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Philosophical Transactions of the Royal... Jun 2016Deciding what constitutes an object, and what background, is an essential task for the visual system. This presents a conundrum: averaging over the visual scene is...
Deciding what constitutes an object, and what background, is an essential task for the visual system. This presents a conundrum: averaging over the visual scene is required to obtain a precise signal for object segregation, but segregation is required to define the region over which averaging should take place. Depth, obtained via binocular disparity (the differences between two eyes' views), could help with segregation by enabling identification of object and background via differences in depth. Here, we explore depth perception in disparity-defined objects. We show that a simple object segregation rule, followed by averaging over that segregated area, can account for depth estimation errors. To do this, we compared objects with smoothly varying depth edges to those with sharp depth edges, and found that perceived peak depth was reduced for the former. A computational model used a rule based on object shape to segregate and average over a central portion of the object, and was able to emulate the reduction in perceived depth. We also demonstrated that the segregated area is not predefined but is dependent on the object shape. We discuss how this segregation strategy could be employed by animals seeking to deter binocular predators.This article is part of the themed issue 'Vision in our three-dimensional world'.
Topics: Depth Perception; Humans; Vision Disparity; Vision, Binocular
PubMed: 27269601
DOI: 10.1098/rstb.2015.0258 -
Journal of Vision Sep 2023Contingent on stereo compatibility, two images presented dichoptically can lead to either binocular integration, thus generating stable stereopsis, or interocular...
Contingent on stereo compatibility, two images presented dichoptically can lead to either binocular integration, thus generating stable stereopsis, or interocular suppression that induces binocular rivalry with bistable perception that alternates between the two images. The relationship between binocular integration and interocular suppression concerns how our brain processes binocular inputs to form unified visual awareness but remains unclear. Here, a series of psychophysical experiments were conducted to address this question, revealing that these collaborative and competitive binocular interactions are interconnected and would mediate one another according to their strength. Specifically, Experiments 1a and 1b showed that the presence of binocular rivalry inhibited peripheral stereopsis, significantly elevating the stereo threshold, with higher elevation resulting from increasing rivalry contrast. Experiments 2a and 2b showed that existing stereopsis with increasing binocular disparity balanced the dynamics of peripheral binocular rivalry, rendering more equivalent eye dominance. Based on these interactions, we suggest that binocular integration and interocular suppression may mediate one another through an overlapping mechanism for regulating eye dominance, with strong stereo percepts tending to reduce eye dominance and strong rivalry tending to increase eye dominance.
Topics: Humans; Vision, Binocular; Depth Perception; Brain; Dominance, Ocular; Vision Disparity
PubMed: 37750747
DOI: 10.1167/jov.23.10.17 -
Journal of Vision May 2017Estimating an accurate and naturalistic dense depth map from a single monocular photographic image is a difficult problem. Nevertheless, human observers have little...
Estimating an accurate and naturalistic dense depth map from a single monocular photographic image is a difficult problem. Nevertheless, human observers have little difficulty understanding the depth structure implied by photographs. Two-dimensional (2D) images of the real-world environment contain significant statistical information regarding the three-dimensional (3D) structure of the world that the vision system likely exploits to compute perceived depth, monocularly as well as binocularly. Toward understanding how this might be accomplished, we propose a Bayesian model of monocular depth computation that recovers detailed 3D scene structures by extracting reliable, robust, depth-sensitive statistical features from single natural images. These features are derived using well-accepted univariate natural scene statistics (NSS) models and recent bivariate/correlation NSS models that describe the relationships between 2D photographic images and their associated depth maps. This is accomplished by building a dictionary of canonical local depth patterns from which NSS features are extracted as prior information. The dictionary is used to create a multivariate Gaussian mixture (MGM) likelihood model that associates local image features with depth patterns. A simple Bayesian predictor is then used to form spatial depth estimates. The depth results produced by the model, despite its simplicity, correlate well with ground-truth depths measured by a current-generation terrestrial light detection and ranging (LIDAR) scanner. Such a strong form of statistical depth information could be used by the visual system when creating overall estimated depth maps incorporating stereopsis, accommodation, and other conditions. Indeed, even in isolation, the Bayesian predictor delivers depth estimates that are competitive with state-of-the-art "computer vision" methods that utilize highly engineered image features and sophisticated machine learning algorithms.
Topics: Algorithms; Bayes Theorem; Depth Perception; Humans; Imaging, Three-Dimensional; Likelihood Functions; Models, Theoretical
PubMed: 28564686
DOI: 10.1167/17.5.22 -
Vision Research Oct 2023Monocular blindness impairs visual depth perception, yet patients seldom report difficulties in targeted actions like reaching, walking, or driving. We hypothesized that...
