for the third time in my life, I ceased to exist.

一年多前，

I was having a small operation, and my brain was filling with anesthetic.

我於人生中第三次不復存在。

I remember a sense of detachment and falling apart

當時我正接受一個小手術， 而我的腦中充滿了麻醉藥劑。

and a coldness.

我還記得當時感覺抽離、崩潰、

And then I was back, drowsy and disoriented,

和冰冷。

but definitely there.

隨後我恢復意識，昏沉又迷惘，

Now, when you wake from a deep sleep,

但我絕對在那裡。

you might feel confused about the time or anxious about oversleeping,

當你從深睡中醒來，

but there's always a basic sense of time having passed,

你可能對時間感到困惑， 或是對睡過頭感到焦慮，

of a continuity between then and now.

但基本上都會意識到時間流逝、

Coming round from anesthesia is very different.

以及彼時與此時之間的連續性。

I could have been under for five minutes, five hours,

麻醉過後恢復意識則截然不同。

five years or even 50 years.

也許我失去意識五分鐘、五小時、

I simply wasn't there.

五年、甚至五十年。

It was total oblivion.

我就是不在那裡，

Anesthesia -- it's a modern kind of magic.

完全處於無意識的狀態。

It turns people into objects,

麻醉是種現代的魔法。

and then, we hope, back again into people.

它把人變成物品，

And in this process

接著，但願由物品再變回人。

is one of the greatest remaining mysteries in science and philosophy.

這個過程中

How does consciousness happen?

有著科學與哲學中 未解的最大謎題之一。

Somehow, within each of our brains,

意識是如何發生的?

the combined activity of many billions of neurons,

在我們每個人的腦中

each one a tiny biological machine,

有數十億個神經元聯手動作，

is generating a conscious experience.

而每個神經元都是個小小生物機器，

And not just any conscious experience --

它們聯合產出意識經驗。

your conscious experience right here and right now.

不僅僅是任何意識經驗，

How does this happen?

而是你在此時此地的意識經驗。

Answering this question is so important

這是如何發生的？

because consciousness for each of us is all there is.

回答這個問題極為重要，

Without it there's no world,

因為意識是我們每個人的一切，

there's no self,

沒有意識，就沒有世界，

there's nothing at all.

沒有自我，

And when we suffer, we suffer consciously

什麼都沒有。

whether it's through mental illness or pain.

當我們受苦時，是有意識地受苦，

And if we can experience joy and suffering,

不管原因是心理疾病或是疼痛。

what about other animals?

且如果我們能體驗喜悅及苦難，

Might they be conscious, too?

其他的動物呢？

Do they also have a sense of self?

牠們也有意識嗎？

And as computers get faster and smarter,

也能感受到自我嗎？

maybe there will come a point, maybe not too far away,

隨著電腦越來越快、越聰明，

when my iPhone develops a sense of its own existence.

也許將來某個時候，也許不用太久，

I actually think the prospects for a conscious AI are pretty remote.

我的 iPhone 就會發展出 對自身存在的感知。

And I think this because my research is telling me

其實我認為，讓人工智慧 具有意識的願景很遙遠。

that consciousness has less to do with pure intelligence

因為我的研究告訴我，

and more to do with our nature as living and breathing organisms.

意識與單純智慧不太相關，

Consciousness and intelligence are very different things.

而與我們是活著、會呼吸的有機體 這個天性比較有關。

You don't have to be smart to suffer, but you probably do have to be alive.

意識與智慧是非常不同的。

In the story I'm going to tell you,

即使不聰明也會受苦， 但大概得要活著才會受苦。

our conscious experiences of the world around us,

在我即將要告訴各位的故事中，

and of ourselves within it,

我們對於周遭世界、

are kinds of controlled hallucinations

及我們身在其中的意識經驗，

that happen with, through and because of our living bodies.

是種被控制的幻覺，

Now, you might have heard that we know nothing

因為我們活著及透過身體發生幻覺。

about how the brain and body give rise to consciousness.

或許你聽過，

Some people even say it's beyond the reach of science altogether.

我們對於頭腦和身體 如何形成意識一無所知。

But in fact,

甚至有些人說 這已超出科學能及的範圍。

the last 25 years have seen an explosion of scientific work in this area.

