0:00:01.026,0:00:02.986
Just over a year ago,

0:00:02.986,0:00:04.412
for the third time in my life,

0:00:04.412,0:00:05.561
I ceased to exist.

0:00:05.561,0:00:07.529
I was having a small operation,

0:00:07.529,0:00:10.395
and my brain was filling with anesthetic.

0:00:10.705,0:00:13.680
I remember a sense[br]of detachment and falling apart

0:00:13.680,0:00:15.085
and a coldness.

0:00:16.022,0:00:17.297
And then I was back,

0:00:17.297,0:00:18.656
drowsy and disoriented,

0:00:18.656,0:00:20.371
but definitely there.

0:00:20.513,0:00:22.043
When you wake from a deep sleep,

0:00:22.043,0:00:25.410
you might feel confused about the time[br]or anxious about oversleeping,

0:00:25.410,0:00:28.450
but there's always a basic sense[br]of time having passed,

0:00:28.450,0:00:30.583
of a continuity between then and now.

0:00:30.583,0:00:32.680
Coming out from[br]anesthesia is very different.

0:00:32.680,0:00:34.661
I could have been under for five minutes,

0:00:34.661,0:00:35.663
five hours,

0:00:35.663,0:00:36.655
five years,

0:00:36.655,0:00:37.663
or even 50 years.

0:00:37.663,0:00:38.723
I simply wasn't there.

0:00:38.723,0:00:40.235
It was total obliviion.

0:00:40.422,0:00:41.424
Anesthesia --

0:00:41.424,0:00:42.770
it's a modern kind of magic.

0:00:42.770,0:00:45.767
It turns people into objects,

0:00:45.767,0:00:46.773
and then we hope,

0:00:46.773,0:00:47.867
back again into people.

0:00:47.867,0:00:48.871
In this process

0:00:48.871,0:00:52.640
is one of the greatest remaining[br]mysteries in science and philosophy.

0:00:52.640,0:00:54.314
How does consciousness happen?

0:00:54.314,0:00:56.414
Somehow, within each of our brains,

0:00:56.414,0:00:59.428
the combined activity[br]of many billions of neurons,

0:00:59.428,0:01:02.530
each one a tiny biological machine,

0:01:02.530,0:01:04.299
is generating a conscious experience.

0:01:04.299,0:01:06.210
And not just any conscious experience --

0:01:06.210,0:01:08.790
your conscious experience[br]right here and right now.

0:01:08.790,0:01:10.825
How does this happen?

0:01:10.825,0:01:12.983
Answering this question is so important

0:01:12.983,0:01:15.620
because consciousness[br]for each of us is all there is.

0:01:15.620,0:01:18.661
Without it there's no world,

0:01:18.661,0:01:20.080
there's no self,

0:01:20.080,0:01:21.452
there's nothing at all.

0:01:21.452,0:01:22.525
And when we suffer,

0:01:22.525,0:01:23.681
we suffer consciously

0:01:23.681,0:01:26.659
whether it's through[br]mental illness or pain.

0:01:26.659,0:01:29.613
And if we can experience[br]joy and suffering,

0:01:29.613,0:01:31.642
what about other animals?

0:01:31.642,0:01:33.168
Might they be conscious, too?

0:01:33.168,0:01:34.796
Do they also have a sense of self?

0:01:34.796,0:01:37.848
And as computers get faster and smarter,

0:01:37.848,0:01:39.285
maybe there will come a point,

0:01:39.285,0:01:40.423
maybe not too far away,

0:01:40.423,0:01:43.300
when my iPhone develops[br]a sense of its own existence.

0:01:43.300,0:01:48.057
I actually think the prospects[br]for a conscious AI are pretty remote.

0:01:48.057,0:01:50.426
And I think this because[br]my research is telling me

0:01:50.426,0:01:53.073
that consciousness has less to do[br]with pure intelligence

0:01:53.073,0:01:57.812
and more to do with our nature[br]as living and breathing organisms.

0:01:57.812,0:02:00.484
Consciousness and intelligence[br]are very different things.

0:02:00.484,0:02:02.245
You don't have to be smart to suffer,

0:02:02.245,0:02:04.762
but you probably do have to be alive.

