Effect of light adaptation on the perceptual red-green and yellow-blue opponent-color responses

Spectral sensitivities of the red-green and yellow-blue opponent-color responses were determined under broad-band light adaptation for the light-adaptation levels of 5 to 5000 Td. With changing light-adaptation level, the spectral-sensitivity functions of the opponent-color systems change in shape, especially in the short-wavelength region of the spectrum. The light-adaptation effect on the red-green responses can be ascribed to the changes at the cone receptor level, whereas the light-adaptation effect on the yellow-blue responses can be ascribed to the changes at two sites, i.e., at the cone receptor site and at the opponent site.