dimensional. So for instance, in a state of dreaming, when you're asleep, and having vivid dreams, are you more or less conscious than in waking the waking state, sometimes, on some dimensions, you might be more conscious, because you might have more vivid perceptual and emotional experiences, but you tend to lack this capacity for self reflection about what's going on about monitoring the situation. So you in along that dimension, you you're less conscious when you're dreaming than when you're awake. Now, for the psychedelic state. super interesting. I mean, it's it's a very powerful manipulation, they use small pharmacological intervention into the brain leads to these systematic phase of and profound, profound alterations in conscious experience. How to think about that? Well, the the collaborative work that we've done with researchers like Robin cart Harris, he was at Imperial. Now in San Francisco, we measured, not the perturbation complexity index, we didn't have the the TMS thing going, but we just measured few like the ongoing bounciness of the brain activity without perturbing it. And that amounts to measuring more technically, the signal diversity of activity in the brain, how random it is, how many different patterns of activity, can we find in the ongoing activity of the brain. And by this measure, which we can just call a measure of complexity. The psychedelic state is higher scores higher than the baseline waking state. And by the same measure of complexity, things go down when you look at states of unconsciousness, like sleeping and anesthesia, and so on. So you could say, Yeah, psychedelic state is a higher state of consciousness, because that goes above the baseline, whereas sleeping, anesthesia go down. But I don't think that really makes much sense, what we show is that the brain activity is more diverse, it's less predictable in the psychedelic state. That is interesting by itself, because we can start to think of how that explain some of the phenomenology of the psychedelic state in terms of it being more free associating, maybe more predict less predictable at the phenomenological level at the level of how it unfolds in our lived experience. But that's not a full characterization of what the psychedelic state is. And there's many things going on in the phenomenology, phenomenology of psychedelics. Another experiment we did, using the same data was to show that there's less information flow between different parts of the brain, in the psychedelic state. So there's less coordination between different regions, which again, might have something to do with the sort of loss of global coherence that sometimes happens, or the dissolution of the boundaries between the self and the world. So there's still early early days, but yeah, I just pushed back quite a bit on the simple story that the psychedelic state is a higher state. And there's a there's a very direct reflection of that in some simple metric of brain activity.

Nick Jikomes 29:52

Yeah, because even even the word complexity as a measure here is a bit problematic, right? Because if I was measuring all the pixels on my screen right now And then we just let them all become completely uncoordinated and it became white noise. You know, you could call that a more complex signal because there's less predictability there. But we wouldn't say that the screen in a state of like noise like that is, you know, it's not it's not complex, it's less complex in another sense, right? Sort of our intuitive notion of what complexity in order is, it's related to this notion of order and disorder. So how do you think about that?

Anil Seth 30:27

Yeah, that's, that's a really good point. And I think that's where a lot of the action is, right. So complexity, it turns out is complex, there are many different ways to think about it. And I think the most intuitive probably the most stable notion about complexity is that it somehow picks out this middle ground between complete order. And complete disorder. If things are totally random, like visual snow, I tend to think of that as relatively uncomplete acts, because there's no structure. But on the other hand, if it's just a black, if it's a grid of parallel lines, then we also say it's not complex, because it can be described, very simple. There's too much this space in the middle, where there's both diversity, and order, both randomness and structure. And there's been a whole history of mathematical and statistical approaches to doing this. And some of them, we've tried to apply to to brain data as well, I developed a measure, which are called causal density back in 2005, which was deliberately constructed to reflect precisely this middle ground. The issue was, when I applied it to brain data, it just didn't work very well, it didn't, wasn't it, it showed results I wasn't expecting, it just was kind of all over the place, it seemed to be very sensitive to unimportant differences in the data wasn't very informative. And so it turns out right now, that some of the more empirically robust and reliable measures, when applied to actual empirical real world data, just look at one end of the scale. So this measure that goes higher in the psychedelic state that has more diversity, that's just measuring how much randomness there is, roughly speaking, it's measuring something fairly equivalent to entropy. It's like how many patterns there are, and it's not really measuring the structure part of it at all. But it turns out to work quite well. But I would not say that's, that's just clearly a starting point, because even theoretically, it's unsatisfactory because it doesn't pick out this middle ground. And that's one of the areas that our group and others are actively working on. So what kinds of quantitative measures of complexity that are based on satisfactory theoretical principles actually work in practice, too? And why don't the ones we already have worked very well, what what's going on here? Is it a bad idea? Or they're just insufficiently good? operationalization of a good idea?

Nick Jikomes 33:14

Yeah, another thing that strikes me here is just riffing on this idea that that consciousness can't be unit dimensional, has to be multi dimensional. You know, when you guys did those studies, I forget what it was. But I think you gave people psilocybin, and you measured this measure of complexity, and it seemed to go up. And if you've ever taken psilocybin, you know that, you know, especially if you've taken a sufficiently high dose, and you're in an interesting room, and you're looking at things, there's more going on in your experience. When you're in that state, you're seeing things you haven't seen before. And it fits with this measure of complexity or randomness going up. On the other hand, if you were to give people other psychedelics, in some sense, the opposite would happen. So with five, methoxy, DMT, for example, people tend to have a very undifferentiated experience where everything becomes very perceptually and emotionally uniform. And there's this experience of oneness. And perhaps the measure would go in the opposite direction there. And I just wanted to mention that to maybe introduce the notion that people have integration and differentiation. So when we're talking about concept consciousness, these terms come up, what are those mean? And how do we think about them?

