So. Are. Hello and welcome to the Oxford Playhouse.
My name is Mark, sister Sautoy. I'm the, uh, Simone professor for the Public Understanding of Science here at the University of Oxford.
And this year, we've got not just one, but two events that we're bringing to the Oxford Playhouse here.
So, uh, next week, on Monday, on the 11th and 12th of November, we've got a premiere of a new play that I've written called The Axiom of Choice,
and which I've just come from rehearsals with a great team that we're putting on.
And so I hope, uh, tickets will be available at the box office as you go out.
So I hope you'll enjoy, uh, me for that's in a week and a bit time.
The theme is all about free will, which is obviously very relevant to tonight's, uh, topic as well.
War and mathematics. But tonight we've got an amazing Simone lecture lined up for you.
Uh, testament to the wonderful speaker we have and the very interesting topic we're going to be talking about.
Um, the theatre tonight is ram to the rafters. So thank you so much, uh, uh, for coming out in such numbers.
Um, tonight's speaker annual. Seth actually grew up around here like myself.
Um, and he said to me just before we came on that, uh, he hasn't actually been back to the Oxford Playhouse, uh, since he was at school here.
So it's wonderful to have him back here, um, on, uh, home turf.
Uh, uh, and he is now a professor of, uh, cognitive and computational neuroscience at the University of Sussex,
where he is also director of the centre for Consciousness Studies.
And he's also the author of this wonderful, uh, bestselling book, uh, Being You.
And tomorrow he will actually be at Blackwell's, uh, at about 11:00, uh, to sign copies.
If you would like to go and get a copy or bring your copy Well-thumbed copy all along and, uh, have a chat to him there.
So that'll be another chance, uh, for you to talk to him.
But tonight, um, he's here to give, um, his, uh, some only lecture entitled consciousness Consciousness in Humans and Other things.
So please give a big Oxford Playhouse. Welcome to our Neil Smith.
Thank you very much, Marcus. And yeah, it's lovely to almost see so many people here.
I can't really see anybody at all because of the lights. But it is it is wonderful to be back.
And indeed today I am going to be talking about this, this subject of consciousness.
Now, consciousness is one of our greatest remaining mysteries.
At the same time, it's a phenomenon that we are each intimately familiar with.
We all know what consciousness is. It's what goes away when we go under something like deep general anaesthesia.
How many people have had sort of deep general anaesthesia?
Quite, quite a few. I can't quite. So for those of you who haven't had it, give it a go.
It's really very interesting. I highly recommend it.
Very existential experiment you can do on yourself.
Of course, we also lose consciousness most nights when we go into a dreamless sleep, not dreaming, but dreamless sleep.
And then consciousness is what returns when we wake up in the morning or come around in the recovery room,
and when we are conscious and when we open our eyes in the morning or in the recovery room, our brains don't just process visual information.
There's another dimension entirely. We see colours, shapes.
We experience smells, sounds, emotions there's experiencing happening.
And a world appears. And parts of this world, within this world, there is the experience of being a self, of being you or being me.
This background experience of being somebody is probably the aspect of consciousness that we each cling to most tightly.
But consciousness very simply, is any kind of experience whatsoever.
It's what makes life worth living. That's the intuitive definition.
I want to just give you a little bit more of a formal definition. This is from a philosopher, Thomas Nagel, and it's the definition that I prefer.
I mean, there's still a lot of disagreement about this kind of thing. Now, Thomas Nagel put it like this.
He said that an organism has conscious mental states if and only if there is something.
It is like to be that organism.
And I think what he means, Meyer, is that it feels like something to just to be made feels like something to be each one of you.
But it doesn't feel like anything to be this, this table or this book or this shoe, or probably this laptop computer or this this wash.
It does feel like something to be about. Although exactly what only a bat will know that, um, for these kinds of things,
for some things in the universe there is experiencing going on and other things there isn't.
Now, one reason I like this definition is for what it does not say.
Consciousness is not the same thing as being intelligent or being able to speak,
having language, or having even this explicit sense of personal identity.
You know, to me that is just any kind of experience count.
Now, putting it this way raises this problem,
this challenge that's vexed scientists and philosophers for millennia, really, which is how does it happen?
Now, on the one hand, we've got this mess of complex stuff inside our brains and bodies,
the brain inside the skull, the brain, this electrified pathway.
And on the other hand, we have the redness of red, the sharpness of pain.
We have the world of experience. How do they relate?
And probably the most influential way of putting this big overall challenge was from the philosopher David Chalmers.
And he coined this idea of the hard problem of consciousness.
He put it like this.
He said it is widely agreed that experience arises from a physical basis, but we have no good explanation of why and how it so arises.
Why should physical processing give rise to a rich inner life at all?
It seems objectively unreasonable that it should. And yes, it does.
We're all conscious. How does this happen? Well,
the intuition sort of that David Chalmers is driving at here is that even if we had
in our hands a complete explanation of how the brain works as a complex object,
and it is a very complex object at most.
Each brain in this room has about 86 billion neurones and about a thousand times more connections,
so that if you counted one connection every second, it would take you about 3 million years to finish.
It's a very, very complicated object. But even if we knew everything about it,
we might still be completely in the dark as to how and why it has anything to do with consciousness seem to be like different things.
That's that's the hard problem of consciousness.
Now, addressing the hard problem, as Chalmers puts it head on, might not be the only or the right way to go about it.
