VISUAL SUPPRESSION AND ITS EFFECT UPON COLOR AND LUMINANCE SENSITIVITY

Psychophysical increment thresholds were compared for periods of pheno menological dominance or suppression produced by different stimulation of the two eyes. Three experimental procedures were used; binocular r ivalry, permanent suppression and flash suppression. The amount of sup pression produced by each procedure was evaluated under conditions int ended to accentuate color or luminance system contribution to the dete ction of a spectral flash. All three procedures resulted in a differen t pattern of color and luminance suppression. Binocular rivalry suppre ssed color sensitivity more than luminance and within color, blue (439 nm) sensitivity was more suppressed than red (613 nm). Permanent supp ression resulted in a similar pattern of suppression but only blue col or sensitivity was reliably more suppressed than luminance sensitivity . Flash suppression produced distinctly different results such that bl ue color sensitivity was reliably less suppressed than luminance or re d color sensitivity, which were not different from each other. Taken t ogether these results provide clues as to where and when the physiolog ical processes mediating visual suppression may be found in the nervou s system.