Is Reality a Controlled Hallucination? - with Anil Seth

thank you all, thank you martin, thank you for coming, it's a pleasure to be back in a really packed conference room after the last 18 months or so this morning you all did something that was fundamental to the nature of the human condition, They made a transition. from being unconscious to being conscious and we do this every day when we wake up and yet we don't really know what that means, we don't really understand what the transition from unconsciousness to consciousness is, actually how consciousness occurs , of course. one of those central ideas that has been driving at least Western thought for the last few thousand years, mostly the preserve of philosophers and artists, and as always, and all these kinds of topics, scientists don't like it when leave aside, etc.

In recent years, scientists have really had a go at this, what that means is that on topics particularly where they could be described as opinion-rich and data-poor, there has been a lot of very bad work on consciousness in scientific fields. and philosophical. domains in recent years I'm just going to quote tonight's speaker this was said by a prominent Cambridge psychologist when he went to study there in 1989 he said that consciousness is a fascinating but elusive phenomenon that is impossible to achieve specify what it is, what it does or why it evolved, nothing worth reading has been written, thanks for coming, no, that's a joke, um, professor

anil

seth

, he is a professor of cognitive and computational neuroscience at the university of sussex, he has written this fantastic. book called Being You, which I think is really destined to be a classic and really is one of the clearest thinkers who fuses philosophy, neuroscience and computational models to really try to get at what has been described as the difficult problem of consciousness: what it is We will be, but I think it is best described by its own coinage, which is the real problem with consciousness, as always with these talks.

I was going to talk for about an hour and then we would have half an hour of questions from you. We in the audience don't have roving microphones so you're going to have to raise your hand and shout and I'll repeat the questions and we have like a thousand people watching at home so I'll be monitoring the chat please be polite and ask questions from the internet that's all from me. All that's left for me is to introduce tonight the speaker, Professor Annel Seth, thank you Adam and sir, thank you very much, wow, there are real people, real people, amazing. so i don't know much about being you, but being me feels really weird right now.

I haven't been to a conference let alone give a talk for over 18 months and here we are, here I am, in this beautiful historic building with wonderful people at the launch of my own book and it feels very disconcerting, but it also feels fairly good. Am I the same person I was two years ago? I mean, how could I be? I have spent the last 18 months practically at home. On my own, this is certainly not my home, but it has been a radical disruption to the flow of events and social interactions that normally define my life.

It seems to me that I am the same person. There seems to be a strong continuity between me. then and me now and that continuity in the sense of self that is a big part of what it means to be anyone, to be me, to be you, now there is a well-known phenomenon in the science of perception called change blindness and while I have been talking about The image behind you in the background has been slowly changing. How many of you noticed the change? I hope some of you have done it. I hope the people in my lab have noticed the change.

I can not say it. I can not see them. Not many of you are here, but many things have changed in that image. This is from a colleague of mine, Michael Cohen, in the United States. That's how it started and that's how it ended. I still don't know how. many things change in that image is this is a classic demonstration is is um many things change how it started how it goes how it started how it goes uh your perception changed but you didn't perceive the change that's what reveals the blindness of change reveals that change is not just something that happens to perception.

Change is part of perception. We perceive change in the same way we perceive color, shape, smell other things in the world around us. Now I think the same applies to the experience of being a self. of being any self, in fact, applies even more and in the book I call this personal change blindness, our brains and our minds are oriented by evolutionary design to perceive ourselves changing less than we actually do because we we perceive ourselves to control ourselves. To keep us alive, the experience of being me or being you is a kind of

controlled

hallucination

designed to keep the body functioning.

The kind of key message of the book and this talk is that we perceive the world around us. and ourselves within it through and because of our living bodies, this is the center of what I call in the book this idea theory proposal, the rise of the beast machine, that we have conscious minds and sentient cells because and not despite our nature as living beings. machines, then the challenge that is on the table, the challenge that motivated this idea and the challenge about which nothing worth reading has yet been written, perhaps is that of understanding the consciousness of understanding this relationship between a system physical material like the brain and the body and the private. intrinsically subjective and big, beautiful world of subjective experience and being a self within it, how does that happen?

Well, as always, it's best to start with a definition, and my favorite working definition of consciousness comes from philosopher Thomas Nagle, who said that an organism has conscious mental states if and only if there is something like being that organism is there something like being that organism. there is something like being me there is something like being you probably there is something like being an elephant or a bat or a kangaroo, but there is probably nothing like being a table, a chair, a laptop or a glass of water, no Nothing happens with those systems, that is all experience of consciousness.

It is also important to say what consciousness is not. It is not the same as simply sensitivity towards the environment, this Venus flytrap goes about its business without anything happening, there is no need to assume that there is consciousness in this plant, it is not the same as intelligence when alphagus defeated lee Sidol in 2016 there was no need to be aware of what you were doing, it's a very complicated machine learning program, you don't have to be aware, it's not the same as agency, these people at Boston Dynamics keep building these incredibly scary robots that give the impression of running. very complex goal directed behavior but again there is no inner light there is nothing in the universe for one of these systems a little more controversial when we think about human consciousness I certainly don't think consciousness is the same as having a completely reflective self you know your I, that means you know that you are conscious, you know your name, etc., that is something that is a little more conscious.

