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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]

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]

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]

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]

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]

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]

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]

Attention helps in selection among competing stimuli, but attentional selection also biases subsequent information processing as a prior experience. Previous studies have demonstrated that intertrial repetition of target features or locations facilitates perceptual processing as selection history guides attention. In the current study, we found that eye selection history in binocular rivalry induces eye-specific attentional bias. In four experiments, participants responded to the target presented at one of the locations on either eye. The results showed that the target was detected faster when presented to the same eye as in the previous trial under binocular rivalry. However, the effect of eye repetition was not observed when the interocular conflict was reduced by presenting stimuli to only one eye on each trial. Our result indicates that eye selection history can affect eye dominance during binocular rivalry as attention amplifies selected information among competing inputs. These findings suggest that prior experience of attentional deployment modulates subsequent information processing owing to the residual effect of attentional amplification. [ABSTRACT FROM AUTHOR]

In an era of increasing screen consumption, the requirement for binocular vision is demanding, leading to the emergence of syndromes such as the computer vision syndrome (CVS) or visual discomfort reported by virtual reality (VR) users. Heterophoria (phoria) is a latent eye misalignment (with a prevalence up to 35%) that appears in conditions that disrupt binocular vision and may affect the quality of binocular fusion. Collinear facilitation (CF), the mechanism for grouping contour elements, is a process that reveals lateral interactions by improving the visibility of a target by flankers placed collinearly. An abnormal pattern of CF has been observed in strabismic amblyopia. We hypothesize that phoria may affect CF in the horizontal meridian (HM) due to latent eye misalignment and its impact on binocular fusion. Fully corrected participants (phoria group and controls) completed a standard CF experiment for horizontal and vertical meridians during binocular and monocular viewing. Phoric observers exhibited (1) an asymmetry and an abnormal pattern of CF only for the HM, during both monocular and binocular viewing, (2) poor binocular summation between the monocular inputs, and (3) no binocular advantage of the CF. Phoria affects the CF in a way that is reminiscent of meridional amblyopia without being attributed to abnormal refraction. The abnormal pattern of CF in monocular viewing suggests that phoria could be a binocular developmental disorder that affects monocular spatial interactions. We suggest that the results could contribute to explain the visual discomfort experienced with VR users or symptoms when presenting CVS. [ABSTRACT FROM AUTHOR]

Aim of the study was to assess: (a) the prevalence and type of strabismus, ptosis and eyelid dynamic disorders features, (b) the prevalence of refractive errors, amblyopia and, (c) their association with ocular/systemic syndromes in a cohort of patients. This is a retrospective observational multicenter cohort study. Patients with coexisting ocular motility disorders, comitant and incomitant strabismus, ptosis and dynamic eyelid disorders who have never undergone surgery were enrolled throughout a 3-years a study period. 137 out of 19,089 patients were enrolled, of which 97 with uniocular and 40 with binocular disease. Isolated congenital ptosis was observed in 84 patients. A polymalformative syndrome was present in almost one third of cases, whilst among strabismus type, esotropia was slightly more prevalent. Most patients were hypermetropic. In monocular disease, myopia mainly affected older patients, who were characterized by a worse ptosis margin reflex distance and levator function, and significantly higher astigmatism. Amblyopia occurred in 67.4% of the study sub-population. Of note, in monocular disease this was mild in 25.8%, moderate in 24.2% and severe in 11.3% of cases, whilst in binocular disease it was mild in 25%, moderate in 41.7% and severe in 16.7%. All patients with coexisting eyelid and ocular motility dysfunctions in pediatric age need ophthalmologic and systemic evaluation to accurately assess amblyopia, refractive errors and systemic/ocular disorders. [ABSTRACT FROM AUTHOR]

The purpose of stereoscopic image quality assessment (SIQA) is to design an objective evaluation algorithm to automatically evaluate the quality of stereoscopic image. In this paper, we propose a blind SIQA method via 3D saliency selected binocular perception and 3D convolutional neural network (CNN). Given a pair of stereoscopic images, we first generate 3D saliency map by weighted average of 2D saliency map and depth saliency map. Then, when the value of 3D saliency map patches is higher than the setting threshold, these patches from left and right images are selected to feed to 3D-CNN to predict the perceived quality. Finally, the score of the distorted stereoscopic image is computed by the weighted average of the quality scores of these saliency image patches. Experimental results on LIVE 3D Phase I and Phase II databases show that our proposed method is robust and competitive with the state-of-the-art NR SIQA methods. [ABSTRACT FROM AUTHOR]

Introduction: Past studies have provided evidence that the effects of tactile stimulation on binocular rivalry are mediated by primitive features (orientation and spatial frequency) common in vision and touch. In this study, we examined whether such effects on binocular rivalry can be obtained through the roughness of naturalistic objects. In three experiments, the total dominant time of visual percepts of two objects was measured under binocular rivalry when participants touched one of the objects. Result: In Experiment 1, the total dominant time for the image of artificial turf and bathmat was prolonged by congruent tactile stimulation and shortened by incongruent tactile stimulation. In Experiment 2, we used the same stimuli but rotated their visual images in opposite directions. The dominant time for either image was prolonged by congruent tactile stimulation. In Experiment 3, we used different types of stimuli, smooth marble and rough fabric, and noted significant effects of the congruent and incongruent tactile stimulation on the dominant time of visual percepts. Conclusion: These three experiments demonstrated that visuo-tactile interaction on binocular rivalry can be mediated by roughness. [ABSTRACT FROM AUTHOR]

