Binocular Rivalry Paradigm Research Articles

Enhanced mental imagery and intact perceptual organization in schizotypal personality disorder

According to a widely held view, psychotic disorders such as schizophrenia are characterized by a vague boundary between the perception of the external world and the inner imagery of persons, objects, and events. In this study, we addressed the perception-imagery debate in schizotypal personality disorder (SPD). Thirty individuals with SPD and 30 matched healthy subjects completed a lateral masking task. Participants were asked to detect a low-contrast Gabor patch flanked by two collinear Gabor masks. In the perceptual task, the masks were physically present, whereas in the imagery task, participants only imagined the masks. By applying a binocular rivalry paradigm, we also measured the imagery priming effect. Results revealed that, in the perceptual task, collinear masks similarly decreased contrast threshold in SPD and controls. In the imagery task, contrast threshold reduction (facilitation by the imagined masks) was more pronounced in SPD relative to the controls. In the binocular rivalry paradigm, individuals with SPD showed higher imagery priming effects as compared to healthy controls. Enhanced imagery was not related to schizotypal traits. These results indicate intact early visual perception and heightened imagery in SPD, which may be a trait marker of unusual experiences without psychotic disorganization.

The blind mind: No sensory visual imagery in aphantasia

For most people the use of visual imagery is pervasive in daily life, but for a small group of people the experience of visual imagery is entirely unknown. Research based on subjective phenomenology indicates that otherwise healthy people can completely lack the experience of visual imagery, a condition now referred to as aphantasia. As congenital aphantasia has thus far been based on subjective reports, it remains unclear whether individuals are really unable to imagine visually, or if they have very poor metacognition – they have images in their mind, but are blind to them. Here we measured sensory imagery in subjectively self-diagnosed aphantasics, using the binocular rivalry paradigm, as well as measuring their self-rated object and spatial imagery with multiple questionnaires (VVIQ, SUIS and OSIQ). Unlike, the general population, experimentally naive aphantasics showed almost no imagery-based rivalry priming. Aphantasic participants' self-rated visual object imagery was significantly below average, however their spatial imagery scores were above average. These data suggest that aphantasia is a condition involving a lack of sensory and phenomenal imagery, and not a lack of metacognition. The possible underlying neurological cause of aphantasia is discussed as well as future research directions.

Regulating the Access to Awareness: Brain Activity Related to Probe-related and Spontaneous Reversals in Binocular Rivalry.

Research on the neural correlates of consciousness (NCC) has implicated an assortment of brain regions, ERP components, and network properties associated with visual awareness. Recently, the P3b ERP component has emerged as a leading NCC candidate. However, typical P3b paradigms depend on the detection of some stimulus change, making it difficult to separate brain processes elicited by the stimulus itself from those associated with updates or changes in visual awareness. Here we used binocular rivalry to ask whether the P3b is associated with changes in awareness even in the absence of changes in the object of awareness. We recorded ERPs during a probe-mediated binocular rivalry paradigm in which brief probes were presented over the image in either the suppressed or dominant eye to determine whether the elicited P3b activity is probe or reversal related. We found that the timing of P3b (but not its amplitude) was closely related to the timing of the report of a perceptual change rather than to the onset of the probe. This is consistent with the proposal that P3b indexes updates in conscious awareness, rather than being related to stimulus processing per se. Conversely, the probe-related P1 amplitude (but not its latency) was associated with reversal latency, suggesting that the degree to which the probe is processed increases the likelihood of a fast perceptual reversal. Finally, the response-locked P3b amplitude (but not its latency) was associated with the duration of an intermediate stage between reversals in which parts of both percepts coexist (piecemeal period). Together, the data suggest that the P3b reflects an update in consciousness and that the intensity of that process (as indexed by P3b amplitude) predicts how immediate that update is.

Binocular rivalry transitions predict inattention symptom severity in adult ADHD.

