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

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. © 2001 Published by Elsevier Science Ltd.