And in my work over the last decade or so,
I prefer to tackle on what I've been calling the real problem of consciousness just to annoy David Chalmers a little bit.
The real problem, um, and it goes like this.
It's it's to accept that consciousness exists and there will be some people, some philosophers that will tell you we were wrong about that,
and that consciousness isn't this kind of special, distinctive phenomenon at all.
But let's say that it exists. In fact, consciousness really is the only thing we can be sure of.
Everything else is is sort of indirectly present, inferred through our consciousness.
It exists, and it depends in some way on the brain and the body.
So the question is how can mechanisms, this complex neural circuitry inside our skulls,
in the brain and the body explain and predict and control properties of consciousness?
Because that's in general what science does. It often doesn't have to tell you why a phenomenon is part of the universe in the first place.
It's nice if it does, but often it doesn't.
It just helps you explain the properties that it has, predict when they're going to happen, and ideally be able to you control.
And that's the business of science. And the idea is that as we kind of try to do this and build bridges of explanation,
I'll give you some examples and bridges of explanation between what's happening in the brain and what's happening in experience.
This sense of mystery about how something is as apparently magical as consciousness
can be so intimately associated with something as apparently mundane as mere stuff.
That sense of mystery begins to dissolve away and may even disappear in a puff of metaphysical smoke.
That's the hope. We're not there yet, but that's the overall strategy.
So rather than solving this hard problem head on in one dramatic eureka moment of a solution where we say,
ah, that's the that's where the magic happens. The hard problem of consciousness may in fact dissolve over time.
And there is a historical precedent for this. Not a perfect one.
But it wasn't that long ago. 150 years, 200 years, certainly, that people at the time thought that life was beyond the reach of science,
that physics and chemistry could not account for the difference between the living and the non-living.
At that time there was this philosophy of vitalism, the idea that there needed to be a special substance,
and along B tau, a spark of life that would explain this difference, but was otherwise beyond the reach of science.
Now we don't understand everything about life. Yet things like the origin of life is still fairly mysterious,
but there's no sense of mystery that life is really something that fits in with our natural picture of the universe as as complicated stuff.
The sense of mystery about life wasn't solved.
People didn't find the spark of life.
It was dissolved as biologists and chemists got on with the job of explaining properties of life in terms of physics and chemistry.
So that's I mean, that's it's not a perfect historical parallel,
but what I think is important is it tells us that what seems mysterious at one point in history,
with the tools and the concepts that we have at this point. Doesn't always have to seem so mysterious,
and we don't have to have a kind of revolution in physics or philosophy for that sense of mystery to dissipate.
So life has many properties too. It's not just one thing.
And so if we think about consciousness, instead of treating it as this one big scary mystery, what are its different aspects?
What are its different properties? And I like to divide this into roughly three kinds of things.
There's conscious level, which I already mentioned.
This is the kind of global state of consciousness that goes away under anaesthesia and then comes back again and might be,
might change in other states like sleep or hypnosis or things like that.
Then when you are conscious, you're conscious of something.
The sights and sounds and smells and colours and shape and people and places that populate your conscious experience.
At any given time, we can think about that as conscious content.
And then finally there's conscious self, the experience of being you or being me, the experience of being somebody that is probably,
for many of us, the most important aspect of consciousness and the aspect we might take most for granted as well.
So today I don't have time to talk about conscious level, but I want to focus a little bit unconscious content and conscious self.
And then towards the end of the talk,
explore some of the implications of what I've been saying for how we might think about consciousness beyond the human and especially,
I think given the times we live in. What about consciousness in machines and artificial intelligence?
What should we think about that? So that's where we're going. But where we're going to start is somewhere fairly simple.
We're just going to start with colour. Now, colour is such a prominent, pervasive part of our conscious lives, especially our visual lives.
It brings meaning and beauty to the way we visually experience the world.
What could be simpler than colour? But of course, colour is far from straightforward.
Now. The cells in our eyes. The photoreceptors in our eyes have long been known for most of us to be only sensitive to three,
roughly three wavelengths in this whole electromagnetic spectrum,
which goes all the way from radio waves at one end through infrared, ultraviolet, to x rays and gamma rays at the other end.
So this thin slice of reality, that's where we live colour wise.
And even within that thin slice, the cells in our eyes are only sensitive to just three wavelengths.
Yet out of those three wavelengths, the brain is able to conjure millions of distinct colours.
So what we experienced when we experienced colour is both less than what's really there,
because it's just a sample of the electromagnetic spectrum, and the wavelengths within that spectrum aren't themselves coloured.
They're just different wavelengths of of radiation, of energy.
There's less than what's there, but it's also more than what's that?
Because we can conjure millions of colours from just three out of three comes many.
So what we see when we see colour is both less than and more than what's out there in the world.
And I think that applies not just to colour, but to everything we experience.
But let me stick with colour for a second. And here's just one. One illustration of this.
This is one of my favourite visual illusions. The nice thing about talking about consciousness is you can use some of these fun illusions.
How many people have seen this one before? I'm going to see if I can have a look.
A few of you. Okay. This is one of my favourite. It's called the Lilac Chaser Illusion.
I hope it's going to work in this theatre, but I'd like you to stare at the black cross in the middle and try not to blink or move your eyes.
And then. I can hear a couple things. Let me know if something strange starts to happen and you start to see a a maybe a green disk.
