Over the course of two decades, Newcastle University neuroscientist Gabriele Jordan and her colleagues have been searching for people endowed with this super-vision. Two years ago, Jordan finally found one. A doctor living in northern England, referred to only as cDa29 in the literature, is the first tetrachromat known to science. She is almost surely not the last.
The first hint that tetrachromats might exist came in a 1948 paper on color blindness. Dutch scientist HL de Vries was studying the eyes of colour-blind men, who, along with two normal cones, possess a mutant cone that is less sensitive to either green or red, making it difficult for them to distinguish the two colours. He tested their vision by having them perform a basic matching task. Twiddling the dials on a lab instrument back and forth, the men had to mix red and green light so that the result, to their eyes, matched a standard shade of yellow. To compensate for their difficulty in discerning hues, colour-blind men need to add more green or red than normal trichromats to make a match — via redwolf.newsvine.com