Abstract
Binocular rivalry is characterized by perceptual switching between monocular images when quite dissimilar stimuli are presented dichoptically. How the visual system can effectively suppress one visual input from awareness is still debated. Two main hypotheses have been proposed: the first posits that rivalry could results from low-level competition between the eyes, whereas the second suggests that the nature of the competition is perceptual, i.e., between the stimuli, whereby high-level visual areas play a crucial role. Recent research interest has been deployed to study the role of attention in resolving binocular rivalry competition. Although some evidence indicates that selective attention can bias dominance phases, whether or not such an attention modulation is specific to one type of visual competition (eye- versus stimulus-based) is unknown. To address this issue, we manipulated the stimulus size (1.4° or 10° diameter with a constant spatial frequency duty-cycle) of two rival (± 45°) gratings to preferentially recruit different levels of competition (Bonneh et al., 2001). Stimuli were presented through stereoscopic goggles using a swapping paradigm to better dissociate eye- and stimulus-based rivalry. While indicating their percepts (stability/dominance, swapping or ambiguity) through different responses keys, observers (n = 11) viewed the stimuli either passively or by focusing their attention as long as possible on the +45° grating stimuli. Catch trials were used in order to detect any response bias that could be induced by attention instruction. As expected, ANOVAs revealed that, in the passive condition, phases of stability were significantly (p <.05) larger for the larger stimuli whereas swapping perception was significantly predominant for the smaller stimuli. In the attention condition, dominance duration was significantly higher for the attended stimulus than for the other but only for the larger stimuli. These results suggest that higher visual areas are preferentially modulated by endogenous attention during binocular rivalry.
Meeting abstract presented at VSS 2012