0:00:00.920,0:00:02.160
Just over a year ago,

0:00:02.840,0:00:05.216
for the third time in my life,[br]I ceased to exist.

0:00:05.240,0:00:09.520
I was having a small operation,[br]and my brain was filling with anesthetic.

0:00:10.520,0:00:13.856
I remember a sense[br]of detachment and falling apart

0:00:13.880,0:00:15.080
and a coldness.

0:00:15.880,0:00:18.296
And then I was back,[br]drowsy and disoriented,

0:00:18.320,0:00:19.760
but definitely there.

0:00:20.280,0:00:22.096
Now, when you wake from a deep sleep,

0:00:22.120,0:00:25.376
you might feel confused about the time[br]or anxious about oversleeping,

0:00:25.400,0:00:28.136
but there's always a basic sense[br]of time having passed,

0:00:28.160,0:00:30.376
of a continuity between then and now.

0:00:30.400,0:00:32.616
Coming round from[br]anesthesia is very different.

0:00:32.640,0:00:35.136
I could have been under[br]for five minutes, five hours,

0:00:35.160,0:00:36.576
five years or even 50 years.

0:00:36.600,0:00:38.056
I simply wasn't there.

0:00:38.080,0:00:39.320
It was total oblivion.

0:00:40.240,0:00:42.296
Anesthesia --[br]it's a modern kind of magic.

0:00:42.320,0:00:45.496
It turns people into objects,

0:00:45.520,0:00:47.520
and then, we hope, back again into people.

0:00:47.544,0:00:48.776
And in this process

0:00:48.800,0:00:52.040
is one of the greatest remaining[br]mysteries in science and philosophy.

0:00:52.400,0:00:54.016
How does consciousness happen?

0:00:54.040,0:00:56.256
Somehow, within each of our brains,

0:00:56.280,0:00:59.176
the combined activity[br]of many billions of neurons,

0:00:59.200,0:01:02.216
each one a tiny biological machine,

0:01:02.240,0:01:04.056
is generating a conscious experience.

0:01:04.080,0:01:06.016
And not just any conscious experience --

0:01:06.040,0:01:08.421
your conscious experience[br]right here and right now.

0:01:08.445,0:01:09.645
How does this happen?

0:01:10.560,0:01:12.616
Answering this question is so important

0:01:12.640,0:01:15.496
because consciousness[br]for each of us is all there is.

0:01:15.520,0:01:17.520
Without it there's no world,

0:01:18.400,0:01:19.776
there's no self,

0:01:19.800,0:01:21.336
there's nothing at all.

0:01:21.360,0:01:23.313
And when we suffer, we suffer consciously

0:01:23.337,0:01:25.417
whether it's through[br]mental illness or pain.

0:01:26.400,0:01:29.336
And if we can experience[br]joy and suffering,

0:01:29.360,0:01:30.800
what about other animals?

0:01:31.320,0:01:32.736
Might they be conscious, too?

0:01:32.760,0:01:34.416
Do they also have a sense of self?

0:01:34.440,0:01:37.576
And as computers get faster and smarter,

0:01:37.600,0:01:40.176
maybe there will come a point,[br]maybe not too far away,

0:01:40.200,0:01:42.936
when my iPhone develops[br]a sense of its own existence.

0:01:42.960,0:01:47.440
I actually think the prospects[br]for a conscious AI are pretty remote.

0:01:47.960,0:01:50.336
And I think this because[br]my research is telling me

0:01:50.360,0:01:53.016
that consciousness has less to do[br]with pure intelligence

0:01:53.040,0:01:57.616
and more to do with our nature[br]as living and breathing organisms.

0:01:57.640,0:02:00.336
Consciousness and intelligence[br]are very different things.

0:02:00.360,0:02:03.920
You don't have to be smart to suffer,[br]but you probably do have to be alive.

0:02:05.200,0:02:06.896
In the story I'm going to tell you,

0:02:06.920,0:02:09.256
our conscious experiences[br]of the world around us,

0:02:09.280,0:02:10.616
and of ourselves within it,

0:02:10.639,0:02:13.176
are kinds of controlled hallucinations

0:02:13.200,0:02:17.040
that happen with, through[br]and because of our living bodies.

