Schematic depiction of binocular rivalry and experimental paradigms.

<p>(A) To induce binocular rivalry, a pair of orthogonal gratings (tilted +45° and −45° away from the vertical) were separately presented to the two eyes of the human subjects, and subjects experienced the alternating dominance between one grating and the other. Between the stimulus onset and the first percept, there existed a short period during which subjects experienced the fusion of the two gratings, rather than the complete dominance of one grating over the other. (B) and (C) To measure the first percept and its latency, rivalry stimuli were briefly presented for a duration varied from 10 msec to 500 msec, and subjects reported their perception through a three-alternative forced choice (+45° grating, the −45° grating, or the fusion of two gratings). The trails in which subjects reported the fusion perception were taken into account only when we calcualted the latency of the first percept, and different conditions of stimulus duration were combined in the analyses except for calculating this latency.