Abstract

Using a simultaneous masking paradigm and a variety of chromatic axes, we have examined the spatial frequency selectivity and orientation bandwidth of mechanisms which respond to isoluminant chromatic gratings. We find similar selectivity along both dimensions to that seen for isochromatic luminance gratings, differing only in that bandwidths for color patterns are often somewhat broader. Furthermore, the contrast dependence of color–color masking is similar to that seen for luminance when mask contrasts are normalized on a multiples-of-threshold metric. When chromatic and luminance patterns are mixed in a masking experiment, chromatic mask gratings significantly impede the detection of luminance gratings when the mask contrast is above its own threshold. The frequency selectivity of this interaction is similar to that seen for luminance–luminance masking. Facilitation is never seen for the combination of a chromatic mask and a luminance test. Luminance masks, however, facilitate the detection of a chromatic test for a wide range of suprathreshold mask contrasts and across a broad range of mask/test frequencies. Only when mask contrast is very high is the detectability of a chromatic test reduced. In all cases, mixed chromatic-luminance masking results are independent of the relative pattern phase at which the mask and test patterns are used.

© 1987 Optical Society of America