0:02:17.840,0:02:21.176
Now, you might have heard[br]that we know nothing

0:02:21.200,0:02:23.936
about how the brain and body[br]give rise to consciousness.

0:02:23.960,0:02:27.096
Some people even say it's beyond[br]the reach of science altogether.

0:02:27.120,0:02:28.336
But in fact,

0:02:28.360,0:02:32.496
the last 25 years have seen an explosion[br]of scientific work in this area.

0:02:32.520,0:02:35.296
If you come to my lab[br]at the University of Sussex,

0:02:35.320,0:02:38.480
you'll find scientists[br]from all different disciplines

0:02:39.200,0:02:41.120
and sometimes even philosophers.

0:02:41.800,0:02:45.776
All of us together trying to understand[br]how consciousness happens

0:02:45.800,0:02:47.520
and what happens when it goes wrong.

0:02:47.880,0:02:50.016
And the strategy is very simple.

0:02:50.040,0:02:52.016
I'd like you to think about consciousness

0:02:52.040,0:02:54.256
in the way that we've[br]come to think about life.

0:02:54.280,0:02:56.896
At one time, people thought[br]the property of being alive

0:02:56.920,0:02:59.536
could not be explained[br]by physics and chemistry --

0:02:59.560,0:03:01.720
that life had to be[br]more than just mechanism.

0:03:02.480,0:03:04.376
But people no longer think that.

0:03:04.400,0:03:06.016
As biologists got on with the job

0:03:06.040,0:03:08.616
of explaining the properties[br]of living systems

0:03:08.640,0:03:10.456
in terms of physics and chemistry --

0:03:10.480,0:03:13.536
things like metabolism,[br]reproduction, homeostasis --

0:03:13.560,0:03:17.376
the basic mystery of what life is[br]started to fade away,

0:03:17.400,0:03:20.456
and people didn't propose[br]any more magical solutions,

0:03:20.480,0:03:22.480
like a force of life or an élan vital.

0:03:23.080,0:03:25.736
So as with life, so with consciousness.

0:03:25.760,0:03:28.056
Once we start explaining its properties

0:03:28.080,0:03:31.776
in terms of things happening[br]inside brains and bodies,

0:03:31.800,0:03:35.216
the apparently insoluble mystery[br]of what consciousness is

0:03:35.240,0:03:36.976
should start to fade away.

0:03:37.000,0:03:38.720
At least that's the plan.

0:03:39.280,0:03:40.536
So let's get started.

0:03:40.560,0:03:42.536
What are the properties of consciousness?

0:03:42.560,0:03:45.084
What should a science[br]of consciousness try to explain?

0:03:45.960,0:03:49.656
Well, for today I'd just like to think[br]of consciousness in two different ways.

0:03:49.680,0:03:52.056
There are experiences[br]of the world around us,

0:03:52.080,0:03:54.296
full of sights, sounds and smells,

0:03:54.320,0:03:58.240
there's multisensory, panoramic,[br]3D, fully immersive inner movie.

0:03:59.000,0:04:00.560
And then there's conscious self.

0:04:01.080,0:04:03.536
The specific experience[br]of being you or being me.

0:04:03.560,0:04:05.576
The lead character in this inner movie,

0:04:05.600,0:04:08.960
and probably the aspect of consciousness[br]we all cling to most tightly.

0:04:09.840,0:04:12.296
Let's start with experiences[br]of the world around us,

0:04:12.320,0:04:16.055
and with the important idea[br]of the brain as a prediction engine.

0:04:16.079,0:04:17.839
Imagine being a brain.

0:04:18.600,0:04:20.255
You're locked inside a bony skull,

0:04:20.279,0:04:22.496
trying to figure[br]what's out there in the world.

0:04:22.520,0:04:25.536
There's no lights inside the skull.[br]There's no sound either.

0:04:25.560,0:04:28.336
All you've got to go on[br]is streams of electrical impulses

0:04:28.360,0:04:31.536
which are only indirectly related[br]to things in the world,

0:04:31.560,0:04:32.760
whatever they may be.