People saying that? Yes. And then if you now move your eyes and blink, what happens?
A lot of murmuring happens, apparently, but what should happen is that the magenta disks come back, right?
Um, so there is no green disk in this illusion at all.
There are only magenta disks that turn off one after the other.
So what's happening here is actually three different things going on.
The first thing that's going on is something called Traxler fading. In psychology.
This is this phenomenon where if some things in the periphery of your vision and it has blurry borders,
tends to fade away and be replaced by what's around it. The second thing that's happening is called apparent motion.
So when things turn on and off next to each other, the brain tends to experience movement.
That's how cinema works. How television works. We infer things as smoothly moving from series of static snapshots.
And the third thing that's happening is colour opponents.
See now for the brain. The opposite in the space of colour from magenta is green.
And so when the brain uh, when, when the brain sort of is adapting to the absence of magenta, it, you end up perceiving green instead of magenta.
So these three things together explain what's happening here.
There's actually a fourth thing, which is that I've already told you that colours don't really exist out there in the world.
They're they're a collaboration between the brain and the world. Now, magenta exists even less than other colours.
And the reason for that is that if you think you make magenta by mixing usually red and blue light together,
although the light isn't actually red and blue. But you mix these two lights together, you get magenta.
And so when um, and that's because the red and blue wavelengths sort of either end of the, uh, of the extreme of this thin slice of reality.
So when the brain gets those wavelengths of light, it's expecting something in the middle which would be experienced as green.
So when it doesn't get it, it has to make something up. And what it makes up is magenta.
So what you're seeing when you're seeing green here is you're seeing not not not green.
I hope that makes sense. It didn't make any sense to me. So I thought example I think.
Just underlines. Get put the details aside.
What it what it underlines is that can be this big difference between how things seen in our experience and how they are.
And there's one simple idea which I think can explain these experiences.
And I've just zooming out from the details and can explain all our experiences in one way or another.
And this is the idea that your brain is a prediction machine,
and that everything that you experience is your brain's best guess about what's going on out there in the world or in here in the body.
The brain's best guess about the causes of the sensory input that it gets.
Now, this is a a very old idea, goes back in philosophy as long as you want.
Certainly it goes back to, to Plato. And this is and is out in Plato's Allegory of the cave.
Prisoners are chained to the wall of a cave, and all they can see, or they have access to are shadows cast on the walls by the light from a fire.
And the prisoners take these shadows to be real, because that's all they have access to.
Now, sort of bringing all this, skipping a few thousand years and coming up to the to the present day,
a more modern version of this way of thinking is instead of prisoners trapped inside a cave,
just try for a second to imagine what it's like to be your own brain.
You are your brain. You're trapped inside this bony cave prison of a skull, trying to figure out what's going on out there in the world.
Now there's no light in the skull. There's no sound. It's completely dark.
It's completely silent.
All the brain has to go on when trying to figure out what's there is noisy, ambiguous, uncertain, and unlabelled sensory information.
Electrical signals that come in through the senses.
Now, these electrical signals, these sensory inputs, they don't tell you they didn't come with labels on like,
I'm from a hat or I'm from a table, or I'm from the kidneys.
They're just electrical signals.
So to make sense of them, the brain has to combine these sensory signals with its prior knowledge or expectations about what's going on in the world.
And by combining this ambiguous sensory information with its prior expectations,
the brain can make a best guess about what's going on, and that the idea here is that is what we perceive.
The brain doesn't see light or hear sound.
What we experience is the brain's best guess of the causes of those kinds of signals.
I'll give you one more example of this. Just just so you might be familiar with this one, but we can think about this in this context.
How many people have seen this one? This is a more common visual illusion.
Still not everybody okay. So this is called Adelson's checkerboard.
And. If you look at those two patches, A and B now, hopefully they should look to you to be different shades of grey.
Is that everyone saying that different shades of grey okay, now because obviously it's an illusion.
Obviously that's not true. If I put the thing up here, you can see that they are in fact exactly the same shade of grey.
Everybody see that looks the same.
And if you think I'm tricking you somehow, well, I'll just move this grey bar across and you can see it really is the same shade of grey.
There's. There's no difference. And if I take it away, it looks different again.
So what's going on here? Well,
what's going on here is that your brain has baked into its visual circuits the knowledge that objects in shadow appear darker than they really are.
And it also has this knowledge of how checkerboards work that they alternate between brightness and darkness.
You don't necessarily know that your brain has this knowledge about the world, but it does.
And that's why we see B as lighter than it really is, because it's in the shadow on the checkerboard from the cylinder.
So the brain's expectations can really deeply shape what we consciously experience.
Now I was going to skip this slide, but because I was introduced by by Marcus, I have to have at least one equation in the talk.
That Mark is not efficient. And this is the only one.
Uh, and it's just showing that there's a, there's like a kind of mathematical way to think about this,
a mathematical way that describes this whole idea of the brain as making best guesses about what's out there in the world.
And it's called Bayes theorem. And Bayes theorem goes back hundreds of years.
And it's really about how one should optimally reason in the face of uncertainty.
And the idea here is that, um, we can have we can have some starting situation, some prior belief about what's going on.
And that's the dashed curve on the left. And we can get some new information.
This could be sensory data coming into the brain. And Bayes theory you call that the likelihood.
So that's the the other dashed curve to the right that the slightly broader one.
