By now, I am sure that you have seen this picture. Some people see it as blue and black and some people see it as white and gold. Two people can be sitting right next to each other and see totally different things! It happened to me last night.
“What’s happening here is your visual system is looking at this thing, and you’re trying to discount the chromatic bias of the daylight axis,” says Bevil Conway, a neuroscientist who studies color and vision at Wellesley College. “So people either discount the blue side, in which case they end up seeing white and gold, or discount the gold side, in which case they end up with blue and black.” (Conway sees blue and orange, somehow.) [ed. that makes her the devil.]
Essentially, it is an issue of color constancy: that the color we perceive is due to its context. Brightening and darkening the image supports that:
See also XKCD:
But that explains one, trivial why – why one ‘color’ can look different depending on context. What it does not explain is why some people see it as white and gold and others see it totally the opposite. Why is there this individual level variation?
It seems to exist right on some threshold: some people have an in-built or learned bias to favor – well, something. Light images? Dark images? Overhead light? And others have a different bias. If it was light or dark, presumably you could lock five people in a closet and when they came out they would see it one way (maybe blue and black). Push five others out in the sun and they’d see it differently (white and gold). But I haven’t seen a good explanation of this nor why it is so bimodal. I would bet someone money there will be a scientific paper on this illusion published within the next year or two.
In conclusion, it’s white and gold because that’s all I can see. Case closed.