0:04:33.520,0:04:35.656
So perception --[br]figuring out what's there --

0:04:35.680,0:04:38.536
has to be a process of informed guesswork

0:04:38.560,0:04:41.696
in which the brain combines[br]these sensory signals

0:04:41.720,0:04:45.776
with its prior expectations or beliefs[br]about the way the world is

0:04:45.800,0:04:48.936
to form its best guess[br]of what caused those signals.

0:04:48.960,0:04:51.656
The brain doesn't hear sound or see light.

0:04:51.680,0:04:56.040
What we perceive is its best guess[br]of what's out there in the world.

0:04:57.040,0:04:59.960
Let me give you a couple[br]of examples of all this.

0:05:00.400,0:05:02.376
You might have seen this illusion before,

0:05:02.400,0:05:04.656
but I'd like you to think[br]about it in a new way.

0:05:04.680,0:05:06.736
If you look at those two patches, A and B,

0:05:06.760,0:05:10.080
they should look to you to be[br]very different shades of gray, right?

0:05:11.040,0:05:14.016
But they are in fact[br]exactly the same shade.

0:05:14.040,0:05:15.376
And I can illustrate this.

0:05:15.400,0:05:17.616
If I put up a second version[br]of the image here

0:05:17.640,0:05:20.656
and join the two patches[br]with a gray-colored bar,

0:05:20.680,0:05:22.336
you can see there's no difference.

0:05:22.360,0:05:24.136
It's exactly the same shade of gray.

0:05:24.160,0:05:25.816
And if you still don't believe me,

0:05:25.840,0:05:28.080
I'll bring the bar across[br]and join them up.

0:05:28.680,0:05:32.040
It's a single colored block of gray,[br]there's no difference at all.

0:05:32.760,0:05:34.456
This isn't any kind of magic trick.

0:05:34.480,0:05:35.896
It's the same shade of gray,

0:05:35.920,0:05:38.120
but take it away again,[br]and it looks different.

0:05:39.240,0:05:40.496
So what's happening here

0:05:40.520,0:05:43.336
is that the brain[br]is using its prior expectations

0:05:43.360,0:05:46.456
built deeply into the circuits[br]of the visual cortex

0:05:46.480,0:05:49.176
that a cast shadow dims[br]the appearance of a surface,

0:05:49.200,0:05:52.840
so that we see B as lighter[br]than it really is.

0:05:53.920,0:05:55.176
Here's one more example,

0:05:55.200,0:05:58.376
which shows just how quickly[br]the brain can use new predictions

0:05:58.400,0:06:00.696
to change what we consciously experience.

0:06:00.720,0:06:01.920
Have a listen to this.

0:06:03.440,0:06:06.480
(Distorted voice)

0:06:07.320,0:06:08.896
Sounded strange, right?

0:06:08.920,0:06:11.349
Have a listen again[br]and see if you can get anything.

0:06:11.760,0:06:14.720
(Distorted voice)

0:06:15.880,0:06:17.136
Still strange.

0:06:17.160,0:06:18.360
Now listen to this.

0:06:18.920,0:06:21.976
(Recording) Anil Seth: I think Brexit[br]is a really terrible idea.

0:06:22.000,0:06:23.336
(Laughter)

0:06:23.360,0:06:24.576
Which I do.

0:06:24.600,0:06:26.416
So you heard some words there, right?

0:06:26.440,0:06:29.536
Now listen to the first sound again.[br]I'm just going to replay it.

0:06:29.560,0:06:32.616
(Distorted voice)

0:06:32.640,0:06:35.136
Yeah? So you can now hear words there.

0:06:35.160,0:06:36.360
Once more for luck.

0:06:37.040,0:06:40.040
(Distorted voice)

0:06:41.000,0:06:43.256
OK, so what's going on here?

0:06:43.280,0:06:46.856
The remarkable thing is the sensory[br]information coming into the brain

0:06:46.880,0:06:48.080
hasn't changed at all.

0:06:48.680,0:06:51.216
All that's changed[br]is your brain's best guess

0:06:51.240,0:06:53.296
of the causes of that sensory information.

0:06:53.320,0:06:55.680
And that changes[br]what you consciously hear.

0:06:56.560,0:06:59.696
All this puts the brain[br]basis of perception

0:06:59.720,0:07:01.176
in a bit of a different light.

