Antagonism between visual channels for pattern and movement?

Abstract

GEORGESON has reported¹ some ingenious psychophysical experiments designed to test the hypothesis that ‘sustained’ visual cortical cells sensitive to the orientation of contours are antagonistically coupled to ‘transient’ cells in the same cortical column sensitive to movement at right angles to those contours. After inspecting one or other, or both, of two counter-rotating dot patterns, his subjects reported seeing “complex patterns of radial lines or curves”. These appeared either to rotate in the opposite sense to the stimulus, or to be stationary if both counter-rotating disks had been viewed simultaneously in superposition. Georgeson attributed their appearance to the rebound response of ‘pattern channels’ inhibited during stimulation by ‘motion channels’ of the kind presumed to be responsible for movement after effects (MAE). We have tested this conclusion by extending the range of stimulus velocities well above and below those used by Georgeson. Our results suggest that stimulation of motion channels is not necessary for the effect observed, so that its appearance in his tests does not confirm his hypothesis.