(upbeat dance music) - So do you remember the dress?

- Of course.

- Did you see this dress or this one?

- It's a simple question, but the answer has divided friends and family.

- White and gold.

- Blue and black.

- I remember it caused quite the stir, right?

- Massive stir.

- A polarizing debate that took over the internet.

(upbeat dance music) - [Rosa] People had existential crises over this image.

People tweeted things like, "If that's not white and gold, my life has been a lie."

- Swear on your mother's grave.

- Because that dress is white and gold.

- Out of her (beep) mind.

- [Rosa] Massive arguments.

I watched videos of people screaming at each other.

- [Speaker] This is white dude, white.

- White?

- White.

- That is dark blue.

It's purple-blue.

- [Rosa] I bet there was a divorce here or there over this image.

- So when you first saw that dress as a vision scientist, what did you think?

- Well, when I first saw the dress, I thought it was blue and black and I thought that the internet was yanking my chain.

- Right, to get the GOAT of vision neuroscientists.

(laughs) - Sure, but in the morning when I looked at my phone, I saw white and gold.

And now, of course, I was obsessed, so I said, "Well, if this is an ambiguous image, all I have to do is disambiguate it.

So I set to work.

I got into Photoshop, cut out the dress, put it into a scene with lots of rich cues, and all of a sudden, boom, you can see the dress is white and gold.

- Wow.

- Now the pixels, the pixels that make up the dress there are identical to the original image.

- [Heather] Now, this doesn't work for everybody, but for most, the visual context can make all the difference.

- What's different here is her skin is tinted blue, the background has blue light cast on it, she's standing in the shadow of that cube.

And so your brain says, "Aha, I need to ignore some amount of blue light that is in this signal that's hitting my eye and render this as white and gold."

- [Heather] And if we flip things around... - [Rosa] Same dress, pasted it into this other scene.

Her skin is tinted yellow.

The background has a yellow cast.

She's standing no longer in the shadow but in the light, boom, blue and black.

- Amazing, that's really amazing.

So again, the dress, the pixels are exactly the same.

- [Rosa] Identical.

- [Heather] The dress is a powerful example of how color really works in the brain.