0:07:01.200,0:07:05.216
Instead of perception depending largely[br]on signals coming into the brain

0:07:05.240,0:07:06.776
from the outside world,

0:07:06.800,0:07:09.296
it depends as much, if not more,

0:07:09.320,0:07:13.240
on perceptual predictions[br]flowing in the opposite direction.

0:07:14.160,0:07:16.216
We don't just passively[br]perceive the world,

0:07:16.240,0:07:17.936
we actively generate it.

0:07:17.960,0:07:20.576
The world we experience[br]comes as much, if not more,

0:07:20.600,0:07:21.936
from the inside out

0:07:21.960,0:07:23.280
as from the outside in.

0:07:23.640,0:07:25.816
Let me give you[br]one more example of perception

0:07:25.840,0:07:28.720
as this active, constructive process.

0:07:29.400,0:07:34.536
Here we've combined immersive[br]virtual reality with image processing

0:07:34.560,0:07:37.536
to simulate the effects[br]of overly strong perceptual predictions

0:07:37.560,0:07:38.896
on experience.

0:07:38.920,0:07:41.816
In this panoramic video,[br]we've transformed the world --

0:07:41.840,0:07:43.736
which is in this case Sussex campus --

0:07:43.760,0:07:45.320
into a psychedelic playground.

0:07:45.760,0:07:49.616
We've processed the footage using[br]an algorithm based on Google's Deep Dream

0:07:49.640,0:07:53.736
to simulate the effects[br]of overly strong perceptual predictions.

0:07:53.760,0:07:55.376
In this case, to see dogs.

0:07:55.400,0:07:57.536
And you can see[br]this is a very strange thing.

0:07:57.560,0:07:59.656
When perceptual[br]predictions are too strong,

0:07:59.680,0:08:01.056
as they are here,

0:08:01.080,0:08:03.976
the result looks very much[br]like the kinds of hallucinations

0:08:04.000,0:08:06.016
people might report in altered states,

0:08:06.040,0:08:08.120
or perhaps even in psychosis.

0:08:09.120,0:08:10.787
Now, think about this for a minute.

0:08:11.160,0:08:16.256
If hallucination is a kind[br]of uncontrolled perception,

0:08:16.280,0:08:20.736
then perception right here and right now[br]is also a kind of hallucination,

0:08:20.760,0:08:22.776
but a controlled hallucination

0:08:22.800,0:08:25.696
in which the brain's predictions[br]are being reigned in

0:08:25.720,0:08:27.600
by sensory information from the world.

0:08:28.200,0:08:31.176
In fact, we're all[br]hallucinating all the time,

0:08:31.200,0:08:32.576
including right now.

0:08:32.600,0:08:35.416
It's just that when we agree[br]about our hallucinations,

0:08:35.440,0:08:36.640
we call that reality.

0:08:37.280,0:08:41.216
(Laughter)

0:08:41.240,0:08:44.576
Now I'm going to tell you[br]that your experience of being a self,

0:08:44.600,0:08:46.416
the specific experience of being you,

0:08:46.440,0:08:49.936
is also a controlled hallucination[br]generated by the brain.

0:08:49.960,0:08:51.976
This seems a very strange idea, right?

0:08:52.000,0:08:54.136
Yes, visual illusions[br]might deceive my eyes,

0:08:54.160,0:08:57.680
but how could I be deceived[br]about what it means to be me?

0:08:58.200,0:08:59.416
For most of us,

0:08:59.440,0:09:01.016
the experience of being a person

0:09:01.040,0:09:03.136
is so familiar, so unified[br]and so continuous

0:09:03.160,0:09:05.376
that it's difficult[br]not to take it for granted.

0:09:05.400,0:09:07.216
But we shouldn't take it for granted.

0:09:07.240,0:09:10.456
There are in fact many different ways[br]we experience being a self.

0:09:10.480,0:09:12.576
There's the experience of having a body

0:09:12.600,0:09:14.056
and of being a body.

0:09:14.080,0:09:16.216
There are experiences[br]of perceiving the world

0:09:16.240,0:09:17.880
from a first person point of view.

0:09:18.240,0:09:20.456
There are experiences[br]of intending to do things

0:09:20.480,0:09:23.200
and of being the cause of things[br]that happen in the world.