And then the idea is Bayes theorem.
You combine these two curves so you optimally integrate what you already know with what you what's what new information you get.
And you combine them and you come up with what Bayes called the posterior belief.
So that's what I should believe, given what I already know and what what's coming in next.
And so the idea is that it's really what the brain is trying to do when it's trying to perceive things out there in the world.
It already knows stuff about the world, but it gets new information all the time.
So it has to update what it knows on the basis of this new information.
Now, the first person to my knowledge you really formalising wrote about perception in this way was a German polymath called Hermann von Helmholtz,
and Hermann von Helmholtz said that perception was this process of unconscious inference, and he called it unconscious inference,
to make the point that we're not aware of all this probabilistic wizardry going on under the hood.
We're only aware of the result of it. We're only aware of the output.
We don't know that our brain is doing all this clever stuff, but if it is, it really casts perception, I think, in a very different light.
It flips how we think about things, even if we have never really thought about these things all that much before.
Now, the classical view of how the brain does perception, and this is something of the sort, this,
this kind of picture I would see in textbooks when I was a student some years ago, many years ago.
And the idea in this sort of old classical view is that perception is this kind of outside in,
bottom up process where signals come into the brain from the retina and they progress.
They sort of marched deeper and deeper into the brain, and more complex features are picked out as the signals go further into the brain.
So simple things like edges and colours early on, more complex things like faces later on, the monkey face because this is a monkey brain.
Um, now there may be some activity going in the other direction, but all the heavy lifting is done in this bottom up,
outside in direction, as if the brain is reading the world through the senses.
And that seems right. I mean, it seems kind of how things are that there's a world,
and my brain is sort of just soaking it in through the transparent windows of my eyes and my ears and my other senses.
Now the prediction machine view turns this completely on its head.
Instead of perception being this business of reading out sensory signals from the outside in.
It's much more about perceptual predictions which flow in the opposite direction from the top down and the inside out.
These green arrows here, the brain is always making predictions about the causes of sensory signals,
and then using the sensory signals to update the predictions.
Turns out if the brain does this and always tries to update its predictions to minimise the error that it gets, then it approximates.
It starts to do this, this process of Bayesian inference. Um, but what it means for perception is that.
What we experience is an active generation, rather than a passive registration of the world around us.
So this theory is known by by kind of many names in neuroscience and psychology.
Predictive processing is probably the most common. And the core idea, at least the way I think about this theory.
The core idea is that perceptual content, what we perceive comes from the inside out just as much, if not more, than from the outside in.
And these sensory signals mainly serve to keep the brain's predictions tied to the world in ways that are not necessarily accurate,
but which are most useful in how we and guiding our behaviour.
Now, William James, who was one of the fathers, uh, the first people founding figures in psychology,
said something very similar over 100 years ago in the late 19th century.
He said that was part of what we perceive comes through our senses from the object before us.
Another part, and it may be the larger part, always comes out of our own heads.
He had the same idea. If you didn't, even if you didn't put it in the same way.
Now we can see echoes and shadows of this process in our everyday lives.
There's a phenomenon called pareidolia, which means seeing patterns in fact, faces a very powerful stimuli.
Uh, we, you know, we're very sensitive to the presence of faces because we're very social creatures.
And, um, what this means is the brain is always casting out the prediction of face into, uh, the world to see where it sticks.
And so we can see faces and clouds,
and we can even see faces in things like the arrangements of windows on a building faces a very, very, very prominent.
And, um, one of the things we've been doing at Sussex is taking this idea and playing with it a little bit in the lab.
So we've been combining virtual reality with some machine learning or AI methods to, uh,
to try to simulate what it would be like if the brain had two strong, overly strong predictions to see faces everywhere.
So this is like this is now quite an old school neural network.
It's very good at telling you what's an image, what's in an image if you present it with that image.
Um, but what we did was we, we used a tweak of this called Deep Dream, which runs it backwards.
And what happens in this, uh, this manipulation is instead of the network telling you what's in an image,
you fix the output to something like dog, and you give it an image as input, and then you update the image until the whole thing settles down.
So it's a bit of a brute force way of saying, how can we simulate what it would be like if the brain had a strong prediction to see dog?
Um, and what we did with, uh, my postdoc Casa Katie Zuki is we took this idea and we took some panoramic video of Sussex campus,
and we applied this method to every frame within the video.
And then, um, gave people a VR headset, which they could wear, and then they experience Sussex Campus in a very unusual way.
So I mean, it is different from Oxford, but it's not this different normally.
There's a few too many dogs. But, um, what's interesting about this for me is that it's it's a it's a sort of computational model,
but it's a not not of what people do or any kind of cognition.
It's a model of a different kind of experience. It's a way of using computational models to to model how we experience the world.
Um, what we've been doing just this week actually was, um, because computers have got faster and faster, we can now do this in real time.
So if you visit my my lab, we can put this headset on.
And right then in the moment, you know, you can have this, this very strange, almost psychedelic like experience of what's going on around you.
And of course, we can tweak it in various, various different ways.
We're also taking the same method. And this isn't just fun.
I mean, it is fun. And a lot of science starts off just by it, to be honest.
Just by playing around to see what you can do, to see what kinds of things you can explore.
But we've also been taking this same method now and applying it to try to understand how and why
different kinds of visual hallucinations are actually the way they are and how they're different.
