Binocular Information Research Articles

Perceived rigidity in motion-in-depth increases with contour perspective.

When observers are asked to match the depth of an object according to its height, they often report systematic errors depending on viewing distance. Systematic biases can also arise while vergence distances are induced by binocular disparities. Observers of stereoscopic images tend to overestimate the depth of objects displayed in front of the screen, while the depth of objects displayed behind the screen plane is underestimated. This phenomenon creates a serious problem in that veridicality in depth perception appears distorted when one attempts to render the metrics of a captured 3-D world. These distortions could also subsist with structure-from-motion information and during motion-in-depth. Observers judged the circularity of transparent rotating cylinders that were either static or moving in depth. Crossed results show that participants could precisely retrieve the best modulation between presented depth and width. As this effect could be amplified with stimuli containing stronger perspective cues (ie contour perspective), participants judged the rigidity of spinning cubes, moving along the line of sight, which were either edges-defined or defined by randomly textured surfaces (dots). The results showed that, although depth constancy was not improved by contour perspective, perceived rigidity was increased by perspective when the best scaling estimate was displayed. This finding suggests that appropriate binocular disparity information in combination to monocular signal is necessary for stereoscopic depth perception.

Strabismus Disrupts Binocular Synaptic Integration in Primary Visual Cortex

Visual disruption early in development dramatically changes how primary visual cortex neurons integrate binocular inputs. The disruption is paradigmatic for investigating the synaptic basis of long-term changes in cortical function, because the primary visual cortex is the site of binocular convergence. The underlying alterations in circuitry by visual disruption remain poorly understood. Here we compare membrane potential responses, observed via whole-cell recordings in vivo, of primary visual cortex neurons in normal adult cats with those of cats in which strabismus was induced before the developmental critical period. In strabismic cats, we observed a dramatic shift in the ocular dominance distribution of simple cells, the first stage of visual cortical processing, toward responding to one eye instead of both, but not in complex cells, which receive inputs from simple cells. Both simple and complex cells no longer conveyed the binocular information needed for depth perception based on binocular cues. There was concomitant binocular suppression such that responses were weaker with binocular than with monocular stimulation. Our estimates of the excitatory and inhibitory input to single neurons indicate binocular suppression that was not evident in synaptic excitation, but arose de novo because of synaptic inhibition. Further constraints on circuit models of plasticity result from indications that the ratio of excitation to inhibition evoked by monocular stimulation decreased mainly for nonpreferred eye stimulation. Although we documented changes in synaptic input throughout primary visual cortex, a circuit model with plasticity at only thalamocortical synapses is sufficient to account for our observations.

The time course of estimating time-to-contact: Switching between sources of information

The different sources of information that can be used to estimate time-to-contact may have different degrees of reliability across time. For example, after a given presentation or display time, an absolute change of angular size can be more reliable than the corresponding estimation of the rate of angular expansion (e.g. motion information). One could then expect systematic biases in the observer's responses for different times of stimulus exposure. In one experiment, observers judged whether approaching objects arrived at the point of observation before or after a reference beep (1.2s) under monocular, and binocular plus monocular vision. Five display times from 0.1 to 0.9s were used. Unlike monocular viewing, where accuracy increased monotonically with display time, an interesting non-linearity occurred for objects with small size when binocular information was available. Accuracy reached maximum values for small objects with only 0.3s of vision with stereopsis. This accuracy, however, dropped significantly after 0.4s of exposure and increased again linearly with time. This is consistent with subjects switching from using binocular information to using monocular motion information when it started to become more reliable. We also explored whether monocular cues were combined differently across time by fitting a model that relates visual angle to its rate of expansion. Results show that subjects relied more on angular motion information (i.e. rate of expansion) with presentation time but interrupting this motion integration process led to a loss of accuracy in time-to-contact judgments.

Binocular integration and disparity selectivity in mouse primary visual cortex

Signals from the two eyes are first integrated in primary visual cortex (V1). In many mammals, this binocular integration is an important first step in the development of stereopsis, the perception of depth from disparity. Neurons in the binocular zone of mouse V1 receive inputs from both eyes, but it is unclear how that binocular information is integrated and whether this integration has a function similar to that found in other mammals. Using extracellular recordings, we demonstrate that mouse V1 neurons are tuned for binocular disparities, or spatial differences, between the inputs from each eye, thus extracting signals potentially useful for estimating depth. The disparities encoded by mouse V1 are significantly larger than those encoded by cat and primate. Interestingly, these larger disparities correspond to distances that are likely to be ecologically relevant in natural viewing, given the stereo-geometry of the mouse visual system. Across mammalian species, it appears that binocular integration is a common cortical computation used to extract information relevant for estimating depth. As such, it is a prime example of how the integration of multiple sensory signals is used to generate accurate estimates of properties in our environment.

