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Journal of Vision Mar 2011A fundamental task of the visual system is to infer depth by using binocular disparity. To encode binocular disparity, the visual cortex performs two distinct...
A fundamental task of the visual system is to infer depth by using binocular disparity. To encode binocular disparity, the visual cortex performs two distinct computations: one detects matched patterns in paired images (matching computation); the other constructs the cross-correlation between the images (correlation computation). How the two computations are used in stereoscopic perception is unclear. We dissociated their contributions in near/far discrimination by varying the magnitude of the disparity across separate sessions. For small disparity (0.03°), subjects performed at chance level to a binocularly opposite-contrast (anti-correlated) random-dot stereogram (RDS) but improved their performance with the proportion of contrast-matched (correlated) dots. For large disparity (0.48°), the direction of perceived depth reversed with an anti-correlated RDS relative to that for a correlated one. Neither reversed nor normal depth was perceived when anti-correlation was applied to half of the dots. We explain the decision process as a weighted average of the two computations, with the relative weight of the correlation computation increasing with the disparity magnitude. We conclude that matching computation dominates fine depth perception, while both computations contribute to coarser depth perception. Thus, stereoscopic depth perception recruits different computations depending on the disparity magnitude.
Topics: Convergence, Ocular; Depth Perception; Discrimination, Psychological; Eye Movements; Humans; Models, Neurological; Photic Stimulation; Psychometrics
PubMed: 21367941
DOI: 10.1167/11.3.1 -
Current Biology : CB Jun 2017How does our brain use differences between the images in our two eyes, binocular disparities, to generate depth perception? New work shows that a type of neural network...
How does our brain use differences between the images in our two eyes, binocular disparities, to generate depth perception? New work shows that a type of neural network trained on natural binocular images can learn parameters that match key properties of visual cortex. Most information is conveyed by cells which sense differences between the two eyes' images.
Topics: Depth Perception; Vision Disparity; Vision, Binocular; Visual Cortex; Visual Perception
PubMed: 28633028
DOI: 10.1016/j.cub.2017.05.013 -
Journal of Vision Nov 2018Binocular disparity signals can provide high acuity information about the positions of points, surfaces, and objects in three-dimensional space. For some stimulus...
Binocular disparity signals can provide high acuity information about the positions of points, surfaces, and objects in three-dimensional space. For some stimulus configurations, however, perceived depth is known to be affected by surface organization. Here we examine the effects of surface continuity and discontinuity on such surface organization biases. Participants were presented with a series of random dot surfaces, each with a cumulative Gaussian form in depth. Surfaces varied in the steepness of disparity gradients, via manipulation of the standard deviation of the Gaussian, and/or the presence of differing forms of surface discontinuity. By varying the relative disparity between surface edges, we measured the points of subjective equality, where surfaces of differing steepness and/or discontinuity were perceptually indistinguishable. We compare our results to a model that considers sensitivity to different frequencies of disparity modulation. Across a series of experiments, the observed patterns of change in points of subjective equality suggest that perceived depth is determined by the integration of measures of relative disparity, with a bias toward sharp changes in disparity. Such disparities increase perceived depth when they are in the same direction as the overall disparity. Conversely, perceived depth is reduced by the presence of sharp disparity changes that oppose the sign of the overall depth change.
Topics: Adult; Bias; Depth Perception; Female; Humans; Male; Normal Distribution; Vision Disparity; Vision, Binocular
PubMed: 30458518
DOI: 10.1167/18.12.13 -
Journal of Vision Oct 2017Binocular disparity is represented by interocular cross-correlation of visual images in the striate and some extrastriate cortices. This correlation-based representation...
Binocular disparity is represented by interocular cross-correlation of visual images in the striate and some extrastriate cortices. This correlation-based representation produces reversed depth perception in a binocularly anticorrelated random-dot stereogram (aRDS) when it is accompanied by an adjacent correlated RDS (cRDS). Removal of the cRDS or spatial separation between the aRDS and cRDS abolishes reversed depth perception. However, how an immediate plane supports reversed depth perception is unclear. One possible explanation is that the correlation-based representation generates reversed depth based on the relative disparity between the aRDS and cRDS rather than the absolute disparity of the aRDS. Here, we psychophysically tested this hypothesis. We found that participants perceived reversed depth in an aRDS with zero absolute disparity when it was surrounded by a cRDS with nonzero absolute disparity (i.e., nonzero relative disparity), suggesting a role of relative disparity on the depth reversal. In addition, manipulation of the absolute disparities of the central aRDS and surrounding cRDS caused depth perception to reverse with respect to the depth of the surround. Further, depth reversal persisted after swapping the locations of the two RDSs. A model of relative-disparity encoding explains all these results. We conclude that reversed depth perception in aRDSs occurs in a relative frame of reference and suggest that the visual system contains correlation-based representation that encodes relative disparity.
