Abstract
Cones are faster than rods, but red is not always faster than blue. In mesopic vision, a jiggling red spot in a blue or purple surround has a bright leading edge from cones, and a dark trailing edge from rods; for a blue spot, it is the leading edge that is dark. If the spots are brighter than the surround, the red is perceptually advanced relative to the blue, and seems to spring toward its bright leading edge as it moves, while the blue lags, apparently reluctant to abandon its bright trailing edge. But when the spots are dimmer than the surround, we find it is the red spot that lags. We suggest that each spot is shifted toward the edge that has the luminance polarity of the spot. Motion phase shifts between differently colored spots become extremely large as isoluminance is approached, and undergo an abrupt sign changes as isoluminance is passed.