Scientists have discovered a woman who is able to see 99 million more colours than the average person, following a 20-year hunt to find somebody with super-human sight
Dr Gabriele Jordan, a researcher at the Institute of Neuroscience, has spent two decades attempting to track down somebody who could accurately be described as a tetrachromat – a person who has four types of cones in their eyes, rather than the usual three (a trichromat), and so is able to gauge far greater colour depth than others.
The hunt began in the 1980s, when Dr Jordan was working with the neuroscientist John Mollon from Cambridge University, who was studying colour vision in monkeys and became interested in De Vries' 1948 study on tetrachromacy.
He explained that colour blindness ran in families, affecting men but not women, and also that while colour-blind men had two normal cones and one mutant cone, the mothers and daughters of colour-blind men had a mutant cone and three normal cones – making a total of four.
Dr Vries speculated that such women might be using the fourth cone to distinguish more colours than a trichromat, and suspected the extra cone could be why the women perceive colour differently.
Since colour blindness - or having less than three cones - is common, Dr Mollon and Dr Jordan ascertained that four-coned women must be as well, and set about testing the mothers of colour-blind sons.
In an attempt to find out if tetrachromats were present in this group, the researchers had them take matching tests similar to the one used by De Vries, but with the twist that true tetrachromats would not be able to make a satisfactory match, as they could not sense colour gradations beyond those available on the test.
After they failed to find the tetrachromat Dr Jordan invented a new test recently involving women sitting in a dark room, looking into a lab device, where three coloured circles flash before their eyes, all of which looked the same to a trichromat.
However, to a true tetrachromat, one would stand out each time because it was not a pure colour, but a subtle combination of shades of red and green light randomly generated by a computer.
In a test of 25 carefully selected women who each had a fourth cone, one from the north of England - code named cDa29 - got every single answer correct – and could be accurately described as a tetrachromat.
Dr Jordan told Discover Magazine she was "jumping up and down" at the finding, though unfortunately cannot explain how the subject sees things compared with normal people, due to the difference in her colour gauge.
“This private perception is what everybody is curious about. I would love to see that," she said, adding that the next challenge is discovering why patient cDa29 is different from other women.
She told the magazine: "We now know tetrachromacy exists. But we don't know what allows someone to become functionally tetrachromatic, when most four-coned women aren't."