0:09:23.640,0:09:24.896
And there are experiences

0:09:24.920,0:09:28.816
of being a continuous[br]and distinctive person over time,

0:09:28.840,0:09:31.680
built from a rich set[br]of memories and social interactions.

0:09:32.200,0:09:33.496
Many experiments show,

0:09:33.520,0:09:35.856
and psychiatrists[br]and neurologists know very well,

0:09:35.880,0:09:38.776
that these different ways[br]in which we experience being a self

0:09:38.800,0:09:40.496
can all come apart.

0:09:40.520,0:09:43.416
What this means is[br]the basic background experience

0:09:43.440,0:09:48.016
of being a unified self is a rather[br]fragile construction of the brain.

0:09:48.040,0:09:50.696
Another experience,[br]which just like all others,

0:09:50.720,0:09:51.920
requires explanation.

0:09:52.720,0:09:54.496
So let's return to the bodily self.

0:09:54.520,0:09:57.256
How does the brain generate[br]the experience of being a body

0:09:57.280,0:09:58.536
and of having a body?

0:09:58.560,0:10:00.416
Well, just the same principles apply.

0:10:00.440,0:10:01.896
The brain makes its best guess

0:10:01.920,0:10:04.120
about what is and what is not[br]part of its body.

0:10:04.880,0:10:08.616
And there's a beautiful experiment[br]in neuroscience to illustrate this.

0:10:08.640,0:10:10.616
And unlike most neuroscience experiments,

0:10:10.640,0:10:12.136
this is one you can do at home.

0:10:12.160,0:10:14.056
All you need is one of these.

0:10:14.080,0:10:15.336
(Laughter)

0:10:15.360,0:10:16.800
And a couple of paintbrushes.

0:10:18.880,0:10:20.256
In the rubber hand illusion,

0:10:20.280,0:10:22.256
a person's real hand is hidden from view,

0:10:22.280,0:10:24.896
and that fake rubber hand[br]is placed in front of them.

0:10:24.920,0:10:28.176
Then both hands are simultaneously[br]stroked with a paintbrush

0:10:28.200,0:10:30.880
while the person stares at the fake hand.

0:10:31.320,0:10:33.296
Now, for most people, after a while,

0:10:33.320,0:10:35.416
this leads to the very uncanny sensation

0:10:35.440,0:10:38.040
that the fake hand[br]is in fact part of their body.

0:10:39.640,0:10:43.816
And the idea is that the congruence[br]between seeing touch and feeling touch

0:10:43.840,0:10:48.216
on an object that looks like hand[br]and is roughly where a hand should be,

0:10:48.240,0:10:51.016
is enough evidence for the brain[br]to make its best guess

0:10:51.040,0:10:54.256
that the fake hand[br]is in fact part of the body.

0:10:54.280,0:10:56.880
(Laughter)

0:11:03.240,0:11:05.496
So you can measure[br]all kinds of clever things.

0:11:05.520,0:11:08.816
You can measure skin conductance[br]and startle responses,

0:11:08.840,0:11:10.096
but there's no need.

0:11:10.120,0:11:13.056
It's clear the guy in blue[br]has assimilated the fake hand.

0:11:13.080,0:11:16.496
This means that even experiences[br]of what our body is

0:11:16.520,0:11:18.056
is a kind of best guessing --

0:11:18.080,0:11:20.560
a kind of controlled[br]hallucination by the brain.

0:11:21.480,0:11:22.680
There's one more thing.

0:11:24.120,0:11:27.776
We don't just experience our bodies[br]as objects in the world from the outside,

0:11:27.800,0:11:29.536
we also experience them from within.

0:11:29.560,0:11:33.800
We all experience the sense[br]of being a body from the inside.

0:11:35.000,0:11:37.576
And sensory signals[br]coming from the inside of the body

0:11:37.600,0:11:41.656
are continually telling the brain[br]about the state of the internal organs,

0:11:41.680,0:11:44.336
how the heart is doing,[br]what the blood pressure is like,

0:11:44.360,0:11:45.576
lots of things.

0:11:45.600,0:11:48.080
This kind of perception,[br]which we call interoception,

0:11:48.840,0:11:50.096
is rather overlooked.