So people with Parkinson's disease have visual hallucinations quite often people with Charles Bonnet syndrome,
which is where people lose a lot of vision through macular degeneration.
They also sometimes have hallucinations. Psychedelics involve hallucinations as well.
They're all kind of different.
But through this method, we can start to understand how and why different kinds of hallucinations are different from each other,
and therefore understand a bit more about perception in the here and now as well.
But there's a sort of single take home from all this, which is that we can think of hallucination.
Here is a kind of uncontrolled perception.
It's what happens when the brain loses its grip.
The brain's predictions lose their grip on their causes in the world.
And now, by the same token,
we can then think of normal perception in the here and now as a kind of controlled hallucination where the brain's best guess is,
uh, reined in by, controlled by that causes in the world.
And I think this way of putting it is important because when we think about hallucination,
we often think of it as, you know, something completely different from how we do things.
Normally. It's another category. People see things here, things that aren't there.
But when we experience things without hallucinating, we have this kind of direct vertical access to how things really are.
I don't think it's like that. I think there's a continuity, a spectrum we can for various parts of the spectrum.
All of our perceptual experience comes from the inside out, and it's all calibrated in some way by sensory input from the outside in.
Now, one implication of this idea is that since we all have different brains, we will all have different experiences.
We will all differ on the inside, just as we do on the outside.
The novelist Anais Nin put this very nicely in her 1961 book, The Seduction of the Minotaur,
when she said we do not see things as they are, we see them as we are and as one.
One last example of this I want to show. I think you've probably seen this before, right?
Remember this. This is almost ten years ago now. This image first exploded across the internet.
So this is a photo of a dress. How many people see this as a white and gold dress?
Quite a few. How many people see it as a blue and black dress?
Many more. How many people don't know what the [INAUDIBLE] I'm talking about? Okay.
No it's not. I mean, this is. Time has passed, so one never knows.
And the lighting in here is strange. See, you know, this came in 2015.
What I think is amazing about this is that those people who see it one way, you know,
the white and gold people out there, it's very hard to imagine what it would be like to see it in a different way.
Right. And you see it the way you see it on. But of course it's the same.
It's the same picture. And the reason we see it differently, we can come back to that later.
It has to do. It probably has to do with how our brains take into account the, you know, the ambient light,
which in this room is quite yellowish, by the way, those people who say it's blue and black, you're right.
The real dress is blue and black. Um, so well done you.
Um but the point and gold people. You might be wrong, but but your brains typically assume that you're outdoors and happy, so, you know, lucky you.
This example is, you know, it exploded into the public consciousness because the difference was so big
that it became noticeable when people started arguing about what do you see?
But that obscures, I think, a deeper point, which is that we will all experience things differently.
And most of the time those differences won't be large enough that they'll surface into our language and behaviour.
You know, we all differ on the outside in terms of body shape, skin colour and so on.
And those differences don't have to be very large. And we can still see them because we can see them.
But differences on the inside a much, much harder to measure because that private my I have my experience and you don't.
We use language to kind of paper over the differences, and it also just seems as though I see the world as it is, you know?
And so why should anybody see it differently? And for me, this has been a very interesting challenge.
We don't know all that much about the diversity of of perceptual experience in this way.
So one project that I've been involved with over the last 2 or 3 years is become the perception senses.
And this has been a very ambitious study involving so far, only 40,000 people each doing hours of experiments to try to understand,
you know, how we each experience the world in our own unique way.
And we've so far had people from, um, 40,000 people from over 100 countries and ages from 18 to 80,
uh, to try to paint a picture of what I've been calling perceptual diversity.
And I use that term because I want to emphasise that it applies to all of us,
and it's not something that's specific to people with so-called neurodivergent conditions like autism or ADHD, who want to study that, too.
But we all differ in how we experience the world.
And there's a kind of I'm dwelling on this because I think there's an important implication.
We haven't analysed the data very much yet, so I don't have any results to show you.
But even just the examples that you've seen,
I think one consequence of thinking about things this way is that it can help us cultivate a bit of humility about our own take on things,
like the way I see things is not the only way other ways are possible.
And so my hope is, and it is very much a hope that by revealing a bit more about how we differ in our perceptual experience of the world,
we will be able to build some some new platforms that will allow better understanding and communication between people,
because we live in perceptual echo chambers. And the first step to getting out of an echo chamber is to realise that you're in one.
Okay, so in the next part of the talk, I want to move on from perception of the world to perception of the self.
And it's easy to take the self for granted, but we should not.
And it's also easy to. So I think make a simple mistake about where the self fits in to this picture of consciousness.
You know the easy how things seem view is something like this. There's a world out there.
We perceive the world. Sensory inputs come into our eyes.
And the self in this view is the is the thing that does the perceiving the essence of you or me.
And that receives that the perception of the world makes and plans decide what to do next and then does that thing.
We make some actions in the world, and the world changes, and round and round we go.
We sense, we think we act. That might be the house, how things seem view.
But how things are is, I think, quite different.
In this view, both experiences of the world and experiences of the self are kinds of perception.
The self is not the thing, the essence, the universe, or the meanness that does the perceiving.
The self is itself a kind of perception, or rather a bundle, a collection of related but different perceptions.
Um. So the self two can be thought of as a kind of controlled hallucination.
The purpose of which is to keep the body alive.
Now, thinking about it this way. First thing that comes up is there are many aspects.