Experience is simply the presence of any experience, in fact you can think of it as the space in which all experiences appear and then the question comes again: how does that happen? How is consciousness related to this mess of wet electrochemical wear and tear inside our skulls? Faced with this problem, it seems almost difficult for science to solve it and, in fact, the philosopher David Chalmers has expressed it very clearly with his famous or now infamous cardiac problem of consciousness. He puts it like this. He says that it is widely accepted that experience arises from a physical basis, but we do not have a good explanation of why and how it arises.

Why does physical experience arise? processing gives rise to a rich inner life, it seems objectively unreasonable for it to be so and yet it does the intuition driving this is that even if you worked out what charm has caused the easy problems and these are the problems basically how does it work brain? a mechanism, how all its complex circuits receive information and deliver information, guide our behavior, implement memory, all these things, even if we solved them all, the difficult problem of why something happens in consciousness would remain pristine and intact, we would not would lead to nowhere. intuition now faces a difficult problem some people some thinkers have leaned towards seemingly quite radical approaches or potential solutions we have bread psyche consciousness is fundamental and ubiquitous it spreads in the universe like a thin layer of jam this is a pancake and this en The problem with panpsychism is not that it seems crazy, the problem is that it explains nothing, cannot be tested, and does not lead to testable predictions.

I don't like it very much, as you can see on the other end. There are certain views that say oh no, actually we are, so we are completely wrong about this sense of mystery when it comes to consciousness, there is nothing really mysterious at all, it's just a mechanism, that's all. there is, consciousness does not really exist, at least not. how we normally think of it now I think of this position it is a bit like a medicine if you take the right amount it is very useful because it opens a small gap between how things seem to you and how you can actually understand them. but if you take too much and you think consciousness doesn't exist, that's a place I don't want to go because I think consciousness for me, for most of us, is really all there is, without consciousness there is nothing at all. , so my approach and it's not just mine, I just call it that's the approach of I think most people who work in this area is called the real problem of consciousness takes the bull by the horns consciousness exists recognizes its intimate dependence on the brain and the body and trying to figure out what is going on and the particular way I like to try to do this is to try to ask how the mechanisms and processes in the brain and the body explain, predict and control the properties of the consciousness and these can be functional. like what can we do because we are conscious when I am conscious I can do various things I can I can drink you know see this glass of water I can drink from it I can ignore it I can throw it over my shoulder there are things I can do by virtue of being conscious, but there are also a phenomenology to it, there is something that it feels like to have a visual experience that is different from what it is like to have an emotional experience or a smell, to experience a smell, if you explain, you predict this. properties, then you are getting somewhere in a science of consciousness.

This is not the hard problem because it is not trying to answer the question of how you experience magic from a mere mechanism, and it is not the easy problem because you are not simply explaining. the brain as a machine any conscious experience swept under the rug has many answers there are many other similar traditions I just want not to pretend that it is completely new at all I am very influenced by what is called neurophenomenology associated with the Chilean neuroscientist Francisco Varela, who died ago 20 years, a similar idea and the underlying intuition is that this way, instead of solving Chalmers' heart problem, we dissolve it and there is a historical analogy for this that I find somewhat useful and that is fading before long.

Years ago scientists, biologists, chemists were perplexed about how science could explain life, life seemed to be something beyond what could be explained in terms of mechanisms, this of course led to vitalism, this idea that We needed a vital element, a spark of life, now we don't think. In this way, there is no need for that hypothesis from a special source and my hope and belief really is that the same will apply to consciousness instead of treating it as a big scary mystery that needs someone to deliver a eureka moment of a solution by examining their properties separating them looking at them explaining them in turn we will dissolve the difficult problem of consciousness just as we dissolved a difficult problem of life in the past now life is not the same as consciousness this is certainly very true, I think one of The most important differences between life and consciousness is that you can't really put a conscious experience on the table and look at it.

Conscious experiences are intrinsically subjective, they exist for the organism that has them, this is a problem that makes consciousness difficult to study how to get the right kind of data, but that does not make a science of consciousness impossible, since some people sometimes claim that it just means it's quite challenging, you can still get data on what people's experiences are like and you can try to predict. explain control, just as in the study of life people identified different properties that living systems have, things like reproduction, homeostasis, metabolism, we can do the same with consciousness, it's not just a big deal, we can Thinking about it in a number of different ways and the ways in which in the book and in my work with my lab in Sussex I focus on different aspects.there is a conscious level how conscious are you when you are conscious in general terms the difference between being under anesthesia and being awake and conscious as you are now so there is conscious content when you are conscious, you are aware of something in this moment, your conscious is my voice and of this somewhat strange experience of being surrounded by many people, but there are colors, shapes, sounds, sensation of your body against the chair, those are the contents of your experience and especially the last one is related to a very important aspect for many of us and certainly for me the most essential of conscious content is the experience of being a self, the experience of being you, so let's begin.

