Contradictory influence of context on predominance during binocular rivalry

Spatially Filtered Emotional Faces Dominate during Binocular Rivalry

The present investigation explores the role of bottom-up and top-down factors in the recognition of emotional facial expressions during binocular rivalry. We manipulated spatial frequencies (SF) and emotive features and asked subjects to indicate whether the emotional or the neutral expression was dominant during binocular rivalry. Controlling the bottom-up saliency with a computational model, physically comparable happy and fearful faces were presented dichoptically with neutral faces. The results showed the dominance of emotional faces over neutral ones. In particular, happy faces were reported more frequently as the first dominant percept even in the presence of coarse information (at a low SF level: 2-6 cycle/degree). Following current theories of emotion processing, the results provide further support for the influence of positive compared to negative meaning on binocular rivalry and, for the first time, showed that individuals perceive the affective quality of happiness even in the absence of details in the visual display. Furthermore, our findings represent an advance in knowledge regarding the association between the high- and low-level mechanisms behind binocular rivalry.

Redundancy Gain in Binocular Rivalry

A behavioural advantage is found across a wide range of stimuli when two targets are presented in opposite hemifields compared with those targets being presented together in one hemifield, or one target being presented alone. This advantage for responses to multiple targets versus a single target is often termed redundancy gain. Here we report on the findings of two experiments investigating redundancy gain in binocular rivalry. Experiment 1 presented a rival pair in one hemifield with an additional image presented to both eyes in the opposite hemifield. There was a weak effect of this stable image on the perceived dominance of the images within the rival pair. Experiment 2 presented a second rival pair in either the same or opposite hemifield and showed that instances of joint predominance were greater when the two pairs were presented in opposite hemifields than within the same hemifield. Therefore, the findings suggest that redundancy gain may be extended to stimuli presented under binocular rivalry conditions.

Perceptual dominance during binocular rivalry is prolonged by a dynamic surround

We examined whether dynamic stimulation that surrounds a rival target influences perceptual alternations during binocular rivalry. We presented a rival target surrounded by dynamic random-dot patterns to both eyes, and measured dominance durations for each eye's rival target. We found that rival target dominance durations were longer when surrounds were dynamic than when they were static or absent. Additionally, prolonged dominance durations were more apparent when the dynamic surround was alternately presented between the two eyes than when it was presented simultaneously to both eyes. These results indicate that dynamic stimulation that surrounds a rival target plays a role in maintaining the current perceptual state, and causes less perceptual alternations during binocular rivalry. Our findings suggest that dynamic signals on the retina may suppress rivalry, and thus provide useful information for stabilizing perceptions in daily life.

High-level binocular rivalry effects

Binocular rivalry (BR) occurs when the brain cannot fuse percepts from the two eyes because they are different. We review results relating to an ongoing controversy regarding the cortical site of the BR mechanism. Some BR qualities suggest it is low-level: (1) BR, as its name implies, is usually between eyes and only low-levels have access to utrocular information. (2) All input to one eye is suppressed: blurring doesn’t stimulate accommodation; pupilary constrictions are reduced; probe detection is reduced. (3) Rivalry is affected by low-level attributes, contrast, spatial frequency, brightness, motion. (4) There is limited priming due to suppressed words or pictures. On the other hand, recent studies favor a high-level mechanism: (1) Rivalry occurs between patterns, not eyes, as in patchwork rivalry or a swapping paradigm. (2) Attention affects alternations. (3) Context affects dominance. There is conflicting evidence from physiological studies (single cell and fMRI) regarding cortical level(s) of conscious perception. We discuss the possibility of multiple BR sites and theoretical considerations that rule out this solution. We present new data regarding the locus of the BR switch by manipulating stimulus semantic content or high-level characteristics. Since these variations are represented at higher cortical levels, their affecting rivalry supports high-level BR intervention. In Experiment I, we measure rivalry when one eye views words and the other non-words and find significantly longer dominance durations for non-words. In Experiment II, we find longer dominance times for line drawings of simple, structurally impossible figures than for similar, possible objects. In Experiment III, we test the influence of idiomatic context on rivalry between words. Results show that generally words within their idiomatic context have longer mean dominance durations. We conclude that BR has high-level cortical influences, and may be controlled by a high-level mechanism.