Anil Seth 34:18

Okay, but yeah, just on your first point, I think this is also currently in quite interesting frontier is what are the differences between these different kinds of interventions, whether they're different kinds of psychedelics or other, as you say, unusual states of consciousness and how do they get reflected? How can we reflect the phenomenological differences in terms of quantitative differences in brain dynamics? That's definitely an ongoing challenge. But yeah, integration and differentiation. I think it's very continuous with what we've been saying. So this line of work actually is the line of work that first got me really optimistic about the science of consciousness. When I was finishing my PhD about 20 years ago, which is a scarily long time ago, the method in play was we touched on it earlier, it was really based on looking for just correlations between brain activity and aspects of consciousness. Like, if you see a house in a binocular rivalry thing, when there's a house to one eye and a face to another eye, and your perception alternates between face and house, what parts of the brain go along with your conscious perception and what, what doesn't? And what are the neural correlates of consciousness. And that's really important, but it doesn't help explain why particular patterns of brain activity are associated with particular conscious experiences. And then I read this paper, which had come out in 1998, by Giulio Tononi, you've already mentioned in Gerald Edelman, who was my former mentor, when I was a postdoc in San Diego. And it was about was called consciousness and complexity. And it made the point that every conscious experience that we have, is both highly informative, because it's different from every other experience we've ever had or ever will have. Not just It's composed of many different parts, but it rules out a vast amounts of alternative possibilities, just highly informative. This is where the word differentiation comes from it is differentiated from a large repertoire of alternatives. The same time every conscious experience is unified, it's integrated, our experiences unfold as unified scenes, and some philosophers would would pick it that a little bit and say, maybe that's not always the case. But we run with that, for the moment, certainly a normal phenomenology. conscious experiences unfold as unified scenes to every conscious experience has these two properties, integration, and differentiation or information. And so the argument in this paper back in 1998, a really seminal paper was that, well, if that's true of consciousness experiences at the level of experience, and that should also be true at the level of the underlying mechanisms. So if you want to look for aspects of brain activity or structure that not only correlate with consciousness, but also explain fundamental properties that describe all conscious experiences, then this is where we should look. And that's how this whole business of developing measures of complexity that balance these two properties came about people started developing measures, there was measures Bio Lab spawns called neural complexity, then my one few years later, and then others and I think we see this now in the provocative theory, but very fascinating theory of Tononi of the integrated information theory of consciousness, just sort of the the current endpoint of this way of thinking.

Nick Jikomes 38:10

So we've touched on the idea of hallucinations, and, you know, the naive view of perception, just that the average person hasn't thought about it is, when you walk around the world, you're having, you're having perceptions, the world is sort of coming into your eyeballs in a way that's not unlike, you know, a video camera recording what's actually out there. And, you know, you could take a tab of acid or you could have a stroke, something could happen to the to the brain that would cause you to hallucinate and see stuff that's not really there. And yet, you know, very quickly, you run into situations such as optical illusions where you take a normal, healthy person in, in a perfectly typical state of waking consciousness, and their brain is clearly being full fooled. You see something moving on, when you know, there's no actually no actual movement on the page. We've all seen these allusions. And so this brings us to the notion that in some sense, all of our perception is a kind of hallucination. And so can you riff on that for a minute, what does it mean for perception to be a controlled hallucination?

Anil Seth 39:07

Yeah, so this, I think, is where the main arc of the story in the book takes off. And it's, it's based on the initial idea that everything in experience is a kind of perception, whether it's a perception of the world, or of the self, or the contents of what we experience when we are conscious, our perceptions of different sorts. And what is it what is a perception then what determines these contents of our of our consciousness? And it's perhaps natural to think that perception is a process of just reading out what's out there in the world, or perhaps in the body, that you open your eyes, and the world just pours itself into the mind through the transparent windows of the senses. Because that's sort of how it seems that there's a real world out there and We, we sense it. And there's maybe the self is the thing inside the brain that's doing the sensing and forming the perceptions. But there's a problem with this, which is that the real world doesn't come labeled with instructions about how to how it should be read out. sensory signals are uncertain, ambiguous, and they don't have the properties that we experienced their causes having. So color is a really good example here. We experienced colors as being Objective Mind independent properties of the world. But we know they aren't. We know there's an electromagnetic spectrum. And different wavelengths on those spectrum, they don't literally have colors, they're just different wavelengths of radiation. And the eyes happen to be sensitive to just three of these wavelengths. And from combinations of those three wavelengths. The brain creates a universe of distinguishable colors, which we then experience as being properties of the world. So there's a sense even as something as limited as color experience where what we perceptual experiences both less than what's really out there, because the eyes are only sensitive to this tiny slice of the electromagnetic spectrum. But also more than what's out there. Because we don't just experience three colors, we experience a vast repertoire of colors. To color, even though it seems to be an objective property is a construction that requires both a brain and a world and some eyes, although you can close your eyes and dream. But we experience it as being a property of the world. What's the best way to think about how this happens? This is where this notion of controlled hallucination comes comes in. Right? That our perception of color of whatever it is, that could be the books on my table here, it could be the the dark sky outside could be the feeling of the chair, my back all results from the brain throwing out predictions about the causes of sensory signals, and then using sensory signals to update those predictions. So perception, this view isn't a reading out of the world, it's writing, it's a projection, that brain is constantly making a best guess about the causes of its sensory signals, and calibrating those best guesses, using sensory signals from the world. And this changes the game in quite a deep way. Because perception comes from the inside out the top down, not from the outside in. So that's why I call it follow using the word no, these weren't my own words I heard them from from Chris Firth. You heard them from somebody else and somebody else the train trail goes cold after a while. But there's a continuity here with hallucination. We typically think of hallucination as when we perceive something or when someone perceives something that that isn't there, or that other people don't perceive. But in this view, all of perception is a construction. It's just normal perception. constructions are reined in by what's actually out there in the world in ways that a useful for the organism, so that's why they're controlled. And the control in this view is really as important as the hallucination. I'm not saying that the mind makes up reality, or that nothing really exists, no stuff exists. But the way it appears, in our experience is always an everywhere, an active construction.

