Transcriber: Reiko Bovee Reviewer: Leonardo Silva
OK, so it's time to let your trousers down.
Let's face it, we all have a couple of secrets, yeah?
Everyone has a secret,
and I'd like to invite you to participate in a simple experiment right now.
I'd like you to think one of your secrets.
Just think it by conjuring up the image in your mind.
We tend to think these secrets are secret; nobody knows about them.
You would think because it's in your mind
it doesn't mean your neighbor sitting next you
can understand or know about your secret.
That's why I want to challenge here.
I want to ask you about whether your privacy is real,
the way you feel it.
Now your secret might be something mundane.
It might be something simple such as, for example, the PIN of your credit card.
It could be something embarrassing you don't want people to know,
for example, it could be you enjoy watching funny cat movies on the Internet,
something like that.
So, is it possible to read out these thoughts?
In fact, we can tell about the person's mental state to some degree
about their feelings from their body language,
from the expressions on their faces.
If you look at these famous Ekman faces here,
you can see that our facial expressions give away what we feel,
but this is still severely limited.
If you look at the person on the left, obviously she is surprised.
But what is she surprised about? What is she looking at?
What is she hearing? What is surprising her? We don't know.
We can't tell this from the surface of the body,
from the body language or from face; we somehow need to go deeper.
And deeper here means that we need to go into that part
of the body that encodes and stores your thoughts,
and that is the human brain.
Now, I am a brain scientist, and for many years brain scientists
have established fact after fact about the brain.
One thing that's always shown up
is that our thoughts are intimately related to the brain processes.
So, it should in theory be possible - if I put someone in a brain scanner -
to find out what they are thinking.
The question though is: How do I know to interpret the language of the brain?
I somehow need to translate it when I want to read it out.
I need some understanding of the way information is stored.
So, a simple analogy can help us here.
We could think of the way in which information is stored
on the surface of a CD. How does this work?
It's the pattern of pits on the surface of a CD that codes a piece of information,
say, for example, about a piece of music:
One piece of music, one pattern of surface;
a different piece of music, a different pattern of surface.
This is very similar to the way your brain stores information.
It stores your thoughts in spatial patterns of the brain activity.
So, how can we read these out?
How do we know what the spatial patterns of the brain activity are?
For this we use so-called brain scanners.
It's a technology known as MRI, Magnetic Resonance Imaging,
and basically involves very strong magnetic fields.
It doesn't do you any harm,
but it gives you a quite well resolved map of your brain activity.
So, that's what we do.
My job is people come to my lab, at the Charité here in Berlin,
and we put people in brain scanners,
we read out the brain activity patterns,
and now we get something that looks like this.
A brain image.
Don't confuse these brain images with photographs.
They are not photographs.
They are not like accurate, perfect depictions of some spatial events.
What they show is a spatial map of probability
that tells you most likely this part of the brain is involved
in some kinds of thought.
You can see some regions are hot colored, red or orange;
they are the regions that become more active than usual
when you engage in a specific thought.
The cold areas, blue areas are where the activity is lower than normal.
But what does this specific pattern of the brain activity mean?
Does anyone know what this person is currently thinking about?
What do you think?
It's difficult.
It doesn't say on there this person is thinking
about the Brandenburg Gate or something like that.
It's not written in there.
Instead it's an abstract code that the brain uses.
This is something that's quite familiar to us.
We know this.
People faced this problem over 200 years ago;
in fact, when they encountered the hieroglyphs.
People 200 years ago were puzzled by hieroglyphs;
they didn't know what hieroglyphs mean.
They saw this on the pyramids.
Some people must have said, "That must be like a pretty wallpaper.
But instead, others might have said, "I think it actually means something."
But what does it mean?
What do you think this means? It's a very similar problem.
What does this mean? Like the brain image, you can't know.
I can tell you this one here means the brain as you might have guessed.
But how do you know this?
I don't have any ancient Egyptians in my family. How do I know this?
It's because people stumbled on the translation.
In 1799, someone found the translation, the famous Rosetta Stone,
that you can see in the British Museum in London.
This famous Rosetta Stone contains a text in hieroglyphs
and a text in ancient Greek -- and Demotic as well,
that wasn't quite so much of interest.
So this allowed us to translate hieroglyphs into ancient Greek,
a language that people did know to understand.
This now makes the task very simple.
All we need to do is to find the "Rosetta Stone" for the brain, right?
It sounds easy.
Where is it? Where do we have to go and dig?
Do we have to go and dig in North Africa or Southeast Asia?
Where is the "Rosetta Stone" for the brain going to be?
Nobody so far unfortunately has found the "Rosetta Stone" for the brain.
The reason is it is very very complicated, much more complicated than hieroglyphs.