Binocular rivalry: competition and inhibition in visual perception

When the brain is presented with ambiguous visual stimuli supporting two interpretations, perception becomes bistable and alternates over time between one interpretation and the other. This process contains elements of competition (between the rivaling percepts) as well as inhibition, as the percepts are mutually exclusive so that one is always suppressed. This review covers the most widely studied form of bistable perception-binocular rivalry. Suppression in rivalry is covered in detail, including discussion of its general and specific components, its local nature and spatial organization, techniques for quantifying it, and the role of global feedback. The competitive dynamics of rivalry are discussed within the context of the classical 'adapting reciprocal inhibition' model of rivalry and recent evidence supporting this model is discussed. This model is contrasted with alternative models based on late competition and with hybrid models. Finally, the role of attention in rivalry is examined and commonalities with other forms of bistable perception are noted. WIREs Cogn Sci 2012, 3:87-103. doi: 10.1002/wcs.151 For further resources related to this article, please visit the WIREs website.

Extrinsic factors in the perception of bistable motion stimuli

When viewing a drifting plaid stimulus, perceived motion alternates over time between coherent pattern motion and a transparent impression of the two component gratings. It is known that changing the intrinsic attributes of such patterns (e.g. speed, orientation and spatial frequency of components) can influence percept predominance. Here, we investigate the contribution of extrinsic factors to perception; specifically contextual motion and eye movements. In the first experiment, the percept most similar to the speed and direction of surround motion increased in dominance, implying a tuned integration process. This shift primarily involved an increase in dominance durations of the consistent percept. The second experiment measured eye movements under similar conditions. Saccades were not associated with perceptual transitions, though blink rate increased around the time of a switch. This indicates that saccades do not cause switches, yet saccades in a congruent direction might help to prolong a percept because (i) more saccades were directionally congruent with the currently reported percept than expected by chance, and (ii) when observers were asked to make deliberate eye movements along one motion axis, this increased percept reports in that direction. Overall, we find evidence that perception of bistable motion can be modulated by information from spatially adjacent regions, and changes to the retinal image caused by blinks and saccades.

Influence of emotional facial expressions on binocular rivalry

Three experiments investigated whether emotional information influences perceptual dominance during binocular rivalry. In Experiment 1, rival emotional and neutral faces in the background were coupled with grating stimuli in the foreground. Results showed that gratings paired with emotional faces dominated over those paired with neutral faces. In Experiment 2, emotional and neutral faces were presented dichoptically, without being paired with other stimuli. Dominance of emotional faces was observed. Fusion and low-level image differences were ruled out by examining dominance periods of upright and inverted emotional and neutral faces presented as face-house pairs (Experiment 3). Here, face stimuli dominated over house stimuli only for upright face conditions. In addition, upright emotional faces were perceived for significantly longer durations than upright neutral faces. The results provide further support for the influence of emotional meaning on binocular rivalry.

The influence of chromatic context on binocular color rivalry: perception and neural representation

The predominance of rivalrous targets is affected by surrounding context when stimuli rival in orientation, motion or color. This study investigated the influence of chromatic context on binocular color rivalry. The predominance of rivalrous chromatic targets was measured in various surrounding contexts. The first experiment showed that a chromatic surround's influence was stronger when the surround was uniform or a grating with luminance contrast (chromatic/black grating) compared to an equiluminant grating (chromatic/white). The second experiment revealed virtually no effect of the orientation of the surrounding chromatic context, using chromatically rivalrous vertical gratings. These results are consistent with a chromatic representation of the context by a non-oriented, chromatically selective and spatially antagonistic receptive field. Neither a double-opponent receptive field nor a receptive field without spatial antagonism accounts for the influence of context on binocular color rivalry.

Adaptive center-surround interactions in human vision revealed during binocular rivalry

We used binocular rivalry as a psychophysical probe to explore center-surround interactions in orientation, motion and color processing. Addition of the surround matching one of the rival targets dramatically altered rivalry dynamics. For all visual sub-modalities tested, predominance of the high-contrast rival target matched to the surround was greatly reduced-a result that disappeared at low contrast. At low contrast, addition of the surround boosted dominance of orientation and motion targets matched to the surround. This contrast-dependent modulation of center-surround interactions seems to be a general property of the visual system and may reflect an adaptive balance between surround suppression and spatial summation.