Nick Jikomes 43:36

Yeah, in you know, in making this notion more intuitive, I thought a great couple of sentences you had in the book, you're just talking about looking at a chair, you just gave a simple example of looking at a chair, and the chair is read and you say, well, the chair isn't actually read in the same way that it's not actually ugly or old fashioned. The surface of the chair is a particular property, it's just the way it reflects light. And your brain is giving you the sort of label of redness as a way to track that property of it. And so it's just it's sort of a way that your brain is using to keep track of something. And when you think of perception in this way, it's really interesting. You mentioned a couple terms that I want to unpack for people. So in this view, perception is you said it was top down as opposed to coming in bottom up. What is that? What does that mean? And I think a good example using the book of thinking about this or learning how to think about this is the so called dress

Anil Seth 44:34

right? Yeah, the dress I think many people will remember the dress the dress was this photo of a dress, a badly exposed photo of the dress. Excuse me that half the world seem to see as a blue and black dress and the other half the world seems to see as a yellow and white or a gold and white dress and it's the same photo. So what's what's going on? In a sense, this, this makes very clear that perception is not just a simple readout of the world, because if it was, then why would everybody see this so differently, or at least in these two completely divergent camps, the reason it's happening is because the photo happened to be such that when the brain is trying to make a best guess about what's actually going on, the information is very ambiguous, we normally make judgments about color, not only in terms of the light that's reflected from the object that then is perceived to have a color. But according to the context in which that object is in, if you take a piece of white paper, and if I picked up a piece of white paper, here, now I've got one piece of white paper, it looks white to me, subjectively. But the light coming into my eyes is the ambient light is very yellowish, it's kind of late evening here in early November, and all my lights are sort of indoor yellowish lights. If I took this outdoors, and let's say it was where you are in the States, and it was still daylight, and I took it out, it would still look like a piece of white paper. But the light reflected from the paper into my eyes is now completely different, because the ambient light is bluish. And so there's this process of color constancy imbedded in our color vision, which is actually why color vision is useful. Because we see, we see the papers, having the same property of being whites, independently of the actual light that is reflected because it's reflecting because the brain is taking into account the broader context of illumination. In making its best guess about what the surface of the paper really is like, this is useful if if color constancy didn't exist. We'd be walking around the world and objects would be continuously changing color as it got darker and lighter. And, and people who do a lot of photography will know this is a real pain. How do you how do you take photographs that look, the way you want them, as ambient lighting is continuously changing, the brain just does this and we don't even notice it. And this is why the dress really works, because there's very little context in that photo of the dress. So if the brain is for some reason, operating under the assumption that that photo was taken in a kind of indoor illumination condition, like the one I'm in in my office now, then, the best guess of the actual color of the dress is that it's blue in black. That is the conclusion reached by the actual the tones the colors of the dots on the page, when the brain assumes that kind of illuminant. But if the brain assumes and illuminant is, is a sort of a bluish one, like a lot of sunshine, then the brains best guess is that it's a white and gold dress. So one hypothesis is that we just for whatever reason, there could be many hypotheses about this. And all sorts of experiments bring to this experience different prior expectations about what the the surrounding illumination actually is. And that's why we can perceive the dress in one of two ways. But the really fascinating thing about it, and forgive me for rambling on a bit about the dress here is the level of disagreement that it caused. People who saw it one way really could not accept that other people would see it the different way. And this is very revealing to me because it shows the problems we can get into in thinking about perception. The reason people disagreed so strongly is because the brain projects this color experience as being a property of the real world. And the old philosopher said this Hume said this as well that the brain paints objects with the colors drawn from they said it very poetically, and beautifully. I can't remember exactly how.

But because we experienced these colors as being properties of the real world, then it's very, very hard to accept that son that you're wrong. Because it seems objectively right, we the brain naturally conflates subjectivity with objectivity. And it sort of has to do that because it would be very weird for for perception to work in a way that we experienced our perceptions as being unreal. And there are some clinical conditions where this happens. But the brains to guide behavior adaptively sort of makes sense that The Brain constructs perceptual contents with the character of being objectively real. And given that it's then almost impossible to accept that somebody else might see it differently. And I think there's there's a really fundamental lesson here for society, right? It's a sort of generalization of echo chambers in social media, but right down to the level of perception.

Nick Jikomes 50:23

Yeah, I mean, it immediately reminds me, so the reason that it's not surprising that someone would get so offended, if you told them no, no, you know, this, this is being perceived differently by other people. In some sense, you're wrong about the color of the dress, I think it probably really is akin to the feeling one has when you get into a political disagreement with someone, and what you're effectively saying to the other person is no, you're wrong about your perception of the state of the world. And this gives such a deep, emotional feeling with negative valence that, you know, it can almost feel life threatening. And we're going to come to that in a little bit what all of this stuff about perception has to do with emotion and regulating our own bodies. But I want to talk first about a special kind of perception that most of us take for granted most of the time, which is that we are selves perceiving the world, that perception is happening to us, and you say in the book that that's not quite right, the self, the feeling that you are you is itself another kind of perception. And if we go with the line of thinking that you've been taking us down so far, having a perception of yourself has something to do with the brain making a guess about the state of things. And so what is that exactly?

