Whether you saw the above dress as blue and black, or white and gold, someone has almost certainly told you that you’re wrong. But you’re not, and neither are they – it’s both colours, depending on who and where you are.
Which colour your eyes see is in fact a consequence of the way our eyes have evolved, and tells you important things about how your eyes work out colour in a world lit by sunlight.
The problem is that the brain has to avoid seeing the colour of the light reflecting off an object, and just see the colour of the object itself. If it sees a white shirt bathed in yellow sun, for instance, it needs to subtract the yellowness of the sun so that it can see the whiteness of the shirt – and it normally does.
The same kind of system is found in cameras, and is called white balance. That allows the camera to do the same thing the brain does – deciding what should be white, within the image, and adjusting the colours accordingly.
But you’re also wired to see the colours one way or the other, according to some explanations of the dress. And it all depends on rods and cones.
Those are the two different kinds of cells that are in your eyes, and allow the brain to see colours. Rods are more sensitive to light and are used to see shapes, but not colour. Cones are less sensitive to light, but are used to see colour. (Having lots more rods than cones is what leads to colour blindness.)
Having more of one or the other will lead you to be likely to see the dress as white or gold, or blue and black.
While it’s ultimately about what your brain decides it needs to do with the ambient light on the image, the types of cells in your eye will help decide
To put the idea to the test, look at the dress on a page with a white background. Then head to a dark room for half an hour, before looking at the dress there on a black background – or just never come back, and avoid the whole argument.
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