Attention deficit and hyperactivity disorder (ADHD) is a prevalent childhood disorder that is often maintained throughout the development and persists into adulthood. Established etiology models suggest that deficient inhibition underlies the core ADHD symptoms. While experimental evidence for impaired motor inhibition is overwhelming, little is known about the sensory inhibition processes, their changes throughout the development, and the relationship to ADHD symptoms. Here, we used the well-established binocular rivalry (BR) paradigm to investigate for the very first time the inhibitory processes related to visual perception in adults with ADHD. In BR, perception alternates between two dichoptically presented images throughout the viewing period, with shorter dominant percept durations and longer transition periods indicating poorer suppression/inhibition. Healthy controls (N = 28) and patients with ADHD (N = 32) were presented with two dissimilar images (orthogonal gratings) separately to each eye through a mirror stereoscope and asked to report their perceptual experiences. There were no differences between groups in any of the BR markers. However, an association between transition durations and symptom severity emerged in the ADHD group. Importantly, an exploratory multiple regression analysis revealed that inattention symptoms were the sole predictor for the duration of transition periods. The lack of impairments to sensory inhibition in adult, but not pediatric ADHD may reflect compensatory changes associated with development, while a correlation between inhibition and inattention symptoms may reveal an invariant core of the disorder.

Binocular rivalry in children on the autism spectrum.

When different images are presented to the eyes, the brain is faced with ambiguity, causing perceptual bistability: visual perception continuously alternates between the monocular images, a phenomenon called binocular rivalry. Many models of rivalry suggest that its temporal dynamics depend on mutual inhibition among neurons representing competing images. These models predict that rivalry should be different in autism, which has been proposed to present an atypical ratio of excitation and inhibition [the E/I imbalance hypothesis; Rubenstein & Merzenich, 2003]. In line with this prediction, some recent studies have provided evidence for atypical binocular rivalry dynamics in autistic adults. In this study, we examined if these findings generalize to autistic children. We developed a child‐friendly binocular rivalry paradigm, which included two types of stimuli, low‐ and high‐complexity, and compared rivalry dynamics in groups of autistic and age‐ and intellectual ability‐matched typical children. Unexpectedly, the two groups of children presented the same number of perceptual transitions and the same mean phase durations (times perceiving one of the two stimuli). Yet autistic children reported mixed percepts for a shorter proportion of time (a difference which was in the opposite direction to previous adult studies), while elevated autistic symptomatology was associated with shorter mixed perception periods. Rivalry in the two groups was affected similarly by stimulus type, and consistent with previous findings. Our results suggest that rivalry dynamics are differentially affected in adults and developing autistic children and could be accounted for by hierarchical models of binocular rivalry, including both inhibition and top‐down influences. Autism Res 2017. ©2017 The Authors Autism Research published by Wiley Periodicals, Inc. on behalf of International Society for Autism Research Autism Res 2017, 10: 1096–1106. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

Sounds can boost the awareness of visual events through attention without cross-modal integration

Cross-modal interactions can lead to enhancement of visual perception, even for visual events below awareness. However, the underlying mechanism is still unclear. Can purely bottom-up cross-modal integration break through the threshold of awareness? We used a binocular rivalry paradigm to measure perceptual switches after brief flashes or sounds which, sometimes, co-occurred. When flashes at the suppressed eye coincided with sounds, perceptual switches occurred the earliest. Yet, contrary to the hypothesis of cross-modal integration, this facilitation never surpassed the assumption of probability summation of independent sensory signals. A follow-up experiment replicated the same pattern of results using silent gaps embedded in continuous noise, instead of sounds. This manipulation should weaken putative sound-flash integration, although keep them salient as bottom-up attention cues. Additional results showed that spatial congruency between flashes and sounds did not determine the effectiveness of cross-modal facilitation, which was again not better than probability summation. Thus, the present findings fail to fully support the hypothesis of bottom-up cross-modal integration, above and beyond the independent contribution of two transient signals, as an account for cross-modal enhancement of visual events below level of awareness.

Social Interactions Receive Priority to Conscious Perception.

Humans are social animals, constantly engaged with other people. The importance of social thought and action is hard to overstate. However, is social information so important that it actually determines which stimuli are promoted to conscious experience and which stimuli are suppressed as invisible? To address this question, we used a binocular rivalry paradigm, in which the two eyes receive different action stimuli. In two experiments we measured the conscious percept of rival actions and found that actions engaged in social interactions are granted preferential access to visual awareness over non-interactive actions. Lastly, an attentional task that presumably engaged the mentalizing system enhanced the priority assigned to social interactions in reaching conscious perception. We also found a positive correlation between human identification of interactive activity and the promotion of socially-relevant information to visual awareness. The present findings suggest that the visual system amplifies socially-relevant sensory information and actively promotes it to consciousness, thereby facilitating inferences about social interactions.

