SURFACE COLOR NAMING IN DICHROMATS

In previous experiments, Montag and Boynton [(1987) Vision Research, 2 7, 2153-2162] found that many dichromats can categorize colors using c olor naming in fair agreement with color-normal subjects. The contribu tion of rods to color vision was suspected as underlying this ability. Here we follow up on these experiments by having dichromats name colo rs under various conditions. When the stimuli are limited to a brief p resentation time (60 msec) the dichromats' categorization in the three dimensions of the OSA color space is impaired. Using high light level s so that the rods are saturated does not impair performance. The dich romats named colors during the period of the cone plateau following a rod bleach. Contrary to Montag and Boynton (1987) there was no deficit . These results suggest that an anomalous third cone pigment is respon sible for the categorization in three dimensions. It is concluded that the receptors containing the anomalous pigment require greater tempor al and spatial summation in order to contribute to the dichromats' col or categorization.