21 June 2012


An average human... can 
perceive a million different colors... Our powers of color vision derive from cells in our eyes called cones, three types in all, each triggered by different wavelengths of light. Every moment our eyes are open, those three flavors of cone fire off messages to the brain. The brain then combines the signals to produce the sensation we call color...

Each cone confers the ability to distinguish around a hundred shades, so the total number of combinations is at least 1003, or a million. Take one cone away—go from being what scientists call a trichromat to a dichromat—and the number of possible combinations drops a factor of 100, to 10,000. Almost all other mammals, including dogs and New World monkeys, are dichromats. The richness of the world we see is rivaled only by that of birds and some insects, which also perceive the ultraviolet part of the spectrum.

Researchers suspect, though, that some people see even more. Living among us are people with four cones, who might experience a range of colors invisible to the rest. It’s possible these so-called tetrachromats see a hundred million colors, with each familiar hue fracturing into a hundred more subtle shades for which there are no names, no paint swatches. And because perceiving color is a personal experience, they would have no way of knowing they see far beyond what we consider the limits of human vision.
The rest of this rather interesting story is at New Scientist.


  1. Google Chrome is warning that the Spectralcolor.com site linked from the old post is hosting malware. Proceed at your own risk.

    1. Noted, and I've removed the link from this post. Tx.

  2. A great Radiolab episode that explores this:


  3. My optometrist said he studied this quite a bit during his schooling and has reason to believe I am a tetrachromat. I spent a while being bounced from doctor to doctor (gp, psychologist, neurologist) because I can see colors on things that are supposed to be relatively uniform in color.

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