Anil Seth 51:39

It's pretty much as you described it. So it's just as we can get away from the initial idea that perception of the world is a process of reading out the self reading the world out through the eyes and the years, we realize now that no perception of the world is this, this constant, this construction, this dance between prediction and sensory prediction error, keeps the brains predictions in line with the world. The same applies to the self, the self, is no longer needed to be the sort of recipient of this process. Our experience of Salford is another part of perception, the brain is making predictions about the body, about behavior, about the past about the future. And at least in most of these dimensions, my argument would be there's a very, very similar process of the brain throwing out predictions and updating these predictions with sensory data of different sorts. And the upshot of that, instead of seeing a red coffee cup on the table is that I experienced, maybe an emotion, or a sense of not particular objects in the world. This hand is my hand, this body is my body, this part of the universe is me, the rest of it is not me. So I think we can think of most aspects of Salford in terms of different kinds of, of perception. And there are many aspects, right? There's low level aspects of being and having a body all the way up to very high level aspects of being a person with a name, and a set of memories, and the cultural and social environment. But the claim here is that all of these restaurants, fundamental principle of prediction, and prediction error, the self is another kind of controlled hallucination in this view.

Nick Jikomes 53:36

One, one aspect of selfhood that we all feel constantly is the volitional aspect. It feels like I am deciding to do things. So you know, I can pick up my phone here. And the sequence of events, as I don't want to give away the punchline here. The sequence of events as I perceive them is, I'm already here, I make my own decisions. I author the thought, I'm gonna pick up the phone, then I execute the behavior. I picked up the phone, then I showed it to you, and and now I'm talking about it. But how much of the sense of volition that is tied to a sense of self is confabulate Tory, that's one of my favorite words, for talking about brain stuff, the brain is confabulating things all of the time. How do you know from a neuroscientific perspective? Do we know if you know the sequence of events was truly the decision was made? And then I did the behavior versus what if I just sort of picked it up outside of the conscious awareness of myself? And then you know, in the milliseconds following the behavior, I just sort of confabulated the story that I decided to begin with,

Anil Seth 54:44

right so there's there's a lot to unpack here. We try and do it without taking six hours to get to every aspect of free will which is always always a risk. I'm not sure confabulation is quite the way I would put it because confabulation connects making up a story after the event. Now there are certain cases where that's a very useful way to describe what people do. And people with amnesia, for instance, will often confabulate what happened because they can't remember what happened. You could argue that memory is an act of confabulation intrinsically. But is our experience of making a voluntary action is that a post hoc story the brain tells itself or is it something else, I think it's probably something else. But it's, it's also not what it might seem. So as you put it very nicely. In many cases, they're not in all cases. But in many cases, when we make a voluntary action, it seems as though there's this particular mental state of intending to do something that then causes something to happen. So my intention to pick up this cup causes a physical series of events, my arm moving in the cup being being picked up to the content, of this experience of volition is partly of causation. So as we can think of we can think of the experience of the outside world is partly determined by experiences of color, though those are partly constitutive of what it is to visually experience the world. The experience of volition is partly constituted by the experience to the mental state is has causal power on the world. But my claim is that it's exactly here the same as color. The fact that the content of an experience of freewill or volition is that it has causal power doesn't mean that this mental state actually has causal power. In exactly the same way that my perceiving an object is being read doesn't mean that the object really is read. It's also a construction. But to take the analogy a bit further, it's not an arbitrary construction, we already have established quite nicely that the ability for the brain to construct colors in its visual interactions with the world is very useful, helps us keep track of, of objects, and the changing lighting conditions helps guide our behavior. So the experience of being the cause of an action is also useful, even if it's not literally true. Useful for the organism in many ways. Why is it useful? Well, it's useful. Because we are complicated creatures, we can, we can do many different things, in any given circumstance, I could pick up this cup, I could throw it across the room, I could just leave the room. We have in engineering terms, what's called many degrees of freedom, we can do many, many different things. Some of the things that we do are very reflexive. If I put my hand on the old hot stove example, it flies away before I've even noticed, I don't have to make a voluntary decision to remove my hand, if somebody hypnotizes me, I might do something without feeling any voluntary control over that thing. voluntary actions

do come from within in a, in a very, very legitimate way. They, they have their causes more within the previous history of the brain and the body, then, in the outside world. If I voluntarily pick a cup up the causes, why I did that stem from my past history, if somebody who makes tea likes tea happens to be in a place where tea is available. It's not that just somebody brought a cup of tea in and lifted it up to my mouth. It makes sense for the brain to be able to distinguish these conditions. And that's what I think experiences of freewill are all about their perceptions of actions that come largely from within and that to me explains all the interesting phenomenology of what voluntary actions are like. So they feel like they come from within. They feel like they're aligned with our beliefs and desires and goals. And we also have this feeling that we could have done otherwise. That's another classic aspect of the experience of volition that I, I could have picked up this thermos instead of the cup, but I didn't I picked up the cup, and then I picked up the thermos. Does this mean I could actually have done differently? No, in exactly the same way again, that content of the experience doesn't justify reifying that content as a property of the world, but it is still useful. Why is it useful? Well, if I picked up this cup of tea, and then I found out that it was cold Well, the next time I might want to pick up the thermos of tea instead because it's probably going to be warmer. So there's a utility in experiencing void reactions the way we do not because they cause things to happen in the here and now. But because it's useful in my view for the brain, when it's facing a similar situation the next time. So we experience, volition freewill, so that we can do better in the future.

