Rivalry Suppression Research Articles

Distinct dorsal and ventral streams for binocular rivalry dominance and suppression revealed by magnetoencephalography.

Binocular rivalry is an example of bistable visual perception extensively examined in neuroimaging. Magnetoencephalography can track brain responses to phasic visual stimulations of predetermined frequency and phase to advance our understanding of perceptual dominance and suppression in binocular rivalry. We used left and right eye stimuli that flickered at two tagging frequencies to track their respective oscillatory cortical evoked responses. We computed time-resolved measures of coherence to track brain responses phase locked with stimulus frequencies and with respect to the participants' indications of alternations of visual rivalry they experienced. We compared the brain maps obtained to those from a non-rivalrous control replay condition that used physically changing stimuli to mimic rivalry. We found stronger coherence within a posterior cortical network of visual areas during rivalry dominance compared with rivalry suppression and replay control. This network extended beyond the primary visual cortex to several retinotopic visual areas. Moreover, network coherence with dominant percepts in primary visual cortex peaked at least 50 ms prior to the suppressed percept nadir, consistent with the escape theory of alternations. Individual alternation rates were correlated with the rate of change in dominant evoked peaks, but not for the slope of response to suppressed percepts. Effective connectivity measures revealed that dominant (respectively, suppressed) percepts were expressed in dorsal (respectively ventral) streams. We thus demonstrate that binocular rivalry dominance and suppression engage distinct mechanisms and brain networks. These findings advance neural models of rivalry and may relate to more general aspects of selection and suppression in natural vision.

Conflict defined by global gestalt can modulate binocular rivalry suppression.

Binocular rivalry suppression is thought to necessarily require local interocular conflict: the presence of incompatible image elements, such as orthogonal contours, in retinally corresponding regions of two monocular displays. Whether suppression can also be driven by conflict at the level of spatially nonlocal surface or object representations is unclear. Here, we kept local contour conflict constant while varying global conflict, defined by the gestalt formed by the two monocular displays. Specifically, each eye was presented with a grid of image elements (crosses or plusses), placed such that the two eyes’ individual grid elements did not directly overlap but the grids as a whole did. In a “shared motion” condition, all elements moved in unison, inviting a gestalt made up of all elements across both eyes; in a “different motions” condition, the elements’ trajectories differed between eyes, inviting a gestalt of two overlapping surfaces, each associated with one eye. Perceptual disappearances of image elements occurred more readily in the different motions condition, an observation that could not be explained by any between-condition differences in local contour conflict. In a second experiment, we furthermore established that, whereas perceptual disappearances in the shared motion condition tended to involve a single element at a time, in the different motions condition, multiple elements belonging to the same gestalt often disappeared together. These findings indicate that, even though binocular rivalry may critically rely on inhibition due to locally incompatible image elements, this inhibition also depends on the global gestalt to which these elements contribute.

The functional effects of voluntary and involuntary phantom color on conscious awareness.

The constructive nature of vision is perhaps most evident during hallucinations, mental imagery, synesthesia, perceptual filling-in, and many illusions in which conscious visual experience does not overtly correspond to retinal stimulation: phantom vision. However, the relationship between voluntary and involuntary phantom vision remains largely unknown. Here, we investigated 2 forms of visual phantom color, neon phantom color spreading and voluntary color mental imagery, and their effect on subsequent binocular rivalry perception. Passively viewing neon phantom color induced time sensitive, suppressive effects on subsequent binocular rivalry. These effects could be attenuated by rotating the color inducers, or like color imagery, by concurrent uniform luminance stimulation. The degree of neon color induced rivalry suppression predicted the degree of voluntary color imagery facilitation, both on subsequent rivalry perception. Further, there were functional interactions between voluntary imagery and involuntary neon phantom vision when experienced successively. Our results suggest potential sensory mechanistic commonalities between voluntary and involuntary phantom vision. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Binocular Rivalry: A Window into Cortical Competition and Suppression

When the two eyes view very dissimilar images, the visual system often fails to combine the images and one experiences stochastically alternating percepts. This phenomenon, called binocular rivalry, has fascinated researchers for centuries since it provides insights into two critical aspects of visual perception: visual consciousness and cortical suppression. Here, we review the mechanisms of binocular rivalry from a cognitive neuroscience perspective, focusing on empirical findings from two widely used methods—functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). With these techniques, researchers have been able to identify the cortical sites of suppression in binocular rivalry, probe neural responses evoked by unconscious (invisible) visual stimuli, and examine the role of top-down attentional signals in rivalry. We conclude by proposing some future directions for the study of binocular rivalry.

