Gestalt grouping via closure degrades suprathreshold depth percepts

Deas, Lesley; Wilcox, Laurie M.

doi:10.1167/14.9.14

Cited by 16 publications

(27 citation statements)

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“…The fact that the surface condition produced a significantly greater bias than when only the vertical edges were present suggests that the relative depth of the near and far edges is perceived differently (i.e., underestimated) when the edges are connected to form an isolated slanted surface. These results are related to previously reported effects of closure on subthreshold and suprathreshold depth discrimination (Westheimer 1979b;McKee, 1983;Mitchison andWestheimer, 1984, Zalevski, Henning, &Hill, 2007;Deas & Wilcox, 2014), which will be addressed in the General discussion.…”

Section: Resultssupporting

confidence: 86%

“…Our finding in Experiment 1 that the probe bias was reduced when the two horizontal lines connecting the vertical lines into a rectangle were removed (i.e., leaving only the vertical lines at the near and far edges) is consistent with previous results of the effect of closure on depth discrimination (Westheimer, 1979b;McKee, 1983;Mitchison & Westheimer, 1984;Deas & Wilcox, 2014). Depth discrimination thresholds are increased when horizontal lines are added to a pair of vertical lines to form a closed rectangle, compared to when only the vertical lines are present (McKee, 1983;Mitchison & Westheimer, 1984).…”

Section: Discussionsupporting

confidence: 91%

“…Depth discrimination thresholds are increased when horizontal lines are added to a pair of vertical lines to form a closed rectangle, compared to when only the vertical lines are present (McKee, 1983;Mitchison & Westheimer, 1984). Similarly, Deas and Wilcox (2014) used a suprathreshold depth estimation task and found that the relative depth of two vertical lines was underestimated when they were connected by horizontal lines to form a closed object, compared to when the lines were either isolated or connected to form two separate closed objects. Experiment 1 confirms this result using a substantially different method (the probe bias task) to estimate perceived depth.…”

Section: Discussionmentioning

confidence: 99%

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Gradients of relative disparity underlie the perceived slant of stereoscopic surfaces

Wardle

Gillam

2016

Journal of Vision

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Perceived stereoscopic slant around a vertical axis is strongly underestimated for isolated surfaces, suggesting that neither uniocular image compression nor linear gradients of absolute disparity are very effective cues. However, slant increases to a level close to geometric prediction if gradients of relative disparity are introduced, for example by placing flanking frontal-parallel surfaces at the horizontal boundaries of the slanted surface. Here we examine the mechanisms underlying this slant enhancement by manipulating properties of the slanted surface or the flanking surfaces. Perceived slant was measured using a probe bias method. In Experiment 1, an outlined surface and a randomly textured surface showed similar slant underestimation when presented in isolation, but the enhancement in slant produced by flankers was significantly greater for the textured surface. In Experiment 2, we degraded the relative disparity gradient by (a) reducing overall texture density, (b) reducing flanker width, or (c) adding disparity noise to the flankers. Density had no effect while adding noise to the flankers, or reducing their width significantly decreased perceived slant of the central surface. These results support the view that the enhancement of slant produced by adding flanking surfaces is attributable to the presence of a relative disparity gradient and that the flanker effect can spread to regions of the surface not directly above or below the gradient.

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Section: Resultssupporting

confidence: 86%

Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

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Gradients of relative disparity underlie the perceived slant of stereoscopic surfaces

Wardle

Gillam

2016

Journal of Vision

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“…These results may be interpreted as the consequence of combining conflicting evidence to the best segmentation of the image into distinct surfaces, rather than any direct effect on the way in which binocular disparity itself it processed. However, Gestalt grouping via closure also reduces the amount of depth that is perceived [34,35]…”

