Binocular Disparity Cues Research Articles

Accommodation and Vergence Response Gains to Different Near Cues Characterize Specific Esotropias

Aim: To describe preliminary findings of how the profile of the use of blur, disparity, and proximal cues varies between non-strabismic groups and those with different types of esotropia.Design: This was a case control study.Methodology: A remote haploscopic photorefractor measured simultaneous convergence and accommodation to a range of targets containing all combinations of binocular disparity, blur, and proximal (looming) cues. Thirteen constant esotropes, 16 fully accommodative esotropes, and 8 convergence excess esotropes were compared with age- and refractive error–matched controls and 27 young adult emmetropic controls. All wore full refractive correction if not emmetropic. Response AC/A and CA/C ratios were also assessed.Results: Cue use differed between the groups. Even esotropes with constant suppression and no binocular vision (BV) responded to disparity in cues. The constant esotropes with weak BV showed trends for more stable responses and better vergence and accommodation than those without any BV. The accommodative esotropes made less use of disparity cues to drive accommodation (p = 0.04) and more use of blur to drive vergence (p = 0.008) than controls. All esotropic groups failed to show the strong bias for better responses to disparity cues found in the controls, with convergence excess esotropes favoring blur cues. AC/A and CA/C ratios existed in an inverse relationship in the different groups. Accommodative lag of >1.0 D at 33 cm was common (46%) in the pooled esotropia groups compared with 11% in typical children (p = 0.05).Conclusion: Esotropic children use near cues differently from matched non-esotropic children in ways characteristic to their deviations. Relatively higher weighting for blur cues was found in accommodative esotropia compared to matched controls.

Perceived depth magnitude with a combination of motion parallax and binocular disparity cues

Perceived depth magnitude with a combination of motion parallax and binocular disparity cues

The Clinical Near Gradient Stimulus AC/A Ratio Correlates Better With the Response CA/C Ratio Than With the Response AC/A Ratio

Aim: To provide evidence that a near clinical gradient AC/A ratio could instead reflect the CA/C relationship (the accommodation driven by response to disparity).Design: Case control study.Methodology: 27 emmetropic participants with heterophoria <4 PD, 19 with intermittent distance exotropia, and 17 with near exophoria >6 PD were tested. A remote haploscopic photorefractor, which can measure simultaneous convergence and accommodation to a range of targets containing all combinations of presence or absence of binocular disparity, blur, and proximal (looming) cues, was used to assess response AC/A and CA/C relationships. These were compared with clinical gradient AC/A ratios at near and distance fixation using alternate prism cover test and plus or minus lenses.Results: Although the near and distance clinical AC/A ratios correlated weakly with each other (p = 0.03), neither clinical method correlated with the more accurate response AC/A ratio from the laboratory method (p = 0.88 and p = 0.93, respectively). The laboratory CA/C ratio correlated strongly with the near clinical AC/A ratio (p = 0.004) but only very weakly with the distance ratio (p = 0.16).Conclusions: The “near gradient AC/A ratio” may actually reflect the CA/C linkage as the dissociation of the prism cover test disrupts vergence accommodation. If the near deviation diverges more with plus lenses, it may be because the lenses allow clear near vision without needing to recruit convergence accommodation to achieve it.

