What do you think of this fact?
In February 2015, a washed-out photo of a striped dress split the internet. Some people saw blue and black, others saw white and gold. Friends argued, celebrities weighed in. And the dress itself? Royal blue with black lace.
One photo, two realities
According to Wikipedia, the picture was taken by the mother of a bride and posted on Tumblr. By the next day it was everywhere. Scientists quickly realized this was more than a meme: a rare case where perfectly ordinary viewers completely disagree about the colors of the same pixels.
In May 2015, the journal Current Biology published three short studies on it. A team led by neuroscientist Bevil Conway of Wellesley College and MIT surveyed about 1,400 people. According to Wellesley, 57 percent described the dress as blue and black, 30 percent as white and gold, 11 percent as blue and brown, and 2 percent as something else. Older people and women were more likely to see white and gold.
Your brain guesses the light
The explanation is color constancy. Your brain constantly tries to subtract the color of the lighting so that things look the same no matter what light they are in. Conway put it this way: “The brain has figured out how to ‘erase’ that contaminating light.”
The photo is overexposed and gives few hints about the light in the room. Live Science sums it up: people who saw white and gold probably assumed daylight and discounted bluish wavelengths. People who saw blue and black probably assumed warm artificial light and discounted reddish wavelengths. Same pixels, different assumption about the room, a completely different dress.
A second study, led by Karl Gegenfurtner of Giessen University, showed that people actually saw a continuous range of blues. His team wrote: “The question should thus not be whether the dress is blue or white, but whether it is light blue or dark blue.”
Bonus fact: When researchers at the University of Nevada, Reno inverted the image’s colors, nearly 95 percent of viewers saw the stripes as yellow or gold.
You don’t see colors. You see your brain’s best guess.