Early models of multisensory integration posited that cross-modal signals only converged in higher-order association cortices and that vision automatically dominates. However, recent studies have challenged this view. In this study, the significance of the alignment of motion axes and spatial alignment across visual and tactile stimuli, as well as the effect of hand visibility on visuo-tactile interactions were examined. Using binocular rivalry, opposed motions were presented to each eye and participants were required to track the perceived visual direction. A tactile motion that was either a leftward or rightward sweep across the fingerpad was intermittently presented. Results showed that tactile effects on visual percepts were dependent on the alignment of motion axes: rivalry between up/down visual motions was not modulated at all by left/right tactile motion. On the other hand, visual percepts could be altered by tactile motion signals when both modalities shared a common axis of motion: a tactile stimulus could maintain the dominance duration of a congruent visual stimulus and shorten its suppression period. The effects were also conditional on the spatial alignment of the visual and tactile stimuli, being eliminated when the tactile device was displaced 15 cm away to the right of the visual stimulus. In contrast, visibility of the hand touching the tactile stimulus facilitated congruent switches relative to a visual-only baseline but did not present a significant advantage overall. In sum, these results show a low-level sensory interaction that is conditional on visual and tactile stimuli sharing a common motion axis and location in space. [ABSTRACT FROM AUTHOR]

Sensory differences between autism and neuro-typical populations are well-documented and have often been explained by either weak-central-coherence or excitation/inhibition-imbalance cortical theories. We tested these theories with perceptual multi-stability paradigms in which dissimilar images presented to each eye generate dynamic cyclopean percepts based on ongoing cortical grouping and suppression processes. We studied perceptual multi-stability with Interocular Grouping (IOG), which requires the simultaneous integration and suppression of image fragments from both eyes, and Conventional Binocular Rivalry (CBR), which only requires global suppression of either eye, in 17 autistic adults and 18 neurotypical participants. We used a Hidden-Markov-Model as tool to analyze the multistable dynamics of these processes. Overall, the dynamics of multi-stable perception were slower (i.e. there were longer durations and fewer transitions among perceptual states) in the autistic group compared to the neurotypical group for both IOG and CBR. The weighted Markovian transition distributions revealed key differences between both groups and paradigms. The results indicate overall lower levels of suppression and decreased levels of grouping in autistic than neurotypical participants, consistent with elements of excitation/inhibition imbalance and weak-central-coherence theories. [ABSTRACT FROM AUTHOR]

The numerous multistable phenomena in vision, hearing and touch attest that the inner workings of perception are prone to instability. We investigated a visual example—binocular rivalry—with an accurate no-report paradigm, and uncovered developmental and maturational lifespan trajectories that were specific for age and sex. To interpret these trajectories, we hypothesized that conflicting objectives of visual perception—such as stability of appearance, sensitivity to visual detail, and exploration of fundamental alternatives—change in relative importance over the lifespan. Computational modelling of our empirical results allowed us to estimate this putative development of stability, sensitivity, and exploration over the lifespan. Our results confirmed prior findings of developmental psychology and appear to quantify important aspects of neurocognitive phenotype. Additionally, we report atypical function of binocular rivalry in autism spectrum disorder and borderline personality disorder. Our computational approach offers new ways of quantifying neurocognitive phenotypes both in development and in dysfunction. [ABSTRACT FROM AUTHOR]

When several multistable displays are viewed simultaneously, their perception is synchronized, as they tend to be in the same perceptual state. Here, we investigated the possibility that perception may reflect embedded statistical knowledge of physical interaction between objects for specific combinations of displays and layouts. We used a novel display with two ambiguously rotating gears and an ambiguous walker-on-a-ball display. Both stimuli produce a physically congruent perception when an interaction is possible (i.e., gears counterrotate, and the ball rolls under the walker's feet). Next, we gradually manipulated the stimuli to either introduce abrupt changes to the potential physical interaction between objects or keep it constant despite changes in the visual stimulus. We characterized the data using four different models that assumed (1) independence of perception of the stimulus, (2) dependence on the stimulus's properties, (3) dependence on physical configuration alone, and (4) an interaction between stimulus properties and a physical configuration. We observed that for the ambiguous gears, the perception was correlated with the stimulus changes rather than with the possibility of physical interaction. The perception of walker-on-a-ball was independent of the stimulus but depended instead on whether participants responded about a relative motion of two objects (perception was biased towards physically congruent motion) or the absolute motion of the walker alone (perception was independent of the rotation of the ball). None of the two experiments supported the idea of embedded knowledge of physical interaction. [ABSTRACT FROM AUTHOR]

The Wilson–Cowan equations were developed to provide a simplified yet powerful description of neural network dynamics. As such, they embraced nonlinear dynamics, but in an interpretable form. Most importantly, it was the first mathematical formulation to emphasize the significance of interactions between excitatory and inhibitory neural populations, thereby incorporating both cooperation and competition. Subsequent research by many has documented the Wilson–Cowan significance in such diverse fields as visual hallucinations, memory, binocular rivalry, and epilepsy. The fact that these equations are still being used to elucidate a wide range of phenomena attests to their validity as a dynamical approximation to more detailed descriptions of complex neural computations. [ABSTRACT FROM AUTHOR]