A Face Detection Algorithm Based on Skin Color and Template Matching

Face detection is significant to application. The paper proposes an algorithm based on color of skin and binocular information for color images in complicated background. The algorithm roughly detects face-like regions for input images according to the color of skin, rejects the areas that the faces do not exist, gets possible face-like regions at the same time, so, it can shorten detection time. Experiment results show this algorithm has better robustness and it can be efficiently used in the conditions of multi-faces, different face sizes, various expressions and complex background. It has stronger adaptability for faces with certain rotation and side slip angles, accordingly, it can effectively reduce error eye location on the basis of skin color and template matching. Experiment results show the algorithm can achieve better detection effects.

Detection of 3D curved trajectories: the role of binocular disparity

We examined the ability of observers to detect the 3D curvature of motion paths when binocular disparity and motion information were present. On each trial, two displays were observed through shutter-glasses. In one display, a sphere moved along a linear path in the horizontal and depth dimensions. In the other display, the sphere moved from the same starting position to the same ending position as in the linear path, but moved along an arc in depth. Observers were asked to indicate whether the first or second display simulated a curved trajectory. Adaptive staircases were used to derive the observers' thresholds of curvature detection. In the first experiment, two independent variables were manipulated: viewing condition (binocular vs. monocular) and type of curvature (concave vs. convex). In the second experiment, three independent variables were manipulated: viewing condition, type of curvature, and whether the motion direction was approaching or receding. In both experiments, detection thresholds were lower for binocular viewing conditions as compared to monocular viewing conditions. In addition, concave trajectories were easier to detect than convex trajectories. In the second experiment, the direction of motion did not significantly affect curvature detection. These results indicate the detection of curved motion paths from monocular information was improved when binocular information was present. The results also indicate the importance of the type of curvature, suggesting that the rate of change of disparity may be important in detecting curved trajectories.

Straight or curved? From deterministic to probabilistic models of 3D motion perception

Straight or curved? From deterministic to probabilistic models of 3D motion perception

Measuring young infants' sensitivity to height‐in‐the‐picture‐plane by contrasting monocular and binocular preferential‐looking

To examine young infants' sensitivity to a pictorial depth cue, we compared monocular and binocular preferential looking to objects of which depth was specified by height-in-the-picture-plane. For adults, this cue generates the perception that a lower object is closer than a higher object. This study showed that 4- and 5-month-old infants fixated the lower, apparently closer, figure more often under the monocular than binocular presentation providing evidence of their sensitivity to the pictorial depth cue. Because the displays were identical in the two conditions except for binocular information for depth, the difference in looking-behavior indicated sensitivity to depth information, excluding a possibility that they responded to 2D characteristics. This study also confirmed the usefulness of the method, preferential looking with a monocular and binocular comparison, to examine sensitivity to a pictorial depth cue in young infants, who are too immature to reach reliably for the closer of two objects.

Binocular Eye Movement Control and Motion Perception: What Is Being Tracked?

We investigated under what conditions humans can make independent slow phase eye movements. The ability to make independent movements of the two eyes generally is attributed to few specialized lateral eyed animal species, for example chameleons. In our study, we showed that humans also can move the eyes in different directions. To maintain binocular retinal correspondence independent slow phase movements of each eye are produced. We used the scleral search coil method to measure binocular eye movements in response to dichoptically viewed visual stimuli oscillating in orthogonal direction. Correlated stimuli led to orthogonal slow eye movements, while the binocularly perceived motion was the vector sum of the motion presented to each eye. The importance of binocular fusion on independency of the movements of the two eyes was investigated with anti-correlated stimuli. The perceived global motion pattern of anti-correlated dichoptic stimuli was perceived as an oblique oscillatory motion, as well as resulted in a conjugate oblique motion of the eyes. We propose that the ability to make independent slow phase eye movements in humans is used to maintain binocular retinal correspondence. Eye-of-origin and binocular information are used during the processing of binocular visual information, and it is decided at an early stage whether binocular or monocular motion information and independent slow phase eye movements of each eye are produced during binocular tracking.

