Selective color effects in dichoptic masking.

Dichoptic masking was investigated under conditions designed to isolate, in turn, achromatic and chromatic pathways in the visual system. Red, green, and blue tests and masks were used in various combinations. For the achromatic condition, achieved with a 3 min, 10 msec test flash and a 3 deg masking flash and with both eyes light adapted, there is essentially no dichoptic masking. With a 50 min test flash and conditions otherwise the same, a small amount of chromatically nonselective dichoptic masking occurs which is attributed to interaction between fairly remote contours, a form of weak pattern masking. For the chromatic condition, achieved with a 1 deg test flash delivered for 200 msec with both eyes light adapted, a small, nonselective masking effect, also attributed to weak pattern masking, occurs for most color combinations. The only chromatically-selective effect observed occurs for blue tests seen with blue masks. For this condition, dichoptic thresholds reach a maximum at modest photopic luminances of the mask and then decline.