Occipital GABA levels in older adults and their relationship to visual perceptual suppression

Several studies have attributed certain visual perceptual alterations in older adults to a likely decrease in GABA (Gamma Aminobutyric Acid) concentration in visual cortex, an assumption based on findings in aged non-human primates. However, to our knowledge, there is no direct evidence for an age-related decrease in GABA concentration in human visual cortex. Here, we estimated visual cortical GABA levels and Glx (combined estimate of glutamate and glutamine) levels using magnetic resonance spectroscopy. We also measured performance for two visual tasks that are hypothesised to be mediated, at least in part, by GABAergic inhibition: spatial suppression of motion and binocular rivalry. Our results show increased visual cortical GABA levels, and reduced Glx levels, in older adults. Perceptual performance differed between younger and older groups for both tasks. When subjects of all ages were combined, visual cortical GABA levels but not Glx levels correlated with perceptual performance. No relationship was found between perception and GABA levels in dorsolateral prefrontal cortex. Perceptual measures and GABA were not correlated when either age group was considered separately. Our results challenge current assumptions regarding neurobiological changes that occur within the aging human visual cortex and their association with certain age-related changes in visual perception.

On the functional order of binocular rivalry and blind spot filling-in

Binocular rivalry is an important phenomenon for understanding the mechanisms of visual awareness. Here we assessed the functional locus of binocular rivalry relative to blind spot filling-in, which is thought to transpire in V1, thus providing a reference point for assessing the locus of rivalry. We conducted two experiments to explore the functional order of binocular rivalry and blind spot filling-in. Experiment 1 examined if the information filled-in at the blind spot can engage in rivalry with a physical stimulus at the corresponding location in the fellow eye. Participants’ perceptual reports showed no difference between this condition and a condition where filling-in was precluded by presenting the same stimuli away from the blind spot, suggesting that the rivalry process is not influenced by any filling-in that might occur. In Experiment 2, we presented the fellow eye’s stimulus directly in rivalry with the ‘inducer’ stimulus that surrounds the blind spot, and compared it with two control conditions away from the blind spot: one involving a ring physically identical to the inducer, and one involving a disc that resembled the filled-in percept. Perceptual reports in the blind spot condition resembled those in the ‘ring’ condition, more than those in the latter, ‘disc’ condition, indicating that a perceptually suppressed inducer does not engender filling-in. Thus, our behavioral data suggest binocular rivalry functionally precedes blind spot filling-in. We conjecture that the neural substrate of binocular rivalry suppression includes processing stages at or before V1.

Seeing it both ways: Openness to experience and binocular rivalry suppression

Openness to experience is characterised by flexible and inclusive cognition. Here we investigated whether this extends to basic visual perception, such that open people combine information more flexibly, even at low-levels of perceptual processing. We used binocular rivalry, where the brain alternates between perceptual solutions and times where neither solution is fully suppressed, mixed percept. Study 1 showed that openness is positively associated with duration of mixed percept and ruled out the possibility of response bias. Study 2 showed that mixed percept increased following a positive mood induction particularly for open people. Overall, the results showed that openness is linked to differences in low-level visual perceptual experience. Further studies should investigate whether this may be driven by common neural processes.

Brain activity from stimuli that are not perceived: Visual mismatch negativity during binocular rivalry suppression.

