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Introduction: The binocular system provides a stereoscopic view from slightly different retinal images and produces perceptual alternations, namely, binocular rivalry, from significantly different retinal images. When we observe a stereogram in which the stimulus configurations induce stereopsis and rivalry simultaneously, the binocular system prefers stereopsis to rivalry. However, changes in visual perception are yet to be investigated by parametrically manipulating the components of a stereogram. Methods: We examined stereopsis preferences in stereograms with various horizontal disparities. The stereograms of our paradigms included horizontal and vertical bars in one eye and a vertical bar alone in the other. Under experimental conditions, the vertical bar superimposed on the horizontal bar varied its position relative to the opposite vertical bar: range of horizontal disparity, 0.0′ to 42.3′. The superimposed vertical bar was absent under the control condition. Observers were instructed to indicate the disappearance of monocular horizontal bars, that is, targets, from their perception during the 30-s trials. Results: The total disappearance duration decreased under experimental conditions compared with that under control conditions, and it gradually increased with an increase in the disparity of the stereoscopic vertical bars. Discussion: These results indicate that the disparity in the stereoscopic components biases binocular perception away from the rivalry between the vertical and horizontal bars toward the stereopsis of the vertical bars. Furthermore, the disappearance duration showed a unimodal and asymmetric distribution across all disparity conditions. This suggests that rivalry processing occurs in parallel when stereopsis is dominant. We found that stereopsis preference is an outcome of binocular perception selection biased by disparity. [ABSTRACT FROM AUTHOR]

Patching one eye of an adult human for a few hours has been found to promote the dominance of the patched eye, which is called short‐term monocular deprivation effect. Interestingly, recent work has reported that prolonged eye‐specific attention can also cause a shift of ocular dominance toward the unattended eye though visual inputs during adaptation are balanced across the eyes. Considering that patching blocks all input information from one eye, attention is presumably deployed to the opposite eye. Therefore, the short‐term monocular deprivation effect might be, in part, mediated by eye‐specific attentional modulation. Yet this question remains largely unanswered. To address this issue, here we asked participants to perform an attentive tracking task with one eye patched. During the tracking, participants were presented with both target gratings (attended stimuli) and distractor gratings (unattended stimuli) that were distinct from each other in fundamental visual features. Before and after one hour of tracking, they completed a binocular rivalry task to measure perceptual ocular dominance. A larger shift of ocular dominance toward the deprived eye was observed when the binocular rivalry testing gratings shared features with the target gratings during the tracking compared to when they shared features with the distractor gratings. This result, for the first time, suggests that attention can boost the strength of the short‐term monocular deprivation effect. Therefore, the present study sheds new light on the role of attention in ocular dominance plasticity. [ABSTRACT FROM AUTHOR]

Sensory signals from the body's visceral organs (e.g. the heart) can robustly influence the perception of exteroceptive sensations. This interoceptive--exteroceptive interaction has been argued to underlie self-awareness by situating one's perceptual awareness of exteroceptive stimuli in the context of one's internal state, but studies probing cardiac influences on visual awareness have yielded conflicting findings. In this study, we presented separate grating stimuli to each of subjects' eyes as in a classic binocular rivalry paradigm -- measuring the duration for which each stimulus dominates in perception. However, we caused the gratings to 'pulse' at specific times relative to subjects' real-time electrocardiogram, manipulating whether pulses occurred during cardiac systole, when baroreceptors signal to the brain that the heart has contracted, or in diastole when baroreceptors are silent. The influential 'Baroreceptor Hypothesis' predicts the effect of baroreceptive input on visual perception should be uniformly suppressive. In contrast, we observed that dominance durations increased for systole-entrained stimuli, inconsistent with the Baroreceptor Hypothesis. Furthermore, we show that this cardiac-dependent rivalry effect is preserved in subjects who are at-chance discriminating between systole-entrained and diastole-presented stimuli in a separate interoceptive awareness task, suggesting that our results are not dependent on conscious access to heartbeat sensations. [ABSTRACT FROM AUTHOR]

IntroductionThe binocular system provides a stereoscopic view from slightly different retinal images and produces perceptual alternations, namely, binocular rivalry, from significantly different retinal images. When we observe a stereogram in which the stimulus configurations induce stereopsis and rivalry simultaneously, the binocular system prefers stereopsis to rivalry. However, changes in visual perception are yet to be investigated by parametrically manipulating the components of a stereogram.MethodsWe examined stereopsis preferences in stereograms with various horizontal disparities. The stereograms of our paradigms included horizontal and vertical bars in one eye and a vertical bar alone in the other. Under experimental conditions, the vertical bar superimposed on the horizontal bar varied its position relative to the opposite vertical bar: range of horizontal disparity, 0.0′ to 42.3′. The superimposed vertical bar was absent under the control condition. Observers were instructed to indicate the disappearance of monocular horizontal bars, that is, targets, from their perception during the 30-s trials.ResultsThe total disappearance duration decreased under experimental conditions compared with that under control conditions, and it gradually increased with an increase in the disparity of the stereoscopic vertical bars.DiscussionThese results indicate that the disparity in the stereoscopic components biases binocular perception away from the rivalry between the vertical and horizontal bars toward the stereopsis of the vertical bars. Furthermore, the disappearance duration showed a unimodal and asymmetric distribution across all disparity conditions. This suggests that rivalry processing occurs in parallel when stereopsis is dominant. We found that stereopsis preference is an outcome of binocular perception selection biased by disparity.

The inability to visualise was given the name aphantasia in 2015 by Zeman and colleagues. In 2018 we published research showing that fifteen individuals who self-identified as having aphantasia also demonstrated a lack of sensory visual imagery when undergoing the binocular rivalry imagery paradigm, suggesting more than just a metacognitive difference. Here we update these findings with over fifty participants with aphantasia and show that there is evidence for a lack of sensory imagery in aphantasia. How the binocular rivalry paradigm scores relate to the vividness of visual imagery questionnaire (VVIQ) and how aphantasia can be confirmed is discussed.

Slower perceptual alternations, a notable perceptual effect observed in psychiatric disorders, can be alleviated by antidepressant therapies that affect serotonin levels in the brain. While these phenomena have been well documented, the underlying neurocognitive mechanisms remain to be elucidated. Our study bridges this gap by employing a computational cognitive approach within a Bayesian predictive coding framework to explore these mechanisms in depression. We fitted a prediction error (PE) model to behavioral data from a binocular rivalry task, uncovering that significantly higher initial prior precision and lower PE led to a slower switch rate in patients with depression. Furthermore, serotonin‐targeting antidepressant treatments significantly decreased the prior precision and increased PE, both of which were predictive of improvements in the perceptual alternation rate of depression patients. These findings indicated that the substantially slower perception switch rate in patients with depression was caused by the greater reliance on top‐down priors and that serotonin treatment's efficacy was in its recalibration of these priors and enhancement of PE. Our study not only elucidates the cognitive underpinnings of depression, but also suggests computational modeling as a potent tool for integrating cognitive science with clinical psychology, advancing our understanding and treatment of cognitive impairments in depression. [ABSTRACT FROM AUTHOR]