I'm going to go over a few things about each of these domains of consciousness and we'll start with the conscious level, which in the brain explains the difference between being awake and conscious and just being a piece of living flesh with nothing happening to you the first thing you do. The thing to say about this is that the conscious level is not the same as waking now they normally go together right you can go to sleep and you might lose consciousness a little bit and you wake up you come around um, but there are times when the two dissociate when you are asleep and you are dreaming, of course you are conscious when you are dreaming, the dream is conscious but you are asleep and on the other side there are states like the vegetative state or unconscious waking state where people after an injury severe brain go through cycles of sleep and wakefulness but nothing seems to be happening that doesn't seem to be anyone at home, there seems to be no consciousness happening so consciousness is not the same as being awake so what we need to do is to ask what in the brain goes along with consciousness and not just with wakefulness and among many different approaches to this and it is a long and very short story, I will only tell you one approach that we have been following in the laboratory and now with colleagues in cambridge and london who are here dan and pedro media pedro and fernando and so on tristan uh we use this measure called lempel ziv complexity this is basically very simple it really sounds complicated, it's really the same as taking a digital photo and compressing it into a short file that you can email and it does this by basically counting the number of repeating patterns in a photo or in any type of data and seeing how many composition patterns, yes it asks questions about that later complicated thing at the bottom but it basically just says how many different combinations of ones and zeros there are in any data set, count the number of those libraries you need to recreate the original and that is the length of the complexity in general terms, you can think that the higher it is, the more diverse, the more patterns there is in the data you are looking at and if you apply this measurement to the brain data instead of a photo you see some interesting things this is work with adam barrett and michael shartner in sussex and our collaborators under anesthesia excuse me for the complexity level goes down when you lose consciousness your brain becomes more regular more predictable as you lose consciousness the same thing happens during sleep this is another data set that we recorded or our colleagues recorded from electrodes placed deep in the brain.

What's interesting here, I wonder if this is going to work, you can see it, oh yeah, look at that, that's clever, you can see the awake rest here. and remote rapid eye movement sleep are basically the same patterns there, meaning that this measure is the same for the stage of sleep where you are likely to be conscious and dreaming as it is when you are awake and conscious, but at other stages of the dream. I'm going to do this all the time now it's much lower and finally in what was a pretty surprising finding when we applied the same measure with colleagues at imperial to data from people in the psychedelic state, whether it was LSD here but also psilocybin. or ketamine, the other goes the other way, the brain becomes more diverse, more unpredictable in the psychedelic state, this was often written about in the media when scientists discovered evidence of a higher state of consciousness which is not really what we were trying to say.

There is something that can be measured in the dynamics of the brain, although that is characteristic of the psychedelic state, which is interesting now. These are a first step toward tracking the neural fingerprints of the conscious level in the brain, but they don't necessarily explain anything about why that happens. should be the case and to get them to where we are, with this kind of work it's about developing measures based on this idea, but that actually give us a principled reason for why they should be in accordance with conscience and this. is based on the work that actually first inspired me to pursue consciousness science as a career.

I tried to get into it anyway in the late 1990s, I was doing my PhD and I read these articles by Gerald Adelman, who became my boss in San Diego, and Julio Tanoni, one of his protégés, who is now a real leading figure in the field and he had the idea that every conscious experience, every conscious experience you have, has two properties, they are both integrated, it's all in one piece, like there's nothing, experiences in pieces. They're not all happening separately from other parts right now, it's all happening in a unified scene, but it's also very informative, so every conscious experience you have rules out the simultaneous occurrence of a vast repertoire of possible alternative experiences you could have. . in a very strictly technical way, it's informative, it's reducing uncertainty in the space of all the experiences you can have.

These are two very distinctive things about consciousness that never or do not easily apply to other things related to biology. that we might want to explain, so we want measures in the brain that reflect these two properties while also capturing this middle ground between information and integration and this is something we've been working on in other groups for two years. for several years now and that this is still at the level of just developing the actual measurements and again these are the last equation, the only equations are going to appear in all the talk and they really are not particularly irrelevant. just to show that there are now ways to write things that capture this middle ground and the idea is that we can test these measures with brain data and see how they behave right now;

They don't perform as well as the simpler ones. measures, so there is still a lot of work to do and one of the things that we are moving towards and this is the last thing I will say about the level is to also build measures that capture the emergency. This is another super interesting, quite controversial one. It is a difficult to define phenomenon in which a set of parts, like in this case a flock of starlings, the flock seems to somehow have a life of its own, it seems to be more than the sum of the individual birds that make it up, this is a we.

You'll recognize when it's happening in a situation like this, but it's surprisingly difficult to figure out how you can mathematically determine where and when it's happening in other systems - for example, if your neurons fire in complicated ways, how can you tell if it's like a flock ? about birds or not, it's a pretty difficult question to ask, so with Lionel Barnett, Fernando Rosas and other people here we have been trying to develop ways to quantify that and see if that can also act as a measure of the conscious level. Okay, so this is a brief tour of these things, so I'll move quickly to conscious content, the question of how our conscious experience comes to be populated by all the different things that are, at any given moment, the objects that people place , colors, shapes, etc. go ahead and here's another demonstration to come down from the heady heights of equations and so on um oops I don't know if you've seen this before if it really works let me see yeah, again um what I'd like you to do is focus your eyes on the black cross on the center of this image and try not to move your eyes and try not to blink.

