“The Women With Superhuman Vision” by David Robson. BBC.com, 9/12/2014.
(This is a recently discovered posting written years ago, then lost.)
Sometime during the 1980s, I took an evening watercolor class held in the basement of a local woman artist. Our first assignment was to paint a dark green bottle she displayed. I painted a dark green bottle. “No, no,” she said. “See all of those colors where the neck curves out to join the body? You want to get all of those.”
To me, it was just a green bottle, but I redid it, this time adding splashes of garish blue, pink, and yellow. She was very pleased, declared it the best in the class, and showed it to the others as an example of real talent. But I was a fake, and I knew it. The strain proved too much for me, and I dropped out after only a few lessons.
Now, I find, she may had been one of the few tetrachromats, people who can see far more colors, far more vividly, than the rest of us. They can easily differentiate between close shades that look identical to most of us. If the theory is correct, this phenomenon is limited to women.
I know I am color blind. I prefer “color impaired” since I can still see colors, but I am told that is what “color blind” means. Almost all color blind people see some colors, just not as vividly. My problem is reds that I see as red, but they don’t stand out, and if they are small, I see them only as gray. At our local swimming pool, the second marks on the pace clock up on the wall are red, and at a certain distance, I see them as red. But just one step farther away and they look gray. Forward a step: red. Back a step: gray. My wife often points out small red berries on a shrub that I didn’t notice. Secretaries where I worked wanted corrections marked in red. The red jumped off the page for them. I could see the thin line was red, but it did not stand out.
I discovered my problem when we moved to Massachusetts. and I applied for a driver’s license. The policeman testing me handed me a print filled with circles of different sizes and colors. I was supposed to see a number formed by the circles, but I saw nothing. The policeman said he would give me the yarn test instead. He handed me a box containing hanks of yarn and asked me to pick out red, green, and yellow hanks. I could do that easily.
We all have three types of cones in our retina that detect colors. (I suspect my red cones are too far apart.) The genes for the cones lie on the X chromosome, and women have two of these. The theory being postulated is that the double chromosome could produce an extra cone sensitive to slightly different wavelengths of light (four cones altogether, hence the term “tetrachromatic”).
About 12% of women do have this extra cone, but most have normal vision. The publicity surrounding this phenomenon has brought out many more tetrachromats than had been previously known, and larger studies can now be done.
Being a true tetrachromat is not an unmixed blessing. One woman describes a grocery store as a nightmare of colors. “It’s like a trash pile of color coming in at every angle.” Her favorite color is white, which is a relief from the cacophony of the others. White is still vivid for her, but is not so overwhelming as the other colors.