“Two Years Later, We Finally Know Why People Saw ‘The Dress” Differently: Remember “the Dress’? It Disrupted Our Understanding of Color, And, Yes, It Took Science Two Years to Catch Up”, 2017-04-12 (; backlinks):
[may also influence tennis ball color choice] …But the phenomenon continues to be utterly fascinating to vision scientists like me, and for good reason. The very existence of “the dress” challenged our entire understanding of color vision. Up until early 2015, a close reading of the literature could suggest that the entire field had gone somewhat stale—we thought we basically knew how color vision worked, more or less. The dress upended that idea. No one had any idea why some people see “the dress” differently than others—we arguably still don’t fully understand it. It was like discovering a new continent. Plus, the stimulus first arose in the wild (in England, no less), making it all the more impressive. (Most other stimuli used by vision science are generally created in labs.)
…Two years later we have a much better idea of what may have been a reason for the varied perceptions: People’s perceived color is also informed by their perception of lighting. And the image of the dress, taken on a cellphone, contained a lot of uncertainty in terms of lighting conditions. Was it taken inside or outside? This matters because it implies artificial or natural light. Was the dress illuminated from the front or the back? This matters because if it was back-lit, it would be in a shadow, otherwise not.The brain cannot be accused of epistemic modesty. It is well-known that in situations like this—where it faces profound uncertainty—it confidently fills in the gaps in knowledge by making assumptions…Color and lighting are no exception.
As the illumination conditions are impossible to clearly assess in the dress image, people make assumptions about what they are. Different people do this in differing ways, which is what causes the different interpretations of color. At least, that’s what my research shows, thanks to 13,000 people, including many Slate readers, who took surveys on what they saw when they saw the dress and also compiled other information about how they generally perceived the photo and the world.
Remember, the dress is actually blue and black, though most people saw it as white and gold, at least at first. My research showed that if you assumed the dress was in a shadow, you were much more likely to see it as white and gold. Why? Because shadows over-represent blue light. Mentally subtracting short-wavelength light (which would appear blue-ish) from an image will make it look yellow-ish. Natural light has a similar effect—people who thought it was illuminated by natural light were also more likely to see it as white and gold. Why? Because the sky is blue, daylight also over-represents short wavelengths, compared with relatively long-wavelength artificial (until recently, usually incandescent) light. Just as mentally subtracting blue light leaves the image looking more yellow, mentally subtracting yellow light from an image leaves an image looking more blue, which is what I found empirically.
…As a matter of fact, I can legitimately be accused of being a fairly extreme owl, yet I initially saw “the dress” strongly as white and gold. However, I did assume it to be in a shadow, so that assumption seemed to override the other. Moreover, viewing histories can change. Admittedly, I looked more at images of dresses (and this specific one at that) in the days following “the dress” than in my entire life before that combined. And it quite abruptly changed to a black and blue percept after 4 days, and I have never seen it as white and gold again. Of course, I also learned the true color of the dress in the intervening time, and my research suggests that people are more likely to switch to the true color of the dress than vice versa.