ABSTRACT
The perception of color must depend on both sensory and cognitive processes. This chapter and the next put forward two main arguments. First, that there is a simple and coherent psychophysics of contrast colors, which includes the phenomena of simultaneous contrast and adaptation and reflects the contrast coding that we know to be a prime function of early vision. Second, that the higher levels of the visual system must, because of the variety of circumstances under which we can see, use the contrast-coded signal in radically different ways in different contexts. The higher processes can mask the lower, so that to understand the system we must distinguish these different levels.