Section: Introductionmentioning

confidence: 99%

Binocular Depth Judgments on Smoothly Curved Surfaces

2016

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Binocular disparity is an important cue to depth, allowing us to make very fine discriminations of the relative depth of objects. In complex scenes, this sensitivity depends on the particular shape and layout of the objects viewed. For example, judgments of the relative depths of points on a smoothly curved surface are less accurate than those for points in empty space. It has been argued that this occurs because depth relationships are represented accurately only within a local spatial area. A consequence of this is that, when judging the relative depths of points separated by depth maxima and minima, information must be integrated across separate local representations. This integration, by adding more stages of processing, might be expected to reduce the accuracy of depth judgements. We tested this idea directly by measuring how accurately human participants could report the relative depths of two dots, presented with different binocular disparities. In the first, Two Dot condition the two dots were presented in front of a square grid. In the second, Three Dot condition, an additional dot was presented midway between the target dots, at a range of depths, both nearer and further than the target dots. In the final, Surface condition, the target dots were placed on a smooth surface defined by binocular disparity cues. In some trials, this contained a depth maximum or minimum between the target dots. In the Three Dot condition, performance was impaired when the central dot was presented with a large disparity, in line with predictions. In the Surface condition, performance was worst when the midpoint of the surface was at a similar distance to the targets, and relatively unaffected when there was a large depth maximum or minimum present. These results are not consistent with the idea that depth order is represented only within a local spatial area.

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“…Beginning at V2, and continuing through multiple cortical sites, neurons show selectivity for relative disparities, that is, for differences between absolute disparity measurements across space (Fang et al, 2018;Neri, Bridge & Heeger, 2004;Thomas, Cumming & Parker, 2002;Umeda, Tanabe & Fujita, 2007). Although sensitivity for relative disparities has not been modeled extensively (cf., Assee & Qian 2007;Zhaoping, 2002), numerous psychophysical observations suggest the importance of processes operating at this level (e.g., Deas & Wilcox, 2014;Deas & Wilcox, 2015;Glennerster & McKee, 1999;Glennerster & McKee, 2004;Goutcher & Hibbard, 2010;Goutcher, Connolly & Hibbard, 2018;Goutcher & Wilcox, 2016;Vreven, McKee & Verghese, 2002;Wardle & Gillam 2016). Such results indicate that the tuning properties of relative disparity mechanisms are critically important for understanding the perception of cyclopean form (Goutcher et al, 2018;Hibbard, 2005;Tyler, 1975;Tyler, 2012;Tyler & Kontsevich, 2001).…”

Section: Introductionmentioning

confidence: 98%

Impairment of cyclopean surface processing by disparity-defined masking stimuli

Goutcher

Hibbard

2020

Journal of Vision

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Binocular disparity signals allow for the estimation of three-dimensional shape, even in the absence of monocular depth cues. The perception of such disparity-defined form depends, however, on the linkage of multiple disparity measurements over space. Performance limitations in cyclopean tasks thus inform us about errors arising in disparity measurement and difficulties in the linkage of such measurements. We used a cyclopean orientation discrimination task to examine the perception of disparity-defined form. Participants were presented with random-dot sinusoidal modulations in depth and asked to report whether they were clockwise or counter-clockwise rotated. To assess the effect of different noise structures on measurement and linkage processes, task performance was measured in the presence of binocular, random-dot masks, structured as either antiphase depth sinusoids, or as random distributions of dots in depth. For a fixed number of surface dots, the ratio of mask-to-surface dots was varied to obtain thresholds for orientation discrimination. Antiphase masks were found to be more effective than random depth masks, requiring a lower mask-to-surface dot ratio to inhibit performance. For antiphase masks, performance improved with decreased cyclopean frequency, increased disparity amplitude, and/or an increase in the total number of stimulus dots. Although a cross-correlation model of disparity measurement could account for antiphase mask performance, random depth masking effects were consistent with limitations in relative disparity processing. This suggests that performance is noise-limited for antiphase masks and complexity-limited for random masks. We propose that use of differing mask types may prove effective in understanding these distinct forms of impairment.Citation: Goutcher, R. & Hibbard, P. B. (2020). Impairment of cyclopean surface processing by disparity-defined masking stimuli.

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Gestalt grouping via closure degrades suprathreshold depth percepts

Cited by 16 publications

References 50 publications

Gradients of relative disparity underlie the perceived slant of stereoscopic surfaces

Gradients of relative disparity underlie the perceived slant of stereoscopic surfaces

Binocular Depth Judgments on Smoothly Curved Surfaces

Impairment of cyclopean surface processing by disparity-defined masking stimuli

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