Predictive coding explains visual perception as the result of an interaction between bottom-up sensory input and top-down generative models at each level of the visual hierarchy. Evidence for this comes from the visual mismatch negativity (vMMN): a more negative ERP for rare, unpredictable visual stimuli-deviants, than for frequent, predictable visual stimuli-standards. Here, we show that the vMMN does not require conscious experience. We measured the vMMN from monocular luminance-decrement deviants that were either perceived or not during binocular rivalry dominance or suppression, respectively. We found that both sorts of deviants elicited the vMMN at about 250 ms after stimulus onset, with perceived deviants eliciting a bigger vMMN than not-perceived deviants. These results show that vMMN occurs in the absence of consciousness, and that consciousness enhances the processing underlying vMMN. We conclude that generative models of visual perception are tested, even when sensory input for those models is not perceived.

Supplemental Material for No Impact of Affective Person Knowledge on Visual Awareness: Evidence From Binocular Rivalry and Continuous Flash Suppression

Supplemental Material for No Impact of Affective Person Knowledge on Visual Awareness: Evidence From Binocular Rivalry and Continuous Flash Suppression

Training of binocular rivalry suppression suggests stimulus-specific plasticity in monocular and binocular visual areas.

The plasticity of the human brain, as shown in perceptual learning, is generally reflected by improved task performance after training. Here, we show that perceptual suppression can be increased through training. In the first experiment, binocular rivalry suppression of a specific orientation was trained, leading to a relative reduction in sensitivity to the trained orientation. In a second experiment, two orthogonal orientations were suppressed in alternating training blocks, in the left and right eye, respectively. This double-training procedure lead to reduced sensitivity for the orientation that was suppression-trained in each specific eye, implying that training of feature suppression is specific for the eye in which the oriented grating was presented during training. Results of a control experiment indicate that the obtained effects are indeed due to suppression during training, instead of being merely due to the repetitive presentation of the oriented gratings. Visual plasticity is essential for a person’s visual development. The finding that plasticity can result in increased perceptual suppression reported here may prove to be significant in understanding human visual development. It emphasizes that for stable vision, not only the enhancement of relevant signals is crucial, but also the reliable and stable suppression of (task) irrelevant signals.

A Stereoscopic 3-D Broadcasting System Using Fixed and Mobile Hybrid Delivery and the Quality Assessment of the Mixed Resolution Stereoscopic Video

In this paper, we demonstrate the structure and characteristics of the bandwidth-efficient stereoscopic 3-D broadcasting system entitled service compatible 3-D-TV using main and mobile hybrid delivery (SC-MMH), which enables the broadcasters to provide three different types of services (2-D fixed, mobile, and 3-D) by transmitting only the two legacy broadcast streams (2-D fixed and mobile). By combining the two existing broadcast networks, the proposed system provides high quality 3-D services, fully guarantees backward-compatibility with the legacy fixed/mobile 2-D receivers, and maximizes the channel efficiency. One major feature of the proposed system is bit-rate saving based on the video resolution asymmetry between the left and right eye views, also referred to as “mixed-resolution.” Although it is well-known wisdom that the mixed-resolution stereoscopic videos are perceived close to the higher resolution based on the binocular rivalry suppression theory, the perceived quality also depends on the factors such as scale ratio, viewing distance, bit-rate distribution, and types of codecs. Therefore, we conducted the objective and subjective tests to measure the service quality of the proposed system and find the optimum bit-rate distribution points, and with the results, we demonstrate that SC-MMH can provide the satisfactory quality when the proper level of bit-rate is allocated to the mobile service.

Congruent tactile stimulation reduces the strength of visual suppression during binocular rivalry.

Presenting different images to each eye triggers ‘binocular rivalry’ in which one image is visible and the other suppressed, with the visible image alternating every second or so. We previously showed that binocular rivalry between cross-oriented gratings is altered when the fingertip explores a grooved stimulus aligned with one of the rivaling gratings: the matching visual grating's dominance duration was lengthened and its suppression duration shortened. In a more robust test, we here measure visual contrast sensitivity during rivalry dominance and suppression, with and without exploration of the grooved surface, to determine if rivalry suppression strength is modulated by touch. We find that a visual grating undergoes 45% less suppression when observers touch an aligned grating, compared to a cross-oriented one. Touching an aligned grating also improved visual detection thresholds for the ‘invisible’ suppressed grating by 2.4 dB, relative to a vision-only condition. These results show that congruent haptic stimulation prevents a visual stimulus from becoming deeply suppressed in binocular rivalry. Moreover, because congruent touch acted on the phenomenally invisible grating, this visuo-haptic interaction must precede awareness and likely occurs early in visual processing.

