Abstract
Binocular rivalry refers to perceived alternations between non-alternating, distinct images presented dichoptically. Recently, Said & Heeger (2016) showed that the incidence of intermixed percepts during binocular rivalry increased after prolonged viewing of (i.e. adaptation to) interocular conflict. They attributed this effect to the adaptation of conflict detectors, which would presumably drive binocular rivalry. Here we test an alternative explanation by asking to what degree adaptation to (perceived) transient changes affects the incidence of intermixed percepts during binocular rivalry.
In three experiments, observers were adapted to stimuli in which the amount of (1) interocular conflict, (2) monocular changes in contrast, (3) monocular changes in orientation, and (4) perceived changes in orientation were systematically varied. The adaptation stimuli consisted of sinewave gratings which were phase-reversing at 0.94 Hz. On each trial, an observer would undergo 100 s of adaptation to the above variants of dichoptic displays, after which exclusive percepts as well as mixed percepts were reported in a 80 (Experiment 1) or 40 s (Experiments 2&3) test phase.
Across the three experiments, the amount of exclusive percepts was influenced most by the amount of (1) monocular changes in contrast and of (2) perceived changes in orientation during adaptation. Interestingly, however, the amount of interocular conflict during the adaptation phase hardly affected subsequent reports of exclusive rivalry. The latter observation is further supported by a general linear model in which we incorporated our four principal variants during adaptation as factors: in this model the beta factor for interocular conflict was not significant. We conclude that (perceived) transient changes in the rivalling images and not the amount of interocular conflict affects the spatio-temporal dynamics of binocular rivalry.