There are many different ways in which we each experience being a self.
It might feel like the self is one thing,
but it breaks down in many ways that the experience of being and having a particular object in the world, the body.
Now this is my body and that isn't. There's the experience of perceiving the world from a particular first person point of view.
There's the volitional self, the experience of being the cause of particular actions,
or the author of my own thoughts when people talk about free will.
This is one of the things they talk about, and only then things like the narrative in the social self.
This is where personal identity comes in. So there's a sense of self in me that's bound to a name and identity.
Memories of the past and plans for the future. Now all of these aspects of self might seem unified intrinsically.
Maybe necessarily so, but we know they aren't. There's many examples in the lab and also in psychiatry, in neurology,
where these different aspects of self come apart in all sorts of different ways.
And I think what this tells us is that the experience of being a self, being you, is not something to take for granted.
It's a fragile construction of the brain, for the brain and the body.
Now I want to focus just on one aspect of this, which is the bodily self, the experience of being and having a particular body.
Now again, we don't really think about this very much, right? The body is just that.
It's this kind of meat robot that takes me from one meeting to another.
But if you think about it from the brain's perspective, the body is also inaccessible.
The brain only gets electrical signals that in this case, come from the body rather than the world.
But it's always having to make a best guess about what is and what is not the body.
And that's a lovely demonstration of this I love this. This is called the rubber hand illusion.
You've probably seen this before. I won't start it just yet. And this shows how easily our experience of what is the body can be altered.
Now, in the rubber hand illusion, what happens is the guy in blue, his real hand is hidden from sight.
Behind this put partition and then a fake rubber hand is placed in front of him.
Um, and he's looking at that.
Then the experiment in green takes two paintbrushes and [INAUDIBLE] stroke both hands simultaneously while the guy's looking at the fake hand.
And what happens, um, for most people,
is that they start to experience a rather uncanny sensation that maybe this rubber hand is in some way part of the body.
And that's the best way to test whether it's working or not.
Um, now, the standard story told about this is that I can't resist a bit of a diversion here.
The standard story told about this is that the bright. It's to do with integration of senses from different modalities.
So you've got vision and you've got touch, and the brain sees this hand and it feels the touch.
So it puts them together and, and comes to the conclusion that the rubber hand is in your hand.
Um, but there's another story actually, which is, which is also part of it.
My colleague at Sussex, Peter Lush, for a number of years has been pointing out that, um, in the rubber hand illusion,
you're basically in a situation where you're strongly encouraged that you should experience something weird.
You know, you've given a fake hand, ask to stare at it, and then asked, is it your hand?
It's a very strong, um, example of what psychologists call demand characteristics.
You're in a situation which is implicitly encouraging you to have a particular kind of experience.
So to test this for Pete, did, uh, the rubber hand illusion on over 350 people at Sussex, uh,
a couple of years ago and found that the degree to which people experienced it correlated with the, um, how hypnotised they were.
We're all hypnotised, able uh, to some degree or other.
It's not a good thing. It's not a bad thing. It's just it's just a thing. It's a stable psychological trait.
And those people who were more suggestible, uh, experienced the rubber hand illusion to a stronger extent.
So I think that tells us that that's at least part of the story.
And it's very compatible with what I've been saying, too,
because what it shows is that that kind of experimental context of the rubber hand allusion, it's a kind of expectation.
You're giving the brain an expectation about what to experience.
And so it does. So talks a bit about having a body and how that is actually something the brain constructs on the fly.
There's also this experience of being a body, of being a living flesh and blood organism with emotions and moods.
And I think at the base of all experience of self and possibly of all experience at all, this simple background feeling of being alive.
Um, this experience of being a body. And this brings up another form of perception entirely, which is called interception.
Interception is rather overlooked in in science, psychology, neuroscience, but is very important.
Interception is all about how the brain senses and controls the interior of the body because again, from the brain's perspective, the interior,
interior, physiological states, the internal physiological state that's also not directly accessible, the brain locked away in its bony skull.
And if it's trying to figure out what the heart is doing, what how the how the lungs are doing,
it has to infer that make a best guess about it on the basis of, um, sensory input and its prior expectations.
So now we have the same dance of prediction and prediction error, but now it's all taking place or largely taking place inside the body itself.
The brain is making predictions about what's happening in the body and updating those predictions.
So what happens when it does this? What? When the brain does this out there in the world, we might experience objects and people and places.
But what happens when the brain is making predictions about the heart or the lungs, or the overall physiological condition of the body itself?
Basically, how good a job it's doing is staying alive. Well, the idea here is that that's what emotion is.
Now again, we tend or there's been a tendency to think of emotion is very different kind of thing.
Now we have thought, we have perception. We have emotion. The the overall picture that that's emerging here is that these are all aspects
of the same underlying process of the brain making and updating predictions.
And when it comes to emotion, these predictions are about the interior of the body, that that's what an emotion is on this view.
William James again said something very similar and sort of slightly flowery Victorian language.
He said bodily changes followed directly the perception of the exciting fact,
and there are feeling of these same changes as they occur is the emotion.
The intuition here is that here's the key.
And the example that William James famously gave was if somebody sees a bear and they feel the frightened run away, what's happening?
It could be that they see the bear that causes them to feel afraid, and the feeling of fear causes them to run away.
But what James said and what what's what I think is happening also in this story,
is that the person sees the bear that immediately induces all kinds of changes in the body.
