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Aishwarya Sudhama, Lesley Deas, Laurie Wilcox; The impact of disparity-based grouping on 3D slant perception. Journal of Vision 2016;16(12):836. doi: https://doi.org/10.1167/16.12.836.
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© ARVO (1962-2015); The Authors (2016-present)
The amount of depth perceived between two isolated features is dramatically reduced when those features are grouped to form boundaries of a surface (Deas & Wilcox, 2014). The strength of this disruption of depth perception is modulated by 2D grouping principles (e.g. closure and good continuation). Moreover, the reduction in depth perception also depends on the smoothness of the disparity gradient along the surface, which we called good disparity continuation (Deas & Wilcox, 2015). The aim of this series of experiments is to determine if the reduction in depth from disparity is a general property of smoothly varying surfaces. If so, it should not be restricted to these simple interpolated surfaces, slanted about a vertical axis. We replicated and extended previous experiments with simple line stimuli known to reduce perceived depth when connected to form surfaces. Four equally spaced lines were presented; the central pair was manipulated to create three conditions: isolated lines, a single closed object, and two closed objects. These configurations were presented vertically and horizontally in separate blocks of trials. The orientation manipulation had the important consequence of changing the direction of the disparity gradient in the two conditions. On all trials, observers estimated the amount of depth between the two central lines using a touch sensitive sensor strip. The results showed that when the closed object contained a horizontal disparity gradient, depth percepts were consistently reduced compared to isolated lines. However, this reduction was eliminated when the stimuli were orientated around the horizontal axis. The same pattern of results was obtained using a row of dots – which required no surface interpolation. We conclude that the reduction in suprathreshold depth percepts linked to good disparity continuation is specific to horizontal disparity gradients, and may partially account for well-known orientation anisotropies in 3D slant perception.
Meeting abstract presented at VSS 2016
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