Gradients of relative disparity underlie the perceived slant of stereoscopic surfaces

Wardle, Susan G.; Gillam, Barbara

doi:10.1167/16.5.16

Cited by 8 publications

(13 citation statements)

References 51 publications

(96 reference statements)

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“…This is evident in an increase in apparent slant [40, 42–47] and a decrease in the time taken for it to be seen [40–42, 48]. This increase in apparent depth results from gradients of relative disparity provided by both the outline of the surface, and its texture [49]. …”

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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Section: Introductionmentioning

confidence: 99%

Binocular Depth Judgments on Smoothly Curved Surfaces

2016

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“…The fixation cross was not visible during stimulus presentation, leaving only the flanking lines as a fixation aid and cue to the depth of the screen plane. This minimal fixation aid ensured that participants could not make judgments using relative disparity information between the stimulus edges and any surrounding fixation stimulus (e.g., Wardle & Gillam, 2016).…”

Section: Stimulimentioning

confidence: 99%

“…Previous research on surface discontinuities has shown contradictory effects. In some cases, the presence of discontinuous edges can enhance perceived depth compared to continuous disparity changes (Cammack & Harris, 2016;Deas & Wilcox, 2014, 2015, and can improve slant discrimination thresholds (Wardle & Gillam, 2016). Conversely, some discontinuous surface arrangements lead to reductions in perceived depth, as in the depth variant of the Craik-O'Brien-Cornsweet illusion (Anstis, Howard, & Rogers, 1978;Rogers & Graham, 1983).…”

Section: Introductionmentioning

confidence: 99%

Surface continuity and discontinuity bias the perception of stereoscopic depth

2018

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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.

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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%

“…Cyclopean perception (Julesz, 1971), our ability to perceive the 3D shape and structure of surfaces from binocular disparity alone, may, for example, be limited primarily by early absolute disparity measurement processes, as noted earlier. Alternatively, performance impairments may be more directly related to limitations in the measurement of relative disparities, or in the use of these measurements for the description of cyclopean form (e.g., Goutcher & Wilcox, 2016;Goutcher et al, 2018;Wardle & Gillam, 2016). In this article, we report the results of experiments measuring performance impairments for cyclopean surface perception in the presence of different forms of random-dot masking stimuli.…”

Section: Introductionmentioning

confidence: 99%

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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Gradients of relative disparity underlie the perceived slant of stereoscopic surfaces

Cited by 8 publications

References 51 publications

Binocular Depth Judgments on Smoothly Curved Surfaces

Binocular Depth Judgments on Smoothly Curved Surfaces

Surface continuity and discontinuity bias the perception of stereoscopic depth

Impairment of cyclopean surface processing by disparity-defined masking stimuli

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