Adrenaline starts coursing. Cortisol shoots around.
Heart rate goes up. And it's the perception of those changes.
That is the emotion of fear. So it's kind of flipping things around.
Once again, things between how things seem and how they are.
Now there's another. Final aspect of this story, which I think sort of fleshes out a little bit.
So why do emotions feel the way they are and sort of visual experience feels a different way?
Well, these predictions about the interior of the body.
You know that they don't care where things are. They're not about figuring out what's out there in the world.
They really care about controlling and regulating the body.
That that's that's what, um, this process is fundamentally, um, doing.
It's for keeping the body in the States compatible with being alive,
keeping heart rate where it needs to be, keeping blood pressure right where it needs to be, and so on.
So introspective predictions are about controlling things rather than finding things out.
When you can predict something, you can control it pretty well.
So the idea here is that's actually why the brain is a prediction machine in the first place,
because that basic process evolved to keep the body alive, to provide an effective way of regulating the body.
Now, there are many other kind of lines of work that support that, which I'll just skip over.
But it's it's sort of has ancestry in many different areas of psychology and neuroscience.
But I think it explains quite nicely why different experiences are the way they are and not some other way.
Visual predictions underpin visual experiences with objects and people, because that's what those predictions are trying to do.
They're trying to figure out where things are, how they're moving, what they are,
but intercept if predictions underpin emotions and this simple feeling of being alive, because that's what these predictions are all about.
They're about controlling, regulating the body.
Now I'm cutting a long story very short here, but if you pull this thread long enough, I at least for me,
you get to this kind of picture where conscious experience and consciousness itself is intimately related to our nature as living systems.
Because these, this, this whole, um, edifice of the brain is a prediction machine evolved over many millions of years,
develops in each of us, and operates moment to moment in light of this fundamental biological imperative to stay alive.
The reason the brain makes predictions about the world and updates them is
because that circuitry has been there from the get go to keep the body going.
So consciousness in this case, less to do with something like intelligence, more to do with something like being alive.
And this brings me to René Descartes. René Descartes, one of the most famous philosophers of all time,
and cause all sorts of mischief in the philosophy of mind by separating the mind and the body.
And we've struggled to put them back together ever since. But he also separated life from consciousness.
And, um, it's called being a beast machine because he was listening to what he wrote.
He was quite uncharitable about whether non-human animals were conscious.
He called them beast machines. He said, without minds to direct their bodily movements.
Animals must be regarded as unthinking, unfeeling machines that move like clockwork.
So for Descartes, being alive was irrelevant to consciousness or to the kind of consciousness that that matters.
And I've come to think almost the opposite is the case,
that being alive is why we are also conscious that we perceive and experience the world around us and ourselves within it,
with, through, and because of our living bodies.
We are not kind of meat based computers. We are feeling machines.
So I want to finish just the next five minutes. By talking about consciousness in other things, and especially in artificial intelligence,
because I think this view of consciousness is intimately tied to our natures living systems has seen some interesting things to say about us.
So the idea of AI has been with us for a long time.
All those are very, very much more prominent now.
And the idea that I could become not only smart but also conscious has also been around for a long time.
Alan Turing, who basically gave us the many of ideas about computation as we use them now,
also seeded the idea that I could be conscious when he asked the famous question whether machines can think, um.
And in doing this, he also tied consciousness in AI to something that we might call intelligence,
thinking, you know, if an AI can think, maybe it's conscious.
We see this also in a lot of science fiction, whether it's how from 2001,
in intelligence here and consciousness are bound up not with a body, but with this kind of disembodied mind.
Ex Machina, a brilliant film by Alex Garland,
also plays beautifully with this idea of artificial intelligence becoming conscious and for a long time, these.
These ideas, these these possibilities of building machines that had experience, that were sentient was the realm of literature and science fiction.
But now it seems we might actually be able to do that.
And in fact, some people think we're already there.
A couple of years ago, a Google engineer called Blake Lemoine got fired from Google because he claimed that the language model,
the chat bot he was working on, was actually conscious.
Not that many people took him that seriously, but the fact that he even, you know, raised the question with was itself pretty interesting.
So there is this question here. Can artificial intelligence lead to real consciousness?
Answering this question is fundamentally important because it has a huge number of ethical and moral implications,
not only for how we treat AI systems, but for how we understand and deal with our own interactions with them.
And the ground here is really muddy. I read this in the New Statesman last year.
It was something just when there was a lot of fuss and bother about open AI,
and in this paragraph talks about artificial general intelligence and says that, um,
company documents state that the board's purpose is to decide when the company has developed highly
autonomous artificial general intelligence that outperforms humans at most economically valuable work.
And to ensure this technology reshaped society in a in a manner that's safe and benevolent.
In other words, the board exists to decide when the machine is sentient, when it is alive, and to ensure the new consciousness is moral.
So this is mixing all kinds of things together, which are actually very different.
Consciousness is having an experience. Intelligence is doing the right thing at the right time, and being alive is something else altogether.
So we get confused. I think talking about consciousness in AI, when we mix consciousness and intelligence together, they are very different things.
They may correlate quite often in living creatures. The more intelligent you are, the more ways you have of being conscious.
But fundamentally they're different concepts, and I think we confuse them because we're very susceptible to particular psychological biases.
We tend to be very anthropocentric creatures.