I'll do it too, but it's a little difficult from here while still seeing how many people watch. that the magenta patches are gone, the green patch is that this is the kind of thing you couldn't do on zoom all last year, just like asking people questions, it's brilliant, I love it, so now it's flashing and move your eyes and you have a look around of course the magenta patch has returned there is no green patch this is called the lilac hunter illusion and what is actually happening here is a few different things there is something called troxler fading when there are things with indistinct edges on the periphery of your vision.

They tend to disappear from your experience. There is also apparent movement when things turn on and off near each other. The brain infers movement between them and there is color opposition. The opposite. The brain has a color space and the opposite in the color space. magenta is green and The reason for this is actually quite interesting because you get magenta by mixing red and blue light, but if you think about the electromagnetic spectrum, red and blue and green are in the middle, red and blue in the middle. the edges, so if the brain turns red and blue it's like expecting the green cells to activate too, but it doesn't because you're just mixing red and blue, so magenta is not green, so when you see the afterimage green, what you're really seeing is No, no, no, green, okay, well then the way to understand that nonsense is that your brain is a prediction machine.

You know there is a gap. You can already see that there is a gap between how things are and what you experience and the idea that I. What I've been saying is that this happens because the brain is always making sense, trying to make sense of what is essentially noisy, ambiguous, and uncertain data. Now imagine being a brain for a second, imagine you are trapped inside this bony vault of your skull. trying to figure out what's in the world now there's no sound in the skull there's no light in the skull it's dark it's silent all you have to follow are these electrical signals that are only indirectly related to things in the world, whatever it is Whether they can be like that, perception has to be this best-guess inference process where the brain combines this uncertain, colorless, soundless, soundless sensory information with the best, with its prior expectations, its prior knowledge about what the world is really like. world and that is what we consciously see. the brain's best guess of what's out there is some sort of high-level abstract description of what's happening there's another equation damn, I forgot what does this mean what does it translate to if you think about what does this actually mean to the brain does it mean that the brain is doing something called Bayesian inference Bayesian inference is a very old idea of ​​probability in statistics and mathematics it is a kind of reasoning under conditions of uncertainty everything is uncertain we can use Bayesian statistics to find out what could be happening in the pandemic to try and locating a lost submarine is a kind of reverse reasoning from the effects to what you think caused those effects, as in this case the effects are the sensory signals that hit our eyes and ears and the causes are what is in the world that gave rise to those sensory signals now, it's actually generally very complicated to do anything, you know, writing it, making a computer to get any machine or doing anything based on inference is really complicated, but one way to do it at less getting an approximation is doing something called predictive processing and this is the idea that this is what the brain does when it makes a best guess and the reason it does it is because it's a way of doing Bayesian inference to try and find out. what caused your sensory environment and the idea of ​​predictive processing is very simple: you have signals going in both directions in the brain, one is cut off, one direction is from the outside in, from the world deeper and deeper into the brain and the The other direction is the other direction from the inside out, from the brain to the senses and back to the world, and if you take the signals from the inside out and think of them as predictions, those are the predictions about what is happening and the outside. -in signals of what comes in and filters up through the brain, those are just prediction errors, they just tell the brain the difference between what it expects and what it gets and by continually trying to minimize these prediction errors , get rid of them, update your predictions or change the data to get rid of prediction errors, these predictions collectively sit on the brain's best guess about what's out there and that turns out to be very close to what Bayesian inference is. , but beyond that kind of nice mathematical equivalence there is a real Here's a conceptual message that I still find quite disconcerting when thinking about it.

I mean, we're so used to thinking that perception is this process of just reading sensory cues.It seems as if the world is pouring into our minds through the transparent windows of our senses, but it's the other way around, what we perceive comes from the inside out and the sensory data simply keeps our best perceptual guesses in check, so perceptual content is conveyed by top-down predictions and bottom-up sensory signals simply convey prediction errors, so the green arrows are the most important, um, skip, skip this, we don't need it. Now, if you start asking what the evidence is for these kinds of proposals, there are some and we've made some.

In the lab, this is an old study with a former postdoc of many pinto. What we do here is show different images to each eye so that one eye can see the image of a face that appears gradually and the other eye can see initially. this changing pattern of blocks of colors that gradually fades and if you show them to separate your eyes, the brain instead of combining them in a kind of mess, starts with the most dominant one, so you only see the changing colors and then after After a while, the face breaks through and that's what you see.

Look, the prediction you can make is that well, if perception is conveyed primarily by predictions of what the brain expects, then if you tell the person the word face so that they expect a face, then they should see a face more quickly. and more accurately than when We're not expecting it and that's what we see in the data so that people see more accurately and quickly what they expect to see compared to what they don't expect to see, but that's a kind of psychophysics that Can be done. in the lab and that's fine, but it doesn't really bring us that close to our lived experience, this rich panorama of perceptual experience is so doing that is one of the things that we are doing in the group now I like to call it comp It's a term a Bit complicated, I know, but I like to call it computational neurophenomenology.

I mean, I really should call it something else, but this is just the idea of ​​using computational models to try to build this bridge between what's happening in the brain. and what our experiences are like and we're doing this right now focusing on unusual experiences like a good way to understand the system in general is to look at it when you press it and that's why it behaves a little bit differently than normal and in particular in the vision we have this phenomenon of something like a

hallucination

now this is an image of a face in the cloud that we are all familiar with in some way we see faces in clouds we can see faces and toast we can see faces in basically anything that the brain is strongly wired to be sensitive to seeing faces um oh, we can even see faces in churches and what's happening here suggests that the brain has a strong prediction about faces, so can we understand?