但事實上，

If you come to my lab at the University of Sussex,

過去 25 年中這領域 出現了大量的科學研究。

you'll find scientists from all different disciplines

如果你來到我位於 薩塞克斯大學的實驗室，

and sometimes even philosophers.

會看到來自各學門的科學家，

All of us together trying to understand how consciousness happens

甚至有時會有哲學家。

and what happens when it goes wrong.

我們所有人聯手 試圖了解意識是如何發生的，

And the strategy is very simple.

以及如果出了錯會發生什麼事。

I'd like you to think about consciousness

策略十分簡單。

in the way that we've come to think about life.

我想請各位

At one time, people thought the property of being alive

用我們思考人生的方式來思考意識。

could not be explained by physics and chemistry --

人們曾以為

that life had to be more than just mechanism.

無法用物理和化學 來解釋活著的特性，

But people no longer think that.

認為生命必然不只是機制。

As biologists got on with the job

但現在人們不再那麼想了。

of explaining the properties of living systems

生物學家

in terms of physics and chemistry --

繼續用物理和化學來解釋 生命系統的特性──

things like metabolism, reproduction, homeostasis --

像是心陳代謝、繁殖、體內平衡──

the basic mystery of what life is started to fade away,

關於生命的基本謎題已漸漸消逝，

and people didn't propose any more magical solutions,

人們不再提出魔術般的解答，

like a force of life or an élan vital.

像是生命之力或生命衝力。

So as with life, so with consciousness.

所以，意識就跟生命的狀況很像。

Once we start explaining its properties

一旦我們開始解釋意識的特性，

in terms of things happening inside brains and bodies,

用的是頭腦和身體中發生的狀況，

the apparently insoluble mystery of what consciousness is

「意識到底是什麼」 這個明顯的無解謎題

should start to fade away.

應該就會漸漸消逝了。

At least that's the plan.

至少計畫是這樣的。

So let's get started.

所以，我們開始吧。

What are the properties of consciousness?

意識的特性是什麼？

What should a science of consciousness try to explain?

意識科學應該試圖解釋什麼？

Well, for today I'd just like to think of consciousness in two different ways.

今天我想要用兩種方式來思考意識，

There are experiences of the world around us,

有關我們周遭世界的經驗，

full of sights, sounds and smells,

充滿了景象、聲音、味道，

there's multisensory, panoramic, 3D, fully immersive inner movie.

像是多種感官、全景式、

And then there's conscious self.

3D、完全身歷其境的內在電影。

The specific experience of being you or being me.

另外還有自我意識。

The lead character in this inner movie,

身為你或是身為我的特定經驗。

and probably the aspect of consciousness we all cling to most tightly.

也就是這部內在電影的主角，

Let's start with experiences of the world around us,

可能也是各個意識面向中 我們最緊抓不放的一面。

and with the important idea of the brain as a prediction engine.

先從對我們周遭世界的經驗開始，

Imagine being a brain.

先來談談一個重要想法： 頭腦是預測引擎。

You're locked inside a bony skull,

想像你是個頭腦。

trying to figure what's out there in the world.

你被關在頭骨中，

There's no lights inside the skull. There's no sound either.

試圖知道外面世界有什麼。

All you've got to go on is streams of electrical impulses

頭骨內沒有光，也沒有聲音。

which are only indirectly related to things in the world,

你只有電脈衝，

whatever they may be.

它們和世界中的事物只間接相關，

So perception -- figuring out what's there --

不論是什麼。

has to be a process of informed guesswork

所以，感知──理解外面有什麼──

in which the brain combines these sensory signals

一定是種根據資訊的猜測過程，

with its prior expectations or beliefs about the way the world is

過程中頭腦結合這些感官訊號，

to form its best guess of what caused those signals.

連同先前對於世界的期待或信念，

The brain doesn't hear sound or see light.

來猜測最佳的訊號成因。

What we perceive is its best guess of what's out there in the world.

頭腦聽不見聲音也看不見光線。

Let me give you a couple of examples of all this.

我們所感知到的

You might have seen this illusion before,

是頭腦對於外在世界的最佳猜測。

but I'd like you to think about it in a new way.

讓我為各位舉幾個例子。

If you look at those two patches, A and B,

你們以前可能看過這個幻覺，

they should look to you to be very different shades of gray, right?