Natural Tendency towards Beauty in Humans: Evidence from Binocular Rivalry

Although human preference for beauty is common and compelling in daily life, it remains unknown whether such preference is essentially subserved by social cognitive demands or natural tendency towards beauty encoded in the human mind intrinsically. Here we demonstrate experimentally that humans automatically exhibit preference for visual and moral beauty without explicit cognitive efforts. Using a binocular rivalry paradigm, we identified enhanced gender-independent perceptual dominance for physically attractive persons, and the results suggested universal preference for visual beauty based on perceivable forms. Moreover, we also identified perceptual dominance enhancement for characters associated with virtuous descriptions after controlling for facial attractiveness and vigilance-related attention effects, which suggested a similar implicit preference for moral beauty conveyed in prosocial behaviours. Our findings show that behavioural preference for beauty is driven by an inherent natural tendency towards beauty in humans rather than explicit social cognitive processes.

Are visual threats prioritized without awareness? A critical review and meta-analysis involving 3 behavioral paradigms and 2696 observers.

Given capacity limits, only a subset of stimuli give rise to a conscious percept. Neurocognitive models suggest that humans have evolved mechanisms that operate without awareness and prioritize threatening stimuli over neutral stimuli in subsequent perception. In this meta-analysis, we review evidence for this 'standard hypothesis' emanating from 3 widely used, but rather different experimental paradigms that have been used to manipulate awareness. We found a small pooled threat-bias effect in the masked visual probe paradigm, a medium effect in the binocular rivalry paradigm and highly inconsistent effects in the breaking continuous flash suppression paradigm. Substantial heterogeneity was explained by the stimulus type: the only threat stimuli that were robustly prioritized across all 3 paradigms were fearful faces. Meta regression revealed that anxiety may modulate threat-biases, but only under specific presentation conditions. We also found that insufficiently rigorous awareness measures, inadequate control of response biases and low level confounds may undermine claims of genuine unconscious threat processing. Considering the data together, we suggest that uncritical acceptance of the standard hypothesis is premature: current behavioral evidence for threat-sensitive visual processing that operates without awareness is weak. (PsycINFO Database Record

A study of binocular rivalry in patients with depression

Objective To investigate rivalry alternating rates in patients with depression using binocular rivalry paradigm. Methods Thirty-five patients with depression and 30 healthy controls matched for gender, age, education were recruited to assess the rivalry alternating rate using binocular rivalry test. Results The rivalry alternating rate of depression group was significantly slower than that of the control group ((0.27±0.06)Hz vs (0.43±0.11)Hz, t=–6.657, P<0.001). Pearson correlation analysis showed that there was no significant correlation between the rivalry alternation rates and HAMD scores in the patients with depression (r=–0.158, P=0.364). Conclusion The binocular rivalry alternation rate of the patients with depression was significantly slower than that of the healthy controls. The depressed mood itself has no significant effect on binocular rivalry rate. Key words: Depression; Binocular rivalry; Serotonin

Reward modulates perception in binocular rivalry.

Our perception does not provide us with an exact imprint of the outside world, but is continuously adapted to our internal expectations, task sets, and behavioral goals. Although effects of reward-or value in general-on perception therefore seem likely, how valuation modulates perception and how such modulation relates to attention is largely unknown. We probed effects of reward on perception by using a binocular-rivalry paradigm. Distinct gratings drifting in opposite directions were presented to each observer's eyes. To objectify their subjective perceptual experience, the optokinetic nystagmus was used as measure of current perceptual dominance. In a first experiment, one of the percepts was either rewarded or attended. We found that reward and attention similarly biased perception. In a second experiment, observers performed an attentionally demanding task either on the rewarded stimulus, the other stimulus, or both. We found that-on top of an attentional effect on perception-at each level of attentional load, reward still modulated perception by increasing the dominance of the rewarded percept. Similarly, penalizing one percept increased dominance of the other at each level of attentional load. In turn, rewarding-and similarly nonpunishing-a percept yielded performance benefits that are typically associated with selective attention. In conclusion, our data show that value modulates perception in a similar way as the volitional deployment of attention, even though the relative effect of value is largely unaffected by an attention task.

The sensory strength of voluntary visual imagery predicts visual working memory capacity.

