Abstract
We determined the influence of awareness on orientation-specific adaptation using binocular rivalry. We found that, if both eyes briefly viewed an adapting grating in peripheral vision prior to the presentation of the same grating to one eye and an orthogonal grating to the other eye, subjects tended to report perceptual dominance of the non-adapted grating. Next, we measured the strength of this visual adaptation when the adapting grating was surrounded by gratings of different orientation such that subjects were not aware of the adaptor's orientation (crowding). We found that crowding dramatically reduced the effect of adaptation on subsequent binocular rivalry. That is, subjects were more likely to report perceptual dominance of the adapted grating during crowding compared to the non-crowded (single) condition. Finally, we tested adaptation when the adaptor was surrounded by gratings of the same orientation. In this situation, subjects were aware of the orientation of the adaptor and reported adaptation that was equivalent to the non-crowded condition. The implication is that the surrounding gratings only reduce the strength of the adaptation if they affect awareness of the adaptor. In conclusion, our results show that binocular rivalry depends on processing that occurs beyond the stage that is affected by crowding.