0:11:50.120,0:11:51.536
But it's critically important

0:11:51.560,0:11:54.896
because perception and regulation[br]of the internal state of the body --

0:11:54.920,0:11:56.520
well, that's what keeps us alive.

0:11:57.400,0:11:59.816
Here's another version[br]of the rubber hand illusion.

0:11:59.840,0:12:01.336
This is from our lab at Sussex.

0:12:01.360,0:12:04.776
And here, people see[br]a virtual reality version of their hand,

0:12:04.800,0:12:06.176
which flashes red and back

0:12:06.200,0:12:09.456
either in time or out of time[br]with their heartbeat.

0:12:09.480,0:12:11.936
And when it's flashing[br]in time with their heartbeat,

0:12:11.960,0:12:15.080
people have a stronger sense[br]that it's in fact part of their body.

0:12:15.720,0:12:19.216
So experiences of having a body[br]are deeply grounded

0:12:19.240,0:12:21.640
in perceiving our bodies from within.

0:12:23.680,0:12:26.336
There's one last thing[br]I want to draw your attention to,

0:12:26.360,0:12:30.016
which is that experiences of the body[br]from the inside are very different

0:12:30.040,0:12:32.096
from experiences of the world around us.

0:12:32.120,0:12:34.816
When I look around me,[br]the world seems full of objects --

0:12:34.840,0:12:37.016
tables, chairs, rubber hands,

0:12:37.040,0:12:38.776
people, you lot --

0:12:38.800,0:12:40.776
even my own body in the world,

0:12:40.800,0:12:43.056
I can perceive it[br]as an object from the outside.

0:12:43.080,0:12:45.136
But my experiences[br]of the body from within,

0:12:45.160,0:12:46.576
they're not like that at all.

0:12:46.600,0:12:48.656
I don't perceive my kidneys here,

0:12:48.680,0:12:50.256
my liver here,

0:12:50.280,0:12:51.536
my spleen ...

0:12:51.560,0:12:53.456
I don't know where my spleen is,

0:12:53.480,0:12:54.856
but it's somewhere.

0:12:54.880,0:12:56.776
I don't perceive my insides as objects.

0:12:56.800,0:13:00.440
In fact, I don't experience them[br]much at all unless they go wrong.

0:13:01.400,0:13:02.880
And this is important, I think.

0:13:03.600,0:13:05.696
Perception of the internal[br]state of the body

0:13:05.720,0:13:07.576
isn't about figuring out what's there,

0:13:07.600,0:13:09.736
it's about control and regulation --

0:13:09.760,0:13:13.656
keeping the physiological variables[br]within the tight bounds

0:13:13.680,0:13:15.520
that are compatible with survival.

0:13:16.640,0:13:19.496
When the brain uses predictions[br]to figure out what's there,

0:13:19.520,0:13:22.616
we perceive objects[br]as the causes of sensations.

0:13:22.640,0:13:26.256
When the brain uses predictions[br]to control and regulate things,

0:13:26.280,0:13:29.440
we experience how well[br]or how badly that control is going.

0:13:29.880,0:13:32.696
So our most basic experiences[br]of being a self,

0:13:32.720,0:13:34.776
of being an embodied organism,

0:13:34.800,0:13:38.760
are deeply grounded in the biological[br]mechanisms that keep us alive.

0:13:40.760,0:13:43.096
And when we follow this idea[br]all the way through,

0:13:43.120,0:13:46.816
we can start to see[br]that all of our conscious experiences,

0:13:46.840,0:13:51.576
since they all depend on the same[br]mechanisms of predictive perception,

0:13:51.600,0:13:55.016
all stem from this basic[br]drive to stay alive.

0:13:55.040,0:13:57.656
We experience the world and ourselves

0:13:57.680,0:14:00.760
with, through and because of[br]our living bodies.

0:14:01.560,0:14:03.960
Let me bring things together step-by-step.

0:14:04.560,0:14:06.136
What we consciously see depends

0:14:06.160,0:14:08.456
on the brain's best guess[br]of what's out there.

0:14:08.480,0:14:10.856
Our experienced world[br]comes from the inside out,

0:14:10.880,0:14:12.120
not just the outside in.