We can try? and simulate that in some way and this balance is what happens when you increase the predictions a little bit, so this is quite old work now with Kesake Suzuki and others in the lab where we took one of these very well-known neural networks. This is just a neural network that takes images and tells you what's in them, all the information flows from the image up, but you can turn it around and you can fix the result and basically say something like dog and then run it backwards and change the image so in that case what you're doing is projecting a prediction onto a pre-existing image and if you do that and we did that in a widescreen video and we played it through headphones so people can put the headphones on and they watch around them and what they see is a world full of dogs and dog parts and we call this the hallucination machine and if you actually look at it through headphones it's surprisingly convincing and it's not, some people say this is a bit mind-blowing and It's probably not, but it's definitely unusual and something is happening.

It's not just photoshopped dogs in this image, there's a canine character emerging from the image in all sorts of interesting ways and this is what happens if you are. This is a simulation of what happens. If your brain has too strong predictions to see a dog, then what we're doing now is just going through again to bring it to, we're taking this further and trying to simulate different types of hallucinations. Now hallucinations are a complicated concept, lots of them. People have many different types, particularly people with Parkinson's disease or certain types of dementia, they can have very complex hallucinations where there are entire scenes in people, objects and places, other types of hallucinations can be very simple patterns and shapes and nothing more than that.

So now we have a more sophisticated set of neural networks that we connect in many different ways and what we can do now is simulate different types of hallucinations. So what you see here, each of these images, is like a starting point. There's a bird, a mushroom, a lamp, a volcano and something that's some kind of flower and, um, the second row down is a little blurry and that's deliberate. What we are simulating are hallucinations that happen when people lose central vision, it happens in something called hi-hats. Bonnet syndrome and if we run the system we will see that we end up with very different types of hallucinations in each of these cases, so this is where we can be a little more specific about the mechanisms underlying the different types of perceptual experience.

I think this brings us a little closer to understanding how experiences are constructed in our own brains. We are also coming full circle by finding people with these conditions who experience these hallucinations in real life and simply asking them to match. the output of the model with what they encounter in their daily life so that we can calibrate what we are doing with what people actually experience, so this way of thinking leads to the idea that hallucination is a type of un

controlled

perception, it's what happens when the normal business of inferring what's out there by balancing perceptual predictions with prediction errors goes a little off the rails, and in turn, what that means to me anyway and I heard this phrase for the first time by chris frith uh, you heard it from someone else you've never been with. able to discover where it originally came from is that perception perception is a kind of controlled hallucination now this is often misinterpreted as saying that perception is a statement that perception has nothing to do with the outside world that everything is made um you know go stand in front of a bus, people tell me and see if you still think perception is a hallucination, it's like no, control is just as important here, the way we perceive things is dominated around the world in all kinds of interesting and useful ways for the organism but I like this phrase because it simply underlines a continuity hallucination is not a completely different species it is the same underlying process it is just the balance between predictions and prediction errors the The brain's best guesses have lost their grip on the world and people see things that other people don't now in the book.

I'm trying to take this idea much further than just seeing dogs on the Sussex campus or seeing a face more quickly, and the most important statement here is that this way of thinking applies to all of our experiences. of time applies to experiences of color, sound, touch, taste, but also to more fundamental things like the sense of time and duration, whether a visual impression feels like an object or not, and, ultimately, whether the Things somehow seem real, even that is an aspect of perception. This experience we have infers that what we perceive really exists, just as change is another aspect of perception, the image on the back was trying to give a sense of real world experience, it was one of the few summer days in Brighton. that was beautiful in the water and the next part and for me the most interesting part is when you take these ideas and direct them inwards within yourself and recognize that the self is also a form of perception, now it's quite natural to think that maybe that the self is what perceives that you have a world out there the sensory data comes from the world there is a self that in some way is the recipient of this data that forms perceptions that reflect the way the world is, but in

reality

it is not So.

Don't think that it is like that at all, the self itself is another form of perception, it is another type of controlled hallucination, but very special because it is the experience of being you now. The first implication of this again is not something new, it is just the The self is not a thing, this is another small division between how things seem and how things are, what they might seem to us in our normal life, unless we are suffering from a mental illness of some kind or something, that the experience of being a self is unified. it's just you and you going from one place to another or from one zoom meeting to another and it's the same you that is there during the journey all the time, but there are many ways in which we all experience being a self, there is the self corporal, the experience of being a body simply being alive and identified with this thing this thing in the world this object that is your body there is a place where your body ends and the rest of the world begins there is the experience of perceiving the world from one perspective in first person somewhere behind your eyes maybe we know that this can go away because people report things like out of body experiences where they see themselves from an external perspective, there is the volitional self, the experience of performing actions, decide to do something, be the cause of things that happen in the world.

I often think that this, well, free will is related to this, we can talk about free will later, it's kind of a rabbit hole and ultimately there are higher levels of the self, there is something like the narrative self where the self it is associated with a set of memories with a persistent identity over time, a name and then there is the social self. I think many of us have been missing this part of ourselves that depends on being with others. Part of what it is to be me is refracted through the minds of the people I meet.