Attention and Rivalry Suppression: Two Sides of the Same Coin

Attention and Rivalry Suppression: Two Sides of the Same Coin

Does microchimerism mediate kin conflicts?

Fetal microchimerism (FMc) is predicted to promote the fitness of the fetus and maternal microchimerism (MMc) to promote the fitness of the mother. Offspring and mothers benefit from each other's health. Therefore, microchimeric cells should usually not be harmful to their host. However, the evolutionary interests of mothers and offspring diverge when there is competition among siblings for maternal investment. Fetal cells in mothers' bodies could benefit their own offspring at the expense of its sibs by promoting lactogenesis or by extending the interbirth interval. Maternal cells in fetal bodies could benefit from the suppression of sibling rivalry. Non-inherited haplotypes in MMc or sibling microchimerism (SMc) gain no direct benefit from their hosts' health and could be associated with substantial detrimental effects.

The role of lateral inhibition in binocular motion rivalry

It is generally believed that percept alternations in binocular rivalry result from the interplay between mutual inhibition and slow adaptation of the competing percepts. This view is supported by growing evidence that dynamic changes in adaptation indeed support percept alternations in binocular rivalry. Empirical evidence for the involvement of mutual inhibition, however, is still scarce. To fill this gap, we presented human subjects with dichoptic random-dot motion stimuli and manipulated the angle between the monocular directions of motion from pure opponent horizontal motion to pure vertical motion in the same direction. We hypothesized that this decrease in motion-direction disparity increases the cross-inhibition gain due to lateral inhibition between neurons in the brain that are coarsely tuned to adjacent directions of visual motion, which predicts the largest changes in dominance at the smallest instead of the largest motion-direction disparities. We found that decreasing the angle between the two monocular directions of motion indeed systematically increased the predominance and mean dominance durations of the motion pattern presented to the ocular dominant eye (as identified by the hole-in-card test). Moreover, this effect was stronger if the contrast of the stimuli was lowered. Simulations showed that these features are indeed hallmark of weighted lateral inhibition between populations of directionally tuned motion-sensitive neurons. Our findings thus suggest dominance and suppression in binocular rivalry arises naturally from this fundamental principle in sensory processing. Interestingly, if the two monocular directions of motion differed <60°, the percept alternations also included transitions to in-between (vertical) motion percepts. We speculate that this behavior might result from positive feedback arising from adapting disinhibitory circuits in the network.

Touch Interacts with Vision during Binocular Rivalry with a Tight Orientation Tuning

Multisensory integration is a common feature of the mammalian brain that allows it to deal more efficiently with the ambiguity of sensory input by combining complementary signals from several sensory sources. Growing evidence suggests that multisensory interactions can occur as early as primary sensory cortices. Here we present incompatible visual signals (orthogonal gratings) to each eye to create visual competition between monocular inputs in primary visual cortex where binocular combination would normally take place. The incompatibility prevents binocular fusion and triggers an ambiguous perceptual response in which the two images are perceived one at a time in an irregular alternation. One key function of multisensory integration is to minimize perceptual ambiguity by exploiting cross-sensory congruence. We show that a haptic signal matching one of the visual alternatives helps disambiguate visual perception during binocular rivalry by both prolonging the dominance period of the congruent visual stimulus and by shortening its suppression period. Importantly, this interaction is strictly tuned for orientation, with a mismatch as small as 7.5° between visual and haptic orientations sufficient to annul the interaction. These results indicate important conclusions: first, that vision and touch interact at early levels of visual processing where interocular conflicts are first detected and orientation tunings are narrow, and second, that haptic input can influence visual signals outside of visual awareness, bringing a stimulus made invisible by binocular rivalry suppression back to awareness sooner than would occur without congruent haptic input.