Topics: Adult; Depth Perception; Female; Humans; Male; Photic Stimulation; Psychophysics; Reference Values; Vision Disparity; Vision, Binocular
PubMed: 29071354
DOI: 10.1167/17.12.17 -
Vision Research Aug 2016Investigations of the relationship between binocular disparity and suprathreshold depth magnitude percepts have used a variety of tasks, stimuli, and methods....
Investigations of the relationship between binocular disparity and suprathreshold depth magnitude percepts have used a variety of tasks, stimuli, and methods. Collectively, the results confirm that depth percepts increase with increasing disparity, but there are large differences in how well the estimates correspond to geometric predictions. To evaluate the source of these differences, we assessed depth magnitude percepts for simple stereoscopic stimuli, using both intra- and cross-modal estimation methods, and a large range of test disparities for both experienced and inexperienced observers. Our results confirm that there is a proportional relationship between perceived depth and binocular disparity; this relationship is not impacted by the measurement method. However, observers with minimal prior experience showed strong systematic biases in depth estimation, which resulted in large overestimates at small disparities and substantial underestimates at large disparities. By comparison, experienced observers' depth judgements were much closer to geometric predictions. In subsequent studies we show that unpracticed observers' depth estimates are improved by removing conflicting depth cues, and the observed biases are eliminated when they view physical targets. We conclude that differences in the depth magnitude estimates as a function of disparity in the existing literature are likely due to observers' experience with stereoscopic display systems in which binocular disparity is manipulated while other depth cues are held constant.
Topics: Cues; Depth Perception; Humans; Vision Disparity; Vision Tests; Vision, Binocular
PubMed: 27369096
DOI: 10.1016/j.visres.2016.05.006 -
The British Journal of Ophthalmology May 1980The monocular and binocular depth thresholds of strabismic subjects have been measured with a modified Howard-Dolman apparatus. Seven out of the 14 strabismic subjects...
The monocular and binocular depth thresholds of strabismic subjects have been measured with a modified Howard-Dolman apparatus. Seven out of the 14 strabismic subjects tested were found to have binocular thresholds significantly higher than their monocular ones. These strabismic subjects all had small angles of deviation less than 8 prism dioptres and high acuities in both eyes.
Topics: Adolescent; Adult; Depth Perception; Humans; Middle Aged; Strabismus; Vision Tests; Visual Acuity
PubMed: 7437398
DOI: 10.1136/bjo.64.5.349 -
Vision Research Dec 2016Perceptual constancy refers to the ability to stabilize the representation of an object even though the retinal image of the object undergoes variations. In previous...
Perceptual constancy refers to the ability to stabilize the representation of an object even though the retinal image of the object undergoes variations. In previous studies, we proposed a General Object Constancy (GOC) hypothesis to demonstrate a common stabilization mechanism for perception of an object's features, such as size, contrast and depth, as the perceived distance varies. In the present study, we report another depth illusion supporting the GOC model. The stimuli comprised pairs of disks moving in a pattern of radial optic flow. Each pair consisted of a white disk positioned upper left to a dark disk, creating a percept of the white disk casting a shadow. As the pairs contracted towards the center of the screen in accordance with motion away from the observer, the two disks in each pair appeared to increase in contrast and separate farther away from each other both in the fronto-parallel plane (angular separation illusion) and in depth (depth separation illusion). While the contrast illusion and the angular separation illusion, which is a variant of the size illusion, replicated our previous findings, the illusion of depth separation revealed a depth constancy phenomenon. We further confirmed that the size and depth perception were related, e.g., the depth separation and the angular separation illusions were highly correlated across observers. Whereas the illusory increase in the angular separation between a disk and its 'shadow' could not be canceled by modulation of depth, decreasing the angular separation could offset the illusory increase in depth separation. The results can be explained by the GOC hypothesis: the visual system uses the same scaling factor to account for contrast, size (angular separation), and depth variations with distance; additionally, the perceived size of the object is used to scale its depth and contrast signals in order to achieve constancy.
Topics: Adult; Awareness; Depth Perception; Distance Perception; Female; Humans; Male; Models, Theoretical; Optic Flow; Optical Illusions; Photic Stimulation; Size Perception
PubMed: 27810350
DOI: 10.1016/j.visres.2016.09.015 -
Perception 2013Among monocular depth cues, ocular parallax (first described formally by Brewster in 1844) remains mostly unknown, its role in perception still not investigated...