I know who I interact with and all these different aspects of oneself seem to be tied together, they all seem to be part of one piece, but they can be separated in many ways and we know that especially, I think, from people's writings. Like Oliver Sacks, they are beautiful illustrations of what happens when one part of the self changes, but the other parts can remain in the book. I'm talking about a person called Clive who dressed Clive Waring is a musicologist and he had a very, very severe form of amnesia. a very serious brain disease that caused one of the most dramatic and profound memory losses due to amnesia ever recorded.

He couldn't remember anything new. He lived in what was called a permanent present tense of about 10 seconds for years. He was 80 years old and now. It happened in the '80s, but the rest of him is still there and I never met him. I knew him secondhand, but there was a famous event where he returned to a choir that he used to direct and was able to. Conducting the music with the fluidity that made him seem whole again. I think it's a wonderful story. I'm going to talk a little about the bodily self. This is where we have done it.

I think that's where my interests have focused the most. In our groups, this is the experience of identifying with this object in the world that is your body and a more basic experience of simply being a formless living organism. Now the idea, of course, is that these experiences of having and being a body are perceptual constructions, they are best guesses based on the brain, like everything else, and there is a very famous illustration of this that I think many of you You may have seen it called the rubber hand illusion. What happens in the rubber hand illusion is that in this case it is a volunteer.

The guy in blue hides his real hand behind a partition, he can't see it, and a fake rubber hand is placed in front of him, which can be seen. Then the experimenter, the guy in green, takes two paintbrushes and strokes both hands simultaneously. and what happens to a lot of people, not all, but what happens to a lot of people when you do this is they report this slightly strange feeling that the fake hand is kind of like maybe a little bit part of their body. um not completely, but maybe a little. a little bit and if you pet them out of time that doesn't happen so this has been I actually use it in a lot of talks it's like or I used to do it as a fantastic example of the brain making a better guess about what their body is and isn't. , You can see it here.

I forgot to start in the movie. It's always fun to see. They are petting it and there is a way to test if it really worked, which is to use a kitchen utensil. yeah, it worked, look at that, so there's kind of a nice story here where you can think that yeah, the brain is getting evidence that all the sensory information is coming through. I see. The brain sees a hand. She feels touched. The hand looks. sort of like a hand, where a hand should be, so now you're making your best guess. This couldbe part of history, but what is it if not one of the fascinating lines of work that has been happening at Sussex, especially with my leadership of my colleagues Pete Larson? and zoltan dienos is that that's not the whole story, in fact, it may not be part of the story at all.

Pete embarked on the largest rubber hand study in the world, probably a couple of years ago, doing the rubber hand illusion with about 400 college students in these sort of rubber hand factory farms that were set up in Sussex at the start of the pre-pandemic academic year, so we did the rubber hand illusion on a bunch of people, but at the same time we also measured something called suggestibility, now that everyone has it. I've heard of hypnosis, right? And hypnosis is not just a stage trick. We all differ in how suggestible we are. We all have a tendency that if someone encourages us to do something or to wait for something to happen, or to wait or experience something if we are very suggestible, we will be more likely to do that, we will have that experience and it is a very stable trait and it turns out that this correlates pretty strongly with the rubber hand illusion, so you can see that line is one that's not a statistically appropriate Line that I Photoshopped into the graph on the paper, it just goes up that way, but basically, how much The more suggestible you are, the stronger the illusion of the rubber hand is now, those two colored bars here because that is compared when you caress in time and outside. time and you might say aha but there's still a big difference um well yeah but actually and this is another important work that Pete has done, people expect there to be a difference if you tell people what you're going to do in the rubber handles I'm going to caress your hands whether in time or out of time, what do you expect to feel?

People know what they should experience and therefore it is not surprising that there is always a difference between them in psychology. This is a very old problem. of demand characteristics that we always worry about how we control what people expect to happen because people who do psychology experiments are really annoying, they always try to figure out what you want to happen and they do it or, more likely, They do the opposite, um, but everything. This is part of the same thing, it says that what we experience is still this construct, but there are many different factors now, not only is there the sensory data, but there are all the things that the brain is bringing into that context to expect, is it?

OK? Now, in the last part of the talk, I don't want to talk about the experience of the body as an object, but the experience of simply being a body, this basic basic state of what it feels like to be alive. I call this this idea of ​​being. a beast machine that I will explain why in one moment having a body is one thing and by the way, I mean there is something really distinctive about that, in other cases we know from many neurological cases that there are cases like This thing called somatoparaphrenia where people who have had a specific type of brain damage will experience their actual limb that they have, you know they still have maybe a right arm, they will experience it as if it belongs to someone else and that experience is sustained in a very powerful way.

They'll try to jump off the bed, they may just not believe it's their arm even when you point out that it's attached to their shoulder, so that's the kind of strong experience you never get in something like the hand illusion. eraser. Well, so it's this body ownership thing, it's fundamental to oneself, but there's also the experience of just being a living organism and we don't think about this much or at least I didn't used to think about this. a lot, but I think it's really at the heart of what it means to be you and highlights another way of perception.