Faces contain rich information and play a pivotal role in human daily social interactions. Previous studies have provided evidence for the left-visual-field-advantage in face perception. The current study investigated lateralisation when face stimuli were unconsciously presented using interocular suppression methods. The results showed that when an unconscious face stimulus was presented in one side of the visual field without other face stimuli, the unconscious face in the right visual field could break through interocular suppression faster than that in the left (Experiments 1 and 2). However, this right visual field processing advantage reversed to the left when a face stimulus either with (Experiment 2) or without (Experiment 3) visual awareness was presented concurrently with or prior to (Experiment 4) the unconscious face stimuli. These results showed that the unconscious face might have a different processing pattern compared with the conscious face. The relationship between this novel behavioural observation and known functional lateralisation of the fusiform face areas is discussed, suggesting a dynamic interaction between the two cortical hemispheres may underlie the formation of visual awareness for faces. The current study expands our understanding of face processing lateralisation and provided evidence on the asymmetric inter-hemisphere interaction patterns in forming visual awareness. [ABSTRACT FROM AUTHOR]

Locomotion has been shown to impact aspects of visual processing in both humans and animal models. In the current study, we assess the impact of locomotion on the dynamics of binocular rivalry. We presented orthogonal gratings, one contrast-modulating at 0.8 Hz (matching average step frequency) and the other at 3.2 Hz, to participants using a virtual reality headset. We compared two conditions: stationary and walking. We continuously monitored participants' foot position using tracking devices to measure the step cycle. During the walking condition, participants viewed the rivaling gratings for 60-second trials while walking on a circular path in a virtual reality environment. During the stationary condition, observers viewed the same stimuli and environment while standing still. The task was to continuously indicate the dominant percept via button press using handheld controllers. We found no significant differences between walking and standing for normalized dominance duration distributions, mean normalized dominance distributions, mean alternation rates, or mean fitted frequencies. Although our findings do not align with prior research highlighting distinctions in normalized dominance distributions between walking and standing, our study contributes unique evidence indicating that alternation rates vary across the step cycle. Specifically, we observed that the number of alternations is at its lowest during toe-off phases and reaches its peak at heel strike. This novel insight enhances our understanding of the dynamic nature of alternation patterns throughout the step cycle. [ABSTRACT FROM AUTHOR]

Visual masking plays a crucial role in optimizing distortion position and intensity in information hiding. However, existing studies on stereoscopic visual masking effects are insufficient and may not align with human perceptual thresholds. This paper aims to fill this research gap by conducting psychophysical experiments to investigate binocular target-to-target visual masking effects that leverage the perceptual mechanisms of the human eye, leading to precise determination of masking thresholds. The experiments involve adjusting the orientation of noise gratings in two scenarios: binocular combination and binocular rivalry, and quantitatively measure the masking thresholds for various binocular noise orientations. Experiment I focuses on investigating the intraocular target-to-target orientation modulation effects in binocular combination, while Experiments II and III explore the interocular target-to-target masking effects and orientation modulation effects in binocular rivalry. The findings indicate that the target-to-target masking effects can increase stereoscopic visual masking thresholds by 23% to 65% compared to previous context-to-target masking effects, while ensuring the noise remains invisible. These findings have practical implications for information hiding technologies related to stereoscopic images and videos. By selecting the orientation, position, and intensity for distortion, improvements can be made in metrics such as embedding strength and capacity while ensuring high-quality display. [ABSTRACT FROM AUTHOR]

Previous research has found that prolonged eye-based attention can bias ocular dominance. If one eye long-termly views a regular movie meanwhile the opposite eye views a backward movie of the same episode, perceptual ocular dominance will shift towards the eye previously viewing the backward movie. Yet it remains unclear whether the role of eye-based attention in this phenomenon is causal or not. To address this issue, the present study relied on both the functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) techniques. We found robust activation of the frontal eye field (FEF) and intraparietal sulcus (IPS) when participants were watching the dichoptic movie while focusing their attention on the regular movie. Interestingly, we found a robust effect of attention-induced ocular dominance shift when the cortical function of vertex or IPS was transiently inhibited by continuous theta burst stimulation (cTBS), yet the effect was significantly attenuated to a negligible extent when cTBS was delivered to FEF. A control experiment verified that the attenuation of ocular dominance shift after inhibitory stimulation of FEF was not due to any impact of the cTBS on the binocular rivalry measurement of ocular dominance. These findings suggest that the fronto-parietal attentional network is involved in controlling eye-based attention in the 'dichoptic-backward-movie' adaptation paradigm, and in this network, FEF plays a crucial causal role in generating the attention-induced ocular dominance shift. [ABSTRACT FROM AUTHOR]

The relationship between integration and awareness is central to contemporary theories and research on consciousness. Here, we investigated whether and how information integration over time, by incorporating the underlying regularities, contributes to our awareness of the dynamic world. Using binocular rivalry, we demonstrated that structured visual streams, constituted by shape, motion, or idiom sequences containing perceptual‐ or semantic‐level regularities, predominated over their nonstructured but otherwise matched counterparts in the competition for visual awareness. Despite the apparent resemblance, a substantial dissociation of the observed rivalry advantages emerged between perceptual‐ and semantic‐level regularities. These effects stem from nonconscious and conscious temporal integration processes, respectively, with the former but not the latter being vulnerable to perturbations in the spatiotemporal integration window. These findings corroborate the essential role of structure‐guided information integration in visual awareness and highlight a multi‐level mechanism where temporal integration by perceptually and semantically defined regularities fosters the emergence of continuous conscious experience. [ABSTRACT FROM AUTHOR]

This study explored how congruency between facial mimicry and observed expressions affects the stability of conscious facial expression representations. Focusing on the congruency effect between proprioceptive/sensorimotor signals and visual stimuli for happy expressions, participants underwent a binocular rivalry task displaying neutral and happy faces. Mimicry was either facilitated with a chopstick or left unrestricted. Key metrics included Initial Percept (bias indicator), Onset Resolution Time (time from onset to Initial Percept), and Cumulative Time (content stabilization measure). Results indicated that mimicry manipulation significantly impacted Cumulative Time for happy faces, highlighting the importance of congruent mimicry in stabilizing conscious awareness of facial expressions. This supports embodied cognition models, showing the integration of proprioceptive information significantly biases conscious visual perception of facial expressions. [ABSTRACT FROM AUTHOR]

Calorie content and hunger are two fundamental cues acting upon the processing of visually presented food items. However, whether and to which extent they affect visual awareness is still an open question. Here, high- and low-calorie food images administered to hungry or satiated participants were confronted in a breaking-Continuous Flash Suppression paradigm (Experiment 1), measuring the time required to access to visual awareness, and in a Binocular Rivalry paradigm (Experiment 2), quantifying the dominance time in visual awareness. Experiment 1 showed that high-calorie food accessed faster visual awareness, but mostly in satiated participants. Experiment 2 indicated that high-calorie food dominated longer visual awareness, regardless the degree of hunger. We argued that the unconscious advantage (Experiment 1) would represent a default state of the visual system towards highest-energy nutrients, yet the advantage is lost in hunger so to be tuned towards an increased need for any nutritional category. On the other hand, the conscious advantage of high-calorie food (Experiment 2) would represent a conscious perceptual and attentional bias towards highest energy-dense food useful for the actual detection of these stimuli in the environment.