0:02:05.264,0:02:06.953
In the story I'm going to tell you,

0:02:06.953,0:02:09.239
our conscious experiences[br]of the world around us,

0:02:09.239,0:02:10.754
and of ourselves within it,

0:02:10.754,0:02:13.500
are kinds of controlled hallucinations

0:02:13.500,0:02:17.345
that happen with, through[br]and because of our living bodies.

0:02:18.041,0:02:21.411
Now, you might have heard[br]that we know nothing

0:02:21.411,0:02:24.201
about how the brain and body[br]give rise to consciousness.

0:02:24.201,0:02:27.357
Some people even say it's beyond[br]the reach of science all together.

0:02:27.357,0:02:28.360
But in fact,

0:02:28.360,0:02:32.839
the last 25 years have seen an explosion[br]of scientific work in this area.

0:02:32.839,0:02:35.757
If you come to my lab [br]at the University of Sussex,

0:02:35.757,0:02:39.560
you'll find scientists[br]from all different disciplines,

0:02:39.560,0:02:41.965
and sometimes even philosophers.

0:02:41.965,0:02:46.015
All of us together trying to understand[br]how conscioussness happens

0:02:46.015,0:02:48.188
and what happens when it goes wrong.

0:02:48.188,0:02:50.232
The strategy is very simple.

0:02:50.232,0:02:52.181
I'd like you to think about consciousness

0:02:52.181,0:02:54.377
in the way that we've[br]come to think about life.

0:02:54.377,0:02:55.377
At one time,

0:02:55.377,0:02:58.420
people thought the property[br]of being alive could not be explained

0:02:58.420,0:02:59.814
by physics and chemistry --

0:02:59.814,0:03:02.777
that life had to be more[br]than just mechanism.

0:03:02.777,0:03:04.654
But people no longer think that.

0:03:04.654,0:03:06.241
As biologists got on with the job

0:03:06.241,0:03:08.951
of explaining the properties[br]of living systems

0:03:08.951,0:03:10.750
in terms of physics and chemistry --

0:03:10.750,0:03:13.833
things like metabolism,[br]reproduction, homeostasis --

0:03:13.833,0:03:17.719
the basic mystery of what life is[br]started to fade away,

0:03:17.719,0:03:20.883
and people didn't propose[br]any more magical solutions,

0:03:20.883,0:03:23.157
like a force of life or an élan vital.

0:03:23.330,0:03:24.568
So as with life,

0:03:24.568,0:03:25.959
so with consciousness.

0:03:25.959,0:03:28.447
Once we start explaining its properties

0:03:28.447,0:03:32.179
in terms of things happening[br]inside brains and bodies,

0:03:32.179,0:03:35.601
the apparently insoluble mystery[br]of what consciousness is

0:03:35.601,0:03:37.400
should start to fade away.

0:03:37.400,0:03:39.226
At least that's the plan.

0:03:39.461,0:03:40.847
So let's get started.

0:03:40.847,0:03:42.809
What are the properties of consciousness?

0:03:42.809,0:03:45.841
What should a science[br]of consciousness try to explain?

0:03:46.025,0:03:49.691
Well, for today I'd just like to think[br]of consciousness in two different ways.

0:03:49.691,0:03:52.345
There are experiences[br]of the world around us,

0:03:52.345,0:03:54.447
full of sights, sounds and smells,

0:03:54.447,0:03:58.440
there's multisensory, panoramic,[br]3D, fully immersive inner movie.

0:03:59.257,0:04:01.242
And then there's conscious self.

0:04:01.242,0:04:03.882
The specific experience[br]of being you or being me.

0:04:03.882,0:04:05.897
The lead character in this inner movie,

0:04:05.897,0:04:09.497
and probably the aspect of consciousness[br]we all cling to most tightly.

0:04:10.044,0:04:12.505
Let's start with experiences[br]of the world around us,

0:04:12.505,0:04:16.144
and with the important idea[br]of the brain as a prediction engine.

0:04:16.350,0:04:18.458
Imagine being a brain.

0:04:18.753,0:04:20.457
You're locked inside a bony skull,

0:04:20.457,0:04:22.653
trying to figure what's[br]out there in the world.

0:04:22.653,0:04:24.429
There are no lights inside the skull.

0:04:24.429,0:04:25.923
There's no sound either.

0:04:25.923,0:04:28.606
All you've got to go on is streams[br]of electrical impulses

0:04:28.606,0:04:31.771
which are only indirectly related[br]to things in the world,

0:04:31.771,0:04:33.318
whatever they may be.