P1-13: Color Induction from Surround Color under Interocular Suppression

The effect of surround colors on color appearance is known to subserve color constancy in humans, but how multiple mechanisms in the visual system are involved in this effect is controversial. We used an interocular-suppression technique to examine how the effect occurs at the level higher than the interaction of binocular information. A test color chip (1.7 × 1.7 deg visual angle) was presented in a static surround either with continuous-flash suppression in the dominant eye (CFS condition) to make the surround inperceptible or without the suppression (no-CFS condition). The surround stimulus was either a Mondrian or a uniform field of the same mean chromaticity. Stimuli were simulated OSA color chips under red, white (D65), or green illuminant color and were presented on a CRT display. Unique yellows were measured by asking the subjects to judge whether the test stimulus appeared reddish or greenish. Two sizes of the surround stimuli (widths of 1 deg and 4 deg) were used. Results showed significant shifts in unique yellow even under the CFS conditions, except for the 1 deg uniform-surround condition. Under the no-CFS condition, the shifts showed remarkable difference between subjects, except for the 4 deg Mondrian-surround condition. Interestingly, trends of the shifts showed high consistency within each subject, across conditions. These results indicate that mechanisms at both higher and lower levels than the neuronal site of interocular suppression are involved, and that the color shifts follow each subject's strategy in the higher-order mechanisms when only insufficient clues are available in the surround to estimate illuminant color.

Gaze Estimation Interpolation Methods Based on Binocular Data

Video oculography (VOG) is one of the most commonly used techniques for gaze tracking because it enables nonintrusive eye detection and tracking. Improving the eye tracking's accuracy and tolerance to user head movements is a common task in the field of gaze tracking; thus, a thorough study of how binocular information can improve a gaze tracking system's accuracy and tolerance to user head movements has been carried out. The analysis is focused on interpolation-based methods and systems with one and two infrared lights. New mapping features are proposed based on the commonly used pupil-glint vector using different distances as the normalization factor. For this study, an experimental procedure with six users based on a real VOG gaze tracking system was performed, and the results were contrasted with an eye simulator. Important conclusions have been obtained in terms of configuration, equation, and mapping features, such as the outperformance of the interglint distance as the normalization factor. Furthermore, the binocular gaze tracking system was found to have a similar or improved level of accuracy compared to that of the monocular gaze tracking system.

Oculomotor Effects in the Size-Distance Paradox and the Moon Illusion

Drawing on 2 concepts—the resting position of the eyes and a binocular geometry for perceived size, the moon illusion is explained as the consequence of different oculomotor adjustments caused by change in the direction of gaze contingent upon the viewing conditions of the moon. Hence, each particular moon will be viewed with a different vergence state which, in turn, yields a different amount of binocular disparity. The vergence state will determine the perceived size of an object whereas disparity will determine its perceived distance. It is further contended that the perceived size of the moon is based on a new binocular information source for size perception enabling the size of an object to be perceived even in the absence of egocentric distance information. Discussion focuses on the paradoxical aspect of the moon illusion and how the size-distance invariance hypothesis may have contributed to its effect.

Corrections to: Motion aftereffect in depth based on binocular information

Corrections to: Motion aftereffect in depth based on binocular information

Motion aftereffect in depth based on binocular information

We examined whether a negative motion aftereffect occurs in the depth direction following adaptation to motion in depth based on changing disparity and/or interocular velocity differences. To dissociate these cues, we used three types of adapters: random-element stereograms that were correlated (1) temporally and binocularly, (2) temporally but not binocularly, and (3) binocularly but not temporally. Only the temporally correlated adapters contained coherent interocular velocity differences while only the binocularly correlated adapters contained coherent changing disparity. A motion aftereffect in depth occurred after adaptation to the temporally correlated stereograms while little or no aftereffect occurred following adaptation to the temporally uncorrelated stereograms. Interestingly, a monocular test pattern also showed a comparable motion aftereffect in a diagonal direction in depth after adaptation to the temporally correlated stereograms. The lack of the aftereffect following adaptation to pure changing disparity was also confirmed using spatially separated random-dot patterns. These results are consistent with the existence of a mechanism sensitive to interocular velocity differences, which is adaptable (at least in part) at binocular stages of motion-in-depth processing. We did not find any evidence for the existence of an "adaptable" mechanism specialized to see motion in depth based on changing disparity.