Nick Jikomes 1:00:22

So you mentioned in the book that, you know, and thinking about these things, you say that we do not perceive ourselves to know ourselves, we perceive ourselves in order to control ourselves. And this ties into some of the things that you were saying. But it also gets into this notion of interoception, in what having a body has to do with all of your ideas about conscious perception. So can you walk people through what is interoception? And what does this kind of sense have to do with our sense of self and our ability to feel things like emotional states,

Anil Seth 1:00:54

the domain of interoception is really very simply perception and sensation applied to the interior of the body. And we have many more than five senses, it's often thought that we have vision, hearing, taste, touch, smell, and those are the five senses. And that's it. But we have many other senses, we have a sense of where the body is in space, this is kinesthesia, proprioception. And then we have sensory receptors throughout the interior of the body that are reporting things like blood pressure, gastric tension, so on heartbeat, heart rate, the brain has to make sense of these sensory signals to figure out what's causing them. And so the same principle applies these, that's what the argument is that the brain has no direct access to the interior of the body, it has to infer states of the body from ambiguous sensory signals, just the same way as to infer states of the outside world. And that's the process of interoception, the brain perceiving, through in my view, through prediction and prediction error, the internal states of the body. And what's the contents of interoception, just as like when we have make a very Mexican prediction about the causes of visual experience, we experience objects in the world? Well, when we, when the brain makes a prediction about the causes of interoceptive signals, the idea here is that what we experienced is something like emotion, or mood. There's a long history in psychology of thinking about emotion, as perception of changes in the body's physiological state. And, in a sense, this is just taking that idea, and fleshing it out with the language of prediction and prediction, error. So that's how I think interoception then becomes continuous with all these other forms of perception that we've been talking about. But with one very, very important characteristic, which is that when the brain is perceiving the interior of the body doesn't really care where things are, within the body, in terms of their spatial location, or shape or color, it cares how well they're doing and keeping the body alive. Now, brain's primary duty is to keep itself and the body going. And to do that has to maintain things like body temperature in very, very precise ranges, blood pressure, in precise ranges. And it turns out that a good way to control a system is to use exactly the same machinery of prediction and prediction error. But now the Prediction Service set points as targets for control. And instead of updating your predictions to explain away the prediction error, you now make actions to bring the sensory data in line with your prior predictions. So you just change the balance of this dance between prediction and prediction error. This in the literature is called active inference. And by doing that predictions can be used for control. And I think that's what's happening in interoception, the brain is deploying predictions to regulate the physiology of the body and the perceptual content of that process is what we experience as the embodied self.

Nick Jikomes 1:04:21

So is it fair to say that so in a normally functioning person, where you know that they're in the body are healthy and normal? You know, an emotion? How do we think about valence? So we have these built in set points that the body is literally just pre programmed to want to keep us at, whether it's blood salinity, or temperature, or just whether or not my bladder is full? Are the things that feel good? Am I perceiving things to feel good when the body is moving back towards that set points and bad when I'm actually potentially moving away from them? Or how do you think about balance there?

Anil Seth 1:04:55

I think that would be a good starting point. There's there's people now there are many people who know much more than About this specific thing of Valence. Very broadly, I would say that's correct that Valence is going to be a function of some overall assessment about how well the, the, the brain is doing at keeping the body in the state it needs to be in. But there are complications here. So it depends on time scale to, like something can feel bad at one level. But if you know, it's, it's essential for your actual long term survival, maybe it doesn't feel feel so bad. Like if you're running away from a danger, you know, sure, some of your more immediate physiological variables are going to go go haywire, right, your blood pressure is going to go up your oxygen, blood oxygenation is going to change. But you might not feel that as as bad because the context of it is still in line with you staying alive for longer. So valence is not going to be that simple. But I do think it picks out an important dimension along which interoceptive experiences vary.

Nick Jikomes 1:06:05

So these guesses the brain is making, whether they're interoceptive or exteroceptive, their inferences. And you sort of mentioned the idea that when it comes to external ception, you know, if I'm looking at the world, and and photons are coming into my eyeballs, the brain is using that information, basically to find things to parse the world into objects that I can actually potentially interact with. Whereas the interoceptive side of it has a very different character. And it's much more about controlling the body. Is that a fair summary? So far?

Anil Seth 1:06:38

Almost, I think it's a useful way to to describe the two extreme points because vision can be used this way we can, as I can sit here in my chair, and I can I can look around, and I can use vision to figure out what's that. But vision isn't always used that way, extra reception is not always used that way. So if someone throws a ball at me, and I'm trying to catch it, then I don't really use vision to find out exactly where the ball is in three dimensional space in relation to every other object. Turns out when I'm catching a ball, visual perception is doing something that's quite control oriented as well, it's trying to minimize how the ball appears, in terms of its angle to the horizon. So in the case of catching a ball, vision is operating in this controller oriented manner. And there's a long legacy of ideas of this sort. In psychology, too. There's there's perceptual control theory introduced by William Powers in the 1970s, and probably much before then. So this distinction between perception as finding out which we can think of as sort of epistemic perception, and perception as geared towards control, to think of is kind of goal oriented or instrumental perception. That's actually it doesn't map neatly onto extra reception versus interoception. But I do think there's, it's not completely orthogonal either. So interoception, in my view, is more geared towards control, but maybe not exclusively. Like, if you have injury to your body, suddenly, you want to find out where that injury is what's gone wrong. And likewise, an extra reception. While you may be largely concerned with figuring out what's there, especially in vision, that's certainly not always the case, and definitely not the case, when you start moving around in the world and trying to do things, then your perceptual experience of the world becomes quite instrumental to

Nick Jikomes 1:08:42

So in either case, interoceptive or exteroceptive, you're saying that these perceptual inferences are the, the qualia of conscious experience. Is that accurate? That's the hypothesis. Yes. And so can you sort of tie that back a little bit to what we're talking about? more towards the beginning? So so, you know, I have some perception, it's based on some kind of internal or external deceptive inference, it results in some some experience that I have, there's going to be some kind of spatial temporal pattern in the brain that corresponds exactly to that inference. And right, correct me if I'm wrong, you know, no matter what the experience is, there should be some character to that pattern that is distinguishable from patterns that have nothing to do with with what I'm conscious of. And so neuro scientifically, experimentally, in principle, how would you identify those things and tie them to the experience beyond just identifying them as mere correlates of consciousness? Yeah, this

