Powered by Guardian.co.ukThis article titled “The dress quandary: ‘It’s an illusion. But everything is an illusion'” was written by Jessica Glenza in New York, for theguardian.com on Friday 27th February 2015 22.41 UTC

It’s a rare feat for a meme to crawl out of the muck of internet culture and into the consciousness of everyday folks. Especially when it happens as quickly as “the dress” did.

Between Thursday evening and Friday morning, the dress grew from a Tumblr post by an Irish musician to an international phenomenon and subject of debate across the globe.

The crux of the dress question, and perhaps its appeal, is simple: is the frock white and gold, or blue and black?

The phenomenon could be the result of a simple optical illusion, an ambiguity, or it could be a more complex. Whatever the cause, it’s a photo that not even perception researchers can agree on.

“So much of our vision and hearing is really accurate,” said Howard C Hughes, who investigates the mechanisms of perception at Dartmouth College’s department of psychological and brain sciences. “If that weren’t so, we couldn’t walk through the door, and we certainly couldn’t run 50 yards and catch a fly ball in center field.”

In short, you’re not crazy: most of what you see is what other people see. But Hughes reminds us that the objects we “see” don’t necessarily have the fundamental qualities we perceive, especially when we’re working with limited information, such as a grainy, two-dimensional photo.

Those images are chewed up data collected by our eyes and reassembled by our minds, composed through complex biological and psychological processes.

“That creates, I think, the feeling that … we just see what’s out there,” he said. “But we have to construct that – the brain has to construct that – and people have to realize in a trivial way you need eyes to see, but you need a brain to perceive, and so that perception is something that’s derived.”

The dress quandary focuses on color, a perception that is not “real” per se. The experience of color is the perception of the length of visible light rays reflected from a surface, interpreted as one of three primary colors by the human eye.

For example, what we see as “red,” is not an intrinsic quality of an object. Rather, it’s humans’ remarkably homogenous perception of reflected light. And there are plenty of animals that experience much color much differently than humans. The eyeballs of mantis shrimp, for example, have 12 color receptors compared to humans’ three.

And while the question may seem inconsequential, many have found that the picture serves as a fascinating example of the interplay of human biology and perception – constructs that make up some of the most studied fields of brain science.

“There’s no reason to think that all the detail of the incredible process that nobody really, fully understands doesn’t have individual differences,” said Hughes. “Now, how this image has done such an amazing job of making that painfully obvious – I’m not sure. But I think the reason it generate so much heat between people is most of us think we just see what’s out there.”

Hughes said the subject will likely be subject to more research, and hypothesized that the blue-white phenomenon could be the result of anything from anomalous trichromats (people who have slightly different perceptions of primary colors) to a (very difficult) reversing optical illusion, sometimes called an ambiguity.

Anyone who has tried to reverse the orientation of convex and concave circles, or a spinning silhouette will have an idea how difficult some such images are to flip, or “disambiguate”.

Another perception researcher. Robert Fendrich, told Hughes he saw the dress as gold-white on Thursday evening, and blue-black on Friday morning, one of which appears to be a minority of people able to reorient the image. Fendrich is a visiting scholar at Dartmouth College, also in the psychological and brain sciences department.

At the Whitney Laboratory for Perception and Action at University of California Berkeley, David Whitney said the image’s effect is simple – it’s an ambiguity of inference.

“You infer the light is hitting the dress directly, and I infer that the light is coming from behind the dress,” said Whitney. “It boils down to a really simple difference, and it’s a really simple ambiguity.”

“It’s an illusion,” said Whitney. “But everything is an illusion.”

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