Current research practices have revealed that the neural mechanisms driving visual consciousness alternations in binocular rivalry come from the primary visual cortex, i.e., stimulus rivalry can be induced by monocular neurons. However, the competition mechanisms of the monocular neurons remain unclear. In this paper, we probe the dynamical characteristics of a monolayer binocular rivalry model (which contains four monocular neurons) with different types of stimuli, including fixed inputs, swap, flicker, swap and flicker, swap and blanks, respectively. Firstly, we study the dynamic effects of the traditional stimuli with fixed inputs (but with different grating conditions) on the monolayer rivalry model. Results show that Hopf bifurcations can induce three types of dynamical behaviors: winner-take-all (WTA), rivalry oscillation (RIV), and same activity (SAM), which are similar to other binocular rivalry models. Besides, the simulation results indicate that the competition mechanisms of the monolayer binocular rivalry model are more consistent with the experimental results compared with the hierarchical rivalry model proposed by Wilson. Secondly, the dynamical mechanisms of the monolayer rivalry model with four types of time-dependent stimuli are investigated. More complex dynamical behaviors including WTA-Mod, RIV-Mod, SAM-Mod induced by torus bifurcations and cycle skipping, multi-cycle skipping, chaos induced by period-doubling bifurcation, appear with different types of periodic stimuli. Finally, we analyze the perceptual alternation mechanisms based on the temporal characteristics of the monolayer rivalry model, and results are more consistent with the empirical findings compared with the hierarchical rivalry model. Our simulations and analysis provide a new opportunity for future experiments to investigate the neural mechanisms of binocular rivalry. [ABSTRACT FROM AUTHOR]

Affective states influence our decisions even when processed unconsciously. Continuous flash suppression (CFS) is a new variant of binocular rivalry that can be used to render the prime subliminal. Nonetheless, how prior information from emotional faces suppressed by CFS influences subsequent decision-making remains unclear. Here, we employed a CFS priming task to examine the effect of the two main types of information conveyed by faces, i.e., facial identity and emotion, on the evaluation of target words as positive or negative. The hierarchical diffusion model was used to investigate the underlying mechanisms. A significant interaction effect on response time was observed following the angry face prime but not the happy or neutral face primes. The results of the diffusion model analyses revealed that the priming effects of facial identity were mapped onto the drift rate and erased the 'positive bias' (the processing advantage of positive over negative stimuli). Meanwhile, the positive emotional faces increased the nondecision time in response to negative target words. The model-based analysis implies that both facial identity and emotion are processed under CFS. [ABSTRACT FROM AUTHOR]

Interocular suppression is the phenomenon in which the signal from one eye inhibits the other eye in the presence of dissimilar images. Various clinical and laboratory-based tests have been used to assess suppression, which vary in color, contrast, and stimulus size. These stimulus variations may yield different spatial extents of suppression, which makes it difficult to compare the outcomes. To evaluate the role of stimulus characteristics, we measured the suppression zone using a binocular rivalry paradigm in normally-sighted observers by systematically varying the stimulus parameters. The stimuli consist of a constantly visible horizontal reference seen by one eye while two vertical suppressors were presented to the other eye. With a keypress, the suppressors appeared for 1 s, to induce a transient suppression zone in the middle part of the reference. Subjects adjusted the width between the suppressors to determine the zone. The zone decreased significantly with increasing spatial frequency and lower contrast. The width was 1.4 times larger than the height. The zone was smaller with negative compared to positive contrast polarity but independent of eye dominance, luminance, and colored filters. A departure from scale invariance was captured with a model suggesting a stimulus-dependent and a small fixed non-stimulus-dependent portion. [ABSTRACT FROM AUTHOR]

Binocular rivalry occurs when the two eyes are presented with incompatible stimuli and perception alternates between these two stimuli. This phenomenon has been investigated in two types of experiments: (1) Traditional experiments where the stimulus is fixed, (2) eye-swap experiments in which the stimulus periodically swaps between eyes many times per second (Logothetis et al. in Nature 380(6575):621–624, 1996). In spite of the rapid swapping between eyes, perception can be stable for many seconds with specific stimulus parameter configurations. Wilson introduced a two-stage, hierarchical model to explain both types of experiments (Wilson in Proc. Natl. Acad. Sci. 100(24):14499–14503, 2003). Wilson's model and other rivalry models have been only studied with bifurcation analysis for fixed inputs and different types of dynamical behavior that can occur with periodically forcing inputs have not been investigated. Here we report (1) a more complete description of the complex dynamics in the unforced Wilson model, (2) a bifurcation analysis with periodic forcing. Previously, bifurcation analysis of the Wilson model with fixed inputs has revealed three main types of dynamical behaviors: Winner-takes-all (WTA), Rivalry oscillations (RIV), Simultaneous activity (SIM). Our results have revealed richer dynamics including mixed-mode oscillations (MMOs) and a period-doubling cascade, which corresponds to low-amplitude WTA (LAWTA) oscillations. On the other hand, studying rivalry models with numerical continuation shows that periodic forcing with high frequency (e.g. 18 Hz, known as flicker) modulates the three main types of behaviors that occur with fixed inputs with forcing frequency (WTA-Mod, RIV-Mod, SIM-Mod). However, dynamical behavior will be different with low frequency periodic forcing (around 1.5 Hz, so-called swap). In addition to WTA-Mod and SIM-Mod, cycle skipping, multi-cycle skipping and chaotic dynamics are found. This research provides a framework for either assessing binocular rivalry models to check consistency with empirical results, or for better understanding neural dynamics and mechanisms necessary to implement a minimal binocular rivalry model. [ABSTRACT FROM AUTHOR]

When one eye is presented with an image that is distinct from the image presented to the other eye, the eyes start to rival and suppress each other's image. Binocular rivalry leads to perceptual alternations between the images of each eye, during which only one of the images is perceived at a time. However, when the eyes exert weak and shallow suppression, participants tend to perceive both images intermixed more often. A recent study proposed that the precedence of mixed percepts positively correlates with the degree of adaptation to conflict between the eyes. However, this study neglected the role of visual transients, which covaried with the degree of conflict in the stimulus design. Here we report that not the conflict between the eyes but prolonged and repeated observations of strong visual transients cause participants to report more mixed percepts. We conclude that visual transients, such as sudden changes in contrast, draw attention, strengthen both eyes' image representations, and facilitate the adaptation to interocular suppression, which consequentially disrupts the spatial coherence in binocular rivalry. This finding is relevant to virtual- and augmented reality for which it is crucial to design stereoscopic environments in which binocular rivalry is limited. [ABSTRACT FROM AUTHOR]