Anil Seth 1:09:44

is really good. So this does take us back to where we started about how we should approach the neuroscience of consciousness in general. So the nice thing I think about this prediction machine view of consciousness is that it does help us go beyond question correlation more towards explanation. So for instance, this whole process that I've been describing of the brain throwing out top down predictions, which then become updated in prediction errors, that's an idea called Predictive processing prediction error minimization. And there's a number of ideas out there how brain mechanisms might actually do this. In fact, one of the reasons this is proposed as a mechanism for perception is it is the kind of thing that brain systems can do they seem well set up to actually implement this kind of process. So this already takes us a little bit more past correlation, because we can now say, okay, what are what's the evidence? Or what kinds of evidence should should we be seeking, that attest to this process actually happening? Can we, for instance, build a computational model of prediction and prediction error, and then use that to identify the neural signals that underpin that process, and then see whether they do indeed go along with different kinds of conscious experiences? That, to me is the right trajectory to go? It is different from saying which what activity in the brain generates consciousness or is identical to it? No, we're asking what dynamical patterns in the brain account for in an explanatorily powerful way the character have different kinds of experiences. So that's the hope, where are we in that, in that, in that trajectory in that, in that search quite early on. And here, I think, again, there's some humility needed, the evidence isn't hugely strong, there's some there's there's quite a lot of evidence as compatible, consistent with this idea. Where we can see for instance, there's some beautiful, quite old now experiments by last nucleon, Glasgow, where he took an image, and then one quarter of this image was cut out. So there was no sensory information coming into the eye for one quarter of the image. But then in a brain imaging experiments, by recording the activity from the part of visual cortex that was taking input from where the image was not, not Korean, his team was still able to decode the contents of the image, purely from the top down prediction, predictive signals that were coming back into early visual cortex, which is good evidence that there's not enough information there in the top down signals to characterize some aspects of what people perceive. But it's very far still from showing that these top down predictions actually convey the detailed content of our perceptions. But this is where work is going there was a paper from blue haze lab in New York just a couple of days ago that I saw, using measures of inflammation flow actually using I think, some of the measures we developed here in our lab, to measure inflammation flow between different regions. And they had access to this really lovely data, where it's called ECOG. So like EEG, but recorded from underneath the skull. And we're able to show that top down patterns of information flow, were very predictive of what people consciously perceived, which again, is very much in line with this idea of the brain as a prediction machine, and as conscious content being conveyed by the top down predictions. But there's a very, there's a very long way to go. But it's really an iterative process of finessing computational models of this process and how they map on the one hand to the phenomenology of conscious experiences, the difference between like controller oriented versus non controller oriented, and then seeing whether those can be used to actually uncover the neural dynamics that in practice underlie these different kinds of conscious perceptions.

Nick Jikomes 1:14:14

So, I think I can imagine your answer, but you know, the way that you're thinking about this, how would you answer the question of whether or not consciousness is adaptive versus epi phenomenal?

Anil Seth 1:14:26

How do you think I would answer that, that it would be adaptive? Definitely, definitely. But it's not I mean, there are at least two ways to understand that question, right. One is this very metaphysical type interpretation that could I imagine a system having exactly the same kind of perceptual functionality, but for which there was no consciousness going on? And here we get back into the, this horrible territory of philosophical zombies and is it possible to imagine a creature indistinguishable from you or me from the outside but which is not conscious? I do You will not find this kind of thought experiment, illuminating no practice.

Nick Jikomes 1:15:05

Because it's like to actually imagine it, you would have to imagine not being able to imagine anything. Yeah, I don't actually, I don't think people actually do imagine such zombies. I think they convince themselves that they do. But how can you put yourself into the mind's eye of something with no mind?

Anil Seth 1:15:20

Right? So there's, there's a lot of there's a lot of, if you go really down into the weeds of what this thought experiment means, at the level of philosophy of mind, it becomes, yeah, that their objections in their accounts or objections, because one objection is, it's not so much that our capacity to imagine it precisely, but this space of what is imaginable. And whether we are taking for granted the current laws of nature or some other laws of nature. But really, for me, the whole trajectory of that thought experiment is just going down the wrong going down the wrong track. In practice, we are conscious, and in practice for as consciousness does seem to be highly adaptive. And then just many reasons to believe why that so conscious experiences integrate back to part of our earlier conversation, a lot of information. Whether this is very formally according to measures of complexity or just more informally, a conscious scene is composed of this massive amount of information about the world and the self unified in a way that makes sense for the ongoing physiological preservation of the organism. You can't be more adaptive than that.

Nick Jikomes 1:16:32

So a related a related issue, I'd love to get your take on, it has to do with what I suppose you would call the the causal efficacy of any particular conscious perceptions or the contents of your consciousness at any given point. And and to put this concretely, there's there's an interesting sort of unresolved problem right now in psychedelic medicine, which is, you know, for those that are unfamiliar, although many, many listeners of this podcast will be familiar, if you give something like psilocybin to certain patients, they can have very, very profound therapeutic outcomes after just one large dose of psilocybin in which they have a full psychedelic trip say. So for example, I talked to this man named John Costa coppice on one of the podcast episodes, after a single dose of psilocybin, he went from, you know, being a an alcoholic, a very severe alcoholic that would drink, you know, dozens of drinks at a time. In other words, to put this in control language, right, he could not control that aspect of his behavior when he was exposed to a single drink. So the problem was, how do you change this guy's brain so that he comes to be able to control that aspect of himself. And he has this one, this first experience, and he has lots of imagery related to his alcoholism, and he sees things that are relevant to his alcoholism. And he stops drinking after that one experience. So So here's the question, for which there's two schools of thoughts currently. One is the actual content of that hallucinogenic psychedelic experience necessary for that person to achieve that full therapeutic outcome? Or was it merely incidental? In other words, you could design a drug that had the same magnitude and an enduring therapeutic outcome, but which didn't have the psychedelic trip to it. And so I'm curious how you would think about that problem, given what you've said so far about the adaptive nature and of these perceptual influences that they are, in fact models for how to control behavior, which in this case, is the goal.