Among monocular depth cues, ocular parallax (first described formally by Brewster in 1844) remains mostly unknown, its role in perception still not investigated scientifically. Given that every single eye movement induces ocular parallax, it is a potentially useful depth cue. This paper is an attempt to revive interest in the topic. As a monocular depth cue, ocular parallax naturally leads us to consider its benefit for a monocularly enucleated individual. Throughout history, numerous illustrious personalities coped with this fate in various ways. Here, we consider some historical insights into the visual life of the erstwhile duke of Urbino, Federico da Montefeltro (1422-1482), warlord and patron to the painter Piero della Francesca, and the Japanese warlord, Masamune Date (1567-1636), a vocal patron of exploration and the arts.
Topics: Depth Perception; History, 15th Century; History, 16th Century; Humans; Vision Disparity; Vision, Monocular
PubMed: 23964374
DOI: 10.1068/p7492 -
Vision Research Sep 2021In a random-dot stereogram (RDS), the spatial disparities between the interocularly corresponding black and white random dots determine the depths of object surfaces. If...
Contrast-reversed binocular dot-pairs in random-dot stereograms for depth perception in central visual field: Probing the dynamics of feedforward-feedback processes in visual inference.
In a random-dot stereogram (RDS), the spatial disparities between the interocularly corresponding black and white random dots determine the depths of object surfaces. If a black dot in one monocular image corresponds to a white dot in the other, disparity-tuned neurons in primary visual cortex (V1) respond as if their preferred disparities become non-preferred and vice versa, reversing the disparity sign reported to higher visual areas. Reversed depth is perceptible in the peripheral but not the central visual field. This study demonstrates that, in central vision, adding contrast-reversed dots to a noisy RDS (containing the normal contrast-matched dots) can augment or degrade depth perception. Augmentation occurs when the reversed depth signals are congruent with the normal depth signals to report the same disparity sign, and occurs regardless of the viewing duration. Degradation occurs when the reversed and normal depth signals are incongruent with each other and when the RDS is viewed briefly. These phenomena reflect the Feedforward-Feedback-Verify-and-reWeight (FFVW) process for visual inference in central vision, and are consistent with the central-peripheral dichotomy that central vision has a stronger top-down feedback from higher to lower brain areas to disambiguate noisy and ambiguous inputs from V1. When a RDS is viewed too briefly for feedback, augmentation and degradation work by adding the reversed depth signals from contrast-reversed dots to the feedforward, normal, depth signals. With a sufficiently long viewing duration, the feedback vetoes incongruent reversed depth signals and amends or completes the imperfect, but congruent, reversed depth signals by analysis-by-synthesis computation.
Topics: Depth Perception; Feedback; Humans; Photic Stimulation; Primary Visual Cortex; Vision Disparity; Vision, Binocular; Visual Cortex; Visual Fields
PubMed: 34091397
DOI: 10.1016/j.visres.2021.03.005 -
Vision Research Feb 2015The image blur and binocular disparity of a 3D scene point both increase with distance in depth away from fixation. Perceived depth from disparity has been studied...
The image blur and binocular disparity of a 3D scene point both increase with distance in depth away from fixation. Perceived depth from disparity has been studied extensively and is known to be most precise near fixation. Perceived depth from blur is much less well understood. A recent experiment (Held, R. T, Cooper, E. A., & Banks, M. S. (2012). Current Biology, 22, 426-431) which used a volumetric stereo display found evidence that blur and disparity are complementary cues to depth, namely the disparity cue dominates over the blur cue near the fixation depth and blur dominates over disparity at depths that are far from fixation. Here we present a similar experiment but which used a traditional 3D display so that blur was produced by image processing rather than by the subjects' optics. Contrary to Held et al., we found that subjects did not rely more on blur to discriminate depth at distances far from fixation, even though a sufficient level of blur was available to do so. The discrepancy between the findings of the two studies can be explained in at least two ways. First, Held et al.'s subjects received trial-to-trial feedback in a training phase and may have learned how to perform the task using blur discrimination. Second, Held et al.'s volumetric stereo display may have provided other optical cues that indicated that the blur was real rather than rendered. The latter possibility would have significant implications about how depth is perceived from blur under different viewing conditions.
Topics: Adult; Cues; Depth Perception; Female; Fixation, Ocular; Humans; Male; Photic Stimulation; Vision Disparity; Vision, Binocular
PubMed: 25482222
DOI: 10.1016/j.visres.2014.10.036