Frequency and orientation interactions in the McCollough effect: Interchannel effects?

Previous explanations of the McCollough effect propose that the colour changes are due to neural adaptation of detectors in the visual system tuned to specific spatio‐chromatic parameters. In particular, the effect is known to be induced by either spatial frequency components or orientations of bar gratings of complementary colours. However, recent evidence indicates that the effect is not restricted to grating stimuli and that, in these circumstances, it may be induced by joint occurrences of orientation, curvature and frequency conditions. This experiment was conducted to investigate whether the orientation and frequency parameters have an additive effect on inducing the phenomena, or whether both parameters interact or suppress each other in inducing the effect. The results indicate that both channels can induce the aftereffect in complex patterns, but that orientation specificity seems to be largely enhanced or inhibited by frequency components of the stimulus.