0:04:33.662,0:04:34.656
So perception --

0:04:34.656,0:04:36.004
figuring out what's there --

0:04:36.004,0:04:38.860
has to be a process of informed guess work

0:04:38.860,0:04:41.958
in which the brain combines[br]these sensory signals

0:04:41.958,0:04:46.151
with its prior expectations or beliefs[br]about the way the world is

0:04:46.151,0:04:49.315
to form its best guess of what[br]caused those signals.

0:04:49.315,0:04:51.927
The brain doesn't hear sound or see light.

0:04:51.927,0:04:56.629
What we perceive is its best guess[br]of what's out there in the world.

0:04:57.219,0:05:00.237
Let me give you a couple[br]of examples of all this.

0:05:00.515,0:05:02.470
You might have seen this illusion before,

0:05:02.470,0:05:04.771
but I'd like you to think[br]about it in a new way.

0:05:04.771,0:05:06.978
If you look at those two patches, A and B,

0:05:06.978,0:05:10.810
they should look to you to be[br]very different shades of gray, right?

0:05:11.080,0:05:14.262
But they are in fact[br]exactly the same shade.

0:05:14.262,0:05:15.607
And I can illustrate this.

0:05:15.607,0:05:17.827
If I put up a second version[br]of the image here,

0:05:17.827,0:05:20.903
and join the two patches[br]with a gray-colored bar,

0:05:20.903,0:05:22.525
you can see there's no difference.

0:05:22.525,0:05:24.298
It's exactly the same shade of gray.

0:05:24.298,0:05:26.047
And if you still don't believe me,

0:05:26.047,0:05:28.507
I'll bring the bar across[br]and join them up.

0:05:28.837,0:05:31.225
It's a single colored block of gray,

0:05:31.225,0:05:32.919
there's no difference at all.

0:05:32.919,0:05:34.589
This isn't any kind of magic trick.

0:05:34.589,0:05:35.930
It's the same shade of gray,

0:05:35.930,0:05:37.070
but take it away again,

0:05:37.070,0:05:38.777
and it looks different.

0:05:39.374,0:05:40.698
So what's happening here

0:05:40.698,0:05:43.628
is that the brain is using[br]its prior expectations

0:05:43.628,0:05:46.827
built deeply into the circuits[br]of the visual cortex

0:05:46.827,0:05:49.483
that a cast shadow dims[br]the appearance of a surface,

0:05:49.483,0:05:53.477
so that we see B as lighter[br]than it really is.

0:05:54.101,0:05:55.541
Here's one more example,

0:05:55.541,0:05:58.620
which shows just how quickly[br]the brain can use new predictions

0:05:58.620,0:06:00.888
to change what we consciously experience.

0:06:00.888,0:06:02.791
Have a listen to this.

0:06:03.626,0:06:06.478
[(Distorted voice)]

0:06:07.402,0:06:08.988
Sounded strange, right?

0:06:09.253,0:06:11.733
Have a listen again and see[br]if you can get anything.

0:06:12.008,0:06:14.713
([Distorted voice])

0:06:16.095,0:06:17.249
Still strange.

0:06:17.249,0:06:18.555
Now listen to this.

0:06:19.108,0:06:22.249
Recording: I think breakfast[br]is a really terrible idea.

0:06:22.652,0:06:23.649
(Laughter)

0:06:23.649,0:06:24.648
Which I do.

0:06:24.648,0:06:26.449
So you heard some words there, right?

0:06:26.449,0:06:28.161
Now listen to the first sound again.

0:06:28.161,0:06:29.568
I'm just going to replay it.

0:06:29.568,0:06:32.539
([Distrorted voice])

0:06:32.840,0:06:33.980
Yeah?

0:06:33.980,0:06:35.568
So you can now hear words there.

0:06:35.568,0:06:36.953
Once more for luck.

0:06:37.223,0:06:40.051
([Distorted voice])

0:06:41.197,0:06:42.857
OK, so what's going on here?

0:06:43.946,0:06:47.295
The remarkable thing is the sensory[br]information coming into the brain

0:06:47.295,0:06:48.866
hasn't changed at all.

0:06:48.866,0:06:51.489
All that's changed is your[br]brain's best guess

0:06:51.489,0:06:53.495
of the causes of that sensory information.