How much we can actively hold in mind is severely limited and differs greatly from one person to the next. Why some individuals have greater capacities than others is largely unknown. Here, we investigated why such large variations in visual working memory (VWM) capacity might occur, by examining the relationship between visual working memory and visual mental imagery. To assess visual working memory capacity participants were required to remember the orientation of a number of Gabor patches and make subsequent judgments about relative changes in orientation. The sensory strength of voluntary imagery was measured using a previously documented binocular rivalry paradigm. Participants with greater imagery strength also had greater visual working memory capacity. However, they were no better on a verbal number working memory task. Introducing a uniform luminous background during the retention interval of the visual working memory task reduced memory capacity, but only for those with strong imagery. Likewise, for the good imagers increasing background luminance during imagery generation reduced its effect on subsequent binocular rivalry. Luminance increases did not affect any of the subgroups on the verbal number working memory task. Together, these results suggest that luminance was disrupting sensory mechanisms common to both visual working memory and imagery, and not a general working memory system. The disruptive selectivity of background luminance suggests that good imagers, unlike moderate or poor imagers, may use imagery as a mnemonic strategy to perform the visual working memory task.

Binocular rivalry with peripheral prisms used for hemianopia rehabilitation.

To determine the relative binocular signal strength of moving images that are peripherally viewed through a monocular field expansion prism as opposed to moving images viewed directly. We hypothesised that prism blur might make prism images predominate less than images viewed directly with the other eye. We employed the binocular rivalry paradigm to measure the relative binocular effectiveness of directly viewed vs prism images. Four normally-sighted subjects tracked the rivalrous visibility of opponent-coloured targets seen dichoptically in the same part of the retinal visual field, using monocular field expansion prisms to produce the dichoptic display. We analysed the effects of external signal strength (whether or not motion was present in either image), retinal position or eccentricity of the targets, and controlled for target saturation. We found that prism images predominate less than directly viewed images. When both eyes were presented with pattern in the dichoptic display, direct-to-prism predominance was 51%:31%. When only the direct view was presented with pattern, direct-to-prism predominance was 74%:12%; when only the prism view was presented with pattern, direct-to-prism predominance was 25%:58%. Dominance durations followed established binocular rivalry rules. The prism image in a monocular, peripheral field expansion prism is perceptually weaker than the corresponding direct image in the other eye. However, the prism image is still seen a significant proportion of the time, especially when no moving pattern is present in the direct view. We conclude that the rivalry ratio of the prism device is sufficiently effective for clinical applications.

The Mere Exposure Effect Is Modulated By Selective Attention But Not Visual Awareness

Repeated exposures to an object will lead to an enhancement of evaluation toward that object. Although this mere exposure effect may occur when the objects are presented subliminally, the role of conscious perception per se on evaluation has never been examined. Here we use a binocular rivalry paradigm to investigate whether a variance in conscious perceptual duration of faces has an effect on their subsequent evaluation, and how selective attention and memory interact with this effect. Our results show that face evaluation is positively biased by selective attention but not affected by visual awareness. Furthermore, this effect is not due to participants recalling which face had been attended to.

A neural network approach to fMRI binocular visual rivalry task analysis.

The purpose of this study was to investigate whether artificial neural networks (ANN) are able to decode participants’ conscious experience perception from brain activity alone, using complex and ecological stimuli. To reach the aim we conducted pattern recognition data analysis on fMRI data acquired during the execution of a binocular visual rivalry paradigm (BR). Twelve healthy participants were submitted to fMRI during the execution of a binocular non-rivalry (BNR) and a BR paradigm in which two classes of stimuli (faces and houses) were presented. During the binocular rivalry paradigm, behavioral responses related to the switching between consciously perceived stimuli were also collected. First, we used the BNR paradigm as a functional localizer to identify the brain areas involved the processing of the stimuli. Second, we trained the ANN on the BNR fMRI data restricted to these regions of interest. Third, we applied the trained ANN to the BR data as a ‘brain reading’ tool to discriminate the pattern of neural activity between the two stimuli. Fourth, we verified the consistency of the ANN outputs with the collected behavioral indicators of which stimulus was consciously perceived by the participants. Our main results showed that the trained ANN was able to generalize across the two different tasks (i.e. BNR and BR) and to identify with high accuracy the cognitive state of the participants (i.e. which stimulus was consciously perceived) during the BR condition. The behavioral response, employed as control parameter, was compared with the network output and a statistically significant percentage of correspondences (p-value <0.05) were obtained for all subjects. In conclusion the present study provides a method based on multivariate pattern analysis to investigate the neural basis of visual consciousness during the BR phenomenon when behavioral indicators lack or are inconsistent, like in disorders of consciousness or sedated patients.