Integration of motion and disparity cues to depth in monkey brain

Event Abstract Back to Event Integration of motion and disparity cues to depth in monkey brain Marcelo Armendariz1*, Andrew Welchman2, Hiroshi Ban2 and Wim Vanduffel1 1 KU Leuven, Neuroscience, Belgium 2 University of Birmingham, School of Psychology, United Kingdom Recognising and interacting with objects depends on knowing the three-dimensional (3D) structure of the world around us. Estimating the depth structure of the environment is a principal function of the visual system in primates, enabling many key computations, such as segmentation, object recognition, material perception and the guidance of movements. The brain exploits a range of depth cues to estimate depth, combining information from shading and shadows to linear perspective, motion and binocular disparity. To solve the depth perception there are two computationally distinct ways: independence or fusion. Traditionally, this process has been broadly conceived in modular terms, with the independent processing of individual cues followed by a combination stage in which the influence of each cue reflects the reliability with which it is encoded. However, a recent study with humans (Ban et al., 2012), using fMRI for decoding depth from binocular disparity and motion parallax cues, provided evidence that dorsal visual areas are involved in the fusion mechanism that combines the two cues into a single depth perception. They found that fMRI responses are more discriminable when two cues (binocular disparity and relative motion) concurrently signal depth, since the variance is significantly reduced. Our present study aims to investigate cue integration in monkey (Macaca mulatta) with fMRI. We presented the monkey a set of stimuli representing near or far depths defined by motion parallax, binocular disparity and the combination of both in congruent and incongruent ways. We performed statistical data analysis to obtain all the activation areas in the brain involved in depth processing: V1, V2, V3, V3A, V4, MST, MT, FST, F5 and MIP. Once the regions of interest are defined, we will use multivoxel pattern analysis (MVPA) to reveal depth selectivity in macaque cortex (Preston et al., 2008) and assess the fusion mechanism for cue integration. References Ban, H., Preston, T.J., Meeson, A.,& Welchman, A.E. The integration of motion and disparity cues to depth in dorsal visual cortex. Nature Neuroscience 15, 636–643 (2012). Preston, T.J., Li, S., Kourtzi, Z. & Welchman, A.E. Multivoxel pattern selectivity for perceptually relevant binocular disparities in the human brain. J. Neurosci. 28, 11315–11327 (2008). Keywords: fMRI, monkey, Depth Perception, binocular diparity, motion parallax Conference: Imaging the brain at different scales: How to integrate multi-scale structural information?, Antwerp, Belgium, 2 Sep - 6 Sep, 2013. Presentation Type: Poster presentation Topic: Poster session Citation: Armendariz M, Welchman A, Ban H and Vanduffel W (2013). Integration of motion and disparity cues to depth in monkey brain. Front. Neuroinform. Conference Abstract: Imaging the brain at different scales: How to integrate multi-scale structural information?. doi: 10.3389/conf.fninf.2013.10.00042 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 23 Aug 2013; Published Online: 31 Aug 2013. * Correspondence: Mr. Marcelo Armendariz, KU Leuven, Neuroscience, Leuven, Belgium, m.zimarron@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Marcelo Armendariz Andrew Welchman Hiroshi Ban Wim Vanduffel Google Marcelo Armendariz Andrew Welchman Hiroshi Ban Wim Vanduffel Google Scholar Marcelo Armendariz Andrew Welchman Hiroshi Ban Wim Vanduffel PubMed Marcelo Armendariz Andrew Welchman Hiroshi Ban Wim Vanduffel Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Impaired perceptual processing and conceptual cognition in patients with anxiety disorders: A pilot study with the binocular depth inversion paradigm

The Binocular Depth Inversion Test (BDIT) measures a common illusion of visual perception whereby implausible objects are seen as normal, e.g., a hollow face is perceived as a normal, convex face. Such inversion is frequent, especially for objects with a high degree of familiarity. Under normal conditions, cognitive factors apparently override the binocular disparity cues of stereopsis. This internal mechanism of “censorship” of perception, which balances “top-down” and “bottom-up” processes of perception to come to a cognitive coherence, which is congruent to previous experience and concepts, appears to be disturbed in (pro-)psychotic states. The BDIT has been shown to be a sensitive measure of impaired higher visual processing and conceptual cognition common to conditions including schizophrenia, cannabinoid-intoxication, and sleep deprivation but not depression. In this pilot study, we tested the performance of patients with anxiety disorders (ICD-10 F40 and F41) compared to matched controls using the BDIT paradigm. Anxiety patients scored significantly higher on the BDIT than controls, in a range comparable to propsychotic conditions. The findings suggest that anxiety patients could have abnormalities in central perceptual processing, top-down processing (conceptual cognition), and reality testing similar to (pro-)psychotic conditions. Implications of these findings are discussed in relation to therapeutic interventions with anxiety disorders.