Monocular blindness impairs visual depth perception, yet patients seldom report difficulties in targeted actions like reaching, walking, or driving. We hypothesized that by utilizing monocular depth information and calibrating actions with haptic feedback, monocular patients can perceive egocentric distance and perform targeted actions. We compared targeted reaching in monocular patients, monocular-viewing, and binocular-viewing normal controls. Sixty observers reached either a far or a near target, calibrating reaches to the near target with accurate or false feedback while leaving reaches to the far target uncalibrated. Reaching accuracy and precision were analyzed. Results indicated no difference in reaching accuracy between monocular patients and normal controls; all groups initially underestimated distances before until calibration. Monocular patients responded to calibration sensitively, achieving accuracy in calibrated reaches and generalizing this effect to uncalibrated distances. Thus, with monocular depth information and haptic feedback, monocular patients could perceive distance and accomplish targeted reaching.
Topics: Humans; Distance Perception; Haptic Technology; Vision, Ocular; Depth Perception; Feedback; Vision, Monocular; Vision, Binocular
PubMed: 37343461
DOI: 10.1016/j.visres.2023.108274 -
Journal of Vision Jun 2018Local depth variation is a distinctive property of natural scenes, but its effects on perception have only recently begun to be investigated. Depth variation in natural...
Local depth variation is a distinctive property of natural scenes, but its effects on perception have only recently begun to be investigated. Depth variation in natural scenes is due to depth edges between objects and surface nonuniformities within objects. Here, we demonstrate how natural depth variation impacts performance in two fundamental tasks related to stereopsis: half-occlusion detection and disparity detection. We report the results of a computational study that uses a large database of natural stereo-images and coregistered laser-based distance measurements. First, we develop a procedure for precisely sampling stereo-image patches from the stereo-images and then quantify the local depth variation in each patch by its disparity contrast. Next, we show that increased disparity contrast degrades half-occlusion detection and disparity detection performance and changes the size and shape of the spatial integration areas ("receptive fields") that optimize performance. Then, we show that a simple image-computable binocular statistic predicts disparity contrast in natural scenes. Finally, we report the most likely spatial patterns of disparity variation and disparity discontinuities (half-occlusions) in natural scenes. Our findings motivate computational and psychophysical investigations of the mechanisms that underlie stereo processing tasks in local regions of natural scenes.
Topics: Depth Perception; Humans; Psychophysics; Vision Disparity; Vision, Binocular; Visual Perception
PubMed: 30029214
DOI: 10.1167/18.6.4 -
The Journal of Neuroscience : the... Jul 2020Each of our eyes sees a slightly different view of the physical world. Disparity is the small difference in position of features in the retinal images; stereopsis is the...
Each of our eyes sees a slightly different view of the physical world. Disparity is the small difference in position of features in the retinal images; stereopsis is the percept of depth from disparity. A distance between corresponding features in the retinal images of the two eyes smaller than the "upper disparity limit" yields a percept of depth; distances greater than this limit cause the two unfused monocular features to appear flattened into the fixation plane. This behavioral disparity limit is consistent with neurophysiological estimates of the largest disparity scale in primate, allowing us to relate physiological limits on plausible binocular interactions to separation between retinal locations. Here we test the hypothesis that this upper disparity limit predicts the presence of coarse stereopsis in humans with macular degeneration (MD), which affects the central retina but typically spares the periphery. The pattern of vision loss can be highly asymmetric, such that an intact location in one eye has a corresponding point in the other eye that lies within affected retina. Nevertheless, some individuals with MD have coarse stereopsis that is useful for eye-hand coordination. Our results show that individuals with MD ( = 25, male and female) have coarse stereopsis when the distance between intact retinal locations is less than the behavioral and physiological upper disparity limit at the corresponding eccentricity. Furthermore, for those without stereopsis, we can predict whether they can achieve stereopsis by using alternate retinal loci at further eccentricities whose separation is below the upper disparity limit. We show that the largest separation between features in the two eyes that yields a percept of depth in humans is related to the largest disparity scale in macaque medial temporal area and to the estimated size of the receptive fields in human depth-sensitive cortical regions. This upper disparity limit also predicts whether individuals with retinal damage due to macular degeneration will have stereopsis. Individuals have stereopsis when the separation between intact retinal locations in the two eyes is smaller than the upper disparity limit measured behaviorally. Our results indicate the importance of the behavioral upper disparity limit as a predictor for stereopsis in populations with retinal damage.
