COLOR POOLS, BRIGHTNESS POOLS, ASSIMILATION, AND THE SPATIAL RESOLVING POWER OF THE HUMAN COLOR-VISION SYSTEM

A stimulus is described that demonstrates the spatial pooling of colou r information in the visual system. Chequerboards (or gratings) consis ting of alternating squares (or stripes) of complementary colours beco me achromatic at particular spatial scales; such stimuli have been nam ed 'transchromatic' stimuli. Colour pools are much larger than the rec eptive fields that respond to luminance contrast. Some measurements ar e described which form the basis for estimates of the size of the colo ur pools. The size of colour pools varies according to the colours inv olved. For red - cyan and green - magenta complementary pairs colour i s pooled at spatial frequencies above about 7-8 cycles deg-1, implying pools whose diameter is around 8 min arc. For yellow - blue complemen tary pairs the corresponding figures are about 4 cycles deg-1 and 15 m in arc. Some phenomena of normal colour vision, colour blindness, and the development of infant vision are discussed in the light of these f indings.