Contingent aftereffects and isoluminance: Psychophysical evidence for separation of color, orientation, and motion

Abstract

Anatomical, physiological, and psychophysical evidence is converging to indicate that early image analysis in human vision can be conceptualized as being performed by a variety of distinct systems. These systems are surprisingly independent, except insofar as the output from one is the input to another. The present work reviews some general information about one of these systems (the luminance contrast system) and argues that it interacts with its complement (the color system) in a way that gives rise to some contingent aftereffects (the McCollough Effect in particular). A key point in the argument is that, when input to the luminance contrast system is minimized (by using isoluminant stimuli), the contingent color aftereffect is not generated. Isoluminant stimuli elicit (or fail to elicit) a number of other visual responses. These, as well as some general considerations in the generation of isoluminant stimuli will be reviewed.