There’s a simple reason why the dress debate has taken over our news feeds, our conversations and our lives this week. To put it simply, we’d rather debate something positive, like the dress, than ISIS and Budget 2015.

Not since Monica Lewinsky was a White House intern has one blue dress been the source of so much consternation. And yes, it’s blue.

A single image has polarized the entire Internet into two aggressive camps, The BBs and the GWs. But for the past two days, people across social media have been arguing about whether a picture depicts a perfectly nice bodycon dress as blue with black lace fringe or white with gold lace fringe. And neither side will budge. This fight is about more than just social media—it’s about biology and the way human eyes and brains have evolved to see color in a sunlit world.

Different wavelengths correspond to different colors. The light hits the retina in the back of the eye where pigments fire up neural connections to the visual cortex, the part of the brain that processes those signals into an image. The first burst of light is made of whatever wavelengths are illuminating the world, reflecting off whatever you’re looking at. Without you having to worry about it, your brain figures out what color light is bouncing off the thing your eyes are looking at, and essentially subtracts that color from the “real” color of the object.

Our brains are constantly adjusting for color. Dr. Lieff a practicing psychiatris gives an example: “If you take a white piece of paper and you have it inside, you see it as white, and then you take it outside and you see it as the same white, but in truth, the actual color has changed because of the ambient light. But our brain adjusts for what we think is illuminating something, so that’s part of the mystery of why this works.”

One factor is that these particular colors are complicated colors, they’re not just black or just gold, so you start with a complicated set of colors, and people may be sensitive more to one or the other.

The second feature that’s ambiguous is that you don’t have any idea what the light source is. If it was obvious the light came from a regular light bulb or outside in the sun, the brain would then calculate, ‘Well, this is the light source and this is what that color comes out to be.’ You also can’t tell if there’s a shadow or not. So  there’s a lot of ambiguity and as a result of that, the brain chooses one or the other.

Well for now, Stop talking/caring/worrying about the dress. Story’s over now.

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