Translator: Theresa Ranft Reviewer: Evelyn Tian
Good afternoon.
Today, I want to show you
why it is literally true that there is no such thing as a self.
The self is not a thing but a process.
It is a very interesting and fascinating process.
It is that special process that gives you the conscious experience
of being someone.
And I've been interested in this process for a long time.
I'm a philosopher of mind and consciousness,
and I have cooperated with neuroscientists for many years.
I want to know
what a first-person perspective is, what subjectivity is,
and in order to know this, I have to understand what a self is.
There is no such thing as a self,
but there is some process that creates the very robust experience
of being someone.
And that's what I'm interested in today:
What does it mean to be someone?
As it will turn out,
nobody in this room ever was or had a self.
In order to explain this to you, I've brought three examples for you today.
You will have to learn two philosophical concepts,
and there's just one single point I want to make
at the end of this short lecture.
So, here is something you can all try at home
when you come home tonight.
It is a classic experiment.
It's called the so-called "rubber hand illusion."
If you don't have a rubber hand at home,
you could use some of these rubber gloves you use for dishwashing
and pad them with cotton wool, for instance.
So what the subject does,
it puts one hand on the table, concealed by a screen,
and you look at the rubber hand.
Then the experimenter starts to synchronously stroke this rubber hand.
You can also use Q-tips for that, for instance.
In my own case, after 60 to 90 seconds,
the well-known rubber hand illusion, which was discovered in 1998, emerges.
You hallucinate a connection
from your shoulder to the rubber hand you see.
You begin to feel a sense of ownership
for the rubber hand you see in front of you.
It becomes part of your bodily self.
But what is even more fascinating
is that you begin to feel the seen touch
in the rubber hand on the desk in front of you.
Two tips from your philosopher, when you try this tonight:
(Laughter)
When your subject has the illusion standing,
bend the rubber fingers carefully into an impossible position,
and see what happens to your subject.
A second tip from your philosopher:
Do have a hammer ready,
and suddenly smash the rubber hand, and see how your subject reacts.
What we see in this experiment
is that there is something like a sense of ownership,
a conscious experience:
"This belongs to me."
And this experience can be noninvasively manipulated
as simple statistical correlation is offered to the brain
and conscious experience follows suit.
Now, for the first philosophical concept you have to learn today:
it's the concept of a self-model.
A self-model is an entity in your brain, an active data structure -
it is an inner image of your self as a whole.
I call it the PSM, the phenomenal self-model.
Phenomenal just means it subjectively appears to you,
and it is this representation of your self
as an entity with global properties.
Now, some lessons that can be learned
from the rubber hand illusion, for instance,
are that it is highly context-sensitive and flexible.
The content of your self-model can be manipulated.
Whatever is in the self-model,
whatever is embedded into your conscious self-model
is experienced as your own, a part of your self -
my thought, my feeling, my bodily sensations.
And it is an interesting structure.
It seems to be a representational process
that is driven by many different constraints.
And it can be controlled experimentally.
A self-model is something that can be manipulated.
I promised to bring you three examples
for what I mean by a self-model.
Here is a second example:
Many of you must have heard of phantom limbs.
Some people, after amputations, at some point,
still feel the limb that has been amputated.
If you've never heard of phantom limbs,
I would recommend Ramachandran's 2007 TED Talk,
and you will see a brilliant explanation of these phenomena.
What many people don't know
is that phantom limbs sometimes also appear
in people who were born with missing limbs,
people who have never had arms or legs.
This is patient A. Z. -
a cognitively lucid woman in her late 40s, in Zurich,
who has been investigated
by the famous neuropsychologist Peter Brugger.
She was born without arms and legs, and she has experienced a body -
from whenever she has memories, these phantom limbs were there.
But there are a number of interesting things to be discovered
if you look at them closely.
For instance, scientists can do fascinating things.
They can put a subject like that in a scanner and ask them,
"Move your phantom fingers, move your phantom feet."
They have never existed.
And then you can see what lights up in the brain.
But all technical details aside,
there are some interesting details in the phenomenology.
You see, for instance, the three toes in the middle
are not fully differentiated.
And if you ask the subject,
"Rate how real your bodily self is, on a scale from 0 to 7" -
0 means no conscious experience,
7 means just as realistic as the content of the non-hallucinated body model,
of the body part -
then you get the following result:
For instance, these parts of the legs are just half as real -
they are indeed ghostly - than these parts of the body.
But another interesting thing you can see
is this right hand is more realistic, according to conscious experience
than the left hand.
This right hand has never existed as an input source to the brain.
So here is another example
for what I mean by a phenomenal self-model.
It very likely has a lot to do with body representation.
The human self-model is anchored in body feelings.
Many animals on this planet have self-models,
and it is clear that there is an evolutionary story.
To have a self-model was important to control a body,
to control movement.
And one can, of course, ask,
"Is there maybe a genetic component to it?"
If there is an evolutionary story,
is there an inborn part of the human self-model?
The more interesting question, however, is, What does this represent?
What is this a model of?
Is this the soul?