The efficient processing of complex visual environments is essential for effective functioning. In the natural environment, processing the context is as important as the processing of the target object since no object can be found in isolation. Congruent object-context associations in a visual scene facilitate object recognition, whereas incongruent associations decrease performance accuracy. Although there is a performance reduction, incongruent scenes are reported to have a perceptual bias due to the reallocation of the attentional resources towards the associated semantic conflict. Another key attribute that prepares the visual system to identify the important aspects of the environment is valence, and any visual scene can be classified into one of the three valence categories. Hence, the current study was designed to investigate how valence influences the perceptual bias towards incongruent object-context associations. An intermittent binocular rivalry task was used to measure the perceptual bias across valence categories. The results revealed a significant predominance of incongruent pictures when the associated valence was negative and neutral and remained unbiased for positive valence. We propose a valence–congruency interaction in which perceptual bias towards incongruence is greatly influenced by valence. [ABSTRACT FROM AUTHOR]

When similar visual stimuli are presented binocularly to both eyes, one perceives a fused single image. However, when the two stimuli are distinct, one does not perceive a single image; instead, one perceives binocular rivalry. That is, one perceives one of the stimulated patterns for a few seconds, then the other for few seconds, and so on – with random transitions between the two percepts. Most theoretical studies focus on rivalry, with few considering the coexistence of fusion and rivalry. Here we develop three distinct computational neuronal network models which capture binocular rivalry with realistic stochastic properties, fusion, and the hysteretic transition between. Each is a conductance-based point neuron model, which is multi-layer with two ocular dominance columns (L & R) and with an idealized "ring" architecture where the orientation preference of each neuron labels its location on a ring. In each model, the primary mechanism initiating binocular rivalry is cross-column inhibition, with firing rate adaptation governing the temporal properties of the transitions between percepts. Under stimulation by similar visual patterns, each of three models uses its own mechanism to overcome cross-column inhibition, and thus to prevent rivalry and allow the fusion of similar images: The first model uses cross-column feedforward inhibition from the opposite eye to "shut off" the cross-column feedback inhibition; the second model "turns on" a second layer of monocular neurons as a parallel pathway to the binocular neurons, rivaling out of phase with the first layer, and together these two pathways represent fusion; and the third model uses cross-column excitation to overcome the cross-column inhibition and enable fusion. Thus, each of the idealized ring models depends upon a different mechanism for fusion that might emerge as an underlying mechanism present in real visual cortex. [ABSTRACT FROM AUTHOR]

Ambiguous visual images can generate dynamic and stochastic switches in perceptual interpretation known as perceptual rivalry. Such dynamics have primarily been studied in the context of rivalry between two percepts, but there is growing interest in the neural mechanisms that drive rivalry between more than two percepts. In recent experiments, we showed that split images presented to each eye lead to subjects perceiving four stochastically alternating percepts (Jacot-Guillarmod et al. Vision research, 133, 37–46, 2017): two single eye images and two interocularly grouped images. Here we propose a hierarchical neural network model that exhibits dynamics consistent with our experimental observations. The model consists of two levels, with the first representing monocular activity, and the second representing activity in higher visual areas. The model produces stochastically switching solutions, whose dependence on task parameters is consistent with four generalized Levelt Propositions, and with experiments. Moreover, dynamics restricted to invariant subspaces of the model demonstrate simpler forms of bistable rivalry. Thus, our hierarchical model generalizes past, validated models of binocular rivalry. This neuromechanistic model also allows us to probe the roles of interactions between populations at the network level. Generalized Levelt's Propositions hold as long as feedback from the higher to lower visual areas is weak, and the adaptation and mutual inhibition at the higher level is not too strong. Our results suggest constraints on the architecture of the visual system and show that complex visual stimuli can be used in perceptual rivalry experiments to develop more detailed mechanistic models of perceptual processing. [ABSTRACT FROM AUTHOR]

Anne Treisman investigated many aspects of perception, and in particular the roles of different forms of attention. Four aspects of her work are reviewed here, including visual search, set mean perception, perception in special populations, and binocular rivalry. The importance of the breakthrough in each case is demonstrated. Search is easy or slow depending on whether it depends on the application of global or focused attention. Mean perception depends on global attention and affords simultaneous representation of the means of at least two sets of elements, and then of comparing them. Deficits exhibited in Balint's or unilateral neglect patients identify basic sensory system mechanisms. And, the ability to integrate binocular information for stereopsis despite simultaneous binocular rivalry for color, demonstrates the division of labor underlying visual system computations. All these studies are related to an appreciation of the difference between perceiving the gist of a scene, its elements or objects, versus perceiving the details of the scene and its components. This relationship between Anne Treisman's revolutionary discoveries and the concept of gist perception is the core of the current review. [ABSTRACT FROM AUTHOR]

