Illusions: Hidden in Plain Sight; December 2005; Scientific American Mind; by Vilayanur S. Ramachandran and Edward M. Hubbard; 3 Page(s)

One of the main functions of visual perception is to detect objects in the environment as a prelude to identifying them as prey, predators or mates. Not surprisingly, both prey and predators go to enormous lengths to conceal their physical boundaries by blending in with the color and texture of their surroundings. Indeed, we can almost think of higher visual processing in the brain as having mainly evolved to defeat camouflage. Studying the strategies of camouflage can therefore indirectly also tell us a great deal about the mechanisms of vision.

American painter and amateur naturalist Abbott Handerson Thayer speculated that animals developed "protective coloration." As his theory held, "animals are painted by nature darkest on those parts which tend to be most lighted by the sun's light, and vice versa." He was surely right about this effect (scientists now call it "countershading"). But then he went on, even suggesting that peacocks' tails match foliage and that flamingos are pink to allow them to blend in with the sunset!