P2-1: Visual Short-Term Memory Lacks Sensitivity to Stereoscopic Depth Changes but is Much Sensitive to Monocular Depth Changes

Depth from both binocular disparity and monocular depth cues presumably is one of most salient features that would characterize a variety of visual objects in our daily life. Therefore it is plausible to expect that human vision should be good at perceiving objects' depth change arising from binocular disparities and monocular pictorial cues. However, what if the estimated depth needs to be remembered in visual short-term memory (VSTM) rather than just perceived? In a series of experiments, we asked participants to remember depth of items in an array at the beginning of each trial. A set of test items followed after the memory array, and the participants were asked to report if one of the items in the test array have changed its depth from the remembered items or not. The items would differ from each other in three different depth conditions: (1) stereoscopic depth under binocular disparity manipulations, (2) monocular depth under pictorial cue manipulations, and (3) both stereoscopic and monocular depth....

Where do the eyes really go in the hollow-face illusion?

The hollow-face illusion refers to the finding that people typically perceive a concave (hollow) mask as being convex, despite the presence of binocular disparity cues that indicate the contrary. Unlike other illusions of depth, recent research has suggested that the eyes tend to converge at perceived, rather than actual, depths. However, technical and methodological limitations prevented one from knowing whether disparity cues may still have influenced vergence. In the current study, we presented participants with virtual normal or hollow masks and asked them to fixate the tip of the face’s nose until they had indicated whether they perceived it as pointing towards or away from them. The results showed that the direction of vergence was indeed determined by perceived depth, although vergence responses were both somewhat delayed and of smaller amplitude (by a factor of about 0.5) for concave than convex masks. These findings demonstrate how perceived depth can override disparity cues when it comes to vergence, albeit not entirely.

The functional significance of mantis peering behaviour

The aim of this review is to explain the functional significance of mantis peering behaviour from an entomological perspective. First the morphological and optical features of the mantis compound eye that are important for spatial vision are described. The possibility that praying-mantises use binocular retinal disparity (stereopsis) and other alternative visual cues for determining distance in prey capture, are discussed. The primary focus of the review is the importance of peering movements for estimating the distance to stationary objects. Here the following aspects are examined: (1) Direct evidence via object manipulation experiments of absolute distance estimation with the aid of self-induced retinal image motion; (2) the mechanism of absolute distance estimation (with the interaction of visual and proprioceptive information); (3) the range of absolute and relative distance estimation; (4) the influence of target object features on distance estimation; and (5) the relationship between peering behaviour and habitat structures, based on results of studies on three species of mantis.

Vergence eye movements signifying 3D depth perception from 2D movies

A sensation of depth can arise from two-dimensional (2D) movies without any stereoscopic depth cue. Depth perception in three-dimensional (3D) space depends on the stability of stereoscopic gaze by vergence – coordinated movement of the two eyes in opposite directions – compensating the misalignment of the retinal images from the two eyes (i.e. binocular disparity) [1]. On the other hand, the oculomotor mechanisms that stabilize stereoscopic gaze and depth perception in 2D movie space remain unclear [2]. Here, we propose a hypothesis that vergence eye movements signifying 3D depth perception persist during prolonged 2D movie presentation without binocular disparity cues. By measuring eye positions while the subject viewed moving random-dot video stimuli, we show that sustained vergence is induced during 30-s exposure to radially expanding 2D optic flow. Moreover, a 2D video movie showing a passenger’s view of a roller coaster induces continuously changing vergence. In the absence of binocular disparity cues, the pictorial depth information within a 5°×5° gaze window and optic flow in the movie simultaneously and independently influence vergence. The pictorial gaze-area depth information affects vergence mainly in the virtual far space, whereas optic flow robustly affects vergence irrespective of the nearness. These findings demonstrate that vergence serves as a reliable marker signifying 3D depth perception from 2D movies, imposing critical constraints on creation of an effective and safe virtual reality.

