Red–green and blue–yellow mechanisms are matched in sensitivity for temporal and spatial modulation

Abstract

The spatial and temporal properties of human colour vision are examined using isoluminant, red–green and blue–yellow tritanopic gratings. Chromatic sensitivity is found to be low-pass as a function of both spatial and temporal frequency along all the chromatic axes investigated, including the tritanopic confusion lines employed to examine the properties of the S-cone driven mechanism. Comparison of sensitivity to on-off and contrast reversing stimuli indicates that transient mechanisms contribute to the detection of red–green patterns but that the detection of S-cone specific patterns is governed by sustained mechanisms. By compensating for transient contributions to red–green sensitivity, it is shown that sensitivity of chromatic mechanisms dominated by L- and M-cone input are closely matched to those with S-cone input.