A different point of hue

摘要

A distinguished line-up of scholars recently got together to stir up discussion about the physiological basis for color and have, with a simple manipulation of decades-old data, challenged one of the fundamental tenets of our current understanding of the neurobiology of color. Understanding color is not easy. Newton made some headway, but his demonstration of color's physical basis provided only limited insight because, as Young pointed out, there simply is not enough space for a receptor for each of the seven million or so perceivable colors at each retinal location. Young argued for a triplet color code, and we now know that such a code exists in the form of the three cone types (Fig. 1). Young's idea made color a construction of the brain, not a physical attribute, and paved the way for opponent color theory in which color is determined not by trichromacy but by three opponent processes: red-green, blue-yellow, and black-white. This theory gained ground because it accounted for the fact that we are unable to see a continuous mixture of "reddish-greens" and "bluish-yellows," which should be perceivable if color were simply trichromatic.