Anil Seth 1:18:31

Yeah, that's a it's a lovely example, actually, to bring up in this context. It's very, as he as you know, it's it's actually very current, right. And in one way, it's current. One thing that sort of surprises me in a way is that there is an active pharmaceutical research effort to develop non psychedelic psychedelics, things that have a similar maybe clinical outcome or mechanism of action, but just don't have the, the subjective components. And for me, this is like, well, it's an empirical question, what clinical efficacy they will have, and it's made complicated by all sorts of things such as the placebo effect, and patient expectations and so on. But fundamentally, for me, there's a deep irony in trying to do that kind of thing. You think about medicines in general, when you're looking for, let's say, you're looking for a new compound to treat a particular disorder. There are typically three things you might look for you want a substance that is not poisonous, not toxic to the body. Ideally, you want something that is not addictive, ideally, so that there's less potential for abuse. And you want something that affects the system in question. You want some if you've got if it's a problem with your digestion, you want something that affects digestive system, she has a heart problem, something affects that that's where you would look for good candidate compounds to To explore for their clinical value. So when we come to something like mental illness, whether it's PTSD or depression, or addiction, what's the system in question that you're trying to effect. It's not just the brain as a, as an unconscious mechanism. It's, it's your conscious experiences of the world, and the self, that instantiate particular patterns of behavior for you as the organism. And it's just interesting to me how for the back in the 1950s, psychedelics were being widely explored for their clinical value. But of course, that was, was shut down. And then it wasn't until 2030 years later, we had these SSRIs, the selective serotonin reuptake inhibitors that became Prozac, and now many other brand names. And it's fascinating to me that the reason that these compounds became widely used was precisely because they did not affect the system in question, you could take an SSRI, and you might feel a little bit anxious, if it's the first time you've taken one or you starting a new course. But it certainly doesn't wildly change your experience. But that's precisely why they were allowed to be used. And there's a deep irony there. So for me, the fact that psychedelics have an effect on your experience is an important part of the causal pathway by which they have clinical efficacy. It at least makes sense to me to think that way. It may, it may, in fact, be that you could, you could still get some effects through non psychedelic psychedelics. But I do think it's likely to be very important, certainly important. Because in psychedelic psychotherapy, there's also this process of integration, right? It's it's really, in cases where it works. It's not just you put someone in a room, you give them a trip, and then they go home now, it's how you integrate the experience they've had. And of course, for that integration process to happen, they have to have had an experience to integrate.

Nick Jikomes 1:22:06

Yeah, I mean, that is the focal point of the subsequent therapy sessions, as I've pointed out elsewhere, and I just thought, I thought your idea is really tied to this in a powerful way. Because with a severe neuro psychiatric condition, it is your ability to act and to feel that needs changing. And so if I think all the things you're saying are an accurate view of what a conscious experience is, it seems to me, at the very least, very unlikely that you would be able to design a therapeutic that had the same the same magnitude of effect, right, but did not have the same subjective effects that that psilocybin and other psychedelics do, I would, I would guess, I mean, my sort of bet on this is, they will engineer nude. I mean, they're already doing this, you will make drugs, they don't have the same hallucinogenic impact. And they will have some kind of antidepressant effect to say, but I don't think it will be of the same magnitude and duration of efficacy.

Anil Seth 1:23:00

I think that's probably right. But also, there's a note of caution on both sides of the argument here, because this example that you had of this, this chap who had one trip and resolved his alcoholism, I think these happen, but they don't always happen. And yeah, you still get relapses in some of the clinical studies now to first double blind, we can't do a double blind study with this stuff. But the first, certainly large scale clinical studies are not showing, you know, cases where everybody dramatically improves in one arm of the study, and nobody in the other. There is an effect. It's it's not as strong, certainly as, as we might have hoped to begin with. There are expectations to SIBO effects going on to so that I think there's, there's there's a lot well, there's still just basically a lot of work to do and in how who, because they're going to be individual variation to not everyone's going to benefit from a psychedelic intervention in the same way. It's a very personalized thing. But that is to me, just to circle back a very reasonable argument that the experience matters and why does it matter? Well, one, one reason there's and this gets back to other parts of our conversation that a psychedelic experience reveals to you in the first person that the way things seem in your conscious experience is not necessarily the way they are. Your perception is revealed. Your perception is revealed to be a construction in the first person in a way that can be quite powerful. That's one reason I think the experiential component is important for its therapy, potential therapeutic outcome.

Nick Jikomes 1:24:56

Now I loved I love the analogy that you drew with a drug that was meant to treat Something about the digestive system directly or indirectly, that drug is going to have to impact the digestive system, because that's the thing whose function is not optimal. But for these kinds of conditions, the thing that is not optimal is, is literally the thing in your brain, quote, unquote, that is responsible for how you act and how, how your experiences feel in the moment,

Anil Seth 1:25:23

right, I mean, the counter argument, again, would be there might be a way to influence the brain, that doesn't affect consciousness, but that still has the same therapeutic outcome, you're still affecting the system in question, which is the brain but you maybe don't need to affect the conscious experience that goes along with particular brain states. And I just think maybe that's the case. But it seems unlikely to me, given this this, I think, reasonable belief that conscious experiences do have an adaptive function, and they are involved in our in our behavior.

