#TheDress Explained

You know about "The Dress"? It first appeared on Tumblr? The one that's freaking out the Internet? Or at least, making it lose its composure? And Twitter's, well, all a-twitter about it, too? Yeah, that one. Here's the deal: some people look at the photo and see a black-and-blue dress. But others look at the same photo and see a gold-and-white dress. Wha--? How can that be?

Calm down, Internet. I'm here to explain. I'm a psychologist specializing in perception. I'm trained to handle situations like this.

What we "see" is affected not just by the pattern of light that falls on our retinas, but also by unconscious assumptions that we make about the visible world. Like, for example, the ambient illumination.

Say you "see" a piece of red paper. Is it red paper under white light? Or is it white paper under red light? If you don't know for sure about the light falling on the paper, your assumption about the illumination makes all the difference. Your unconscious assumption makes you see the object one way, or another. Same goes for the dress. (What if it's red paper under red light? Shut up. I'm trying to make a point here.)

Usually, our assumptions about things match the reality. We know what the ambient illumination is. It's obvious. But what if reality is ambiguous? That is, what if we don't know for sure what the ambient lighting actually is? Like, say, in a poorly exposed photo? Can we force our perception to change?

Let's try. Want to see the dress as gold and white? Try scrolling the photo so all you see is the topmost part--just to where the frilly ruffly bits start. Then tell yourself that the black neckline under bright illumination is actually a gold colour under low illumination. Also, think about the lighter areas as actually being white, again under low illumination. (Likewise, if all you see is a gold-and-white dress, imagine that you're looking at the dress under much brighter illumination.) You're using "top-down" perception, driven by your beliefs about the stimulus, not just about the "bottom-up" incoming signals from your eyes.

Still not working for you? Wait until it's dark outside, or go into a completely dark room. Download an image of the dress from the original Tumblr page. Pull it up in a graphics viewer. (I like FastStone.) View it full screen, with nothing else around it, just a black background. Now decrease the brightness of your computer screen, and turn off the lights in your room. At the lowest screen brightness, try again to convince yourself that you're looking at a white-and-gold dress. There's no guarantee this will work. I mean, maybe you're brain damaged, I dunno. It's late and I'm tired, and I want students from my classes to stop sending me emails about this dress. It's pretty ugly. (Sorry.)

There ya go, mystery solved. It's all about your unconscious assumptions. As to why some people can more easily see it as gold and white, whereas others cannot, well, that's an interesting question!
(By the way, the dress is actually blue and black, according to Amazon. That's the objective reality. So stop arguing.)

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