We wrote in Ever Hear of the Purkinje Effect? about how the cones and rods in normal human eyesight function to perceive color and take over from one another as the light levels fall. The average human sees colors in what is called a trichromatic color space of Red, Green and Blue, which corresponds to the three types of photoreceptors, or cones, in our retinas. But, cutting edge research is showing that this may not be true for all of us.
|NOAA Photograph of Double Rainbow.
A 20-year long research study has been able to identify at least one person with the ability to see in a four-color space. Referred to as a functional tetrachromat, this woman is able to distinguish colors invisible to others. She apparently possesses a fully-functioning fourth retinal cone that lies between the standard red and green cones. To give you an idea of what her Super-Vision is like, when she looks at a rainbow, she can see ten distinct colors, while the rest of us can see only five. The accepted number of hues that an average human with trichromatic vision can differentiate between is one million. With her tetrachomatic vision, she may be able to differentiate between up to one hundred million colors!
While functioning tetrachromats are rare in the population as a whole, studies indicate that as many as two to three percent of the world's women may possess a functioning fourth cone. It all comes down to genetics, and those favor women in this case. This is because, in humans, two cone cell pigment genes are located on the sex X chromosome. It has been suggested that as women have two different X chromosomes in their cells, some of them could be carrying some variant cone cell pigments, thereby possibly being born as full tetrachromats. They would have four different simultaneously functioning kinds of cone cells, each type with a specific pattern of responsiveness to different wavelengths of light in the visible spectrum.
We can only try to imagine the world that an artist with Super-Vision might learn how to paint.
Even without super-vision, we know you'll find something wonderful to see at The Artist's Road, a home for people passionate about art.
–John and Ann