Disparity biasing in depth from monocular occlusions

Monocular occlusions have been shown to play an important role in stereopsis. Among other contributions to binocular depth perception, monocular occlusions can create percepts of illusory occluding surfaces. It has been argued that the precise location in depth of these illusory occluders is based on the constraints imposed by occlusion geometry. Tsirlin et al. (2010) proposed that when these constraints are weak, the depth of the illusory occluder can be biased by a neighboring disparity-defined feature. In the present work we test this hypothesis using a variety of stimuli. We show that when monocular occlusions provide only partial constraints on the magnitude of depth of the illusory occluders, the perceived depth of the occluders can be biased by disparity-defined features in the direction unrestricted by the occlusion geometry. Using this disparity bias phenomenon we also show that in illusory occluder stimuli where disparity information is present, but weak, most observers rely on disparity while some use occlusion information instead to specify the depth of the illusory occluder. Taken together our experiments demonstrate that in binocular depth perception disparity and monocular occlusion cues interact in complex ways to resolve perceptual ambiguity.

On the Inverse Problem of Binocular 3D Motion Perception

It is shown that existing processing schemes of 3D motion perception such as interocular velocity difference, changing disparity over time, as well as joint encoding of motion and disparity, do not offer a general solution to the inverse optics problem of local binocular 3D motion. Instead we suggest that local velocity constraints in combination with binocular disparity and other depth cues provide a more flexible framework for the solution of the inverse problem. In the context of the aperture problem we derive predictions from two plausible default strategies: (1) the vector normal prefers slow motion in 3D whereas (2) the cyclopean average is based on slow motion in 2D. Predicting perceived motion directions for ambiguous line motion provides an opportunity to distinguish between these strategies of 3D motion processing. Our theoretical results suggest that velocity constraints and disparity from feature tracking are needed to solve the inverse problem of 3D motion perception. It seems plausible that motion and disparity input is processed in parallel and integrated late in the visual processing hierarchy.

Depth cue combination in spontaneous eye movements

Where we look when we scan visual scenes is an old question that continues to inspire both fundamental and applied research. Recently, it has been reported that depth is an important variable in driving eye movements: the directions of spontaneous saccades tend to follow depth gradients, or, equivalently, surface tilts (L. Jansen, S. Onat, & P. König, 2009; M. Wexler & N. Ouarti, 2008). This has been found to hold for both simple and complex scenes and for a variety of depth cues. However, it is not known whether saccades are aligned with individual depth cues, or with a combination of depth cues. If saccades do follow a combination of depth cues, then it is interesting to ask whether this combination follows the same rules as the well-studied case of depth cue combination in conscious perception. We showed subjects surfaces inclined in depth, in which perspective and binocular disparity cues specified different plane orientations, with different degrees of both small and large conflict between the two sets of cues. We recorded subjects' spontaneous saccades while they scanned the scene, as well as their reports of perceived plane orientation. We found that distributions of spontaneous saccade directions followed the same pattern of depth cue combination as perceived surface orientation: a weighted linear combination of cues for small conflicts, and cue dominance for large conflicts. The weights assigned to the cues varied considerably from one subject to the next but were strongly correlated for saccades and perception; moreover, for both perception and saccades, cue weights could be modified by manipulating cue reliability in a way compatible with Bayesian theories of optimal cue combination. We also measured vergence, which allowed us to calculate the orientation of the plane fitted to points scanned in depth. Contrary to perception and saccades, vergence was dominated by a single cue, binocular disparity.

The Role of Occlusion Cues in Apparent Motion

Classical apparent motion stimuli exhibit an inherent ambiguity with respect to the onsets and offsets of the stimulus elements. Sigman and Rock (1974, Perception 3 9-28) presented evidence suggesting that occlusion cues are used to resolve this ambiguity. We present results from experiments designed to further test predictions of this hypothesis. As expected, we found that the apparent motion of a target stimulus is suppressed when a 'moving' occluder is positioned such that it rationalises the onsets and offsets of the stimulus elements constituting the target. Somewhat unexpectedly, though, we also observed a slight tendency for motion suppression under conditions where the target was only partially occluded. The expected motion suppression occurred both with solid occluders and purely virtual Kanizsa-like occluders, although it was not always observed in the latter case. Motion suppression was found to occur over a wide range of stimulus onset asynchronies. Finally, we used binocular disparity cues to test the occlusion account of the motion suppression phenomenon against an alternative explanation in terms of attentional factors. The results are in clear favour of the occlusion account.

