Unless you have the good fortune to be shielded from the latest obsessions of social media, you heard last week about “the dress”, an image of a dress that some people see as white and gold while others see it as blue and black, with a few able to switch between the two interpretations.
A week or so late to the game, and now that everyone has made up their minds about what color the dress is and moved on to discussing other matters, the Brains blog is pleased to be hosting a roundtable discussion among several distinguished philosophers, who address the science of the phenomenon as well as deeper questions about whether this all just goes to show that everything is, like, only your opinion, man.
Contributing to the discussion are Kathleen Akins (Simon Fraser University), Keith Allen (University of York, UK), Brit Brogaard (University of Miami), Alex Byrne (MIT) and David Hilbert (University of Illinois, Chicago), Jonathan Cohen (University of California, San Diego), Carolyn Jennings (University of California, Merced), and Yasmina Jraissati (American University of Beirut). [UPDATE: See also the recent guest post by Justin Broackes (Brown).] To expand their contributions, just click their names below. And feel free to continue the discussion in the comments!
Header image source: @budoucha, via Kathleen Akins
As I said, there are a number of things going on in this photograph, but colour constancy is the main one. I myself see The Dress as white and gold. I’m just that sort of person (no, that was a joke). In the Wired article, you can see that the jacket is reflecting mostly blue light. My visual system interprets the jacket as white but as illuminated by blue light. If you shone a blue light on a white and gold dress, and then took at a photograph of the dress, you would see that the white stripes of the dress reflect blue light (because the light is blue) and the gold stripes would reflect a very dark, muddy colour, a mixture of blue and yellow light at a low intensity. Actually, the light reflected from a shiny gold material would also have white ‘glints’—specular reflectance from the gold material, another ‘hint’ in The Dress photograph that the dress is gold. This is why I see The Dress as white and gold, because a white and gold dress, seen under a dim blue light, would look just like this in its image (or photograph).
Other people see the dress as black and blue because their visual systems makes a different ‘guess’ about the colour of the light. Their visual systems interpret the light as white, as emitting all wavelengths of light equally. Given an actual black and blue dress and ‘white’ light source, a photograph of the this dress would show the blue stripes as reflecting blue light, and the black stripes as reflecting almost no light. The photograph would be much closer to the true colours of the dress: there would be blue and black stripes in both.
As you can see from the Wired photograph, both of these interpretations work, more or less, just as a (rare) matter of chance. If your brain interprets the light as blue, you see a white and gold dress; if your brain interprets the light as white (or ‘colourless’) then you see the The Dress as black and blue. In fact, the fact that the dark stripes are shiny, adds to the plausibility of the gold/white interpretation. And because the viewer has never seen The Dress before, it’s up to the brain to figure out which interpretation is more likely. Both interpretations work, so some brains see one thing, and some brains see the other. In fact, some people can make the dress switch back and forth in colour at will, just like some people can make a Necker cube, switch back and forth. It is nice colour illusion, one of the very few natural illusions of this kind.
One reason why we rarely have colour illusions is because, in any natural scene, the scene is complex enough to yield a stable interpretation of object colour. The standard artificial illusions for shape and size depend upon reducing the information within the scene (e.g. Necker cubes have no shading information, and the Ames room reduces depth perception). The Dress manages to do much the same thing simply by ‘hogging’ the photograph — taking up most of the photograph—and thereby providing very little background information.
As any philosopher will have noticed, the above interpretation depends upon a realist view about colour. (Shockingly, I think that the dress is either black and blue or white and gold — and that facts about The Dress’s colours warrant specific shoe/accessory choices.) However, this realism follows from some complex views about human colour vision, namely: (1) Seeing object surfaces as having colours, just like seeing surfaces as light or dark, is a complex task, one that usually occurs sub-personally but can at times require our conscious attention (witness ‘reversing’ the dress colour combination); (2) the luminance and chromatic systems both begin with contrast encodings, the most useful and most general form of visual information for seeing objects; and (3) from these luminance and chromatic contrast encodings, various properties of the world are discerned — and; (4) it is from these properties, not from sensations (be they colour of grayscale), that we come to see surface colours and object albedo (surface lightness/darkness). In other words, seeing surface colour is a high-level cognitive achievement, one that children ‘grow into’ at the ancient age of 3 and onwards, given suitable training with colour names.
Where does this leave us? On the one hand, the cognitive nature of colour perception is what makes it immune to illusion in the ordinary case, when viewing complex natural scenes. This is why The Dress is so…shocking. There are usually too many properties of the scene that coalesce around a single interpretation of object colour. On the other hand, this is what makes colour perception such a prime subject for colour illusions. If we have no access to the properties of scenes that would normally allow us to see stable surface colours, we are easily ‘fooled’ by these artificial stimuli. Notably, no one about to buy The Dress, or to try it on, would be in any doubt about its colours—or be able to convince their shopping partners that The Dress is gold and white when it is black and blue. But the photograph of the dress is another story.
In the picture of the dress the environment is clearly presented to us. It is left vague whether we are seeing the dress in bright sunlight, inside illuminated by artificial light or in the shade. But our brains fixates on one of those environments. When our brains interprets the background as being sunny, we see the dress as blue and black. If our brains takes the dress to be in the shade, then it will be more likely to look white and gold.
2) There is widespread lip service (among both philosophers and non-philosophers) paid to the claim that color is a subjective phenomenon, on the grounds that color appearance varies with the characteristics of the perceiver. Despite this, the reaction to a convincing example of such variation in color appearance was alternately (a) disbelief, and (b) a massive investment of time in trying to understand how what everyone professes to believe happens actually happened.
3) People have an intense commitment to knowing the real colors of things. The debate was not only—or even primarily—about the interesting questions concerning color appearance. People wanted to know the color of the dress.
Recommendation: philosophers should stop saying that color is subjective. It’s not true in any interesting sense and, although we can coerce lip service by sophistical argument, the vulgar really don’t believe it.