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Tetrachromats and Trichromats: What do you see?


Tetrachromats and Trichromats: What do you see?

Kaeley Boyle

How many colors can you count in the image above? Fewer than 20, you’re a dichromat. Between 20 and 32, you’re a trichromat. Above 32, you’re in the select few known as tetrachromats.

While the validity of this “test” is up for debate based on questions about screen color variances in computers and other biological questions to do with the number of cones in our eyes and which chromosomes we posses. (Those with XY chromosomes have less of a chance of being a tetrachromat). That being said, it’s still fun. And it tracks with the historians take on human evolution and our perception of color. Up until 6,000 years ago humans couldn’t perceive the color blue. It’s suggested that it wasn’t until we started making our own pigmentations that we discovered the color.


Typical humans (trichromats) have three types of cones near the retina that allow you to see various colors on the spectrum:

  • short-wave (S) cones: sensitive to colors with short wavelengths – purple and blue.
  • middle-wave (M) cones: sensitive to colors with medium wavelengths – yellow and green
  • long-wave (L) cones: sensitive to colors with long wavelengths – red and orange


Tetrachromats have a fourth cone. But not all people with a fourth cone are tetrachromats. Tetrachromacy is quite rare. Trichromats see 1 million color variations. Tetrachromats see 100 million. True tetrachromats consist of less than 1% of the human population.

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The best way to identify potential tetrachromats is by looking at your mother’s male relatives. Research at New Castle University shows that the most likely candidates for tetrachromacy are those who carry the gene for very mild color vision deficiency (or mild color blindness).

Although the above test might not be scientifically valid, it still illustrates the spectrum of human color perception. Even if it’s only on a remedial scale. If you’re interested in seeing if you’re a true tetrachromat, you can get tested for genetic mutations along the “X” chromosome. Well, that and a painstaking color matching test.

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