Some aspects of decision-making are known to decline with normal aging. One of the known perceptual decision-making processes which is vastly studied is binocular rivalry. It is well-established that the older the person, the slower the perceptual dynamics. However, the underlying neurobiological cause is unknown. So, to understand how age affects visual decision-making, we investigated age-related changes in perception during binocular rivalry. In binocular rivalry, the image presented to one eye competes for perceptual dominance with the image presented to the other eye. Perception during binocular rivalry consists of alternations between exclusive percepts. However, frequently, mixed percepts with combinations of the two monocular images occur. The mixed percepts reflect a transition from the percept of one eye to the other but frequently the transitions do not complete the full cycle and the previous exclusive percept becomes dominant again. The transitional idiosyncrasy of mixed percepts has not been studied systematically in different age groups. Previously, we have found evidence for adaptation and noise, and not inhibition, as underlying neural factors that are related to age-dependent perceptual decisions. Based on those conclusions, we predict that mixed percepts/inhibitory interactions should not change with aging. Therefore, in an old and a young age group, we studied binocular rivalry dynamics considering both exclusive and mixed percepts by using two paradigms: percept-choice and percept-switch. We found a decrease in perceptual alternation Probability for older adults, although the rate of mixed percepts did not differ significantly compared to younger adults. Interestingly, the mixed percepts play a very similar transitional idiosyncrasy in our different age groups. Further analyses suggest that differences in synaptic depression, gain modulation at the input level, and/or slower execution of motor commands are not the determining factors to explain these findings. We then argue that changes in perceptual decisions at an older age are the result of changes in neural adaptation and noise. [ABSTRACT FROM AUTHOR]

An animal's environment is rich with affordances. Different possible actions are specified by visual information while competing for dominance over neural dynamics. Affordance competition models account for this in terms of winner-takes-all cross-inhibition dynamics. Multistable phenomena also reveal how the visual system deals with ambiguity. Their key property is spontaneous instability, in forms such as alternating dominance in binocular rivalry. Theoretical models of self-inhibition or self-organized instability posit that the instability is tied to some kind of neural adaptation and that its functional significance is to enable flexible perceptual transitions. We hypothesized that the two perspectives are interlinked. Spontaneous instability is an intrinsic property of perceptual systems, but it is revealed when they are stripped from the constraints of possibilities for action. To test this, we compared a multistable gestalt phenomenon against its embodied version and estimated the neural adaptation and competition parameters of an affordance transition dynamic model. Wertheimer's (Zeitschrift fur Psychologie 61, 161–265, 1912) optimal (β) and pure (φ) forms of apparent motion from a stroboscopic point-light display were endowed with action relevance by embedding the display in a visual object-tracking task. Thus, each mode was complemented by its action, because each perceptual mode uniquely enabled different ways of tracking the target. Perceptual judgment of the traditional apparent motion exhibited spontaneous instabilities, in the form of earlier switching when the frame rate was changed stepwise. In contrast, the embodied version exhibited hysteresis, consistent with affordance transition studies. Consistent with our predictions, the parameter for competition between modes in the affordance transition model increased, and the parameter for self-inhibition vanished. [ABSTRACT FROM AUTHOR]

There is an ongoing debate whether or not multisensory interactions require awareness of the sensory signals. Static visual and tactile stimuli have been shown to influence each other even in the absence of visual awareness. However, it is unclear if this finding generalizes to dynamic contexts. In the present study, we presented visual and tactile motion stimuli and induced fluctuations of visual awareness by means of binocular rivalry: two gratings which drifted in opposite directions were displayed, one to each eye. One visual motion stimulus dominated and reached awareness while the other visual stimulus was suppressed from awareness. Tactile motion stimuli were presented at random time points during the visual stimulation. The motion direction of a tactile stimulus always matched the direction of one of the concurrently presented visual stimuli. The visual gratings were differently tinted, and participants reported the color of the currently seen stimulus. Tactile motion delayed perceptual switches that ended dominance periods of congruently moving visual stimuli compared to switches during visual-only stimulation. In addition, tactile motion fostered the return to dominance of suppressed, congruently moving visual stimuli, but only if the tactile motion started at a late stage of the ongoing visual suppression period. At later stages, perceptual suppression is typically decreasing. These results suggest that visual awareness facilitates but does not gate multisensory interactions between visual and tactile motion signals. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Identifying the neuronal basis of spontaneous changes in conscious experience in the absence of changes in the external environment is a major challenge. Binocular rivalry, in which two stationary monocular images lead to continuously changing perception, provides a unique opportunity to address this issue. We studied the activity of human single neurons in the medial temporal and frontal lobes while patients were engaged in binocular rivalry. Here we report that internal changes in the content of perception are signaled by very early (~-2000 ms) nonselective medial frontal activity, followed by selective activity of medial temporal lobe neurons that precedes the perceptual change by ~1000 ms. Such early activations are not found for externally driven perceptual changes. These results suggest that a medial fronto-temporal network may be involved in the preconscious internal generation of perceptual transitions. [ABSTRACT FROM AUTHOR]

We apply the competitive model of Loxley and Robinson (Phys Rev Lett 102:258701, 2009. doi:) to the study of a special case of visual rivalry. Three-peaked inputs with maxima at symmetrical locations are introduced, and the role of three-bump configurations is then considered. The model yields conditions for what can be interpreted as a bistable percept analogous to the one-dimensional version of a competition between the central and flanking parts of an image. [ABSTRACT FROM AUTHOR]

When two eyes are simultaneously stimulated by two inconsistent images, the observer's perception switches between the two images every few seconds such that only one image is perceived at a time. This phenomenon is named binocular rivalry (BR). However, sometimes the perceived image is a piecemeal mixed of two stimuli known as piecemeal perceptions. In this study, a BR task was designed in which orthogonal gratings are presented to the two eyes. The subjects were trained to report 3 states: dominant perceptions (two state matching to perceived grating orientation) and the piecemeal perceptions (third state). We explored the scale-freeness of the BR percept durations considering the two dominant monocular states as well as the piecemeal transition state using detrended fluctuation analysis. Our results reproduced the previous finding of memory in the perceptual switches between the monocular perception states. Moreover, we showed that such memory also exists in the transitory periods of dichoptic piecemeal perceptions. These results support our hypothesis that the pool of unstable piecemeal perceptions could be regarded as separate multiple low-depth basin in the perceptual state landscape. Likewise, the transitions from these piecemeal state basins and stable monocular state basins are faced with resistance. Therefore there is inertia and memory (i.e. positive serial correlation) for the piecemeal dichoptic perception states as well as the monocular states. [ABSTRACT FROM AUTHOR]

