Humans have three kinds of color receptors in our eyes. If only two kinds are working properly, the result is color blindness. Some animals — reptiles and birds among them — are speculated to have four: they’re tetrachromats, and can detect color in the ultraviolet range, with wavelengths too short for humans to see. But some humans may also be tetrachromats.
Due to genetics, some women may be born with two kinds of red receptors, making them tetrachromat. They won’t see wavelengths we don’t, but if the brain can accomodate the fourth stream of data from the eye, they may be able to distinguish colors within the spectrum we do see far better than any of us. To a true tetrachromat, we may all be as the colorblind are to trichromats.
