Eye movements, afterimages and monocular rivalry.

The eye-movement/afterimage theory of "monocular rivalry" (MR) between gratings was tested and strongly supported. In three experiments perceptual dominance of vertical or horizontal components of the pattern and fluctuations in perceived contrast of a single grating were shown to depend on the nature of the preceding shift in fixation position in the manner predicted by the theory. In a fourth experiment the angular selectivity of these fluctuations was eliminated, as predicted, when appropriate eye movements were made. Fixation-contingent fluctuations became equally strong for 15 degrees and 90 degrees angles. Taken together with data on afterimages, the results appear to resolve most of the problems recently raised against the theory.