The mere exposure effect is modulated by selective attention but not visual awareness

Repeated exposures to an object will lead to an enhancement of evaluation toward that object. Although this mere exposure effect may occur when the objects are presented subliminally, the role of conscious perception per se on evaluation has never been examined. Here we use a binocular rivalry paradigm to investigate whether a variance in conscious perceptual duration of faces has an effect on their subsequent evaluation, and how selective attention and memory interact with this effect. Our results show that face evaluation is positively biased by selective attention but not affected by visual awareness. Furthermore, this effect is not due to participants recalling which face had been attended to.

Effects of Spatial Frequency on the Own-Race Effect using a Binocular Rivalry Paradigm

Effects of Spatial Frequency on the Own-Race Effect using a Binocular Rivalry Paradigm

Binocular rivalry in children with schizophrenia: the conscious and unconscious cognitive processing of interpersonal information.

BackgroundChildhood schizophrenia is a severe mental disorder that is believed to affect both conscious and unconscious cognitive functioning, but there have been few studies that have assessed this.ObjectiveDevelop a version of the binocular rivalry test that will assess the conscious and unconscious cognitive processing of interpersonal information and use this test to determine whether or not social cognition is impaired in children with schizophrenia.MethodsThirty images of three types – with no persons, with 2-3 persons and with 4+ persons – were selected for use in a binocular rivalry test that presented the images both in an interocularly suppressed (unconscious) format and an unsuppressed (conscious) format. Fifteen children under 16 years of age with schizophrenia who had prominent delusional symptoms and 15 healthy children were administered the test. Accuracy rates (in assessing the left or right orientation of a patch presented immediately after the target images) and reaction times were compared between patients and controls.ResultsFor all types of pictures, the accuracy of patients was less than that of controls, though the differences were only significant in two of the twelve comparisons assessed. Compared to controls, patients showed a non-significant increase in the attention paid to images with people in them compared to images without people in them, both for conscious and unconscious presentations of the images. We did not find any relationship between the severity of psychotic symptoms in the patients and the degree of impairment in the cognitive processing of images. When asked to assess the attributes of the images, patients reported significantly higher levels of happiness depicted in images with 2-3 people than controls.ConclusionsThe non-significant increase in the attention children with schizophrenia paid to images depicting interpersonal relationships suggests, but does not prove, that the illness is associated with impairments in the cognitive processing of social information. Our use of the binocular rivalry paradigm to identify these differences was only partially successful, largely because of the wide variability in the key index from the test used to assess the amount of attention respondents pay to different types of images.

Randomly oriented edge arrangements dominate naturalistic arrangements in binocular rivalry

Biological visual systems are highly adapted to the image statistics of the natural world. A particularly important aspect of the statistics of natural scenes is the arrangements of edges they contain. Here, we examined how different arrangements of edges influence human perceptual saliency using a binocular rivalry paradigm. We constructed fields of randomly positioned Gabor patches with orientation arrangements containing co-oriented, co-circular and naturalistic structure. We rivalled these against arrangements with random orientations, which have higher entropy. Surprisingly, we found that fields with randomly oriented edges consistently dominated over the more ordered arrangements. These results suggest that visual scene entropy may be a key variable in early perceptual saliency.

Voluntary Attention Modulates Processing of Eye-Specific Visual Information

Visual attention functions to select relevant information from a vast amount of visual input that is available for further processing. Information from the two eyes is processed separately in early stages before converging and giving rise to a coherent percept. Observers normally cannot access eye-of-origin information. In the research reported here, we demonstrated that voluntary attention can be eye-specific, modulating visual processing within a specific monocular channel. Using a modified binocular-rivalry paradigm, we found that attending to a monocular cue while remaining oblivious to its eye of origin significantly enhanced the competition strength of a stimulus presented to the cued eye, even when the stimulus was suppressed from consciousness. Furthermore, this eye-specific attentional effect was insensitive to low-level properties of the cue (e.g., size and contrast) but sensitive to the attentional load. Together, these findings suggest that top-down attention can have a significant modulation effect at the eye-specific stage of visual information processing.