The average human can perceive one million different colors, but researchers suspect that a small percentage of women may be capable of seeing one hundred times that amount. Finding out who these women are, however, will be no easy task.
The science of super-vision all boils down to cones — special neurons, located in your retinas, that convert incoming light into the electrical signals that feed your brain information pertaining to color. Your typical retina houses millions of cones, but in humans those cones usually fall into just three categories. Each category of cone, on its own, is capable of detecting around 100 different hues; but pair it with either of the remaining two classes of cones and their powers complement one another. Just like that, the number of perceivable colors jumps from just 100 to 10,000 (1002). Combine the signals from all three kinds of cones and that number leaps to one million colors(1003).
Mutations in the genes that code for cones are responsible for color blindness in males. The fact that many of these genes reside on the X chromosome makes color blindness much more common among males than females, but it also gives rise to another possibility: a small percentage of women may actually posses four color cones.
Over at Discover Magazine, Veronique Greenwood tells the story of Newcastle University neuroscientist Gabriele Jordan, and her search for women in possession of this rare trait — one that could, in theory, allow them to experience the world in colors the rest of us can't even imagine:
[These women] might experience a range of colors invisible to the rest. It's possible these so-called tetrachromats see a hundred million colors , with each familiar hue fracturing into a hundred more subtle shades for which there are no names, no paint swatches. And because perceiving color is a personal experience, they would have no way of knowing they see far beyond what we consider the limits of human vision.
As you might expect, the fact that the women Jordan is looking for have no way of knowing their perception of the world is, in effect, super-human has made finding them incredibly difficult. And it gets even more complicated:
Jay Neitz, a vision researcher at the University of Washington, thinks that potential tetrachromats may need practice to awaken their abilities. "Most of the things that we see as colored are manufactured by people who are trying to make colors that work for trichromats," he says. "It could be that our whole world is tuned to the world of the trichromat." He also suspects the natural world may not have enough variation in color for the brain to learn to use a fourth cone.
In other words, the rest of us trichromats could be keeping our tetrachromat peers from realizing their full, technicolorrific potential without even realizing it. As a man, I almost feel guilty; if I were a woman, I have to imagine I'd feel a bit cheated. Either way, I'm immensely curious. If a potential tetrachromat could actually "train" herself to see more colors, would she be able to notice the difference in her daily life? Is tetrachromacy something that could be introduced, genetically, to the male gender? Are there already secret tetrachromatic societies living among us undetected, organizing meet-and-greets and movie nights by tagging landmarks in colors only they can see? The mind reels!
Read more about this fascinating research over at Discover Magazine.