0:06:53.495,0:06:56.286
And that changes[br]what you consciously hear.

0:06:56.862,0:06:59.994
All this puts the brain[br]basis of perception

0:06:59.994,0:07:01.433
in a bit of a different light.

0:07:01.433,0:07:05.562
Instead of perception depending largely[br]on signals coming into the brain

0:07:05.562,0:07:07.246
from the outside world,

0:07:07.246,0:07:08.394
it depends as much,

0:07:08.394,0:07:09.524
if not more,

0:07:09.524,0:07:13.780
on perceptual predictions flowing[br]in the opposite direction.

0:07:14.209,0:07:16.215
We don't just passively[br]perceive the world,

0:07:16.215,0:07:17.762
we actively generate it.

0:07:18.077,0:07:20.849
The world we experience[br]comes as much if not more

0:07:20.849,0:07:22.271
from the inside out

0:07:22.271,0:07:23.707
as from the outside in.

0:07:23.947,0:07:26.225
Let me give you one more[br]example of perception

0:07:26.225,0:07:29.030
as this active, constructive process.

0:07:30.901,0:07:34.815
Here we've combined immersive[br]virtual reality with image processing

0:07:34.815,0:07:37.817
to simulate the effects of overly[br]strong perceptual predictions

0:07:37.817,0:07:39.186
on our experience.

0:07:39.186,0:07:40.376
In this panoramic video,

0:07:40.376,0:07:42.125
we've tranformed the world --

0:07:42.125,0:07:44.087
which is in this case Sussex campus --

0:07:44.087,0:07:45.995
into a psychedilic playground.

0:07:45.995,0:07:49.973
We've processed the footage using[br]an alogrithm based on Google's Deep Dream

0:07:49.973,0:07:53.599
to simulate the effects of overly strong[br]perceptual predictions.

0:07:53.913,0:07:55.797
In this case, to see dogs.

0:07:55.797,0:07:57.770
You can see this is a very strange thing.

0:07:57.770,0:08:00.119
When perceptual[br]predictions are too strong,

0:08:00.119,0:08:01.407
as they are here,

0:08:01.407,0:08:05.467
the result looks very much like the kinds[br]of hallucinations people might report

0:08:05.467,0:08:06.472
in altered states,

0:08:06.472,0:08:08.568
or perhaps even in psychosis.

0:08:09.398,0:08:10.983
Think about this for a minute.

0:08:11.334,0:08:16.471
If hallucination is a kind[br]of uncontrolled perception,

0:08:16.471,0:08:20.988
then perception right here and right now[br]is also a kind of hallucination,

0:08:20.988,0:08:23.136
but a controlled hallucination

0:08:23.136,0:08:26.052
in which the brain's predictions[br]are being reigned in

0:08:26.052,0:08:28.039
by sensory information from the world.

0:08:28.365,0:08:31.473
In fact, we're all[br]hallucinating all the time,

0:08:31.473,0:08:32.867
including right now.

0:08:32.867,0:08:35.816
It's just that when we agree[br]about our hallucinations,

0:08:35.816,0:08:37.268
we call that reality.

0:08:37.774,0:08:39.995
(Laughter)

0:08:41.480,0:08:44.916
Now I'm going to tell you that your[br]experience of being a self,

0:08:44.916,0:08:46.729
the specific experience of being you,

0:08:46.729,0:08:50.011
is also a controlled hallucination[br]generated by the brain.

0:08:50.178,0:08:52.304
This seems a very strange idea, right?

0:08:52.304,0:08:54.419
Yes, visual illusions[br]might deceive my eyes,

0:08:54.419,0:08:58.226
but how could I be deceived[br]about what it means to be me?

0:08:58.347,0:08:59.347
For most of us,

0:08:59.347,0:09:02.112
the experience of being a person[br]is so familiar, so unified

0:09:02.112,0:09:03.413
and so continuous

0:09:03.413,0:09:05.628
that it's difficult not[br]to take it for granted.

0:09:05.628,0:09:07.401
But we shouldn't take it for granted.

0:09:07.401,0:09:10.764
There are in fact many different ways[br]we experience being a self.

0:09:10.764,0:09:12.920
There's the experience of having a body

0:09:12.920,0:09:14.393
and of being a body.

0:09:14.393,0:09:16.487
There are experiences[br]of perceiving the world

0:09:16.487,0:09:18.231
from a first person point of view.

