Welcome to another week of Sketchy Science. We should all be thankful that we can still take these few minutes out of our day to enjoy a slice of knowledge, because there were moments last week when the future of our civilization was in serious doubt. In addition to losing our interstellar voice of reason and logic through the passing of Leonard Nimoy, our society was on the verge of collapse as millions of people argued over the colour of adress. Thankfully, science prevailed as we learned once and for all that the dubious garment was in fact blue and black. But how could so many people see the same image so differently? The answer lies in the way our brain interpret colour.
Wired offered a great and much more timely explanation of the mechanism at work than this one, but they don’t have our flare for comics, so what follows is largely based on their explanation with a Sketchy Science twist. The heart of the problem lies in the fact that what we all take as reality is just an interpretation based on our five senses. The three dimensional wonderland we all navigate through in our waking lives is the result of electrical impulses zipping through our brains that make a picture we can use. Some philosophers have even suggested that it is possible that each of us is nothing more than a brain in a vat in the lab of a mad scientists who has us hooked up to strategically placed wires. The really interesting part about that Matrix-eqsue theory is that there is literally nothing anyone can do to prove it wrong.
But back to the dress. Assuming for a minute that we are in fact living breathing, non-wired-up beings and that the image we all saw this week was in fact real, there is a simple (albeit super interesting) explanation for the confusion. The truth is, that what we think of as colour is just our brains’ interpretation of light reflecting off different objects. A universe without light, as anyone who has ever gone spelunking can tell you, is a universe without colour. When you see an object as, for example, red, that object is just absorbing all the wavelengths of light except for red which it reflects back into your eyes. As we all know from elementary school science, normal white light is actually made up of different wavelengths that our brains see as red, orange, yellow, green, blue, indigo and violet. Interestingly, some people debate whether indigo is actually a colour of the rainbow, but that is another article.
The thing about our brains is that they aren’t always operating in a world of perfect lighting conditions. At twilight, for example there is less light for objects to reflect but our brains still have to see our car is red, lest we commit an accidental felony at the supermarket. To do this, the area of your brain that interprets colour factors in the context in which it is seeing an object. Though this works in most situations, it is possible for mistakes to occur. The internet is loaded with examples of optical illusions where two identically coloured shapes are presented against different coloured backgrounds and the effect is that they look like two totally different shades.
That is basically what is happening with this dress. You look at the image and your brain has to decide whether to discount the blue end or the gold end of what is called the “chromatic bias of the daylight axis.” Basically, it needs to decide whether it is seeing a blue dress in good lighting conditions or a white dress in poor lighting. If you see the dress as white and gold, your brain is discounting the blue end of the light spectrum. If you see the dress as blue and black, your brain is (correctly) discounting the gold in the visible light. To make things even more confusing, your brain can change its mind as so many people (myself included) found out when they loaded an image of a white and gold dress that gradually turned blue and black.