3D Anaglyph system is among the most popular 3D displaying techniques thanks to its simplicity and the cheap glasses that it uses. Anaglyph generation and watermarking are two essential techniques that attracted researchers in 3D anaglyph domain where several techniques have been proposed. However, most of the previous anaglyph watermarking studies focused on the robustness and the visual difference between original and marked content and they have not considered the three deficiencies caused by the generation step, which are the distortion of colors, the retinal rivalry and the ghosting effect. In this paper, we propose the first watermarking technique that protect 3D anaglyph content before its transmission by embedding the signature simultaneously with generation step. In this technique, three signatures were embedded before, during and after the generation process using different domains to obtain robustness to several manipulations, especially against malicious attacks. Moreover, the chosen generation process avoids generation deficiencies and allows obtaining high visual quality of the marked content. The experimental results illustrate robustness against attacks such as compression and collusion where the minimum value of NC is close to 0.7 and the maximum value of BER is close to 0.2. Besides, the suggested technique provides high invisibility where PSNR and SSIM values are respectively close to 58 and 0.9, and it minimizes the generation deficiencies. [ABSTRACT FROM AUTHOR]

Introduction: Modeling work on binocular rivalry has described how ocular opponency neurons represent interocular conflict. These neurons have recently been considered to mediate an ocular dominance shift to the eye that has viewed a backward movie for long during which time the other eye is presented with a regular movie. Unlike typical short-term monocular deprivation, the visual inputs are comparable across eyes in that "dichoptic-backward-movie" paradigm. Therefore, it remains unclear whether the ocular opponency neurons are also responsible for the short-term monocular deprivation effect which is prevalently explained by the homeostatic compensation theory. We designed two experiments from distinct perspectives to investigate this question. Methods: In Experiment 1, we mitigated the imbalance in the activity of opponency neurons between the two eyes during monocular deprivation by presenting video stimuli alternately. In Experiment 2, we directly evaluated the response of opponency neurons before and after monocular deprivation using SSVEP techniques. Results: Consistent with each other, both experiments failed to provide reliable evidence supporting the involvement of ocular opponency neurons in the shortterm monocular deprivation effect. Discussion: Our results suggest that ocular opponency neurons may not play an essential role in the short-term monocular deprivation effect, potentially due to interference from the homeostatic plasticity mechanism. [ABSTRACT FROM AUTHOR]

Head‐mounted displays (HMDs) for virtual and augmented reality applications could have severe nonuniformities due to complex optical components and the choice of light source technologies. In addition, module variations between the two eyes can result in different colors being seen with the left and right eyes. Binocular rivalry is expected for large color differences between the two eyes, which can severely affect product usability. Thus, it is important to characterize and predict the binocular rivalry in HMDs caused by interocular color differences. As a step toward this end, we propose the first binocular color difference metric, ΔE*bino, to predict the just noticeable binocular rivalry for a pair of solid colors. A psychophysical experiment was conducted using Meta Quest 2, in which we presented different colors to the left and right eye. The collected data were analyzed to derive the metric using ROC curves. We show that the ΔE*bino metric showed significant improvements over conventional color difference formulae. Both the ΔE*bino formula and the anonymized experiment results are available for download. [ABSTRACT FROM AUTHOR]

The contents of awareness can substantially change without any modification to the external world. Such effects are exemplified in binocular rivalry, where a different stimulus is presented to each eye causing instability in perception. This phenomenon has made binocular rivalry a quintessential method for studying consciousness and the necessary neural correlates for awareness. However, to conduct research on binocular rivalry usually requires self-reports of changes in percept, which can produce confounds and exclude states and contexts where self-reports are undesirable or unreliable. Here, we use a novel multivariate spatial filter dubbed 'Rhythmic Entrainment Source Separation' to extract steady state visual evoked potentials from electroencephalography data. We show that this method can be used to quantify the perceptual switch-rate of participants during binocular rivalry and therefore may be valuable in experimental contexts where self-reports are methodologically problematic or impossible, particularly as an adjunct. Our analyses also reveal that 'no-report' conditions may affect the deployment of attention and thereby neural correlates, another important consideration for consciousness research. [ABSTRACT FROM AUTHOR]

Head‐mounted displays (HMDs) for virtual and augmented reality applications could have severe nonuniformities due to complex optical components and the choice of light source technologies. In addition, module variations between the two eyes can result in different colors being seen with the left and right eyes. Binocular rivalry is expected for large color differences between the two eyes, which can severely affect product usability. Thus, it is important to characterize and predict the binocular rivalry in HMDs caused by interocular color differences. As a step toward this end, we propose the first binocular color difference metric, ΔE*bino, to predict the just noticeable binocular rivalry for a pair of solid colors. A psychophysical experiment was conducted using Meta Quest 2, in which we presented different colors to the left and right eye. The collected data were analyzed to derive the metric using ROC curves. We show that the ΔE*bino metric showed significant improvements over conventional color difference formulae. Both the ΔE*bino formula and the anonymized experiment results are available for download. [ABSTRACT FROM AUTHOR]

During binocular rivalry, conflicting images are presented one to each eye and perception alternates stochastically between them. Despite stable percepts between alternations, modeling suggests that neural signals representing the two images change gradually, and that the duration of stable percepts are determined by the time required for these signals to reach a threshold that triggers an alternation. However, direct physiological evidence for such signals has been lacking. Here, we identify a neural signal in the human visual cortex that shows these predicted properties. We measured steady-state visual evoked potentials (SSVEPs) in 84 human participants (62 females, 22 males) who were presented with orthogonal gratings, one to each eye, flickering at different frequencies. Participants indicated their percept while EEG data were collected. The time courses of the SSVEP amplitudes at the two frequencies were then compared across different percept durations, within participants. For all durations, the amplitude of signals corresponding to the suppressed stimulus increased and the amplitude corresponding to the dominant stimulus decreased throughout the percept. Critically, longer percepts were characterized by more gradual increases in the suppressed signal and more gradual decreases of the dominant signal. Changes in signals were similar and rapid at the end of all percepts, presumably reflecting perceptual transitions. These features of the SSVEP time courses are well predicted by a model in which perceptual transitions are produced by the accumulation of noisy signals. Identification of this signal underlying binocular rivalry should allow strong tests of neural models of rivalry, bistable perception, and neural suppression. [ABSTRACT FROM AUTHOR]