Topics: Aged; Aged, 80 and over; Depth Perception; Female; Humans; Macular Degeneration; Male; Middle Aged; Photic Stimulation; Retina; Vision Disparity; Visual Acuity
PubMed: 32487694
DOI: 10.1523/JNEUROSCI.0491-20.2020 -
Proceedings of the National Academy of... Jun 2020Arguably the most foundational principle in perception research is that our experience of the world goes beyond the retinal image; we perceive the distal environment...
Arguably the most foundational principle in perception research is that our experience of the world goes beyond the retinal image; we perceive the distal environment itself, not the proximal stimulation it causes. Shape may be the paradigm case of such "unconscious inference": When a coin is rotated in depth, we infer the circular object it truly is, discarding the perspectival ellipse projected on our eyes. But is this really the fate of such perspectival shapes? Or does a tilted coin retain an elliptical appearance even when we know it's circular? This question has generated heated debate from Locke and Hume to the present; but whereas extant arguments rely primarily on introspection, this problem is also open to empirical test. If tilted coins bear a representational similarity to elliptical objects, then a circular coin should, when rotated, impair search for a distal ellipse. Here, nine experiments demonstrate that this is so, suggesting that perspectival shapes persist in the mind far longer than traditionally assumed. Subjects saw search arrays of three-dimensional "coins," and simply had to locate a distally elliptical coin. Surprisingly, rotated circular coins slowed search for elliptical targets, even when subjects clearly knew the rotated coins were circular. This pattern arose with static and dynamic cues, couldn't be explained by strategic responding or unfamiliarity, generalized across shape classes, and occurred even with sustained viewing. Finally, these effects extended beyond artificial displays to real-world objects viewed in naturalistic, full-cue conditions. We conclude that objects have a remarkably persistent dual character: their objective shape "out there," and their perspectival shape "from here."
Topics: Cues; Depth Perception; Form Perception; Humans; Philosophy; Rotation
PubMed: 32532920
DOI: 10.1073/pnas.2000715117 -
Vision Research Apr 2022
Topics: Depth Perception; Humans; Vision Disparity; Vision, Binocular
PubMed: 34973631
DOI: 10.1016/j.visres.2021.107989 -
Strabismus Sep 2022In the early 19 century the doctrine of identical retinal points, linked with the Vieth-Müller circle, was a pillar of German physiological optics. It was challenged by...
In the early 19 century the doctrine of identical retinal points, linked with the Vieth-Müller circle, was a pillar of German physiological optics. It was challenged by Wheatstone's observations of stereoscopic depth perception announced in 1838; he also advanced a cognitive theory of binocular vision that attacked physiological interpretations. In 1841 Brücke mounted a defense of the doctrine by questioning Wheatstone's observations and offering an alternative interpretation in terms of the integration over time of a rapid sequence of convergence eye movements. The theory could not be sustained because of evidence that stereoscopic depth occurred without eye movements. Brücke also questioned Wheatstone's observations that with some stereoscopic displays stimulation of identical retinal points could result in double vision. The binocular combination of circles differing in size was accounted for by differentially dissociating accommodation in opposite directions for each eye from convergence. Despite the negative reaction to Brücke's proposals, his speculations about the nature of rapid eye movements and of their neural basis were ahead of his time.
Topics: Male; Humans; Vision, Binocular; Eye Movements; Accommodation, Ocular; Diplopia; Depth Perception
PubMed: 36263956
DOI: 10.1080/09273972.2022.2106048 -
Science Advances Jan 2020The camera-type eyes of vertebrates and cephalopods exhibit remarkable convergence, but it is currently unknown whether the mechanisms for visual information processing...
The camera-type eyes of vertebrates and cephalopods exhibit remarkable convergence, but it is currently unknown whether the mechanisms for visual information processing in these brains, which exhibit wildly disparate architecture, are also shared. To investigate stereopsis in a cephalopod species, we affixed "anaglyph" glasses to cuttlefish and used a three-dimensional perception paradigm. We show that (i) cuttlefish have also evolved stereopsis (i.e., the ability to extract depth information from the disparity between left and right visual fields); (ii) when stereopsis information is intact, the time and distance covered before striking at a target are shorter; (iii) stereopsis in cuttlefish works differently to vertebrates, as cuttlefish can extract stereopsis cues from anticorrelated stimuli. These findings demonstrate that although there is convergent evolution in depth computation, cuttlefish stereopsis is likely afforded by a different algorithm than in humans, and not just a different implementation.
Topics: Animals; Decapodiformes; Depth Perception; Eye Movements; Imaging, Three-Dimensional; Predatory Behavior; Vision, Binocular
PubMed: 31934631
DOI: 10.1126/sciadv.aay6036