We are very accustomed to thinking of perception as having primarily to do with the outside world. You open your eyes, you can hear, he's thinking. We don't know what there is in the world, but there is a whole variety of perception called interoception and it is about the brain perceiving and regulating the inside of the body. If you think again about what it's like to be a brain, it doesn't have direct access to anything, whether it's in the world or in the body all it receives are sensory signals electrical signals don't come with labels like oh I'm from the heart I'm from the kidneys it doesn't work like that um so this concept of interception refers to the various ways in which the brain perceives its own physiological condition and if you think about it, that's fundamentally what the brain needs to do, you know they're not there to write poetry, However nice it may be, or devising marketing plans for it by following the calling circles, they are there to keep the body alive, but how do they do it well?

They face the same problem, there is no direct access, so this perception of the body from the inside follows the same principles, at least this is what I think follows these principles of prediction and prediction error, but now this dance between prediction and prediction error is developing primarily within the body itself. This is this concept of interreceptive inference and there is a crucial difference between perceiving the body from within and perceiving it. things that are in the world like this this glass of water that is that interceptive predictions these predictions these perceptions predictions about the body it's not about discovering things, it's much more about controlling things so what does it matter about the state of my body?

From the brain's perspective it's not about where my lungs and kidneys are and what shape they are, what color they might be, but how well they are doing their job to keep me alive now and in the future, whereas when I perceive the outside world I I mean ultimately. That's what it's also for, you know, my vision ultimately works in the service of me staying alive, but more immediately, yes, I need to know where things are, if it's coming at me, if it's leaving, it's going to eat me, it's going to eat me. Whatever, interceptive predictions are basically doing something fundamentally different and I think that's why perceptions of the body from within feel very different and have a very different character than the experience of the world around us when we think about experience of the world around us, its objects in places and people and things and smells, but these embodied experiences, emotions and moods, things that feel good or bad, or are more likely to be good in the future or more likely that they will be bad in the future.

I mean, that's a pretty limited view of emotions, but it kind of boils down to that. Ultimately, things are good or bad in some way. Now this idea comes together and in the book we go a little deeper into this. It brings together many different ways of thinking about the brain. I think for me there's something very exciting, but A very overlooked tradition called cybernetics back in the 1950s, when people first thought about computers, they didn't just think about computers for playing chess or playing go. or reason, there was another line of thought completely integrated at that time about the systems they could control. things like it was right after the war, so things like radar and guidance missiles were critical.

This idea that a good control system has to have tightly coupled feedback, it has to be very sensitive to predicting errors and it also has to have a model of the system you are controlling you have to be able to make predictions about it, you need to know what will happen to you in the future, so the idea is that any worthwhile control system in a complex situation will involve this prediction process. The heating system at home or the air conditioning system for the audience in the United States can work very simply, if it's too cold it turns on, if it's too hot it turns off, but when it comes to something like the body, it doesn't.

It's enough. that you don't want to wait until your heart rate has skyrocketed before you decide to try to dilate your blood vessels or do something else or that your brain decides to do that you have to predict in advance in order to keep things stable in physiology, this is called allostasis , achieving stability through change, so this idea has a very long origin that motivates this idea of ​​predictive perception from the perspective that this is how the brain controls the things that this achieves, I think it is more fully elaborated and beautiful apogee in this idea of ​​the free energy principle that was developed by Carl Fristan, who is also here, and this is the idea that pretty organisms, especially organisms, are basically things, anything that counts as a thing stays at bay. itself over time, it does not dissipate anywhere. in nothingness in organisms or things that are maintained over time, just think about like a fish, a fish swimming in the water is still a fish because it is in the water, if you take a fish out of the water and put it on the table, you know. they dissolve into mush after a while, living systems in particular remain in states they expect to be in long term they try to stay in a very small repertoire of possible states they could inhabit I'm not turning into mush and my brain My job is basically to try to stay in this very small state of all the possible states I could be in, most of which would be mush, and it turns out that this very basic imperative to remain a thing gives rise to this rich machinery. prediction. and prediction and control error, so to summarize the latter, I think I've already hinted at it, but the reason this is particularly relevant to consciousness is that these different types of prediction explain why different perceptions are the way they are. . visual perception underpins visual perception underpins visual perception we see objects in places because that's what matters that's the character that's what visual predictions are about interceptive predictions underpin embodied experience how well things are going things are going wrong I'm anxious am I out of the race eventually or not, they have a very different qualitative character, but I think it all comes down to the different types of predictions at play and this brings us back to where we started this idea of ​​self-change blindness.