Binocular rivalry, a visual perception phenomenon where two or more percepts alternate every few seconds when distinct stimuli are presented to the two eyes, has been reported as a biomarker in several psychiatric disorders. It is unclear whether abnormalities of binocular rivalry in depression could occur when emotional rivaling stimuli are used, and if so, whether an emotional binocular rivalry test could provide a trait‐dependent or state‐dependent biomarker. In the current study, 34 individuals with subthreshold depression and 31 non‐depressed individuals performed a binocular rivalry task associated with implicit emotional processing. Participants were required to report their perceived orientations of the rival gratings in the foreground and to neglect emotional face stimuli in the background. The participants were retested after an approximately 4‐month time interval. Compared to the non‐depressed group, the subthreshold depression group showed significantly longer perceptual dominance durations of the grating with emotional faces as the background (i.e., implicit emotional dominance) at the initial assessment. However, the abnormality was not found at the follow‐up assessment. More importantly, we found smaller changes in depressive severity at the follow‐up assessment for individuals displaying longer emotional dominance at the initial assessment than for individuals with weaker emotional dominance. The current emotional binocular rivalry test may provide an objective, state‐dependent biomarker for distinguishing individuals with subthreshold depression from non‐depressed individuals. [ABSTRACT FROM AUTHOR]

In healthy adults with normal vision, temporary deprivation of one eye’s visual experience produces transient yet robust homeostatic plasticity effects, where the deprived eye becomes more dominant. This shift in ocular dominance is short-lived and compensatory. Previous work shows that monocular deprivation decreases resting state gamma aminobutyric acid (GABA; inhibitory neurotransmitter) levels in visual cortex, and that those with the greatest reduction in GABA have stronger shifts due to monocular deprivation. Components of the GABAergic system in visual cortex vary with age (early childhood, early teen years, ageing); hence if GABA is critical to homeostatic plasticity within the visual system, adolescence may be a key developmental period where differences in plasticity manifest. Here we measured short-term visual deprivation effects on binocular rivalry in 24 adolescents (aged 10–15 years) and 23 young adults (aged 20–25 years). Despite differences in baseline features of binocular rivalry (adolescents showed more mixed percept p

Spatial perspective and identity of visual bodily stimuli are two key cues for the self-other distinction. However, how they emerge into visual awareness is largely unknown. Here, self- or other-hands presented in first- or third-person perspective were compared in a breaking-Continuous Flash Suppression paradigm (Experiment 1) measuring the time the stimuli need to access visual awareness, and in a Binocular Rivalry paradigm (Experiment 2), measuring predominance in perceptual awareness. Results showed that, irrespectively of identity, first-person perspective speeded up the access, whereas the third-person one increased the dominance. We suggest that the effect of first-person perspective represents an unconscious prioritization of an egocentric body coding important for visuomotor control. On the other hand, the effect of third-person perspective indicates a conscious advantage of an allocentric body representation fundamental for detecting the presence of another intentional agent. Summarizing, the emergence of self-other distinction into visual awareness would strongly depend on the interplay between spatial perspectives, with an inverse prioritization before and after conscious perception. On the other hand, identity features might rely on post-perceptual processes. [ABSTRACT FROM AUTHOR]

Recent research suggests imagery is functionally equivalent to a weak form of visual perception. Here we report evidence across five independent experiments on adults that perception and imagery are supported by fundamentally different mechanisms: Whereas perceptual representations are largely formed via increases in excitatory activity, imagery representations are largely supported by modulating nonimagined content. We developed two behavioral techniques that allowed us to first put the visual system into a state of adaptation and then probe the additivity of perception and imagery. If imagery drives similar excitatory visual activity to perception, pairing imagery with perceptual adapters should increase the state of adaptation. Whereas pairing weak perception with adapters increased measures of adaptation, pairing imagery reversed their effects. Further experiments demonstrated that these nonadditive effects were due to imagery weakening representations of nonimagined content. Together these data provide empirical evidence that the brain uses categorically different mechanisms to represent imagery and perception. [ABSTRACT FROM AUTHOR]

Introduction: Recent research shows ambivalent results regarding the relationship between mental imagery and schizophrenia. The role of voluntary visual imagery in schizophrenic hallucinations remains unclear. The aim of the study was to investigate the association between visual imagery, schizophrenia, and the occurrence of schizophrenic hallucinations using an objective visual imagery task. Methods: The sample consisted of 16 participants with schizophrenia (59.1% female; MAge = 45.55) and 44 participants without schizophrenia (62.5% female; MAge = 43.94). Visual imagery was measured using the Vividness of Visual Imagery Questionnaire (VVIQ) as well as the well‐validated Binocular Rivalry Task (BRT). Occurrences of hallucinations were assessed using the Launay–Slade Hallucination Scale. Results: Participants with schizophrenia showed more hallucinatory experiences but did not score higher on either the VVIQ or the BRT than participants without schizophrenia. A correlation between the VVIQ and the BRT was found, validating the measurement of visual imagery and enabling the interpretation that visual imagery vividness is not enhanced in people with schizophrenia. Conclusion: The association between mental imagery vividness and schizophrenia found in previous studies may be based on other facets of mental imagery than visual imagery. [ABSTRACT FROM AUTHOR]

Background: Social anxiousness is a pervasive symptom in both social anxiety disorder and autism spectrum conditions. Binocular rivalry, which occurs when different images are presented to each eye, has been used to explore how visual and cognitive processing differs across various clinical diagnoses. Previous studies have separately explored whether individuals with autism or anxiety experience binocular rivalry in ways that are different from neurotypical individuals. Methods: We applied rivalry paradigms that are similar to those used in previous studies of autism and general anxiety to individuals experiencing symptoms of social anxiousness at clinical or subclinical levels. We also incorporated rivalrous stimuli featuring neutral and emotional facial valances to explore potential overlap of social processing components in social anxiety and autism. Results: We hypothesized that higher levels of social anxiousness would increase binocular rivalry switch rates and that higher levels of autistic traits would decrease switch rates. However, stimulus condition did not affect switch rates in either diagnostic group, and switch rate was not significantly predictive of dimensional measures of either autism or social anxiety. Discussion: This may suggest a common mechanism for atypical visual cognition styles previously associated with social anxiety and autism. Alternatively, differences in switch rates may only emerge at higher trait levels than reported by the participants in our studies. Furthermore, these findings may be influenced by sex differences in our unique sample. [ABSTRACT FROM AUTHOR]

Introduction: Psychosis is in part defined by disturbances in perception. Recent investigations have implicated the speed of alpha oscillations observed in brain electrical activity as reflective of a sampling rate of the visual environment and perception. Although both slowed alpha oscillations and aberrant percept formation are evident in disorders of psychotic psychopathology such as schizophrenia it is unclear whether slow alpha accounts for abnormal visual perception in these disorders. Methods: To examine the role of the speed of alpha oscillations in perception in psychotic psychopathology we gathered resting-state magneto-encephalography data from probands with psychotic psychopathology (i.e., schizophrenia, schizoaffective disorder, and bipolar disorder with a history of psychosis), their biological siblings, and healthy controls. We appraised visual perceptual function without the confound of cognitive ability and effort through the use of a simple binocular rivalry task. Results: We found a slowed pace of alpha oscillations in psychotic psychopathology that was associated with longer percept durations during binocular rivalry, consistent with the assertion that occipital alpha oscillations govern the rate of accumulation of visual information used to generate percepts. Alpha speed varied widely across individuals with psychotic psychopathology and was highly stable across several months indicating that it is likely a trait characteristic of neural function that is relevant to visual perception. Finally, a lower speed of alpha oscillation was associated with a lower IQ and greater disorder symptomatology implying that the effects of the endogenous neural oscillation on visual perception may have wider consequences for everyday functioning. Discussion: Slowed alpha oscillations in individuals with psychotic psychopathology appear to reflect altered neural functions related to percept formation. [ABSTRACT FROM AUTHOR]

