Contrast adaptation dissociates different measures of luminous efficiency.

We compared how contrast adaptation influences three alternative measures of luminous efficiency. Subjects judged the lightness, the flicker, or the motion of chromatic sine-wave gratings. Adaptation to gratings with correlated luminance and chromatic contrast strongly biases lightness matches and moderately biases minimum-motion settings for gratings that are counterphased at 1 Hz, but it has little effect on motion or flicker settings for gratings that are counterphased at 15 Hz. These results suggest that different measures of equiluminance tap neural pathways that can have different spectral sensitivities. At low temporal frequencies both perceived lightness and minimum-motion settings appear to depend on channels that do not represent luminance and color independently.