0:09:18.677,0:09:20.645
There are experiences[br]of intending to do things

0:09:20.834,0:09:23.863
and of being the cause of things[br]that happen in the world.

0:09:24.075,0:09:27.786
And there are experiences of being[br]a continuous and distinctive person

0:09:27.931,0:09:29.151
over time,

0:09:29.358,0:09:31.858
built from a rich set of memories[br]and social interactions.

0:09:32.465,0:09:33.792
Many experiments show,

0:09:33.986,0:09:35.796
and psychiatrists and[br]neurologists know very well

0:09:36.073,0:09:38.836
that these different ways in which[br]we experience being a self

0:09:39.064,0:09:40.119
can all come apart.

0:09:40.796,0:09:43.553
What this means is the basic[br]background experience

0:09:43.727,0:09:48.251
of being a unified self is a rather[br]fragile construction of the brain,

0:09:48.391,0:09:49.588
another experience,

0:09:49.784,0:09:50.917
which just like all others,

0:09:51.089,0:09:52.255
requires explanation.

0:09:52.962,0:09:54.750
So let's return to the bodily self.

0:09:54.925,0:09:57.535
How does the brain generate[br]the experience of being a body

0:09:57.762,0:09:58.843
and having a body?

0:09:59.070,0:10:00.727
Well, just the same principles apply.

0:10:00.926,0:10:01.838
The brain makes its best guess

0:10:02.066,0:10:04.632
about what is and what is not[br]part of its body.

0:10:05.268,0:10:08.939
There's a beautiful experiment[br]in neuroscience to illustrate this.

0:10:09.176,0:10:10.723
And unlike most neuroscience experiments,

0:10:10.930,0:10:12.061
this is one you can do at home.

0:10:12.439,0:10:14.290
All you need is one of these.

0:10:14.774,0:10:15.639
(Laughter)

0:10:15.901,0:10:17.490
And a couple of paint brushes.

0:10:19.155,0:10:20.331
In the rubber hand illusion,

0:10:20.508,0:10:22.373
a person's real hand is hidden from view.

0:10:22.576,0:10:24.778
And that fake rubber hand[br]is placed in front of them.

0:10:25.044,0:10:28.461
Then both hands are simultaneously[br]stroked with a paintbrush

0:10:28.657,0:10:31.258
while the person stares at the fake hand.

0:10:31.645,0:10:32.511
Now for most people,

0:10:32.745,0:10:33.526
after a while,

0:10:33.721,0:10:35.832
this leads to the very uncanny sensation

0:10:36.031,0:10:38.536
that the fake hand is[br]in fact part of their body.

0:10:39.876,0:10:44.192
And the idea is that the congruence[br]between seeing touch and feeling touch

0:10:44.375,0:10:46.374
on an object that looks like hand,

0:10:46.581,0:10:48.288
and is roughly where a hand should be,

0:10:48.493,0:10:51.092
is enough evidence for the brain[br]to make its best guess

0:10:51.391,0:10:55.046
that the fake hand is in fact[br]part of the body.

0:10:55.591,0:10:56.666
(Laughter)

0:11:03.526,0:11:05.610
So you can measure[br]all kinds of clever things.

0:11:05.818,0:11:08.010
Like you can measure skin conductants

0:11:08.284,0:11:09.210
and start and responses,

0:11:09.420,0:11:10.039
but there's no need.

0:11:10.266,0:11:13.277
It's clear the guy in blue[br]has assimilated the fake hand.

0:11:13.473,0:11:16.710
This means that even experiences[br]of what our body is

0:11:16.893,0:11:18.344
is kind of best guessing --

0:11:18.518,0:11:20.951
a kind of controlled[br]hallucination by the brain.

9:59:59.000,9:59:59.000
There's one more thing.

9:59:59.000,9:59:59.000
We don't just experience our bodies[br]as objects in the world from the outside,

9:59:59.000,9:59:59.000
we also experience them from within.

9:59:59.000,9:59:59.000
We all experience the sense[br]of being a body from the inside.

9:59:59.000,9:59:59.000
And sensory signals coming from[br]the inside of the body

9:59:59.000,9:59:59.000
are continually telling the brain[br]about the state of the internal organs,

9:59:59.000,9:59:59.000
how the heart is doing,

9:59:59.000,9:59:59.000
what the blood pressure is like,

9:59:59.000,9:59:59.000
lots of things.