Recently, stereoscopic image quality assessment has attracted a lot attention. However, compared with 2D image quality assessment, it is much more difficult to assess the quality of stereoscopic images due to the lack of understanding of 3D visual perception. This paper proposes a novel no-reference quality assessment metric for stereoscopic images using natural scene statistics with consideration of both the quality of the cyclopean image and 3D visual perceptual information (binocular fusion and binocular rivalry). In the proposed method, not only is the quality of the cyclopean image considered, but binocular rivalry and other 3D visual intrinsic properties are also exploited. Specifically, in order to improve the objective quality of the cyclopean image, features of the cyclopean images in both the spatial domain and transformed domain are extracted based on the natural scene statistics (NSS) model. Furthermore, to better comprehend intrinsic properties of the stereoscopic image, in our method, the binocular rivalry effect and other 3D visual properties are also considered in the process of feature extraction. Following adaptive feature pruning using principle component analysis, improved metric accuracy can be found in our proposed method. The experimental results show that the proposed metric can achieve a good and consistent alignment with subjective assessment of stereoscopic images in comparison with existing methods, with the highest SROCC (0.952) and PLCC (0.962) scores being acquired on the LIVE 3D database Phase I. [ABSTRACT FROM AUTHOR]

Purpose: Glaucoma is a progressive optic neuropathy that damages retinal ganglion cells and a neurodegenerative disease as it a􀀀ects neural structures throughout the brain. In this study, we examined binocular rivalry responses in patients with early glaucoma in order to probe the function of stimulus-specific cortical areas involved in face perception. Methods: Participants included 14 individuals (10 females, mean age 65 ± 7 years) with early pre-perimetric glaucoma and 14 age-matched healthy controls (7 females, mean age 59±11 years). The 2 groups were equivalent in visual acuity and stereo-acuity. Three binocular rivalry stimulus pairs were used: (1) real face/house, (2) synthetic face/noise patch, and (3) synthetic face/spiral. For each stimulus pair, the images werematched in size and contrast level; they were viewed dichotically, and presented centrally and eccentrically at 3 degrees in the right (RH) and in the left hemifield (LH), respectively. The outcome measures were rivalry rate (i.e., perceptual switches/min) and time of exclusive dominance of each stimulus. Results: For the face/house stimulus pair, rivalry rate of the glaucoma group (11 ± 6 switches/min) was significantly lower than that of the control group (15 ± 5 switches/min), but only in the LH location. The face dominated longer than the house in the LH for both groups. Likewise, for the synthetic face/noise patch stimulus pair, rivalry rate of the glaucoma group (11 ± 6 switches/min) was lower than that of the control group (16 ± 7 switches/min) in the LH, but the di􀀀erence failed to reach significance. Interestingly, the mixed percept dominated less in glaucoma than in the control group. For the synthetic face/spiral stimulus pair, the glaucoma group had lower rivalry rate at all 3 stimulus locations. Conclusion: This study reveals atypical responses to faces during binocular rivalry in patients with early glaucoma. The results may be suggestive of early neurodegeneration a􀀀ecting stimulus-specific neural structures involved in face processing starting in the pre-perimetric phase of the disease. [ABSTRACT FROM AUTHOR]

Contents of consciousness change over time. However, the study of dynamics in consciousness has been largely neglected. Aru and Bachmann have recently brought to the attention of scientists dealing with consciousness the relevance of making inquiries about its temporal evolution. Importantly, they also pointed out several experimental questions as guidelines for researchers interested in studying the temporal evolution of consciousness, including the phases of formation and dissolution of content. They also suggested that these two phases could be characterized by asymmetric inertia. The main objective of the present investigation was to approximate the dynamics of these two phases in the context of conscious face perception. To this aim, we tested the time course of content transitions during a binocular rivalry task using face stimuli and asked participants to map their subjective experience of transitions from one content to the other through a joystick. We then computed metrics of joystick velocity linked to content transitions as proxies of the formation and dissolution phases. We found a general phase effect such that the formation phase was slower than the dissolution phase. Furthermore, we observed an effect specific to happy facial expressions, such that their contents were slower to form and dissolve than that of neutral expressions. We further propose to include a third phase of stabilization of conscious content between formation and dissolution. [ABSTRACT FROM AUTHOR]

Continuous flash suppression (CFS) is a popular masking technique used to manipulate visual awareness. By presenting a rapidly changing stimulus to one eye (the 'mask'), a static image viewed by the other (the 'target') may remain invisible for many seconds. This effectiveness affords a means to assess unconscious visual processing, leading to the widespread use of CFS in several basic and clinical sciences. However, the lack of principled stimulus selection has impeded generalization of conclusions across studies, as the strength of interocular suppression is dependent on the spatiotemporal properties of the CFS mask and target. To address this, we created CFS-crafter, a point-and-click, open-source tool for creating carefully controlled CFS stimuli. The CFS-crafter provides a streamlined workflow to create, modify, and analyze mask and target stimuli, requiring only a rudimentary understanding of image processing that is well supported by help files in the application. Users can create CFS masks ranging from classic Mondrian patterns to those comprising objects or faces, or they can create, upload, and analyze their own images. Mask and target images can be custom-designed using image-processing operations performed in the frequency domain, including phase-scrambling and spatial/temporal/orientation filtering. By providing the means for the customization and analysis of CFS stimuli, the CFS-crafter offers controlled creation, analysis, and cross-study comparison. Thus, the CFS-crafter—with its easy-to-use image processing functionality—should facilitate the creation of visual conditions that allow a principled assessment of hypotheses about visual processing outside of awareness. [ABSTRACT FROM AUTHOR]