但我想請你們以新的方式思考。

But they are in fact exactly the same shade.

看著這兩塊方格，A 與 B，

And I can illustrate this.

看起來灰色的深淺應該不同，對嗎？

If I put up a second version of the image here

但事實上，它們的灰階相同。

and join the two patches with a gray-colored bar,

我可以用圖解。

you can see there's no difference.

若我放上這張圖的第二個版本，

It's exactly the same shade of gray.

用灰色直條連結兩塊方格，

And if you still don't believe me,

就能看出沒有差別。

I'll bring the bar across and join them up.

它們是同樣的灰色。

It's a single colored block of gray, there's no difference at all.

如果你們仍不相信我，

This isn't any kind of magic trick.

我把直條移過來連接它們。

It's the same shade of gray,

是單一的灰色，完全沒有差別。

but take it away again, and it looks different.

這不是魔術把戲。

So what's happening here

是同樣深淺的灰色，

is that the brain is using its prior expectations

但拿走直條，看起來又不同了。

built deeply into the circuits of the visual cortex

這裡發生的是頭腦用它先前

that a cast shadow dims the appearance of a surface,

深植在視覺中樞的強烈信念，

so that we see B as lighter than it really is.

認為陰影會使表面亮度黯淡下來，

Here's one more example,

所以我們以為 B 的灰色 比實際上的淺。

which shows just how quickly the brain can use new predictions

還有一個例子

to change what we consciously experience.

能展示頭腦多麼快速地用新的預測

Have a listen to this.

來改變我們的意識經驗。

(Distorted voice)

聽聽這個。

Sounded strange, right?

（失真的聲音）

Have a listen again and see if you can get anything.

聽起來很怪，對吧？

(Distorted voice)

再聽一次，看你們能否聽出什麼。

Still strange.

（失真的聲音）

Now listen to this.

仍然很怪。

(Recording) Anil Seth: I think Brexit is a really terrible idea.

現在聽聽這個。

(Laughter)

（錄音）亞尼賽斯：我認為 英國脫歐是個很糟的點子。

Which I do.

（笑聲）

So you heard some words there, right?

我的確這樣認為。

Now listen to the first sound again. I'm just going to replay it.

你們聽見了一些字吧？

(Distorted voice)

現在重聽第一段聲音。重播。

Yeah? So you can now hear words there.

（失真的聲音）

Once more for luck.

如何？現在你們可以聽出一些字了。

(Distorted voice)

再試一次運氣。

OK, so what's going on here?

（失真的聲音）

The remarkable thing is the sensory information coming into the brain

好，發生了什麼事？

hasn't changed at all.

不可思議的

All that's changed is your brain's best guess

是進入頭腦的感官資訊一點也沒變，

of the causes of that sensory information.

改變的只是你的頭腦

And that changes what you consciously hear.

對於感受到的資訊所做出的最佳推測，

All this puts the brain basis of perception

也就改變了你意識下聽到了什麼。

in a bit of a different light.

這一切讓頭腦的感知基礎

Instead of perception depending largely on signals coming into the brain

變得有點不同。

from the outside world,

感知並非大部分依賴於

it depends as much, if not more,

外在世界進入頭腦的訊號，

on perceptual predictions flowing in the opposite direction.

而是同等、或是更多依賴於

We don't just passively perceive the world,

方向完全相反的感知預測。

we actively generate it.

我們不只被動地感知這個世界，

The world we experience comes as much, if not more,

也主動地使這個世界成像。

from the inside out

我們所經驗的世界

as from the outside in.

由內而外和由外而內等量，

Let me give you one more example of perception

或者更多來自由內而外。

as this active, constructive process.

讓我再舉個例子

Here we've combined immersive virtual reality with image processing

說明感知是個主動建構的過程。

to simulate the effects of overly strong perceptual predictions

在這裡我們結合身歷其境的 虛擬實境和影像處理，

on experience.

來模擬過度強大的感知預測

In this panoramic video, we've transformed the world --

對經驗會有什麼影響。

which is in this case Sussex campus --

在這支全景影片中， 我們轉化這個世界──

into a psychedelic playground.

這裡是薩塞克斯校園──

We've processed the footage using an algorithm based on Google's Deep Dream

為幻覺遊樂場。

to simulate the effects of overly strong perceptual predictions.

