Abstract

At ARVO 1992, we reported that when detection thresholds for luminance and red–green chromatic spots are expressed in cone contrast energy (the space–time integral of the squared contrast produced in either the L or M cones), sensitivity for the optimal chromatic spot was 5–8× higher than for the optimal luminance spot. For an ideal observer of chromatic signals, the noise level in P ganglion cells would not be limiting, suggesting that limits are imposed at subsequent stages. The large chromatic sensitivity advantage could result from (a) lower detection uncertainty in the red–green mechanism; (b) common mode rejection (removal of correlated noise) in the opponent pathway; (c) reductions in luminance gain, relative to chromatic gain, at cortical levels; or (d) greater spatial and temporal integration in the chromatic pathway.

© 1992 Optical Society of America