Binocular rivalry is the perceptual dominance of one visual stimulus over another. Conventionally, binocular rivalry is induced using a mirror-stereoscope—a setup involving mirrors oriented at an angle to a display. The respective mirror planes fuse competing visual stimuli in the observer's visual field by projecting the stimuli through the stereoscope to the observed visual field. Since virtual-reality head-mounted displays fuse dichoptic vision in a similar way, and since virtual-reality head-mounted displays are more versatile and more readily available than mirror stereoscopes, this study investigated the efficacy of using a virtual-reality headset (Oculus Rift-S) as an alternative to using a mirror stereoscope to study binocular rivalry. To evaluate the validity of using virtual-reality headsets to induce visual dominance/suppression, two identical experimental sequences—one using a conventional mirror stereoscope and one using a virtual-reality headset—were compared and evaluated. The study used Gabor patches at different orientations to induce binocular rivalry and to evaluate the efficacy of the two experiments. Participants were asked to record all instances of perceptual dominance (complete suppression) and non-dominance (incomplete suppression). Independent sample t-tests confirmed that binocular rivalry with stable vergence was successfully induced for the mirror-stereoscope experiment (t = −4.86; p ≤ 0.0001) and the virtual-reality experiment (t = −9.41; p ≤ 0.0001). Using ANOVA to compare Gabor patch pairs of gratings at +45°/−45° orientations presented in both visual fields, gratings at 0°/90° orientations presented in both visual fields, and mixed gratings (i.e., unconventional grating pairs) presented in both visual fields, the performance of the two experiments was evaluated by comparing observation duration in seconds (F = 0.12; p = 0.91) and the alternation rate per trial (F = 8.1; p = 0.0005). The differences between the stimulus groups were not statistically significant for the observation duration but were significantly different based on the alternation rates per trial. Moreover, ANOVA also showed that the dominance durations (F = 114.1; p < 0.0001) and the alternation rates (F = 91.6; p < 0.0001) per trial were significantly different between the mirror-stereoscope and the virtual-reality experiments, with the virtual-reality experiment showing an increase in alternation rate and a decrease in observation duration. The study was able to show that a virtual-reality head-mounted display can be used as an effective and novel alternative to induce binocular rivalry, but there were some differences in visual bi-stability between the two methods. This paper discusses the experimental measures taken to minimise piecemeal rivalry and to evaluate perceptual dominance between the two experimental designs. [ABSTRACT FROM AUTHOR]

Many interesting theories of consciousness have been proposed, but so far, there is no “unified” theory capable of encompassing all aspects of this phenomenon. We are all aware of what it feels like to be conscious and what happens if there is an absence of consciousness. We are becoming more and more skilled in measuring consciousness states; nevertheless, we still “don’t get it” in its deeper essence. How does all the processed information converge from different brain areas and structures to a common unity, giving us this very private “feeling of being conscious”, despite the constantly changing flow of information between internal and external states? “Multistability” refers to a class of perceptual phenomena where subjective awareness spontaneously and continuously alternates between different percepts, although the objective stimuli do not change, supporting the idea that the brain “interprets” sensorial input in a “constructive” way. In this perspective paper, multistability and perceptual awareness are discussed as a methodological window for understanding the “local” states of consciousness, a privileged position from which it is possible to observe the brain dynamics and mechanisms producing the subjective phenomena of perceptual awareness in the very moment they are happening.

IntroductionPsychosis is in part defined by disturbances in perception. Recent investigations have implicated the speed of alpha oscillations observed in brain electrical activity as reflective of a sampling rate of the visual environment and perception. Although both slowed alpha oscillations and aberrant percept formation are evident in disorders of psychotic psychopathology such as schizophrenia it is unclear whether slow alpha accounts for abnormal visual perception in these disorders.MethodsTo examine the role of the speed of alpha oscillations in perception in psychotic psychopathology we gathered resting-state magneto-encephalography data from probands with psychotic psychopathology (i.e., schizophrenia, schizoaffective disorder, and bipolar disorder with a history of psychosis), their biological siblings, and healthy controls. We appraised visual perceptual function without the confound of cognitive ability and effort through the use of a simple binocular rivalry task.ResultsWe found a slowed pace of alpha oscillations in psychotic psychopathology that was associated with longer percept durations during binocular rivalry, consistent with the assertion that occipital alpha oscillations govern the rate of accumulation of visual information used to generate percepts. Alpha speed varied widely across individuals with psychotic psychopathology and was highly stable across several months indicating that it is likely a trait characteristic of neural function that is relevant to visual perception. Finally, a lower speed of alpha oscillation was associated with a lower IQ and greater disorder symptomatology implying that the effects of the endogenous neural oscillation on visual perception may have wider consequences for everyday functioning.DiscussionSlowed alpha oscillations in individuals with psychotic psychopathology appear to reflect altered neural functions related to percept formation.

BackgroundSocial anxiousness is a pervasive symptom in both social anxiety disorder and autism spectrum conditions. Binocular rivalry, which occurs when different images are presented to each eye, has been used to explore how visual and cognitive processing differs across various clinical diagnoses. Previous studies have separately explored whether individuals with autism or anxiety experience binocular rivalry in ways that are different from neurotypical individuals.MethodsWe applied rivalry paradigms that are similar to those used in previous studies of autism and general anxiety to individuals experiencing symptoms of social anxiousness at clinical or subclinical levels. We also incorporated rivalrous stimuli featuring neutral and emotional facial valances to explore potential overlap of social processing components in social anxiety and autism.ResultsWe hypothesized that higher levels of social anxiousness would increase binocular rivalry switch rates and that higher levels of autistic traits would decrease switch rates. However, stimulus condition did not affect switch rates in either diagnostic group, and switch rate was not significantly predictive of dimensional measures of either autism or social anxiety.DiscussionThis may suggest a common mechanism for atypical visual cognition styles previously associated with social anxiety and autism. Alternatively, differences in switch rates may only emerge at higher trait levels than reported by the participants in our studies. Furthermore, these findings may be influenced by sex differences in our unique sample.

Background: The evaluation of amblyopia treatment efficacy is essential for amblyopia prevention, control, and rehabilitation. Methods: To evaluate the amblyopia treatment efficacy more precisely and quantitatively, this study recorded four visual function examination results, i.e., visual acuity, binocular rivalry balance point, perceptual eye position, and stereopsis before and after amblyopia treatment. Results: We found that all these four results had a significant difference between before and after treatment, and the relationship between visual acuity improvement and the difference of BRBP, PEP, and stereoacuity cannot show a fitting correlation regarding the widely used index of visual acuity as the standard of treatment efficacy. By using the Criteria Importance Through Inter-criteria Correlation (CRITIC) method, a more comprehensive and quantitative index by coupling the selected four indexes with objective weights was obtained for further training efficacy representation, and the validation dataset also showed a good performance. Conclusions: This study proved that our proposed coupling method based on different visual function examination results via the CRITIC algorithm is a potential means to quantify the amblyopia treatment efficacy. [ABSTRACT FROM AUTHOR]

