Contour interpolation revealed by a dot localization paradigm

Guttman, Sharon E.; Kellman, Philip J.

doi:10.1016/j.visres.2004.02.008

Cited by 57 publications

(95 citation statements)

References 36 publications

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“…This research has examined the geometric constraints that underlie the grouping of local elements into extended contours, as well as how these constraints relate to the statistics of natural images. By contrast, there has been relatively little psychophysical work on measuring the shapes of the missing portions (12)(13)(14)(15). Because the missing portions of contours are synthesized entirely by the visual system, their detailed shapes are likely to be revealing about its underlying constraints and mechanisms.…”

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confidence: 99%

Visual extrapolation of contour geometry

Singh

Fulvio

2005

Proc. Natl. Acad. Sci. U.S.A.

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Computing the shapes of object boundaries from fragmentary image contours poses a formidable problem for the visual system. We investigated the extrapolation of contour shape by human vision. Measurements of extrapolation position and orientation were taken at six distances from the point of occlusion, thereby yielding a detailed representation of the extrapolated contours. Analyses of these measurements revealed that: (i) extrapolation curvature increases linearly with the curvature of the inducing contour, although there is individual bias in the slope; (ii) the precision with which an extrapolated contour is represented is roughly constant, in angular terms, with increasing distance from the point of occlusion; (iii) there is a substantial cost of curvature, in that the overall precision of an extrapolated contour decreases systematically with curvature; (iv) the shapes of visually extrapolated contours are characterized by a nonlinear decrease in curvature, asymptoting to zero; and (v) this decaying pattern of curvature is explained by a Bayesian model in which, with increasing distance from the point of occlusion, the prior tendency to minimize curvature gradually dominates the likelihood tendency to minimize variation in curvature.contour completion ͉ curvature ͉ interpolation ͉ occlusion ͉ shape perception A fundamental problem faced by the visual brain in computing object structure is the fragmentary nature of the retinal inputs. Large portions of object boundaries are often missing in the retinal images, either due to partial occlusion or because of insufficient local image contrast. Occlusion in particular poses a ubiquitous problem, given the multiplicity of objects in the world and the loss of one spatial dimension during image projection. To compute object structure from fragmented image data, the visual system must solve two related problems. It must determine (i) whether disparate image elements are in fact part of a single continuous contour (the ''grouping'' problem), and (ii) what shape the contour has in the missing portions (the ''shape'' problem).A great deal of research has addressed the grouping problem in the contexts of partly occluded contours, illusory contours, and discretely sampled contours (1-11). This research has examined the geometric constraints that underlie the grouping of local elements into extended contours, as well as how these constraints relate to the statistics of natural images. By contrast, there has been relatively little psychophysical work on measuring the shapes of the missing portions (12-15). Because the missing portions of contours are synthesized entirely by the visual system, their detailed shapes are likely to be revealing about its underlying constraints and mechanisms.Two constraints have been recognized in computational vision: (i) minimization of total curvature, and (ii) minimization of variation in curvature. Minimizing total curvature ͐ 2 ds (also known as ''bending energy'') tends to make contours as straight as possible and leads to a class of inte...

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confidence: 99%

Visual extrapolation of contour geometry

Singh

Fulvio

2005

Proc. Natl. Acad. Sci. U.S.A.

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“…For example, the dot localization paradigm (e.g., [18], [50], [15]) is a method where observers are asked to localize a point (or line) probe either inside or outside an amodally or modally completed boundary (Fig. 4A), and the distribution of responses is used to determine the likely completed shape.…”

Section: Perceptual and Psychophysical Insightsmentioning

confidence: 99%

“…Often in these experiments the inducers are placed symmetrically in a cocircular configuration, which could be used to very explicitly examine the validity of the roundedness axiom. Somewhat surprisingly, and despite the popularity and the intuitive appeal of this axiom, recent results show that visually completed curves are somewhat flatter than circular arcs [18], [11], thus putting in doubt the validity of the biarc [51], the Euler spiral [27], and the scale-invariant elastica [46] models. It should be mentioned that in these experiments the distribution of results was similar for modal and amodal completions, hence supporting the identity hypothesis.…”

Section: Perceptual and Psychophysical Insightsmentioning

confidence: 99%

“…The short time in which completed curves are constructed (e.g., [18], [40]) is indicative of an early vision process that takes place as early as the primary visual cortex (V1). Some properties of this cortical area indeed motivate much of our proposed theory.…”

Section: Neurophysiological Insightsmentioning

confidence: 99%

“…5B). Subsequent work has shown that orientation selective neurons in two hypercolumns are able to interact via long range horizontal connections [41], [16], [5] to facilitate contextual computations that could [18]). A point probe (in red, numbered by the order of appearance) is presented for a short time on top of a modally or amodally completed figure.…”

Section: Neurophysiological Insightsmentioning

confidence: 99%

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A Tangent Bundle Theory for Visual Curve Completion

Ben-Yosef

Ben-Shahar

2012

IEEE Trans. Pattern Anal. Mach. Intell.

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Abstract-Visual curve completion is a fundamental perceptual mechanism that completes the missing parts (e.g., due to occlusion) between observed contour fragments. Previous research into the shape of completed curves has generally followed an "axiomatic" approach, where desired perceptual/geometrical properties are first defined as axioms, followed by mathematical investigation into curves that satisfy them. However, determining psychophysically such desired properties is difficult and researchers still debate what they should be in the first place. Instead, here we exploit the observation that curve completion is an early visual process to formalize the problem in the unit tangent bundle R 2 Â S 1 , which abstracts the primary visual cortex (V1) and facilitates exploration of basic principles from which perceptual properties are later derived rather than imposed. Exploring here the elementary principle of least action in V1, we show how the problem becomes one of finding minimum-length admissible curves in R 2 Â S 1 . We formalize the problem in variational terms, we analyze it theoretically, and we formulate practical algorithms for the reconstruction of these completed curves. We then explore their induced visual properties vis-à -vis popular perceptual axioms and show how our theory predicts many perceptual properties reported in the corresponding perceptual literature. Finally, we demonstrate a variety of curve completions and report comparisons to psychophysical data and other completion models.

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Global and local visual processing in autism: An objective assessment approach

et al. 2017

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We examined global and local visual processing in autism spectrum disorder (ASD) via a match-to-sample task using Kanizsa illusory contours (KIC). School-aged children with ASD (n = 28) and age-matched typically developing controls (n = 22; 7-13 years) performed a sequential match-to-sample between a solid shape (sample) and two illusory alternatives. We tracked eye gaze and behavioral performance in two task conditions: one with and one without local interference from background noise elements. While analyses revealed lower accuracy and longer reaction time in ASD in the condition with local interference only, eye tracking robustly captured ASD-related global atypicalities across both conditions. Specifically, relative to controls, children with ASD showed decreased fixations to KIC centers, indicating reduced global perception. Notably, they did not differ from controls in regard to fixations to local elements or touch response location. These results indicate impaired global perception in the absence of heightened local processing in ASD. They also underscore the utility of eye-tracking measures as objective indices of global/local visual processing strategies in ASD. Autism Res 2017, 10: 1392-1404. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

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Contour interpolation revealed by a dot localization paradigm

Cited by 57 publications

References 36 publications

Visual extrapolation of contour geometry

Visual extrapolation of contour geometry

A Tangent Bundle Theory for Visual Curve Completion

Global and local visual processing in autism: An objective assessment approach

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