An unknown percentage of women can see a hundred times as many colors as the rest of us. While normal humans have three types of cones in their eyes for perceiving the three primary colors — red, green and blue — some women have an extra cone that gives them four primary colors. Most of us can theoretically distinguish a million colors. These women can see a hundred million colors.
Tetrachromatic women have a strong relationship to color-blind men. How does a deficiency — color-blindness — relate to this increased color perception? It has to do with the X chromosome and the fact that the genes for color perception reside on the two sides of it. With only a Y chromosome, and missing one of the arms of the X chromosome, men have less chance for redundancy. If they have a mutation in a color gene it usually means some loss of color perception. Women related to these men will likely have the same mutation, but they will have redundant genes on the second arm of their X chromosome. So the men will be down to two functioning cones, but the women will still have all three, plus the mutated one, which might still provide some color.
More recent research indicates that we might all be tetrachromatic after all. It turns out that parts of our optical system absorb the shortest wavelengths of the light that passes through them. It was assumed that our vision cut off at about 400 nanometers — blue — but it’s been discovered that the higher blues and the ultraviolets are being absorbed by our corneas and lenses. People who have their lenses removed in cataract surgery often report a new sensitivity to very short wavelengths.
Recently the BBC made a tetrachromatic woman famous. Concetta Antico is an artist and she can see colors that most of us can’t even imagine.
Some women are born with hyper-sensitive eyes that can see the world in ways most of us cannot even imagine. What’s it like to live with this gift?
This led to an Internet spasm, of course, and tetrachromacy became all the rage. There were even websites set up that purported to test you for the condition. Soon thousands were reporting on their social networks that they were tetrachromats. Fortunately, Snopes came to the rescue and showed quite simply why they were wrong. Computer monitors only use three colors so they can’t possibly test you for four. The Snopes article refers to Newcastle University’s tetrachromacy research project and credits them in debunking the Internet fad. Newcastle University has a FAQ on their research.
When I look out the window and see all the shades of green and brown in my back lawn, it’s hard to imagine that I’m not seeing it all. Learning that some people can see a hundred times as many shades makes me think about how little of reality I’m really seeing.