9:59:59.000,9:59:59.000
And this kind of perception,

9:59:59.000,9:59:59.000
which we call intereception,

9:59:59.000,9:59:59.000
is rather over-looked.

9:59:59.000,9:59:59.000
But it's critically important

9:59:59.000,9:59:59.000
because perception and regulation[br]of the internal state of the body --

9:59:59.000,9:59:59.000
well, that's what keeps us alive.

9:59:59.000,9:59:59.000
Here's another version of the[br]rubber hand illusion.

9:59:59.000,9:59:59.000
This is from our lab at Sussex.

9:59:59.000,9:59:59.000
And here, people see a virtual[br]reality version of their hand,

9:59:59.000,9:59:59.000
which flashes red and back

9:59:59.000,9:59:59.000
either in time or out of time[br]with their heartbeat.

9:59:59.000,9:59:59.000
And when it's flashing in time[br]with their heartbeat,

9:59:59.000,9:59:59.000
people have a strong sense that it's[br]in fact part of their body.

9:59:59.000,9:59:59.000
So experiences of having a body[br]are deeply grounded

9:59:59.000,9:59:59.000
in perceiving our bodies from within.

9:59:59.000,9:59:59.000
There's one last thing I want[br]to draw your attention to,

9:59:59.000,9:59:59.000
which is that experiences of the body[br]from the inside are very different

9:59:59.000,9:59:59.000
from experiences of the world around us.

9:59:59.000,9:59:59.000
When I look around me,

9:59:59.000,9:59:59.000
the world seems full of objects --

9:59:59.000,9:59:59.000
tables, chairs , rubber hands,

9:59:59.000,9:59:59.000
people,

9:59:59.000,9:59:59.000
[you lot] --

9:59:59.000,9:59:59.000
even my own body in the world,

9:59:59.000,9:59:59.000
I can perceive it as an object[br]from the outside,

9:59:59.000,9:59:59.000
but my experiences of my body from within,

9:59:59.000,9:59:59.000
they're not like that at all.

9:59:59.000,9:59:59.000
I don't perceive my kidneys here,

9:59:59.000,9:59:59.000
my liver here,

9:59:59.000,9:59:59.000
my spleen ...

9:59:59.000,9:59:59.000
I don't know where my spleen is,

9:59:59.000,9:59:59.000
but somewhere.

9:59:59.000,9:59:59.000
I don't perceive my insides as objects.

9:59:59.000,9:59:59.000
In fact I don't experience them much[br]at all unless they go wrong.

9:59:59.000,9:59:59.000
And this is important I think.

9:59:59.000,9:59:59.000
Perception of the internal[br]state of the body

9:59:59.000,9:59:59.000
isn't about figuring out what's there,

9:59:59.000,9:59:59.000
it's about control and regulation --

9:59:59.000,9:59:59.000
keeping the physiological variables[br]within the tight bounds

9:59:59.000,9:59:59.000
that are compatible with survival.

9:59:59.000,9:59:59.000
When the brain uses predictions[br]to figure out what's there,

9:59:59.000,9:59:59.000
we can see objects[br]as the causes of sensations.

9:59:59.000,9:59:59.000
When the brain uses predictions[br]to control and regulate things,

9:59:59.000,9:59:59.000
we experience how well[br]or how badly that control is going.

9:59:59.000,9:59:59.000
So out most basic experiences[br]of being a self,

9:59:59.000,9:59:59.000
of being a body organism,

9:59:59.000,9:59:59.000
are deeply grounded in the biological[br]mechanisms that keep us alive.

9:59:59.000,9:59:59.000
And when we follow this idea[br]all the way through,

9:59:59.000,9:59:59.000
we can start to see that all[br]of our conscious experiences,

9:59:59.000,9:59:59.000
since they all depend on the same[br]mechanisms of predictive perception,

9:59:59.000,9:59:59.000
all stem from this basic[br]drive to stay alive.

9:59:59.000,9:59:59.000
We experience the world and ourselves

9:59:59.000,9:59:59.000
with, through and because of[br]our living bodies.

9:59:59.000,9:59:59.000
Let me bring things together step by step.

9:59:59.000,9:59:59.000
What we consciously see depends[br]on the brain's best guess

9:59:59.000,9:59:59.000
of what's out there.