You know, we see the world through a human lens, and we think we're intelligent and we know we're conscious,
so we tend to put the two together and confound them always.
We're also very anthropomorphic creatures.
We tend to project human like qualities into things on the basis of what might turn out to be superficial similarities,
and that's become very prominent with this explosion of language models that we have.
Because language, it seems to us, is something that is very distinctively human and very much associated with intelligence.
So when something is able to speak to us fluently.
It's very compelling for us to infer not only that it can speak to us fluently, which it can, but also that it is conscious.
There's a conscious mind behind that,
and I think that is much more a reflection of our biases than an accurate insight into what's going on inside these systems.
By the way, it's often said that language models hallucinate when they make stuff up.
That's part of the problem, too. When we say that we're already assuming something like having an experience.
I think it's much more accurate to say they can. Fabulous. They make stuff up without knowing what they're doing.
There's a deeper reason there, and a deeper reason why. I'm very sceptical of the whole idea that AI or computers could be conscious.
And that's because the more you look at it, the more different brains are from computers.
Now, in a in a computer, there's a very sharp distinction. Give you just one example.
In a computer, there's a sharp distinction by design between the hardware and the software.
What a computer does is independent of what it is.
That's why computers are useful. And you can run the same program on different ones, and they do the same thing in a brain.
There is no distinction between what we might call the mind where and the wetware.
There's no sort of sharp threshold. You can't say what's in my brain and run it on somebody else's brain.
Brains are very much more complicated than computers.
And this this just. And when we reduce ourselves to a computer, I think we just really do a massive disservice to the to how rich,
um, human brains and other animal brains really are.
Now, if these ideas are a little bit on the right track, then it means that what we can do with computers and AI,
we can certainly simulate consciousness, simulate intelligence and so on, but we can't necessarily can't implement it.
And this is this is taken for granted in other things, like if we have computer simulations of weather systems,
we never expect it to get wet or windy inside a computer simulation of a storm.
Right? It just always a simulation.
But for some reason we think that when we have a computer simulation of a brain, we will actually get consciousness out of it.
And I think that's actually very unlikely.
Um, now to finish, I might be wrong.
There are still things to worry about.
Many people disagree with me on this, and think that consciousness is the kind of thing that computers could have.
There are many theories of consciousness. Many of them provide blueprints for how one might build a conscious machine.
I think they're all on the wrong track in this sense. But I might be wrong.
They might be right. And I just want to end by saying there are many reasons why we should not build conscious AI, even if it is very unlikely.
Many reasons. But I think the main reason is that if for some reason we were able to,
we would risk an ethical catastrophe because we would have introduced into the world
a vast new potential for forms of suffering that we might not even recognise.
It would be a very immoral, unethical thing to do. And even AI that seems conscious is also problematic.
It is also bad. And that's almost already here, as we've seen with these language models.
There's many other examples which which I'll skip, but we get ourselves into all kinds of moral quandaries.
If we build technologies that seem conscious, even if they are not, because either we end up caring about them,
even though they're just lifeless hunks of silicon and code, or we don't,
and we treat them badly, even though we can't help feeling that they are conscious,
there's this kind of potential for cognitively impenetrable illusions of consciousness here.
You know, these two lines are different lengths, but you'll never be able to see them.
Sorry, they're the same length, but you will never be able to see them as the same length.
It's a cognitively impenetrable illusion. Same might go for I have a hunch we know we might not be able to avoid experiencing AI systems as conscious,
and that gets us into these really difficult problems. One of my former mentors, the philosopher Daniel Dennett,
who I think gave the first of these lectures 25 years ago, gives a nice thought, I think, which should guide us.
Sadly, we lost Daniel Dennett this year. He died around April.
Um, but he said we should treat AI as tools rather than colleagues and always remember the difference.
I think that's very wise. We are much more than machines. We shouldn't sell ourselves so cheaply.
Do you think that we can be replaced by a language model?
But I want to finish on a more positive note and just point out that consciousness is not just this,
um, this intellectual mystery that fascinates people like me for many years.
It's also a mystery that matters. And that's why I think it's a particularly and important subject to study in medicine,
a better understanding of consciousness to help us deal with conditions in psychiatry,
in neurology, to address the mechanisms rather than just treating the symptoms in technologies not just AI, but also virtual reality.
How we develop and interact with these technologies needs a deeper understanding of how we perceive and experience the world and the self.
Society, which is facing all kinds of challenges, of course,
will benefit from the ability to understand build bridges of empathy between people who experience things in different ways.
We need to make decisions about how we treat non-human animals, um, and even how we treat people before birth.
And at the end of life, too, all of these turn on what we can say about the possibility for consciousness in
non-human animals and unborn humans and in people towards the end of life in law,
when we hold people responsible, depends on what we think about free will.
Now, do we have some consciousness that floats above the brain that makes us do things?
No we don't. So it's a graded, more complex phenomenon.
But of course, it matters when and how we hold people responsible for their actions.
We can also think about how to make life better for those of us who aren't particularly ill or suffering,
but just to cultivate more positive forms of conscious experience by understanding how they might arise.
And again, to understand that we are much more than meat based computers.
But fundamentally, consciousness is worth studying.
It's a bit like the Everest of intellectual problems, really.
It matters because it is there, and for me, it's a real privilege to try to understand this most deep, profound, but also personal of mysteries.
So thank you very much for your attention.