We need to use something different, something called codebreaking.
Now, in the Second World War, the Germans thought they were particularly clever
by encrypting their messages on this famous Enigma machine.
They took a military text, they put it through the machine,
and out came some scrambled version that nobody could understand.
Then in the U-boats they would find a scrambled text,
and they put it through the machine, out they'd get the real message.
This is what you can do if you know the code.
The British were trying to decipher it, but they didn't know the code.
It was said they invented brute force, statistical techniques
that allowed them to translate this hidden code,
and that's what we do today with brain images.
We try to understand what the thoughts are a person has.
How does this work in detail?
l'll just give you a simple example.
What you can see here are three images on the left
the person was looking at inside the brain scanner:
the Brandenburg Gate, a bouquet of flowers and a German shepherd dog.
On the right are the corresponding patterns of the brain activity.
As you can see they are very different.
Every thought you have has its own unique signature pattern of activity
in your brain.
You think one thing, you get one pattern of activity;
you think something else, you get a different pattern of activity.
Now what we do is we train computers
to recognize these patterns of brain activity.
If I know to recognize the pattern of activity in the top right,
I can tell that the person is thinking about the Brandenburg Gate,
similar to recognizing an individual based on their fingerprints.
If I find their fingerprints, and I have them in a database,
I can use the software to detect the fingerprints out of our database.
That's what we do.
We train the computers; we train them to recognize
these brain activity patterns,
and then the computer has to prove that it's worth the money,
or if the program we write is worth its money,
that it can decipher what you are thinking about,
and then you give the computer some pattern of brain activity;
you might not know what it is,
and the proof is if the computer can correctly tell what you're thinking about.
This works remarkably well.
If you do this simple game, you get accuracy of up to 100%.
You get it right almost every time.
So this is for people in brain scanners looking at visual images.
But you could say,
"If someone's in a brain scanner looking at an image,
I just have to look at the image they're looking at
and I'll know what they're thinking about."
So, we need to go one step further.
The next step is we just have to imagine an image.
Put them in a brain scanner, we get them to imagine various things,
for example, watches, hands, faces, all sorts of stuff,
we measure the brain activity patterns, and we can decode
what they're thinking about based on pure imagination.
It's just in their mind, there's nothing in their environment
or on the computer screen to give it away, they're just thinking about it.
This works incredibly well, as well.
But you could say,
"This is still rather academic. Let's look for something even more interesting.
What about people's behavior, their decisions,
things that are relevant?"
So we went ahead and did a number of studies
where we tried to look at people's decisions.
These are the decisions, very simple decisions
among a few alternatives for things either completely irrelevant,
such as, for example:
"Do you want to press left or right button?",
or things that are a bit more relevant, for example:
"Do you like this car? Do you want to buy it?",
or "Do you like this car? Do you want to buy it?"
So we read the brain activity out of their brains.
In the first case, we looked after they've made up their mind.
So people make up their mind, we read their brain activity,
we try to decipher until which choice they've made.
So everyone of you make a choice,
say, for example, between wanting a BMW or a Mercedes.
You make your choice.
Can we read this out of your brain activity?
The answer is yes, with pretty decent accuracy.
The next question is, however, what about the choice itself?
You're more or less free to choose between one or the other.
What made you go one or the other way?
So we look backwards in time before the decision.
And what we found was that you could, to some degree,
predict a person's decision -- a free decision,
they can choose either alternative --
before they actually feel that they're making up their mind,
up to 7 seconds before they think they're making up their mind.
So you think you're deciding now, but your brain has at least started
preparing this decision 7 seconds before.
How is that possible?
Well, it raises an important riddle.
That is, we normally think
of the sequence of events when we make choices,
we decide in our mind, we don't tell anyone, we just decide,
and then we use our brain to put our body into motion,
for example, to tell people what we're thinking about.
But this says it's quite different.
This says the brain starts preparing the decision,
and then your mind comes in a few seconds later,
and then you start moving and doing things.
This is quite different, and it raises lots of interesting questions.
The most important one is: Who's responsible for the action?
If your conscious mind comes after the decision,
that presumably has already been made,
how can you be held responsible for the action?
If you commit a crime, it was my unconscious brain activity
that happened before I made up my mind,
it's not my fault that I committed this crime,
you could say.
So you can see there are lots of interesting questions raised here
with respect to free will.
I'm going to leave that as an open teaser.
I'm going to focus on a different question.
If you're interested in that, go to our website.
I'm going to ask a different question, and that is:
Can we read people's minds in a technology
that is similar now to these stage acts that people did in the 19th century?