I feel relatively stable. over time, even having good photographic evidence to the contrary, why is this happening well, but why is it happening well? I think one of the reasons for this is that if the predictive perceptions in my brain that are geared toward keeping me alive work well, they basically expect me to stay stable. They hope it doesn't change over time. The stability of the self becomes a self-fulfilling prediction because to remain stable to stay alive I predict that I will not change the subject. We are subjectively blind to changing itself for this reason and this applies not only and this is a guess this is not I'm not trying to say this is like oh we have this experiment test this I don't think it makes sense and um and it's the way I have come to think and it applies not only to these basic experiences of simply being a body but to all of our experiences of being oneself, there is something very useful if the brain is trying to keep the body functioning for a long time to experience the The self as unified and stable is a good way to ensure that what the organism does is always drawn towards that as the most likely outcome, so that the subjective stability of the self as a whole becomes a self-fulfilling prediction that we predict so that exists, so let To conclude where we have been, what we consciously see depends on the brain's best guess about the causes of the sensory signals in the rubber hand illusion, and other experiments of this type give clues that this is It applies not only to the world around us but also to the world. self but of course we have suggestibility and all these other explanations too, but the experience of the self is also a thing and that the predictions that matter for the body are not just predictions about the body as an object but about controlling and regulating the state internal physiological. of the body, this means to me that all of our perceptions are fundamentally based on this imperative to stay alive, these predictive mechanisms that emerged during evolution and development, they all have their origin in this primary imperative to keep the body functioning, we perceive the world around us. us and ourselves within it through and because of our living bodies, this means again that consciousness is actually very closely related to life, it is no longer just a historical analogy, there is a close relationship between being alive and being conscious , and this is where we can finally mention to Cartes that it always has to appear in any unconscious but it is not because of his dualism here it is more because of what he said about the relationship between life and the mind and he said about other animals and I always feel bad for giving him a hard time because he lived in difficult times and was brilliant, but he said this about animals without minds to direct their bodily movements.

Animals must be considered as thoughtless and unfeeling machines that move like clockwork, so to be alive wasirrelevant to the type of rational conscious minds. that humans had now, I think it's completely backwards. Conscious identity arises because no, despite our beast-machine nature, we now end in the last few minutes with just a couple of implications of this that are detailed in more detail in the book, of course, one is free will, the free free will is something you know, we can talk about consciousness and how mysterious it is, but free will sometimes seems like another level of mystery entirely, does it depend on whether the world is deterministic or not? just another type, my point of view, anyway, free will is just another aspect of the perceptions that make up being a self, it is the perception of being the core, it is the perception of performing actions that seem to come from within when We experience a voluntary action, it feels like Although we are making something happen that didn't have to happen or that I could have done differently or in the world, I am intervening in the universe in some way, that doesn't mean that that is really true in the same way as when I experience the color red.

It doesn't mean that redness is actually present in the world, it means that it's my brain's way of making better sense of what's happening. voluntary actions are real. We do things that have primarily internal causes, but there is no need to postulate some uncaused cause that abates. it comes from wherever and changes the causal structure of the universe, that's creepy nonsense. The second implication is that we all see the world differently now we know this a little bit at the extremes, we could say someone with psychosis or someone with synesthesia or something they experience. colors when they see black letters, but I think we all experience the world differently and that difference is often unseen, it is hidden because we often use the same words to describe the same things, but those things, as they appear to us, will be subtly different, we inhabit our own unique inner universe and beyond the human there is a vast space of other minds that I spent a week with. octopuses back in 2009, um, which is one of the most incredible weeks of my scientific life and also I write about this.

When you spend time with octopuses, you realize that the particular way we experience being a self simply does not apply to a creature as strange as the octopus that can taste with its suction cups and that its arms are almost like autonomous animals and also has Three hearts and jet propulsion and blue blood are very strange and finally there is the prospect of intelligent machines. Some people think that as AI continues to get smarter and smarter, there will come a point where the lights will turn on and it will become sentient. Now I don't think this is true at all if consciousness is closely tied to being alive, that's what matters.

It's not the same as intelligence, that's just part of our human-centered arrogance, where we think we're intelligent and we're aware that the two must go together, you don't have to be sensitive to suffer, no, you don't have to. be. smart to suffer, but you may have to be alive. I love this Alex Garland x Machinima film that explores these ideas about when we infer consciousness in other things, so if we're worried about artificially creating consciousness, maybe we should worry more about things like brain organoids. This new neural technology where people grow brain-like structures on a plate is advancing rapidly and there was a paper I just saw the other day with a conscious organoid here, I didn't actually do that. and that was my kind of play on yesterday's speech, but this organoid actually has light-sensitive fossae, you know, the beginning of the eyes and the neurons inside of it respond.

These are still relatively simple, but they are made of the same material as They are not made of silicon, so there is no longer a big unknown about what it takes to be conscious. With my colleagues Tim Bain and my Cell Massimini we have written about the perspective of island consciousness and there is another case with Michael Carter, who is also here where we think about patients who have basically had operations that leave one hemisphere of their brain alive but disconnected inside the skull and with that happy note I have just returned to the central message which is that we perceive the world around us. and ourselves within it through and because of our living bodies and before I close, I would really like to thank that this is, of course, the way I know, all the work that I have done in the laboratory has been done by others.

People and I have been very fortunate to work with a brilliant laboratory over the last 10 or 15 years in Sussex, but it has also shaped my way of thinking about everything, it's not just the experiments, the ideas that have emerged as a collective. So I want to thank everyone that I've worked with and the last thing I would say is that I know it's a little unusual, but the book is dedicated to my parents, of course, but I just wanted to dedicate this particular talk to a former doctor. my student paul chorley uh paul died in 2013 shortly after finishing his thesis and although some of you here might remember him a little bit, he was a lovely man and a brilliant intellect too and I sadly missed him and I loved him. to keep his memory alive a little bit so this talk is for Paul and I leave you this summary of everything and thank you very much