Brain Games

Jason Silva: Pay attention.

Keep your eyes on the dragon.

You've probably noticed,

he's keeping his eyes on you.

What you're seeing is not a camera trick

or computer animation.

This dragon is simply a large piece of cardboard

with absolutely no moving parts.

Don't believe us?

So, why does it look like the head is moving?

Stick around to find out.

This is a show about your brain and

how it perceives the world in 3D.

In this episode, we'll mess with your

head as we put you through a series of games

and experiments that will melt your mind.

Woman: Very trippy.

Jason Silva: And astonish your eyes.

We'll prove that you have X-ray vision

and show you that your brain can

actually see into the future.

There's more than meets the eye.

Man: Definitely blows my mind.

Jason Silva: On Brain Games.

3D or not 3D?

That is the question.

But does 3D even exist or

is it all in your head?

We live in a 3 dimensional world.

Every object we encounter has height, width and depth.

If your brain was unable to perceive the world in 3D,

you wouldn't be able to do this or this or this.

3D makes all the difference between a world with real

depth and a world where you're flat as a pancake.

It seems like almost every week Hollywood releases

another 3D film and while the technology for making

3D continues to improve, the most amazing fact is

that we can even see 3D at all.

I mean consider what's happening:

everything we call sight is just

your brain's interpretation of light

entering through the low resolution 2D cameras

we call your eyes, so how do we even see 3D?

To find out, let's take another look at that dragon.

It's a six-foot dragon and even though it has

no moving parts, no matter where you go,

it seems to be looking at you.

So, is my buddy here tripping you out?

Hey, man.

Is his face following you along as the camera moves?

Well, you know, it has to do with your brain's

expectations about what a face looks like.

Your brain receives a series of visual cues and

constructs a 3D image in your mind.

But sometimes those visual cues can weave a tall tale.

The dragon's head is nothing but

a concave piece of cardboard.

But as soon as your brain receives enough

visual cues to make out a face,

everything changes.

In fact, your brain is so adept at recognizing faces,

any time it sees eyes, it can turn something

concave into something convex.

And a paper dragon can suddenly come to life.

To illustrate just you how your brain creates

3-dimensional perception,

let's play a game.

Stop.

Pay attention.

Put your hands to your sides, like this.

Now, bring your fingertips up like this.

Now, looking at your fingertips,

touch them together.

Easy enough, right?

Okay, bring your hands back down to your sides.

Now close one eye.

Now, again, bring your fingertips up like this

and while staring at your fingertips,

touch them together.

Not as easy as it looks, right?

If you couldn't touch your fingertips together

with one eye closed, don't worry,

you're not alone.

With only one eye open you weren't able

to accurately gauge depth.

Why is that?

Here to point us in the right direction is

Dr. Mark Changizi.

He's an expert in understanding how your

brain perceives depth.

Dr. Changizi: In reality, we don't see truly in 3D.

It's a construct that our brain makes for us.

The reason that we see at all is so that we can

interact with the world around us, not bump into it.

But the only way we could do those things is if

we had perception of 3D.

But there's a fundamental difficulty

in perceiving in 3D.

The retina at the back of your eye is 2-dimensional.

It's like a screen on which the world is projected.

How can a brain take a 2-dimensional input and

figure out what that 3-dimensional world is like?

Jason Silva: To help answer that question,

let's go bowling.

Take a look at these pins.

This is how your brain sees them.

With height, width and depth.

But neither of your eyes actually sees this image.

This is what your left eye sees.

And this is what your right eye sees.

Your eyes have slightly different views

of the same image.

But your brain combines those views into one precise

image of where the objects actually are in space,

allowing you to throw a strike

right down the middle.

This is what scientists call Stereoscopic Vision.

Dr. Changizi: The word stereo in your stereo system

at home refers to the left and right speaker.

And it's for that same reason that we use the word

stereo when we refer to stereoscopic vision.

When you're using only one eye to play this

game of putting your fingers together,

it becomes much more difficult because you've

lost the stereoscopic depth effect.

Jason Silva: To give you a better sense of how your

brain uses stereoscopic vision to perceive 3D,

take a look at this photo.

Got it?

Now here's another one.

It's an image of the same trolley but from

a slightly different angle.

Both look pretty 2-dimensional, right?

Do you think there's anything we could do

to make them look 3D?

How about this?

We're not just shaking one image.

We're actually quickly alternating between

the two similar images.

Doesn't it look like you could jump on the trolley

and ride it all the way down the hill?

Take a look at some more examples.

Here are the two photos.

And here's what they look like when we alternate them.

Pretty cool, right?

What you're looking at is a stereo animated illusion.

All we're doing is jumping back and forth

between two similar but different pictures.

Your brain interprets the difference between the two

flat images as depth, simulating what your eyes

do with real 3-dimensional objects.

But stereoscopy is not the only tool your brain

uses to turn 2D into 3D.

Your brain uses other cues like shading and

size to form a 3-dimensional world.

And Deception Specialist Apollo Robbins knows how

to use those cues to fool you.

He was gracious enough to invite us to his home.

But of course, with Apollo,

things aren't always what they seem.

Four of the objects in this room aren't

the size you think they are.

Watch closely and see if you can spot all four.

Notice anything yet?

That's one.

Does anything in the foreground look

a little off?

Keep watching.

Ah, so that tiny bear and his tiny chair were

the second and third.

Have you figured out the last one yet?

Did you get all four?

But more importantly, do you know why your

brain was fooled?

It's because, while viewing this normal sized

room through your TV screen,

you weren't able to accurately perceive depth.

And because we intentionally messed with

certain perspective cues like a large mug far away

or that tiny chair very close to you,

then surrounded them with regular objects,

it appears to you like everything is normal sized.

And the room is picture perfect.

It's one thing to be fooled by a six-foot

paper dragon or Apollo's perspective room;

do you think we could fool your brain using

some ordinary, everyday objects?

Prepare to feast your eyes on this next game.

Stop.

Pay attention.

For this next game, I want you to pretend that you're

a hotel guest about to receive your order

from room service.

Waiter: Good evening sir, your room service.

Jason Silva: All you have to do is keep an eye out for

anything that looks a little out of the ordinary.

Waiter: You ordered the chicken.

I have your cheese plate.

Your flower.

Jason Silva: So far, so good.