Adaptation and heterochromatic matching.

This study is a follow-up of a previous study of the effect of adaptation on heterochromatic matching by flicker photometry and direct comparison. In flicker photometry, two patches of color are applied alternately to a region of the retina adapted to a mixture of the two colors. In direct comparison, the two halves of the pattern are usually applied to regions of the retina adapted to the separate colors. Two additional methods of equalizing the state of adaptation in the two halves of the retina in direct comparison matching have been tested. In both cases, equalizing the states of adaptation reduces the discrepancy between flicker photometry and direct comparison for two of the three subjects tested. For the third subject, the discrepancies are small but one can still demonstrate effects produced by equalizing the states of adaptation. Further study is needed to delineate the specific mechanisms of adaptation involved.