Studies of primary visual cortex have furthered our understanding of amblyopia, long-lasting visual impairment caused by imbalanced input from the two eyes during childhood, which is commonly treated by patching the dominant eye. However, the relative impacts of monocular vs. binocular visual experiences on recovery from amblyopia are unclear. Moreover, while sleep promotes visual cortex plasticity following loss of input from one eye, its role in recovering binocular visual function is unknown. Using monocular deprivation in juvenile male mice to model amblyopia, we compared recovery of cortical neurons' visual responses after identical-duration, identical-quality binocular or monocular visual experiences. We demonstrate that binocular experience is quantitatively superior in restoring binocular responses in visual cortex neurons. However, this recovery was seen only in freely-sleeping mice; post-experience sleep deprivation prevented functional recovery. Thus, both binocular visual experience and subsequent sleep help to optimally renormalize bV1 responses in a mouse model of amblyopia. In a mouse model of amblyopia, binocular sight conditions (including time for sleep) lead to a better recovery of visual function. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Does our personality predict what we see? This question was studied in 100 university students with binocular rivalry paradigm by presenting incompatible images to each eye, allowing multiple interpretations of the same sensory input. During continuous binocular presentation, dominance of perception starts to fluctuate between the images. When neither of the images is fully suppressed, the two images combine into mixed percepts. We focused on the link between mixed percepts, big-five traits, and empathy. The results revealed that openness and agreeableness correlated with the occurrence of mixed percepts after the first dominant perception. However, these correlations of openness and agreeableness were mediated by cognitive empathy. In addition, openness had a direct association with reporting the initial percept in the onset of stimulation as a mixed percept, suggesting a mechanism that is separate from the one mediated by cognitive empathy. Overall, the results provide preliminary evidence suggesting that personality predicts what we see. Such individual differences in perceptual interpretations may be linked to both higher level cognitive mechanisms as well as lower level visual mechanisms. [ABSTRACT FROM AUTHOR]

Three-dimensional video services delivered through wireless communication channels have to deal with numerous challenges due to the limitations of both the transmission channel's bandwidth and receiving devices. Adverse channel conditions, delays, or jitters can result in bit errors and packet losses, which can alter the appearance of stereoscopic 3D (S3D) video. Due to the perception of dissimilar patterns by the two human eyes, they can not be fused into a stable composite pattern in the brain and hence try to dominate by suppressing each other. Thus, a psychovisual sensation that is called binocular rivalry occurs. As a result, undetectable changes causing irritating flickering effects are seen, leading to visual discomforts such as eye strain, headache, nausea, and weariness. This study addresses the observer's quality of experience (QoE) by analyzing the binocular rivalry impact on the macroblock (MB) losses in a frame and its error propagation due to predictive frame encoding in stereoscopic video transmission systems. To simulate the processing of experimental videos, the Joint Test Model (JM) reference software has been used as it is recommended by the International Telecommunication Union (ITU). Existing error concealing techniques were then applied to the contiguous lost MBs for a variety of transmission impairments. In order to validate the authenticity of the simulated packet loss environment, several objective evaluations were carried out. Standard numbers of subjects were then engaged in the subjective testing of common 3D video sequences. The results were then statistically examined using a standard Student's t-test, allowing the impact of binocular rivalry to be compared to that of a non-rivalry error condition. The major goal is to assure error-free video communication by minimizing the negative impacts of binocular rivalry and boosting the ability to efficiently integrate 3D video material to improve viewers' overall QoE. [ABSTRACT FROM AUTHOR]

Binocular disparity provides information about the depth structure of objects and surfaces in our environment. Since disparity depends on the distance to objects as well as the depth separation of points, information about distance is required to estimate depth from disparity. Our perception of size and shape is biased, such that far objects appear too small and flattened in depth, and near objects too big and stretched in depth. The current study assessed the extent to which the failure of depth constancy can be accounted for by the uncertainty of distance information provided by vergence. We measured individual differences in vergence noise using a nonius line task, and the degree of depth constancy using a task in which observers judged the magnitude of a depth interval relative to the vertical distance between two targets in the image plane. We found no correlation between the two measures, and show that depth constancy was much poorer than would be expected from vergence noise measured in this way. This limited ability to take account of vergence in the perception of depth is, however, consistent with our poor sensitivity to absolute disparity differences. This absolute disparity anomaly thus also applies to our poor ability to make use of vergence information for absolute distance judgements. [ABSTRACT FROM AUTHOR]

• Intermodulation frequency components (IMs) can be induced by the binocular synoptic vision paradigm, the dichoptic vision paradigm, and the cross-sensory paradigm. • The location of IMs appears to be associated with the stimulation type and the level of neural integration. • IMs exhibit a role in representing information integration in studies of global perception and binocular rivalry. • IMs can be used in clinical neuroscience to characterize defects in neural integration functions. • IMs can provide information gain for brain-computer interface systems. The steady-state visual evoked potentials (SSVEPs), evoked by dual-frequency or multi-frequency stimulation, likely contains intermodulation frequency components (IMs). Visual IMs are products of nonlinear integration of neural signals and can be evoked by various paradigms that induce neural interaction. IMs have demonstrated many interesting and important characteristics in cognitive psychology, clinical neuroscience, brain–computer interface and other fields, and possess substantial research potential. In this paper, we first review the definition of IMs and summarize the stimulation paradigms capable of inducing them, along with the possible neural origins of IMs. Subsequently, we describe the characteristics and derived applications of IMs in previous studies, and then introduced three signal processing methods favored by researchers to enhance the signal-to-noise ratio of IMs. Finally, we summarize the characteristics of IMs, and propose several potential future research directions related to IMs. [ABSTRACT FROM AUTHOR]

Contents of consciousness change over time. However, the study of dynamics in consciousness has been largely neglected. Aru and Bachmann have recently brought to the attention of scientists dealing with consciousness the relevance of making inquiries about its temporal evolution. Importantly, they also pointed out several experimental questions as guidelines for researchers interested in studying the temporal evolution of consciousness, including the phases of formation and dissolution of content. They also suggested that these two phases could be characterized by asymmetric inertia. The main objective of the present investigation was to approximate the dynamics of these two phases in the context of conscious face perception. To this aim, we tested the time course of content transitions during a binocular rivalry task using face stimuli and asked participants to map their subjective experience of transitions from one content to the other through a joystick. We then computed metrics of joystick velocity linked to content transitions as proxies of the formation and dissolution phases. We found a general phase effect such that the formation phase was slower than the dissolution phase. Furthermore, we observed an effect specific to happy facial expressions, such that their contents were slower to form and dissolve than that of neutral expressions. We further propose to include a third phase of stabilization of conscious content between formation and dissolution.

PurposeGlaucoma is a progressive optic neuropathy that damages retinal ganglion cells and a neurodegenerative disease as it affects neural structures throughout the brain. In this study, we examined binocular rivalry responses in patients with early glaucoma in order to probe the function of stimulus-specific cortical areas involved in face perception.MethodsParticipants included 14 individuals (10 females, mean age 65 ± 7 years) with early pre-perimetric glaucoma and 14 age-matched healthy controls (7 females, mean age 59 ± 11 years). The 2 groups were equivalent in visual acuity and stereo-acuity. Three binocular rivalry stimulus pairs were used: (1) real face/house, (2) synthetic face/noise patch, and (3) synthetic face/spiral. For each stimulus pair, the images were matched in size and contrast level; they were viewed dichotically, and presented centrally and eccentrically at 3 degrees in the right (RH) and in the left hemifield (LH), respectively. The outcome measures were rivalry rate (i.e., perceptual switches/min) and time of exclusive dominance of each stimulus.ResultsFor the face/house stimulus pair, rivalry rate of the glaucoma group (11 ± 6 switches/min) was significantly lower than that of the control group (15 ± 5 switches/min), but only in the LH location. The face dominated longer than the house in the LH for both groups. Likewise, for the synthetic face/noise patch stimulus pair, rivalry rate of the glaucoma group (11 ± 6 switches/min) was lower than that of the control group (16 ± 7 switches/min) in the LH, but the difference failed to reach significance. Interestingly, the mixed percept dominated less in glaucoma than in the control group. For the synthetic face/spiral stimulus pair, the glaucoma group had lower rivalry rate at all 3 stimulus locations.ConclusionThis study reveals atypical responses to faces during binocular rivalry in patients with early glaucoma. The results may be suggestive of early neurodegeneration affecting stimulus-specific neural structures involved in face processing starting in the pre-perimetric phase of the disease.

