A New Study Helps Explain Why Some People Can See So Many Colors

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Last year, Science of Us interviewed the artist Concetta Antico, who can see an explosion of colors invisible to the rest of us. Antico has an exotic condition known as tetrachromacy, which is caused by a mutation on the x chromosome. That mutation tacks on an extra type of cone to the usual three varieties humans are born with in their retinas, leading those with the condition to be able to experience a flood of rainbow hues.

As an example, take mowed grass. Where a normal person might discern green and maybe, just maybe, some yellow and brown, Antico told Alexa Tsoulis-Reay she sees a whole painter’s palette: “I see pinks, reds, oranges, gold in the blades and tips, and gray-blues and violets and dark greens, browns and emeralds and viridians, limes and many more colors — hundreds of other colors in grass. It’s fascinating and mesmerizing.”

And that’s just a blade of grass.

Antico’s condition is a medical mystery. While experts believe that up to 45 percent of women with European ancestry might have the mutation — meaning they, too, have four types of cones in their retinas and can see some varieties of colors indiscernible to the general population — only a tiny group of women with the mutation, like Antico, have her seeming superpower.

To find out more about why some tetrachromats are gifted with this fascinating ability, a pair of psychologists – Kimberly Jameson from the University of California, Irvine, and Alissa Winkler of the University of Nevada, Reno – tested Antico’s ability to judge colors in dim light as compared to other people’s. In particular, Antico was tested against a tetrachromat who was not trained in art along with an artist with normal vision.

Their results, presented at the International Symposium on Electronic Imaging confirmed that Antico does, in fact, see more colors than most other other tetrachromats. Moreover, the artist without tetrachromacy was not able to distinguish as many different types of colors as Antico. One sub-experiment in particular stood out: Jameson took photographs of natural scenes, then adjusted them to how Antico described them, coloring in the shades of grass that Antico described, for example. What Antico found most sensitive to her tetrachromacy were dark, shadowy areas: areas beneath hillsides, spots of shade, and darker areas — all parts of a scene which would be otherwise unremarkable to people with normal human eyes.

Antico had guessed as much. Last year, she told Science of Us that she figured her artistic training had a huge role to play in why she saw so many colors, calling herself a “functioning tetrachromat”: “If I hadn’t been immersed in art and if I hadn’t been an art teacher for the last 30 years I wouldn’t necessarily have the level of color definition that they are finding,” she said. “So while I have this genetic gift of a fourth receptor in my eyes, the fact that I apply it on a daily basis improved my color recognition. Think of someone who has superior muscles but never learned to run. You can have the potential but it’s only realized if you use it.”

Jameson and Winkler aren’t done studying Antico. Next, they hope to gain a better understanding of how her art expresses her condition to those without these abilities — a line of research might help experts better understand night vision deficiencies and colorblindness.

A New Study Helps Explain Tetrachromacy