When dissimilar monocular images are viewed simultaneously by the two eyes, stable binocular vision gives way to unstable vision characterized by alternations in dominance between the two images in a phenomenon called binocular rivalry. These alternations in perception reveal the existence of inhibitory interactions between neural representations associated with conflicting visual inputs. Binocular rivalry has been studied since the days of Wheatstone, but one recent strategy is to investigate its susceptibility to influences caused by one's own motor activity. This paper focused on the activity of walking, which produces an expected, characteristic direction of optic flow dependent upon the direction of one's walking. In a set of experiments, we employed virtual reality technology to present dichoptic stimuli to observers who walked forward, backward, or were sitting. Optic flow was presented to a given eye, and was sometimes congruent with the direction of walking, sometimes incongruent, and sometimes random, except when the participant was sitting. Our results indicate that, while walking had a reliable influence on rivalry dynamics, the predominance of congruent or incongruent motion did not. [ABSTRACT FROM AUTHOR]

Binocular rivalry is a phenomenon of visual competition in which perception alternates between two monocular images. When two eye's images only differ in luminance, observers may perceive shininess, a form of rivalry called binocular luster. Does dichoptic information guide attention in visual search? Wolfe and Franzel ( Perception & Psychophysics, 44(1), 81-93, 1988) reported that rivalry could guide attention only weakly, but that luster (shininess) 'popped out,' producing very shallow Reaction Time (RT) × Set Size functions. In this study, we have revisited the topic with new and improved stimuli. By using a checkerboard pattern in rivalry experiments, we found that search for rivalry can be more efficient (16 ms/item) than standard, rivalrous grating (30 ms/item). The checkerboard may reduce distracting orientation signals that masked the salience of rivalry between simple orthogonal gratings. Lustrous stimuli did not pop out when potential contrast and luminance artifacts were reduced. However, search efficiency was substantially improved when luster was added to the search target. Both rivalry and luster tasks can produce search asymmetries, as is characteristic of guiding features in search. These results suggest that interocular differences that produce rivalry or luster can guide attention, but these effects are relatively weak and can be hidden by other features like luminance and orientation in visual search tasks. [ABSTRACT FROM AUTHOR]

We use the hierarchical nature of Bayesian perceptual inference to explain a fundamental aspect of the temporality of experience, namely the phenomenology of temporal flow. The explanation says that the sense of temporal flow in conscious perception stems from probabilistic inference that the present cannot be trusted. The account begins by describing hierarchical inference under the notion of prediction error minimization, and exemplifies distrust of the present within bistable visual perception and action initiation. Distrust of the present is then discussed in relation to previous research on temporal phenomenology. Finally, we discuss how there may be individual differences in the experience of temporal flow, in particular along the autism spectrum. The resulting view is that the sense of temporal flow in conscious perception results from an internal, inferential process. [ABSTRACT FROM AUTHOR]

In this paper, a no-reference perceptual quality assessment for stereoscopic image is proposed. Inspired by the binocular rivalry mechanism, the observation annoyance perception is explained as a bargain process. Game theory is exploited to model the rivalry of the left eye and right eye. The relation between annoyance perception with binocular disparity is further demonstrated and an annoyance map is calculated to simulate the observer perception. Then, with the consideration of the properties of HVS, the edge map and a saliency map are used to adjust the annoyance map. Finally, Minkowski pooling and multi-scale strategy are applied to compute the final score. We use the EPFL database to validate the proposed metric. The experimental results show that the final objective scores have a high degree of consistency with the subjective scores. [ABSTRACT FROM AUTHOR]

Attentional influence over perception is particularly pronounced when sensory stimulation is ambiguous, where attention can reduce stimulus uncertainty and promote a stable interpretation of the world. However, binocular rivalry, an extensively studied visual ambiguity, has proved to be comparatively resistant to attentional modulation. We hypothesize that this apparent inconsistency reflects fluctuations in the degree of unresolved competition during binocular rivalry. Namely, attentional influence over rivalry dynamics should be limited to phases of relatively unresolved stimulus competition, such as ends of individual dominance periods. We found that transient, feature-based cues congruent with the dominant stimulus prolonged dominance durations, while cues matching the suppressed stimulus hastened its return to dominance. Notably, the effect of cues depended on when the cues are presented. Cues presented late, but not early, during a given episode of perceptual dominance influenced rivalry dynamics. This temporal pattern mirrors known changes in the relative competitive dynamics of rival stimuli, revealing that selective effects occur only during temporal windows containing weak resolution of visual competition. In conclusion, these findings reveal that unresolved competition, which gates attention across a variety of domains, is also crucial in determining the susceptibility of binocular rivalry to selective influences. [ABSTRACT FROM AUTHOR]

Binocular rivalry and stimulus rivalry are two forms of perceptual instability that arise when the visual system is confronted with conflicting stimulus information. In the case of binocular rivalry, dissimilar monocular stimuli are presented to the two eyes for an extended period of time, whereas for stimulus rivalry the dissimilar monocular stimuli are exchanged rapidly and repetitively between the eyes during extended viewing. With both forms of rivalry, one experiences extended durations of exclusive perceptual dominance that fluctuate between the two stimuli. Whether these two forms of rivalry arise within different stages of visual processing has remained debatable. Using an individual-differences approach, we found that both stimulus rivalry and binocular rivalry exhibited same-shaped distributions of dominance durations among a sample of 30 observers and, moreover, that the dominance durations measured during binocular and stimulus rivalry were significantly correlated among our sample of observers. Furthermore, we found a significant, positive correlation between alternation rate in binocular rivalry and the incidence of stimulus rivalry. These results suggest that the two forms of rivalry may be tapping common neural mechanisms, or at least different mechanisms with comparable time constants. It remains to be learned just why the incidences of binocular rivalry and stimulus rivalry vary so greatly among people. [ABSTRACT FROM AUTHOR]

