|MadSci Network: Zoology|
Cats are not color blind - they have the ability to distinguish between blues and greens, but lack the ability to pick out shades of red. The Natural History Museum of L.A. has online images demonstrating how cats view the world.
Cats, like humans, have two primary structures in the retina of the eye for perceiving light: rods which help us see light and dark areas, and cones which have pigments to detect particular wavelengths of light. At low light intensities, rods function to distinguish light from dark. You may notice that you see little color in dim light. At high intensities of light the rods do not function, however, the cones do. Humans have three kinds of cone pigments, ones that can detect red, green and blue light. It's no coincidence that we find these same colors in the screen of an average color-TV set. The ability of an organism to see in "color" thus depends upon the color receptors present in the retina. People (or animals) lacking a specific color receptor are unable to "see" that color. Most often, it appears greyish, or as one of the other colors that can be detected (i.e. purples appearing greyish-blue). Green color-blindness is the most common genetic form of color-blindness in humans, followed by red, then blue.
The Talk Origins website has a good discussion on the nature of color vision and what it means to "see" in color.
-L. Bry, MadSci Admin
Yokoyama S. Radlwimmer FB., The "five-sites" rule and the evolution of red and green color vision in mammals. Molecular Biology & Evolution. 15(5):560- 7, 1998
Loop MS. Bruce LL. Cat color vision: the effect of stimulus size. Science. 199(4334):1221-2, 1978
Try the links in the MadSci Library for more information on Zoology.