Rods also participate in human color vision.

In the retinal periphery, rod and cone thresholds to the same green light were measured. After the rod-cone break in the course of dark adaptation, cone sensitivity decreases gradually as rod sensitivity progressively increases. Cone sensitivity, however, increases when rod sensitivity is decreased by blue light. The emergence of the facilitatory effect of rod activation requires at least a few hundred msec after rod stimulation. It is concluded that rod activation plays a major role in sensitivity regulation of the cone system, i.e., in human color vision.