Presenting dissimilar stimuli to the two eyes of an observer results in perceptual alternations between those stimuli. This phenomenon is called binocular rivalry.
We investigated the influence of the current percept on early components of the human event-related brain potential (ERP) when rivalrous stimulation is changed into non-rivalrous stimulation. Such transitions require the stimulus of one eye to be swapped.
It depends on the prevailing percept whether physically identical changes entail a change in perception (incompatible change) or do not entail a change in perception (compatible change). ERPs to compatible and incompatible changes showed first differences in the P1-range. Compared to percept-incompatible changes, percept-compatible changes elicited an attenuated P1-peak, whereas the P1-amplitude in a non-rivalrous control condition was most pronounced. For the following N1 component the pattern of results differed at parietal sites. Here, percept-incompatible changes and changes in the non-rivalrous control condition showed peaks with similar amplitudes, whilst the amplitude for percept-compatible changes was smaller. The outcomes suggest that in humans the binocular rivalry phenomenon is already (partly) resolved in extrastriate visual areas latest. To further discern related issues these results were compared to modulations of gamma-activity in the appertaining EEG measures.