Abstract
By presenting a high-contrast spatial pattern to one eye, a stable interocular suppression can be produced even if the pattern is stationary. This phenomenon has been named "permanent suppression" (PS) (Mauk et al., 1984). Previous studies reported that the strength of the suppression is maximal when a test probe has the same spatial frequency as the suppressing stimulus. Another type of stable and strong interocular suppression, continuous flash suppression (CFS) (Tsuchiya & Koch, 2005), is now well-known, which is generally produced by presenting a series of different Mondrian patterns to one eye at a rate of about 10 Hz. In contrast to PS studies, a recent study (Yang & Blake, VSS2010) showed that interocular suppression due to CFS is mainly observed over a low spatial-frequency range. To investigate whether dynamic switching of suppressing patterns changes spatial-frequency dependence of interocular suppression, the present study examined an interocular suppression caused by a counterphase flickering grating. The suppressing stimulus was a sinewave grating of 7° and flickered at 10 Hz. Its spatial frequency was varied from 0.5 to 8.5 cpd. The test probe was a Gabor patch (σ=0.6°) of various spatial frequencies and presented to the contralateral eye to the suppressing grating. The results clearly showed frequency-selective suppression; when the spatial frequency of the test probe was the same as that of the suppressing grating, an increase in detection threshold of the probe was the largest. Orientation selectivity of suppression was also observed. In additional experiments using filtered Mondrian patterns, we confirmed that low contrast suppressing stimuli produce similar effects to those previously reported. Overall, these results suggest that interocular suppression caused by dynamic stimuli exhibits spatial-frequency selectivity but the suppression also depends on the contrast of the suppressing stimulus. Low spatial-frequency components seem to produce suppression at lower contrast than high frequency components.
Meeting abstract presented at VSS 2012