The effect of adaptation on the perception of a reversible figure was examined in the context of the so-called 'reverse-bias effect' in which prolonged exposure to an unambiguous version of a bi-stable ambiguous stimulus serves to bias an observer to report the alternative version of the subsequently viewed ambiguous stimulus. Exposure to the unambiguous stimulus presumably selectively adapts and weakens the neural structures underlying that particular interpretation of the ambiguous figure. We extended previous research by examining the dominance durations for the two alternatives of the reversible figure (i.e., how long each alternative was perceived when it was dominant) in addition to the measures of response rate and choice preference used by other researchers. We replicated earlier findings with the previously used measures. Interestingly, adaptation with an unambiguous version of the ambiguous stimulus produced an asymmetrical effect on the dominance durations of the subsequently presented ambiguous stimulus, relative to a no-adaptation control. The dominance durations were lengthened for the perceptual organization that was the opposite of the adaptation stimulus while they were relatively unaffected for the perceptual organization that was the same as the adaptation stimulus. Our findings are consistent with the argument that adaptation effects play an important role in perceptual bistability. The asymmetrical dominance-duration findings further suggest that adaptation operates in a perceptual system in which the alternative perceptual representations of an ambiguous figure reciprocally inhibit one another via cross-inhibitory processes, consistent with views developed in other forms of bistable perception (e.g., binocular rivalry). [ABSTRACT FROM AUTHOR]

Continuous flash suppression (CFS) is a potent method of inducing binocular rivalry, wherein a rapid succession of high-contrast images presented to one eye effectively blocks from awareness a low-contrast image presented to the other eye. Here we addressed whether the contents of the suppressed image can break through to awareness with extended CFS exposure. On 2/3 of the trials, we presented a faint bar (the target) to the nondominant eye while a high-contrast flickering Mondrian (the mask) was displayed to the dominant eye. Participants were first asked to report whether the target had broken through the CFS mask. Furthermore, on target-present trials, the participants were then asked to guess whether the target had appeared above or below the fixation point. In Experiment 1, the target was presented with a fixed orientation for four blocks of trials, whereas in the fifth block, the target could also have the orthogonal orientation. In Experiment 2, the target was always presented with a fixed orientation, but in the fifth block, unbeknownst to participants, the target and the mask were swapped across the eyes. We found that awareness of the target rapidly improved with training in both experiments. However, whereas Experiment 1 revealed that the improvement largely generalized across stimulus orientations, Experiment 2 showed that the effect of practice was eye-specific. The results suggest that increased breakthrough with training was due to a monocular form of learning. Finally, a control experiment was conducted to exclude the possibility that the monocular learning we reported could have been due to sensory adaptation caused by the masks. [ABSTRACT FROM AUTHOR]

The basic connectivity from the vestibular labyrinth to the eye muscles (vestibular ocular reflex, VOR) has been elucidated in the past decade, and we summarise this in graphic format. We also review the concept of 'velocity storage', a brainstem integrator that prolongs vestibular responses. Finally, we present new discoveries of how complex visual stimuli, such as binocular rivalry, influence VOR processing. In contrast to the basic brainstem circuits, cortical vestibular circuits are far from being understood, but parietal-vestibular nuclei projections are likely to be involved. [ABSTRACT FROM AUTHOR]

This study examined the effect of motion on avoidance of interocular suppression in the half-occluded zones, which are non-fusible images projected onto the corresponding retinal areas in natural viewing situations. Six and seven adults participating in Experiments 1 and 2, respectively, measured the amount of suppression in the half-occluded zones. In the moving condition, motion of the occluded surface caused motion of the half-occluded zones in Experiment 1; motion of the occluder caused it in Experiment 2. In the static condition, the occluded surface, half-occluded zones, and occluder were static in Experiments 1 and 2. The results obtained from both experiments indicated that the half-occluded zones were less suppressed in the moving condition than in the static condition. These findings demonstrated that motion of the half-occluded zones contributes to the avoidance of interocular suppression in natural viewing situations. [ABSTRACT FROM AUTHOR]

This project examined whether previous visual history can bias perceptual dominance during onset rivalry. A predictive sequence of non-rivalrous stimuli preceded dichoptically presented rivalrous displays. One of the dichoptic images was the implied next step of the preceding sequence while the other was not. Observers reported their initial dominant percept. Across five experiments, we found that motion sequences biased perceptual selection such that a rivalrous stimulus that continued a motion sequence tended to dominate one that did not. However, signals generated by complex pattern of motion information or verbal-semantic information had no influence on selection. These results are consistent with the view that onset rivalry is an early phase of rivalry that is likely insensitive to modulation by factors originating beyond the visual system. [ABSTRACT FROM AUTHOR]

Previous research has demonstrated that the contents of visual working memory can bias visual processing in favor of matching stimuli in the scene. However, the extent to which such top-down, memory-driven biasing of visual perception is contingent on conscious awareness remains unknown. Here we showed that conscious awareness of critical visual cues is dispensable for working memory to bias perceptual selection mechanisms. Using the procedure of continuous flash suppression, we demonstrated that 'unseen' visual stimuli during interocular suppression can gain preferential access to awareness if they match the contents of visual working memory. Strikingly, the very same effect occurred even when the visual cue to be held in memory was rendered nonconscious by masking. Control experiments ruled out the alternative accounts of repetition priming and different detection criteria. We conclude that working memory biases of visual perception can operate in the absence of conscious awareness. [ABSTRACT FROM AUTHOR]