Is this a global model of body shape?
One colleague of mine, Aristotle, said the soul is the form of the body.
It perishes at death - Aristotle was a naturalist -
but the soul is the form principle, the global shape.
Is that what this woman is experiencing?
The inner form of the body?
Is that the contents of her consciousness?
Another colleague of mine, Spinoza, said,
"The soul is the idea the body develops of itself."
So you see there is a long tradition
in thinking about the relationship between self and body.
But there's a deeper question.
Okay, so there's ownership for mental states,
there's ownership for body parts,
but isn't there a global property,
a property of being a self,
something like a globalized sense of ownership?
And here's the third example I've brought to you.
When I first had the rubber hand illusion, as a philosopher,
I immediately thought,
"We need to make a whole-body analog of this."
It will be absolutely interesting to see if this can happen with a mannequin,
with a rubber figure,
or with a virtual body, with an image of a body as well.
So, with my brilliant neuroscience colleagues from Lausanne -
Bigna Lenggenhager, Tej Tadi, and Olaf Blanke -
we designed the following experiment.
You are wearing goggles, you are in a virtual reality,
you have a head-mounted display.
While you are wearing these goggles, you are being filmed from behind.
You have then an experience you've never had before,
because a 3D encoder inserts the camera image into the virtual reality.
You have the experience like in this 1937 Magritte picture:
You see yourself from behind while you are being stroked,
just like in the rubber hand illusion.
Let's look at how this looks.
So there you are.
Your back is synchronously stroked by the PhD student,
and you will soon see that that is your conscious experience
while this happens.
The effect is that, after a certain time,
for many subjects, you jump into the avatar.
You jump as if the sense of self is transposed out of the body.
You identify with the figure that you see.
There's also an unconscious measure.
If you blindfold people, like in a game of blind man's bluff,
this orients them and tells them,
"Go back to where you think you've been standing."
They always go back to a place
between the avatar and their "physical body."
That is, as soon as you've had the conscious illusion,
the unconscious spatial frame of reference is changed.
Now, for the second philosophical concept you must learn today -
it's fortunately much easier to understand than the self-model.
Transparency is a metaphor, it's a visual metaphor,
and it is more than 100 years old.
It just means that consciousness is like a window,
and we see through this window,
we look onto the world,
but it is very hard to experience the conscious-ness.
So the philosopher who came up with this, George Edward Moore,
was, like us, very much interested in conscious experience,
and he was fascinated by this phenomenon that you always only see the content,
but you never see the conscious-ness itself.
And that is what he meant by this metaphor of transparency:
Conscious states are transparent;
unconscious states in your brain are neither transparent nor opaque.
So this is more about the structure of experience;
it's not about knowledge so much.
And the idea is that you don't have access to the construction process in your brain;
you just see the final result.
So the idea is that consciousness
is like a high dimensional window into the world,
but we never see this window itself,
we just see the bird flying by.
That is one way to understand the transparency metaphor
as a property of conscious representation.
Our brains, your brains, right now,
they create a conscious model of reality.
You live with this conscious model of reality,
and you live through it,
but you don't see it.
You don't see the neurons firing in your brain;
you just see what they represent for you.
You don't see a model of a lectern here;
you have the naive, realistic illusion
of being directly and immediately in contact with the content of that model,
which is now active in your brain.
So, transparency creates something a philosopher colleague of mine
might call "the phenomenology of direct realism" -
the idea that you are directly in contact with the world
and that what you experience is real.
It is simply because you cannot look at the construction process,
it's too fast, too reliable, too robust.
So, transparency also means that we are unaware of the medium
through which information reaches us,
through which information about the world penetrates our minds.
And because this is so,
conscious experience is an invisible interface.
Do you still remember these head-mounted displays
from the last example?
One of the things I'm saying in this talk
is that you are all wearing head-mounted displays right now,
but they are in your heads.
Your brains are reality engines,
virtual reality generating devices,
and they have been mounted in the brains of your ancestors millions of years ago.
And this is one of the best inventions of Mother Nature today.
We have this invisible interface, just like the window with the bird.
We live with it, and we live through it,
but we are unaware of this interface itself.
So now I come to the one point I wanted to make.
Let us imagine a certain kind of information processing system,
a certain kind of creature.
They would not have selves or souls,
but they were conscious,
and they would have conscious self-models.
But these self-models were transparent in the sense just explained.
Then these beings, by necessity, would have the experience
of being directly in contact with themselves.
They would, by necessity,
have the experience of being infinitely close to themselves.
They would, by necessity, have the experience
that whatever is the content of their self-model right now
is real.
Metaphorically speaking, these systems would be confusing themselves
with the content of their conscious self-model.
It would be a wonderful naturally evolved window,
a two-way window,
connecting their inner life with the social world around them,
but it would be an invisible interface to themselves as well.
Such beings would, so to speak,
be glued to the content of their self-model.
They would, therefore, by necessity,
have the absolute robust experience of being someone.
I believe that all of you,
as you've been listening to me during this short talk,
have been beings like that.
Thank you very much for your kind attention.
(Applause)