When the two eyes are presented with highly distinct stimuli, the resulting visual percept generally switches every few seconds between the two monocular images in an irregular fashion, giving rise to a phenomenon known as binocular rivalry. While a host of theoretical studies have explored potential mechanisms for binocular rivalry in the context of evoked model dynamics in response to simple stimuli, here we investigate binocular rivalry directly through complex stimulus reconstructions based on the activity of a two-layer neuronal network model with competing downstream pools driven by disparate monocular stimuli composed of image pixels. To estimate the dynamic percept, we derive a linear input-output mapping rooted in the non-linear network dynamics and iteratively apply compressive sensing techniques for signal recovery. Utilizing a dominance metric, we are able to identify when percept alternations occur and use data collected during each dominance period to generate a sequence of percept reconstructions. We show that despite the approximate nature of the input-output mapping and the significant reduction in neurons downstream relative to stimulus pixels, the dominant monocular image is well-encoded in the network dynamics and improvements are garnered when realistic spatial receptive field structure is incorporated into the feedforward connectivity. Our model demonstrates gamma-distributed dominance durations and well obeys Levelt's four laws for how dominance durations change with stimulus strength, agreeing with key recurring experimental observations often used to benchmark rivalry models. In light of evidence that individuals with autism exhibit relatively slow percept switching in binocular rivalry, we corroborate the ubiquitous hypothesis that autism manifests from reduced inhibition in the brain by systematically probing our model alternation rate across choices of inhibition strength. We exhibit sufficient conditions for producing binocular rivalry in the context of natural scene stimuli, opening a clearer window into the dynamic brain computations that vary with the generated percept and a potential path toward further understanding neurological disorders.

Incoming sensory signals are often ambiguous and consistent with multiple perceptual interpretations. Information from one sensory modality can help to resolve ambiguity in another modality, but the mechanisms by which multisensory associations come to influence the contents of conscious perception are unclear. We asked whether and how novel statistical information about the coupling between sounds and images influences the early stages of awareness of visual stimuli. We exposed subjects to consistent, arbitrary pairings of sounds and images and then measured the impact of this recent passive statistical learning on subjects' initial conscious perception of a stimulus by employing binocular rivalry, a phenomenon in which incompatible images presented separately to the two eyes result in a perceptual alternation between the two images. On each trial of the rivalry test, subjects were presented with a pair of rivalrous images (one of which had been consistently paired with a specific sound during exposure while the other had not) and an accompanying sound. We found that, at the onset of binocular rivalry, an image was significantly more likely to be perceived, and was perceived for a longer duration, when it was presented with its paired sound than when presented with other sounds. Our results indicate that recently acquired multisensory information helps resolve sensory ambiguity, and they demonstrate that statistical learning is a fast, flexible mechanism that facilitates this process.

Introduction: The electroencephalographic brain response to a deviation from the preceding sequential regularity of visual events, called visual mismatch negativity (vMMN), is well known to reflect automatic visual change detection. Our preliminary study showed a significant correlation between the enhancement of the vMMN amplitude and facilitation of perceptual alternation in binocular rivalry when the deviant stimulus was presented unconsciously. This implies that the vMMN is relevant to access processing, in which the unconscious stimulus is consciously perceived. Recent studies have reported that theta band oscillation evoked by a deviant stimulus is involved in evoking vMMN. However, it has not been clarified whether theta band oscillation associated with vMMN is also relevant to access processing. Methods: We analyzed the correlations between event-related spectral perturbation (ERSP) and inter-trial phase coherence (ITPC) in the theta band and the proportion of perceptual alternation from before to after the presentation of deviation in the same experimental paradigm as in our previous study. Results: We found that an increase in ITPC in the theta band tended to correlate with facilitation of perceptual alternation in binocular rivalry when the deviant was presented unconsciously, but there was no significant correlation in ERSP. Discussion: The results suggest that theta phase coherence underlying the visual mismatch process is relevant to the access processing. [ABSTRACT FROM AUTHOR]

Brain plasticity and function is impaired in conditions of metabolic dysregulation, such as obesity. Less is known on whether brain function is also affected by transient and physiological metabolic changes, such as the alternation between fasting and fed state. Here we asked whether these changes affect the transient shift of ocular dominance that follows short‐term monocular deprivation, a form of homeostatic plasticity. We further asked whether variations in three of the main metabolic and hormonal pathways affected in obesity (glucose metabolism, leptin signalling and fatty acid metabolism) correlate with plasticity changes. We measured the effects of 2 h monocular deprivation in three conditions: post‐absorptive state (fasting), after ingestion of a standardised meal and during infusion of glucagon‐like peptide‐1 (GLP‐1), an incretin physiologically released upon meal ingestion that plays a key role in glucose metabolism. We found that short‐term plasticity was less manifest in fasting than in fed state, whereas GLP‐1 infusion did not elicit reliable changes compared to fasting. Although we confirmed a positive association between plasticity and supraphysiological GLP‐1 levels, achieved by GLP‐1 infusion, we found that none of the parameters linked to glucose metabolism could predict the plasticity reduction in the fasting versus fed state. Instead, this was selectively associated with the increase in plasma beta‐hydroxybutyrate (B‐OH) levels during fasting, which suggests a link between neural function and energy substrates alternative to glucose. These results reveal a previously unexplored link between homeostatic brain plasticity and the physiological changes associated with the daily fast‐fed cycle. [ABSTRACT FROM AUTHOR]

Continuous flash suppression leverages binocular rivalry to render observers unaware of a static image for several seconds. To achieve this effect, rapidly flashing noise masks are presented to the dominant eye while a static stimulus is presented to the non-dominant eye. Eventually "breakthrough" occurs, wherein awareness shifts to the static image shown to the non-dominant eye. We tested the hypothesis that Gestalt formation can promote breakthrough. In two experiments, we presented pacman-shaped objects that might or might not align to form illusory Kanizsa objects. To measure the inception of breakthrough, observers were instructed to press a key at the moment of partial breakthrough. After pressing the key, which stopped the trial, observers reported how many pacmen were seen and where they were located. Supporting the Gestalt hypothesis, breakthrough was faster when the pacmen were aligned and observers more often reported pairs of pacmen if they were aligned. To address whether these effects reflected illusory shape perception, a computational model was applied to the pacman report distributions and breakthrough times for an experiment with four pacmen. A full account of the data required an increased joint probability of reporting all four pacmen, suggesting an influence of a perceived illusory cross. [ABSTRACT FROM AUTHOR]