Book Reviews

John J. Siegfried of Vanderbilt University and University of Adelaide reviews, “The Economics of Collusion: Cartels and Bidding Rings” by Robert C. Marshall and Leslie M. Marx. The EconLit Abstract of this book begins: “Presents an introduction to explicit collusion that examines what it is, why it is profitable, how it is implemented, and how it might be detected. Discusses collusion in practice; narrative of a cartel; narrative of a bidding ring; narrative of cartel detection; suppression of rivalry by cartels; implementation of collusion by cartels; beyond the suppression of within-cartel rivalry; suppression of interbidder rivalry by rings; implementation of collusion by rings; the effects of auction design on rings; plus factors; plus factors for rings; and coordinated efforts in horizontal mergers. Marshall is Liberal Arts Research Professor of Economics at Pennsylvania State University. Marx is Professor of Economics in the Fuqua School of Business at Duke University. Name, subject, and case indexes.”

Unconscious processing of emotional faces and its probable neural mechanism

With the advancement of techniques in probing unconscious visual processing, an increasing number of researches have demonstrated that unconscious visual information could have an impact on human being’s cognition and behavior. This review mainly introduces those studies regarding processing of fearful faces which are rendered subconscious through weak bottom-up inputs rather than insufficient top-down attentional resources. Studies that adopted backward masking, binocular rivalry, and interocular suppression paradigms and those conducted on patients who suffered from visual cortex lesion have shown converging evidence that some subcortical structures, like superior colliculus, thalamus, and amygdala, and the functional connectivity between these regions contribute to the unconscious processing of fearful faces. It is thus suggested that the human brain is able to process unconscious emotional faces through a rapid subcortical route bypassing early visual cortex. However, this route still needs further studies to delineate its causal instead of correlational relationship with unconscious processing. In addition, how the highly efficient subcortical route adds to the conscious processing of emotional faces is worthy of future investigations.

The economics of collusion: cartels and bidding rings

An examination of collusive behavior: what it is, why it is profitable, how it is implemented, and how it might be detected. Explicit collusion is an agreement among competitors to suppress rivalry that relies on interfirm communication and/or transfers. Rivalry between competitors erodes profits; the suppression of rivalry through collusion is one avenue by which firms can enhance profits. Many cartels and bidding rings function for years in a stable and peaceful manner despite the illegality of their agreements and incentives for deviation by their members. In The Economics of Collusion, Robert Marshall and Leslie Marx offer an examination of collusive behavior: what it is, why it is profitable, how it is implemented, and how it might be detected. Marshall and Marx, who have studied collusion extensively for two decades, begin with three narratives: the organization and implementation of a cartel, the organization and implementation of a bidding ring, and a parent company's efforts to detect collusion by its divisions. These accounts-fictitious, but rooted in the inner workings and details from actual cases-offer a novel and engaging way for the reader to understand the basics of collusive behavior. The narratives are followed by detailed economic analyses of cartels, bidding rings, and detection. The narratives offer an engaging entree to the more rigorous economic discussion that follows. The book is accessible to any reader who understands basic economic reasoning. Mathematical material is flagged with asterisks.

Normalization regulates competition for visual awareness

Signals in our brain are in a constant state of competition, including those that vie for motor control, sensory dominance, and awareness. To shed light on the mechanisms underlying neural competition, we exploit binocular rivalry, a phenomenon that allows us to probe the competitive process that ordinarily transpires outside of our awareness. By measuring psychometric functions under different states of rivalry, we discovered a pattern of gain changes that are consistent with a model of competition in which attention interacts with normalization processes, thereby driving the ebb and flow between states of awareness. Moreover, we reveal that attention plays a crucial role in modulating competition; without attention, rivalry suppression for high-contrast stimuli is negligible. We propose a framework whereby our visual awareness of competing sensory representations is governed by a common neural computation: normalization.