Opponent Chromatic Induction: Experimental Evaluation and Theoretical Account*

The concept of physiologically based, opponent chromatic induction is fundamental to the opponent-colors theory. A continued quantitative development of this theory to account for color perceptions, equations, and discriminations under various conditions of adaptation and illumination has emphasized the need for systematic quantification of induced color effects. Experiments are reported in which a color-matching technique was used to compare the chromatic responses to focal stimuli seen first in isolation and then in the presence of surrounding stimulus arrays of specified luminances and chromaticities and of various degrees of complexity. The results are analyzed in terms of the chromatic response processes of the opponent-colors theory. Chromatic inductions are shown to decrease systematically with decreasing contiguity of focal and surround stimulus areas. For given degrees of contiguity, induced chromatic responses are shown to be opponent to but proportional in magnitude to the mean chromatic activities of the inducing field, and the constant of proportionality decreases as a function of decreasing contiguity.