Illusory temporal order for stimuli at different depth positions

We used four experiments to examine how the perceived temporal order of two visual stimuli depends on the depth position of the stimuli specified by a binocular disparity cue. When two stimuli were presented simultaneously at different depth positions in front of or around a fixation point, the observer perceived the more distant stimulus before the nearer stimulus (Experiments 1 and 2). This illusory temporal order was found only for sudden stimulus presentation (Experiment 3). These results suggest that a common processing, which is triggered by sudden luminance change, underlies this illusion. The strength of the illusion increased with the disparity gradient and the disparity size (Experiment 4). We propose that this illusion has a basis in the processing of motion in depth, which would alert the observer to a potential collision with an object that suddenly emerges in front of the observer.

Perceptual Incongruence Influences Bistability and Cortical Activation

We employed a parametric psychophysical design in combination with functional imaging to examine the influence of metric changes in perceptual incongruence on perceptual alternation rates and cortical responses. Subjects viewed a bistable stimulus defined by incongruent depth cues; bistability resulted from incongruence between binocular disparity and monocular perspective cues that specify different slants (slant rivalry). Psychophysical results revealed that perceptual alternation rates were positively correlated with the degree of perceived incongruence. Functional imaging revealed systematic increases in activity that paralleled the psychophysical results within anterior intraparietal sulcus, prior to the onset of perceptual alternations. We suggest that this cortical activity predicts the frequency of subsequent alternations, implying a putative causal role for these areas in initiating bistable perception. In contrast, areas implicated in form and depth processing (LOC and V3A) were sensitive to the degree of slant, but failed to show increases in activity when these cues were in conflict.

A Novel Experimental Method for Measuring Vergence and Accommodation Responses to the Main Near Visual Cues in Typical and Atypical Groups

Binocular disparity, blur, and proximal cues drive convergence and accommodation. Disparity is considered to be the main vergence cue and blur the main accommodation cue. We have developed a remote haploscopic photorefractor to measure simultaneous vergence and accommodation objectively in a wide range of participants of all ages while fixating targets at between 0.3 and 2 m. By separating the three main near cues, we can explore their relative weighting in three-, two-, one-, and zero-cue conditions. Disparity can be manipulated by remote occlusion; blur cues manipulated by using either a Gabor patch or a detailed picture target; looming cues by either scaling or not scaling target size with distance. In normal orthophoric, emmetropic, symptom-free, naive visually mature participants, disparity was by far the most significant cue to both vergence and accommodation. Accommodation responses dropped dramatically if disparity was not available. Blur only had a clinically significant effect when disparity was absent. Proximity had very little effect. There was considerable interparticipant variation. We predict that relative weighting of near cue use is likely to vary between clinical groups and present some individual cases as examples. We are using this naturalistic tool to research strabismus, vergence and accommodation development, and emmetropization.

REPRESENTATION OF 3-D VOLUMETRIC OBJECT FROM THE PANTOMIME EFFECT AND SHADING CUES IN HUMAN BRAIN

Human ability to process visual information of outside world is yet far ahead of man-made systems in accuracy and speed. In particular, human beings can perceive 3-D object from various cues, such as binocular disparity and monocular shading cues. Understanding of the mechanism of human visual processing will lead to a breakthrough in creating artificial visual systems. Here, we study the human 3-D volumetric object perception that is induced by a visual phenomenon named as the pantomime effect and by the monocular shading cues. We measured human brain activities using fMRI when the subjects were observing the visual stimuli. A coordinated system of brain areas, including those in the prefrontal and parietal cortex, in addition to the occipital visual areas was found to be involved in the volumetric object perception.