Nick Jikomes 1:26:01

So before we let you go, is there anything you want people to know about the new book that perhaps we didn't touch on? Or perhaps some way of summarizing it that you think is appropriate?

Anil Seth 1:26:12

Well, I think you've, I've really enjoyed this ramble through different aspects of it. Of course, we haven't covered all of it, I don't think that would be a sensible idea to do. Many other topics I do talk about in the book a little bit. Go into a bit more detail on these other theories, like integrated information theory and this free energy principle, which is almost a very physics based equivalent when we think about the brain as a prediction machine. Now, what does that really mean when we drive down as far as we can in terms of in physics, and then talk about other animals? What can we say about consciousness in other animals beyond the human, and finally, the possibility of machine consciousness. And just to say one thing about that without giving the whole game away, but this whole idea of consciousness and self being rooted in perceptual predictions that are themselves geared towards physiological regulation, and keeping us alive, to me that that induces an intimate connection between consciousness and our nature as living machines. And that one of the titles that we didn't choose for the book in the end was going to be beast machine being a beast machine. Descartes had this notion of a beast machine and he was trying to use it to deny consciousness or the sun important kind of consciousness to other animals. In the Cartesian view, non human animals were beast machines, they were flesh and blood machines, but the flesh and blood status didn't can endow them with any morally or ethically relevant, conscious status. But I think the view I've come to and it's not just me, there are many other people who've been saying similar things. People like Lisa Barrett Feldman, Antonio Damasio is a big influence on me, Mark Soames, Evan Thompson, that consciousness self life, a strongly continuous, all our perceptions are ultimately grounded in regulation, physiological preservation of the body. And there's no sharp divide between what we might call the mind where and the wetware as there isn't a computer between the hardware and the software. So all this for me puts the possibility of artificial consciousness or machine consciousness in a slightly different light. For me, it's unlikely to just emerge as a function of disembodied intelligence in a computer as we have them now. It's going to be much more tied to the imperative for preserving life status for regular self regulation all the way down. Doesn't mean that artificial consciousness is impossible, but it does suggest that conscious machines might also have to be living machines.

Nick Jikomes 1:29:11

One final thought I would love to get from you is, it's to do with, I'll unpack this a little bit more. But I suppose the question is, what would it feel like? If it felt like we understood consciousness? And is there even? Can we even answer that? So there's this anecdote in the book from victim Stein that you mentioned that it's maybe worth retelling for people? But you know, let's imagine, let's imagine, 50 years from now, we've just made incredible progress in neuroscience. We have so much more knowledge than we do now. And we feel like we completely understand the necessary and sufficient conditions for what creates any given conscious percept. You can inject some pattern to the brain and create trade a percept for someone at will, and all the pieces seem to be there and yet it would probably not feel like we understood it. And so what was that anecdote with victim Stein and his There are some limitations to our own brains that prevent us from ever feeling like a complete story.

Anil Seth 1:30:04

Right? Yeah, this is that's a that's a really nice connection there. So yeah, there is this this beautiful, it's in a way. It's another motif through the whole book. And the anecdotes, it's lovely. So Vidkun, Stein is going for a walk in the garden after breakfast with Elizabeth Anscombe, who's another philosopher, former student and his biographer. And I have no idea about the veracity of this conversation. But it's it's been so reported now that Vic and Stein asks and skin. Why did people think it was logical that the sun rotated around the Earth rather than the earth rotating on its own axis? And Anscombe says, Well, I suppose because it seems as though the sun rotates around the Earth. Seems as though the sun rises in the east sets in the west. And that good Stein says, Okay, but what would it seem like if it seemed as though the earth rotated on its own axis? I love this, because it's not just simply saying that how things seem is not how they are like, it seems as though the sun goes around the Earth, but actually the earth rotating on its own axis, we go from Ptolemy to Copernicus. Vidkun, Stein's point, is more subtle. It's that even when we understand things, how things are, things still seem the same way? They can seem both ways, it seems gonna seem the same way. I love that. I love that point. And I think it applies throughout the topics we've been talking about. And this is something I tried to try to express in the book. That understanding perception as a top down inside out controlled hallucination doesn't mean that I no longer see colors as being properties of the real world. Of course, I do. Things still seeing the way. But at the same time, everything is also changed. But now you've taken it to another level, what would it seem like if it seemed as if we had a complete explanation of consciousness? This is very interesting. I have no idea because we don't have one. I don't think is the case that we have one we just not recognizing it. I just think it is still not a solve problem. There are two options to me here. One is that we have this kind of whether it's a sudden or gradual aha moment, like I Yeah, it makes sense, was complicated, but it makes sense. This is how consciousness arises from the web, wherever the brain, if it turns out to be a sort of materialist physicalist picture. But another possibility is that it never really feels intuitively satisfying. That we have scientific explanations that allow us to explain why particular experiences happen when they happen, what character they have, we can intervene, we can control, we can predict and so on, we can do all the things that scientific explanations typically are assessed on prediction control explanation, but they may still lack this intuitive sense of Yeah. Now I really understand. I think that's a that's a real possibility. Does that mean it's an incomplete science? Not necessarily, because there's a sort of self referential aspect here. It may be because we are trying to explain ourselves something that we instantiate that bar for what counts is intuitively satisfying, maybe implicitly different. That's a possible outcome. What that means in practice is that I don't think we should judge scientific theories of consciousness, first and foremost on whether they feel intuitively satisfying.

Nick Jikomes 1:34:09

Well, and yourself. Thank you for joining us.

Anil Seth 1:34:12

Thank you for a lovely conversation. I really enjoyed it. It's been a pleasure.


bottom of page