- It's blue. It's obviously blue.

- I cannot see blue anywhere in that dress.

I don't even know how you could see blue.

- It's all coming at me fast too, trust me.

- It's a fact that you're smarter

if you see it in black and blue.

- You are seeing white and gold?

Where you looking at?

I do't get it.

- Oh, it changed to white and gold!

- Wait, no, you're kidding.

- [Voiceover] This lace bodycon dress

has divided the world and threatened to break the internet.

Millions have weighed in on what color they see the dress,

with around 70% seeing white and gold,

and the rest seeing black and blue.

And yes, the dress is black and blue.

But how is it possible we're all seeing it in

two completely different ways?

Are people lying?

Have we gone mad?

We decided to talk with someone

who looks at color all day.

- When I look at the real dress

of course it's black and blue.

But the picture that's been circulating

is not A, has the same contrast,

and that tells me that there was some

kind of a light that was hitting the dress.

And that light quality is a very warm light.

What we are really looking at

is the light that's reflecting

off of the blacks and the blues.

This is the kind of thing

that we constantly deal with in color.

- [Voiceover] OK, so it is about the color of the light,

but how do different minds interpret the light differently?

We still weren't satisfied.

So we decided to venture out

to UCLA's neuroscience department.

- I think it's much more likely perception,

which is actually to do with the brain.

Our brain is really good at filling in information

that's not actually there.

And so the brain is basing what it sees

on its own interpretation of the image.

OK, and if your brain thinks, I guess,

that this dress should be white and gold

based on its interpretation of the picture itself,

the lighting, the conditions that the picture's

being viewed in,

it's gonna build that image as white and gold.

It goes back to the optical illusion issue.

You expect the square that looks lighter to be lighter

because it's in the pattern where it should be lighter.

You can cut the squares out and put them next to each other

and show you that they are in fact the same color.

But in context, your brain is taking that image

and it's making sense of it.

Everybody's realty is different.

Understanding that what you see

is not necessarily what your neighbor sees,

I think this is a really good example of that.

And so I guess the Latin phrase is

de gustibus non est disputandum,

there's no accounting for taste.

Well in this case there's no accounting for color.