影片被用 Google 的 Deep Dream 演算法處理過，

In this case, to see dogs.

來模擬過度強大的感知預測。

And you can see this is a very strange thing.

這例子是看狗。

When perceptual predictions are too strong,

你們可以看見這有多奇怪。

as they are here,

當感知預測太強大時，

the result looks very much like the kinds of hallucinations

就像這裡這樣，

people might report in altered states,

結果看起來很像是幻覺，

or perhaps even in psychosis.

像是人們在意識狀態改變

Now, think about this for a minute.

或甚至精神錯亂時看到的幻覺。

If hallucination is a kind of uncontrolled perception,

花點時間思考這一點。

then perception right here and right now is also a kind of hallucination,

如果幻覺是種無法控制的感知，

but a controlled hallucination

那麼此時此地的感知也是某種幻覺，

in which the brain's predictions are being reigned in

只是它是被控制的幻覺，

by sensory information from the world.

頭腦的預測

In fact, we're all hallucinating all the time,

被感受自外在世界的資訊所統御。

including right now.

事實上，我們隨時都在產生幻覺，

It's just that when we agree about our hallucinations,

包括現在。

we call that reality.

只是當我們對幻覺的看法一致時

(Laughter)

就稱之為現實。

Now I'm going to tell you that your experience of being a self,

（笑聲）

the specific experience of being you,

現在我要告訴各位， 你們身為自我的經驗，

is also a controlled hallucination generated by the brain.

身為「你」的特定經驗，

This seems a very strange idea, right?

也是頭腦所產生的一種控制幻覺。

Yes, visual illusions might deceive my eyes,

這似乎是個很奇怪的想法，是吧？

but how could I be deceived about what it means to be me?

的確，視覺假象 或許欺騙了我們的眼睛，

For most of us,

但我怎可能會被自我的意義騙了呢？

the experience of being a person

對大多數人而言，

is so familiar, so unified and so continuous

身為一個人的經驗

that it's difficult not to take it for granted.

是很熟悉、很一致、很連續的，

But we shouldn't take it for granted.

所以很難不把它視為理所當然。

There are in fact many different ways we experience being a self.

但我們不該視它為理所當然。

There's the experience of having a body

事實上，有許多方式可以 讓我們體驗身為自己。

and of being a body.

一種是擁有身體和是個身體的體驗；

There are experiences of perceiving the world

還有從第一人稱的角度

from a first person point of view.

來感知世界的體驗；

There are experiences of intending to do things

有打定主意要做某事，

and of being the cause of things that happen in the world.

要成為世上事物肇因的體驗；

And there are experiences

有身為連續且獨特個體的體驗，

of being a continuous and distinctive person over time,

隨著時間建立 豐富的記憶與社會互動。

built from a rich set of memories and social interactions.

許多經驗顯示，

Many experiments show,

且精神病學家與 神經病學家都很清楚，

and psychiatrists and neurologists know very well,

我們體驗身為自己的各種不同方式

that these different ways in which we experience being a self

都有可能會崩壞。

can all come apart.

這意味著，「統合的自我」 這種基本背景經驗，

What this means is the basic background experience

是由頭腦建立起的脆弱產物。

of being a unified self is a rather fragile construction of the brain.

另一個經驗， 就和所有其他經驗一樣，

Another experience, which just like all others,

需要解釋。

requires explanation.

讓我們先回到身體的自我。

So let's return to the bodily self.

頭腦如何產生

How does the brain generate the experience of being a body

是個身體以及擁有身體的經驗？

and of having a body?

適用同樣的原則。

Well, just the same principles apply.

頭腦如何做出最佳推測，

The brain makes its best guess

哪些是身體的一部份、而哪些不是。

about what is and what is not part of its body.

神經科學中有個很棒的實驗 可以用來說明這一點。

And there's a beautiful experiment in neuroscience to illustrate this.

和大部份神經科學實驗不同，

And unlike most neuroscience experiments,

這個實驗你可以自己在家做。

this is one you can do at home.

你只需要這個，

All you need is one of these.

（笑聲）

(Laughter)

和幾支畫筆。

And a couple of paintbrushes.

在橡膠手幻覺裡，

In the rubber hand illusion,

這人看不見被遮住的一隻真手，

a person's real hand is hidden from view,