9:59:59.000,9:59:59.000
Our experienced world[br]comes from the inside out,

9:59:59.000,9:59:59.000
not just the outside in.

9:59:59.000,9:59:59.000
The rubber hand illusion shows[br]that this applies to our experienes

9:59:59.000,9:59:59.000
of what is and what is not our body.

9:59:59.000,9:59:59.000
And these self related predictions[br]depend critically on sensory signals

9:59:59.000,9:59:59.000
coming from deep inside the body.

9:59:59.000,9:59:59.000
And finally,

9:59:59.000,9:59:59.000
experiences of being an embodied self[br]are more about control and regulation

9:59:59.000,9:59:59.000
than figuring out what's there.

9:59:59.000,9:59:59.000
So our experiences of the world[br]around us and ourselves within it --

9:59:59.000,9:59:59.000
well, they're kinds[br]of controlled hallucinations

9:59:59.000,9:59:59.000
that have been shaped[br]over millions of years of evolution

9:59:59.000,9:59:59.000
to keep us alive in worlds[br]full of danger and opporunity.

9:59:59.000,9:59:59.000
We predict ourselves into existence.

9:59:59.000,9:59:59.000
Now I leave you with three[br]implications of all this.

9:59:59.000,9:59:59.000
First, just as we can[br]misperceive the world,

9:59:59.000,9:59:59.000
we can misperceive ourselves

9:59:59.000,9:59:59.000
when the mechanisms[br]of prediction go wrong.

9:59:59.000,9:59:59.000
Understanding this opens many new[br]opportunities in psychiatry and neurology,

9:59:59.000,9:59:59.000
because we can finally[br]get at the mechanisms

9:59:59.000,9:59:59.000
rather than just treating the symptoms

9:59:59.000,9:59:59.000
in conditions like[br]depression and schizophrenia.

9:59:59.000,9:59:59.000
Second:

9:59:59.000,9:59:59.000
what it means to be me cannot be[br]reduced to or uploaded to

9:59:59.000,9:59:59.000
a software program running on a robot,

9:59:59.000,9:59:59.000
however smart or sophisticated.

9:59:59.000,9:59:59.000
We are biological, flesh-and-blood animals

9:59:59.000,9:59:59.000
whose conscious experiences[br]are shaped at all levels

9:59:59.000,9:59:59.000
by the biological mechanisms[br]that keep us alive.

9:59:59.000,9:59:59.000
Just making computers smarter[br]is not going to make the sentient.

9:59:59.000,9:59:59.000
Finally,

9:59:59.000,9:59:59.000
our own individual inner universe,

9:59:59.000,9:59:59.000
our way of being conscious,

9:59:59.000,9:59:59.000
is just one possible[br]way of being conscious.

9:59:59.000,9:59:59.000
And even human consciousness generally --

9:59:59.000,9:59:59.000
it's just a tiny region in a vast space[br]of possible consciousnesses.

9:59:59.000,9:59:59.000
Our individual self and worlds[br]are unique to each of us,

9:59:59.000,9:59:59.000
but they're all grounded

9:59:59.000,9:59:59.000
in biological mechanisms shared[br]with many other living creatures.

9:59:59.000,9:59:59.000
Now, these are fundamental changes[br]in how we understand ourselves,

9:59:59.000,9:59:59.000
but I think they should be celebrated,

9:59:59.000,9:59:59.000
because as so often in science,

9:59:59.000,9:59:59.000
when Copernicus --

9:59:59.000,9:59:59.000
we're not at the center[br]of the universe --

9:59:59.000,9:59:59.000
to Darwin --

9:59:59.000,9:59:59.000
we're related to all other creatures --

9:59:59.000,9:59:59.000
to the present day.

9:59:59.000,9:59:59.000
With a greater sense of understanding

9:59:59.000,9:59:59.000
comes a greater sense of wonder,

9:59:59.000,9:59:59.000
and a greater realization that we[br]are part of and not apart from

9:59:59.000,9:59:59.000
the rest of nature.

9:59:59.000,9:59:59.000
And when the end of consciousness comes,

9:59:59.000,9:59:59.000
there's nothing to be afraid of.

9:59:59.000,9:59:59.000
Nothing at all.

9:59:59.000,9:59:59.000
Thank you.

9:59:59.000,9:59:59.000
(Applause)