Hugh Wilson has proposed a class of models that treat higher-level decision making as a competition between patterns coded as levels of a set of attributes in an appropriately defined network (Cortical Mechanisms of Vision, pp. 399-417, 2009; The Constitution of Visual Consciousness: Lessons from Binocular Rivalry, pp. 281-304, 2013). In this paper, we propose that symmetry-breaking Hopf bifurcation from fusion states in suitably modified Wilson networks, which we call rivalry networks, can be used in an algorithmic way to explain the surprising percepts that have been observed in a number of binocular rivalry experiments. These rivalry networks modify and extend Wilson networks by permitting different kinds of attributes and different types of coupling. We apply this algorithm to psychophysics experiments discussed by Kovács et al. (Proc. Natl. Acad. Sci. USA 93:15508-15511, 1996), Shevell and Hong (Vis. Neurosci. 23:561-566, 2006; Vis. Neurosci. 25:355-360, 2008), and Suzuki and Grabowecky (Neuron 36:143-157, 2002). We also analyze an experiment with four colored dots (a simplified version of a 24-dot experiment performed by Kovács), and a three-dot analog of the four-dot experiment. Our algorithm predicts surprising differences between the three- and four-dot experiments [ABSTRACT FROM AUTHOR]

In this study, the effect of defocus blur on the avoidance of interocular suppression in half-occluded zones, which are the monocular zones formed by occlusion, was examined. Six human adults observed a pair of colored random-dot stereograms, and the cumulative time of disappearance of the half-occluded zones was measured. There were three defocus blur conditions (blurry-background, blurry-occluder, and nonblur) and two fixation conditions (fixation-front and fixation-back). The author found that the cumulative time of disappearance was shorter under the blurrybackground condition of the fixation-front condition and under the blurry-occluder condition of the fixation-back condition than under the other conditions. These results indicate that ecologically valid defocus blur contributes to the avoidance of interocular suppression in the half-occluded zones. [ABSTRACT FROM AUTHOR]

People tend to look toward where a sound occurs; however, the role of spatial congruency between sound and sight in the effect of sound facilitation on visual detection remains controversial. We propose that the role of spatial congruency depends on the reliability of the information provided by the facilitator; if it is relatively unreliable, adding spatially congruent information can help to unify different sensory inputs to compensate for this unreliability. To test this, we examine the influence of sound location on visual detection with a non-temporal task, presumably unfavorable for sound since it is better for temporal resolution, and predict that spatial congruency should matter in this situation. We used the continuous flash suppression paradigm that makes the visual stimuli invisible to keep the relationship of sound and sight opaque. The sound is on the same depth plane as the visual stimulus (the congruent condition) or on a different plane (the incongruent condition). The target was presented to one eye with luminance contrast gradually increased and continuously masked by flashed Mondrian masks presented to the other eye until the target was released from suppression. We found that sound facilitated visual detection (measured by released-from-suppression time) in the spatially congruent condition but not in the spatially incongruent condition. Together with previous findings in the literature, it is suggested that both task type and modality determine the reliability of the information for multisensory integration and thus determine whether spatial congruency is critical. [ABSTRACT FROM AUTHOR]

When multistable displays (stimuli consistent with two or more equally plausible perceptual interpretations) are presented intermittently, their perceptions are stabilized by sensory memory. Independent memory traces are generated not only for different types of multistable displays (Maier, Wilke, Logothetis, & Leopold, Current Biology 13:1076-1085, ), but also for different ambiguous features of binocular rivalry (Pearson & Clifford, Journal of Vision 4:196-202, ). In the present study, we examined whether a similar independence of sensory memories is observed in structure-from-motion (SFM), a multistable display with two ambiguous properties. In SFM, a 2-D planar motion creates a vivid impression of a rotating 3-D volume. Both the illusory rotation and illusory depth (i.e., how close parts of an object appear to the observer) of an SFM object are ambiguous. We dissociated the sensory memories of these two ambiguous properties by using an intermittent presentation in combination with a forced-ambiguous-switch paradigm (Pastukhov, Vonau, & Braun, PLoS ONE 7:e37734, ). We demonstrated that the illusory depth of SFM generates a sensory memory trace that is independent from that of illusory rotation. Despite this independence, the specificities levels of the sensory memories were identical for illusory depth and illusory rotation. The history effect was weakened by a change in the volumetric property of a shape (whether it was a hollow band or a filled drum volume), but not by changes in color or size. We discuss how these new results constrain models of sensory memory and SFM processing. [ABSTRACT FROM AUTHOR]

Saccadic and manual reactions to a peripherally presented target are facilitated by removing a central fixation stimulus shortly before a target onset (the gap effect). The present study examined the effects of removal of a visible and invisible fixation point on the saccadic gap effect and the manual gap effect. Participants were required to fixate a central fixation point and respond to a peripherally presented target as quickly and accurately as possible by making a saccade (Experiment 1) or pressing a corresponding key (Experiment 2). The fixation point was dichoptically presented, and visibility was manipulated by using binocular rivalry and continuous flash suppression technique. In both saccade and key-press tasks, removing the visible fixation strongly quickened the responses. Furthermore, the invisible fixation, which remained on the display but suppressed, significantly delayed the saccadic response. Contrarily, the invisible fixation had no effect on the manual task. These results indicate that partially different processes mediate the saccadic gap effect and the manual gap effect. In particular, unconscious processes might modulate an oculomotor-specific component of the saccadic gap effect, presumably via subcortical mechanisms. [ABSTRACT FROM AUTHOR]