Black or gold dress explained by your friendly neighborhood vision scientist. Why black to some and gold to others? It has to do with how your eyes work....
Which dress has the darker gold banding? Well, they are actually the same gold color of course and only look different to our brains. But its not all in our mind. They look different because of the visual processing that happens right in our eyes, in our retinas. The complex connections of photoreceptor cells and neurons actually make the retina into millions of amplifier and transistor-like circuits so we can see in a very large range of light intensities. So we can see edges and very small differences in contrast.
So why does that dress on Tumbler look different to different persons looking at the same picture on the same screen? For several reasons.
First, if we consider the detection of light on a small discreet area of our retina, we have photoreceptor cells in this small area that activate other cells downstream to send this information to our brain. While the small area we are considering is "stimulated" or "on" for detection, there is also a phenomenon called "suppression in the surround". That is the area immediately surrounding the "on" area is actually turned more "off" than it would be if the whole area of your retina was stimulated evenly. This suppression just around the stimulated area tends to make it easier for us to detect changes, differences and edges.
This phenomenon happens with greys but also happens with colors. Our perception of color also depends on its surrounding color. We have red, green and blue cone photoreceptor cells that detect colors in our retinas, and some of the circuits in our retinas for color suppress each other.
If you look at certain checker patterns we can see the illusion of shadows between black squares. That is from the surround suppression effect. The shadows are not really there, but your retinal circuits produce that effect by the time you "see" it in your brain.
Also, a fraction of a percent of all women can be quadro-chromatic and they can actually differentiate colors that us regular tri-chromats cannot. This is because of the way our cone color opsin genes get shuffled and inherited on our X Chromosomes. Women have two X Chromosomes of course while men only have one X Chromosome. Finally, many men are only di-chromats, that is they are color blind. If you have green-red color blindness, for example, the red and green traffic lights just look like two white lights.
So the dress colors, like beauty itself, is in the eye of the beholder. You and your buddy may behold differently.
Professor of Biomedical Sciences
Eye Research Institute