Reversal of simultaneous lightness-contrast

Reviews the theoretical and experimental research on the reversal of simultaneous lightness-contrast (assimilation). H. Helson's differential stimulation hypothesis of contrast and assimilation is examined in view of recent research. It is concluded that before a quantitative formulation incorporating both simultaneous lightness-contrast and assimilation can be complete, research is needed to assess the contribution of (1) area-luminance functions, (2) mode of viewing, (3) contours and divisions, (4) perceptual set, (5) absolute levels of luminance in the viewing situation, (6) adaptation of the eye, and (7) the nature of the experimental stimuli used. (40 ref.)