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Differences Between Tetrachromats & Trichromats

Tetrachromats and trichromats see different things when looking at colors. The number of cone receptors in a person's eyes determine what she sees when she looks at colors. When eyes see colors, they send messages to the brain. The brain interprets the messages, and tells a person what colors are there. For example, when two people look at different shades of green paint swatches, one might see the different shades, and the other might not.

  1. Male Trichromats

    • Most people have three cone receptors in the retinas of their eyes. These people are known as trichromats. Trichromats see red, green and blue. When a person sees all three of these colors, it lets him see all of the colors and hues in the ultraviolet spectrum. Men sometimes have problems with these cone receptors causing color-blindness or dichromatic vision. Dichromatic vision is where the person has problems determining the difference between two colors. This problem affects 7 percent of the male population.

    Female Trichromats

    • Women see the same way as men. They usually have three cone receptors in the retinas of their eyes, but suffer from color-blindness less often. Only .4 percent of women suffer from color-blindness. Color-blindness is carried on the X chromosomes. Since women have two X chromosomes, they have an extra X chromosome. Out of the two chromosomes, most of the time one carries an operative chromosome for the three cone receptors. This reduces the risk of having problems seeing all the colors in the light spectrum.

    Female Tetrachromats

    • All tetrachromats are women. When a person is a tetrachromat, she has an extra cone receptor. This extra cone receptor lets a person see four distinct ranges of color. Instead of three color ranges, the person sees four. Most people distinguish about 1 million different hues. Tetrachromats see up to 100 million different hues. This trait is carried on the X chromosome, so women have a chance of having the extra cone receptor.

    Males and Extra Cone Receptors

    • Since the trait is carried on the X chromosome, men never have an extra cone receptor. A person needs two X chromosomes for developing the extra cone receptor. Instead of having an extra cone receptor, some men have one or more cones that work improperly.

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