What you can see here is a depiction of a stage act,
a magician draws a person from the audience,
they come on the stage and are blindfolded and think about something,
say, for example, a shape or a person,
and the magician can magically read their mind
and draw their thought on the board here.
Can we now replace this stage act with something new?
Can we put a brain scanner on the stage?
And then the famous brain scanner, you put people in it,
and it shows you on a board what they're thinking about.
Is this possible?
The answer is: to some degree, but not that well.
I'll explain to you why.
First of all, there's severe limitation with the resolution of brain scanners.
They have a resolution of a few millimeters,
so that means in every one of these small measurement volumes we have,
we have up to a million nerve cells.
That's a lot of nerve cells in one measurement pixel.
So basically we need to increase the resolution of these brain scanners,
so we can get down to the activity of single cells,
if you really want to read out the full details,
but there are even worse issues in this than just the resolution.
One big problem is that everyone of you has that own signature brain language
that stores information.
You can see here 4 brain activity patterns
for the same thought in 4 different individuals.
They're all different.
Everyone stores information differently,
which explains why we have such a hard time understanding each other,
if our brain activity patterns are so different.
So this is a severe challenge.
So we can't train our machine on one person
and use it for another person.
It doesn't work that well on the second person.
Another problem is:
The preferences and thoughts change on the brain language
presumably changes well across the lifespan.
When you're young your favorite movie might be Lassie,
your favorite food might be a hamburger,
and your favorite music might have been heavy metal.
Come on, we're talking about secrets here. That's your secret, my secret.
When you're older, things might change, now you like schmaltzy Austrian movies,
you like salad or at least pretend to yourself that you like salad
and Bavarian brass music.
Come one, admit it.
So the problem is that the brain activity patterns
causing this kind of information change across a lifespan,
and we got no way of dealing with this.
But now the biggest problem is that we can think so many different things.
One of my favorite sentences is from Monty Python,
it's called, "My hovercraft is full of eels."
Who would've ever thought that someone was going to think this today?
If you're to program the computer to predict
what you might be thinking about today,
I'm pretty sure "My hovercraft is full of eels"
would've been very low on that list.
So we need to be able to account for these situations as well.
We can think so many different things.
We could take a whole dictionary full of different things.
So, we need a dictionary to translate thoughts into brain activity patterns,
and we don't have this dictionary.
So, what could this look like?
Do we get a subject to come, we pay them very well,
they come for 20 years to the brain scanner.
The first day we start reading the dictionary.
We begin with apple, and we continue, and after 20 years we've finally done,
but with zed, we'd start reading zebra and etc.
Is that how we measure the brain activity patterns
for all these thoughts they might have?
Well, luckily we can take a shortcut.
The shortcut is that the brain’s arranged information in a way
that is easier for us to understand.
And that is it uses principles of similarity,
and I explain to you how this works.
You can see in the top right a hypothetical brain activity pattern
while the person is thinking about a car, and the bottom right,
a hypothetical brain activity pattern while they're thinking about a bike.
But now we've measured, with a brain scanner, a different pattern.
It looks like a mixture for the pattern of a car and the pattern of a bike.
What could that be? What do you think?
Well, it's a motorbike.
So you can exploit these principles of similarity.
You don't need to know what every thought looks like in the brain
and you can still read out a large number of thoughts.
Now there are a number of technical issues ensuing from this.
For example, potential lie detectors or brain marketing,
lots of people are interested in commercial applications
or forensic applications of this technology,
and medical applications allowing people who can't move their bodies
to suddenly move and control computers and do things like that.
Now there's a big debate necessary
about what of these technologies we want and what we think is ethically feasible.
But one important question people are always interested in is:
Does that mean now you open to manipulation?
Well, don't worry about that too much because first of all, it would mean
that you could have to put someone inside a brain scanner.
So to some degree, your thoughts are private.
If you're just walking through the world,
nobody has a mobile brain scanner that works remotely.
You can think about your PIN of your credit card,
nobody is going to be able to read it out. Don't worry about that.
Now, one thing that people are still quite interested in
is whether you can be manipulated, "manipulated" here means:
Is it possible to write thoughts into a person's brain
to make them think certain things
as you can see in some science fiction movies
like in "Strange Days," or "Inception," and etc.?
The answer is today this is not possible.
And the reason is that the way our thoughts are coded in our brain
is in very intricate fine grain patterns of brain activity,
there's really lots of detail in these brain activity patterns.
Today, there are techniques for stimulating the brain,
but they're very diffuse;
there's no technique available that would allow us to write
these very detailed patterns of activity into the brain.
So, brain scanners can be used to read out a person's thoughts to some degree.
Don't worry about the technology,
and especially you don't have to worry about people programming thoughts
into your brains.
Thanks very much.
(Applause)