Using Illusions to Understand Delusions

Using Illusions to Understand Delusions

Reweighting visual cues by touch

It is well established that if multiple cues provide information about the same quantity, the information from these cues is combined by weighting each cue by the inverse of its variance. This implies that cue weights are determined by the cue variances only. However, this view is challenged by studies that showed that feedback about the actual value can induce changes in the cue weights when the feedback is consistent with one cue but not the other. We developed a paradigm that allowed us to measure the time course of this reweighting. Subjects placed an object flush onto a slanted surface. Monocular and binocular cues provided information about the slant and could be inconsistent with one another. Subjects received haptic feedback about whether they had oriented the object correctly when the object contacted the surface. This feedback was consistent with either the monocular or the binocular information. We found that the weight given to the visual cue that was consistent with the feedback increased relatively fast, leading to a mean weight change of 0.18 after 52 conflict trials. Thus, unless the haptic feedback somehow influences the reliability of the individual visual cues, the cue weights are not fully determined by the cue variances but also depend on the accuracy of each cue.

Locomoting-to-reach: information variables and control strategies for nested actions

Locomoting-to-reach is a basic perception/action behavior that requires visual information for the control of both locomotion and reaching components. We investigated the visual information and the control strategies used to guide both the head and the hand on approach to a target in a locomotion-to-reach task. In this study, participants were required to locomote in the dark to a lit target in three different conditions: monocular vision/target with image size, binocular vision/target with image size, and binocular vision/point-light target (without image size). In task one, participants brought their eyes to the target. In task two, participants brought their outstretched hand to the target. Movement trajectories for both tasks were analyzed. Results show that participants were significantly more accurate when binocular information was present. In both tasks, participants were found to use a proportional rate control strategy rather than a constant τ strategy. In the walk-to-reach task, they used monocular and/or binocular τ information to guide the head and then switched to using relative disparity τ to guide the hand to final target acquisition, switching when the hand centric τ became less than the head centric τ. Dynamical models of the information and control strategies were used to perform simulations that were found to fit the data well. The conclusion is that proportional rate control is used sequentially with head centric, then hand-centric τ-based information, using at each moment the τ with the smallest value.

Ergonomic evaluation of stereoscopic contents for a museum exhibition

This research entailed the production of stereoscopic 3D (S3D) contents using 2D-to-S3D conversion for exhibition at a museum and subjective evaluation. Hybrid production combining S3D images of existing live-action videos using the 2D-to-S3D conversion technology and computer graphic ones created via stereo rendering was conducted. Design and control of the chronological analysis of the parallactic angle was conducted on the produced contents, using binocular information as well as subjective evaluations, with the intent of conducting an investigation on the characteristics of such contents from the perspectives of the producers and viewers. An investigation was also conducted on the effects of the viewing position on the impressions of the S3D images.

Restoration of Binocular Vision in Amblyopia

Purpose: To develop a treatment for amblyopia based on re-establishing binocular vision.Methods: A novel procedure is outlined for measuring and reducing the extent to which the fixing eye suppresses the fellow amblyopic eye in adults with amblyopia. We hypothesize that suppression renders a structurally binocular system, functionally monocular.Results: We demonstrate that strabismic amblyopes can combine information normally between their eyes under viewing conditions where suppression is reduced by presenting stimuli of different contrast to each eye. Furthermore we show that prolonged periods of binocular combination leads to a strengthening of binocular vision in strabismic amblyopes and eventual combination of binocular information under natural viewing conditions (stimuli of the same contrast in each eye). Concomitant improvement in monocular acuity of the amblyopic eye occurs with this reduction in suppression and strengthening of binocular fusion. Additionally, stereoscopic function was established in the majority of patients tested. We have implemented this approach on a headmounted device as well as on a handheld iPod.Conclusion: This provides the basis for a new treatment of amblyopia, one that is purely binocular and aimed at reducing suppression as a first step.

Linear Visual Servoing-Based Control of the Position and Attitude of Omnidirectional Mobile Robots

This article proposes a Linear Visual Servoing (LVS)-based method of controlling the position and attitude of omnidirectional mobile robots. This article uses two markers to express their target position and attitude in binocular visual space coordinates, based on which new binocular visual space information which includes position and attitude angle information is defined. Binocular visual space information and the motion space of an omnidirectional mobile robot are linearly approximated, and, using the approximation matrix and the difference in the binocular visual space information between a target marker and a robot marker, the robot’s translational velocity and rotational velocity are generated. Since those are all generated based only on disparity information on an image, which is similar to how this is done in existing LVS, a camera angle is not required. Thus, the method is robust against calibration errors in camera angles, as is existing LVS. The effectiveness of the proposed method is confirmed by simulation.