0:14:12.600,0:14:15.856
The rubber hand illusion shows[br]that this applies to our experiences

0:14:15.880,0:14:17.720
of what is and what is not our body.

0:14:18.560,0:14:22.136
And these self-related predictions[br]depend critically on sensory signals

0:14:22.160,0:14:23.920
coming from deep inside the body.

0:14:24.400,0:14:25.616
And finally,

0:14:25.640,0:14:30.016
experiences of being an embodied self[br]are more about control and regulation

0:14:30.040,0:14:31.720
than figuring out what's there.

0:14:32.840,0:14:36.056
So our experiences of the world[br]around us and ourselves within it --

0:14:36.080,0:14:38.336
well, they're kinds[br]of controlled hallucinations

0:14:38.360,0:14:41.256
that have been shaped[br]over millions of years of evolution

0:14:41.280,0:14:44.040
to keep us alive in worlds[br]full of danger and opportunity.

0:14:44.480,0:14:47.160
We predict ourselves into existence.

0:14:48.520,0:14:51.000
Now, I leave you with three[br]implications of all this.

0:14:51.640,0:14:53.856
First, just as we can[br]misperceive the world,

0:14:53.880,0:14:55.656
we can misperceive ourselves

0:14:55.680,0:14:57.816
when the mechanisms[br]of prediction go wrong.

0:14:57.840,0:15:02.056
Understanding this opens many new[br]opportunities in psychiatry and neurology,

0:15:02.080,0:15:04.696
because we can finally[br]get at the mechanisms

0:15:04.720,0:15:06.616
rather than just treating the symptoms

0:15:06.640,0:15:09.160
in conditions like[br]depression and schizophrenia.

0:15:09.720,0:15:10.936
Second:

0:15:10.960,0:15:14.776
what it means to be me[br]cannot be reduced to or uploaded to

0:15:14.800,0:15:17.176
a software program running on a robot,

0:15:17.200,0:15:19.416
however smart or sophisticated.

0:15:19.440,0:15:22.056
We are biological, flesh-and-blood animals

0:15:22.080,0:15:25.336
whose conscious experiences[br]are shaped at all levels

0:15:25.360,0:15:28.336
by the biological mechanisms[br]that keep us alive.

0:15:28.360,0:15:32.000
Just making computers smarter[br]is not going to make them sentient.

0:15:33.000,0:15:34.296
Finally,

0:15:34.320,0:15:36.296
our own individual inner universe,

0:15:36.320,0:15:37.976
our way of being conscious,

0:15:38.000,0:15:40.760
is just one possible[br]way of being conscious.

0:15:41.840,0:15:43.816
And even human consciousness generally --

0:15:43.840,0:15:47.816
it's just a tiny region in a vast space[br]of possible consciousnesses.

0:15:47.840,0:15:51.496
Our individual self and worlds[br]are unique to each of us,

0:15:51.520,0:15:54.736
but they're all grounded[br]in biological mechanisms

0:15:54.760,0:15:57.360
shared with many other living creatures.

0:15:57.920,0:16:00.880
Now, these are fundamental changes

0:16:01.760,0:16:04.016
in how we understand ourselves,

0:16:04.040,0:16:05.896
but I think they should be celebrated,

0:16:05.920,0:16:08.296
because as so often in science,[br]from Copernicus --

0:16:08.320,0:16:10.320
we're not at the center of the universe --

0:16:10.344,0:16:11.576
to Darwin --

0:16:11.600,0:16:13.816
we're related to all other creatures --

0:16:13.840,0:16:15.040
to the present day.

0:16:16.320,0:16:19.056
With a greater sense of understanding

0:16:19.080,0:16:21.496
comes a greater sense of wonder,

0:16:21.520,0:16:23.376
and a greater realization

0:16:23.400,0:16:28.000
that we are part of[br]and not apart from the rest of nature.

0:16:28.920,0:16:30.120
And ...

0:16:30.720,0:16:33.096
when the end of consciousness comes,

0:16:33.120,0:16:35.920
there's nothing to be afraid of.

0:16:36.560,0:16:37.760
Nothing at all.

0:16:38.480,0:16:39.696
Thank you.

0:16:39.720,0:16:47.746
(Applause)