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While most of us can see the wide variety of colors in the world, some people see only shades of gray. If you have normal color vision, you are a trichromat, and if you can see only light and dark, you are totally color-blind, or a monochromat.
It is more common to be partially color-blind, or a dichromat. Color blindness is determined genetically, is sex-linked, and occurs mostly in males. In the United States 10 percent of men are color-blind, while only about 1 percent of women are (Gouras, 1985). The dichromat lacks one of the three types of cones. For example, if the red-green complement of cones is missing, he will be unable to distinguish red and green and will see all colors as yellow or blue. Among men, about 7 percent of the population suffers from red-green color blindness. A few individuals have blue-yellow blindness and see all colors as red or green. Although many animals, including dogs, are monochromats, there are very few cases of total color blindness in humans. |
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