Dissociation between vergence and binocular disparity cues in the control of prehension

Binocular vision provides important advantages for controlling reach-to-grasp movements. We examined the possible source(s) of these advantages by comparing prehension proficiency under four different binocular viewing conditions, created by randomly placing a neutral lens (control), an eight dioptre prism (Base In or Base Out) or a low-power (2.00-3.75 dioptre) Plus lens over the eye opposite the moving limb. The Base In versus Base Out prisms were intended to selectively alter vergence-specified distance (VSD) information, such that the targets appeared beyond or closer than their actual physical position, respectively. The Plus lens was individually tailored to reduce each subject's disparity sensitivity (to 400-800 arc s), while minimizing effects on distance estimation. In pre-testing, subjects pointed (without visual feedback) to mid-line targets at different distances, and produced the systematic directional errors expected of uncorrected movements programmed under each of the perturbed conditions. For the prehension tasks, subjects reached and precision grasped (with visual feedback available) cylindrical objects (two sizes and three locations), either following a 3 s preview in which to plan their actions or immediately after the object became visible. Viewing condition markedly affected performance, but the planning time allowed did not. Participants made the most errors suggesting premature collision with the object (shortest 'braking' times after peak deceleration; fastest velocity and widest grip at initial contact) under Base In prism viewing, consistent with over-reaching movements programmed to transport the hand beyond the actual target due to its 'further' VSD. Conversely, they produced the longest terminal reaches and grip closure times, with multiple corrections just before and after object contact, under the Plus lens (reduced disparity) condition. Base Out prism performance was intermediate between these two, with significant increases in additional forward movements during the transport end-phase, indicative of initial under-reaching in response to the target's 'nearer' VSD. Our findings suggest dissociations between the role of vergence and binocular disparity in natural prehension movements, with vergence contributing mainly to reach planning and high-grade disparity cues providing particular advantages for grasp-point selection during grip programming and application.

Subjective appearance of ambiguous structure-from-motion can be driven by objective switches of a separate less ambiguous context

Two ambiguous transparent structure-from-motion (SFM) stimuli often appear to co-rotate. Grossmann and Dobbins (2003) reported breakdown of such perceptual coupling when one stimulus was made unambiguous (by rendering it opaque), leading them to propose that coupling depends generally on differential stimulus ambiguity. In contrast, we demonstrate robust stimulus-driven coupling even when one SFM stimulus is relatively disambiguated, by using relative-luminance and/or binocular-disparity cues. Such context stimuli could induce stimulus-driven coupling by disambiguating the transparent stimulus, though critically only when the context was clearly non-opaque and coaxial with the ambiguous stimulus. This demonstrates long-range information-sharing between separate stimulus representations, subject to specific constraints.

Distance impairs postural stability only under binocular viewing

Prior studies indicate that postural stability under binocular viewing is not better than under monocular viewing. This was tested at the distances of 145 cm [Fox, C.R. (1990). Some visual influences on human postural equilibrium: binocular versus monocular fixation. Perception and Psychophysics, 47 (5), 409–422] and 90 cm [Isotalo, E., Kapoula, Z., Feret, P.H., Gauchon, K., Zamfirescu, F., & Gagey, P.M. (2004). Monocular versus binocular vision in postural control. Auris Nasus Larynx, 31 (1), 11–17]. On the other hand, postural stability is known to decrease with distance increase. We re-examined the effect of binocular versus monocular viewing on postural stability at near and far distances (40 and 200 cm), and for both young (25.7 ± 2.7 years), and old subjects (61.2 ± 4.6 years). For both groups of subjects, proximity decreased the area of CoP, the standard deviation of antero-posterior sway (SDy) and the variance of speed. The group of elderly presented increased variance of speed at far distance in comparison with young subjects. The novel finding is the interaction between distance and viewing condition. Under binocular viewing, the area of CoP was significantly higher at far distance than at near; in contrast, monocular viewing produced similar CoP values at both distances. Increased instability at far distance when both eyes are viewing is attributed to decreased sensitivity to binocular disparity cues and to visual motion in depth resulting from body sway. Monocular viewing would provide similar stability at far and at near distance, because sensitivity to lateral visual motion, detected monocularly, decreases less with distance than sensitivity to binocularly detected motion in depth. Alternatively, such monocular viewing could increase subject’s attention and lead to tighter postural control regardless of the distance.