Psychology, Faculty of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK.
Department of Psychology, Centre for Vision Research, York University, Toronto, ON, Canada.
Vision Res. 2021 Mar;180:37-50. doi: 10.1016/j.visres.2020.12.001. Epub 2020 Dec 23.
Binocular disparity signals are highly informative about the three-dimensional structure of visual scenes, including aiding the detection of depth discontinuities between surfaces. Here, we examine factors affecting sensitivity to such surface discontinuities. Participants were presented with random dot stereograms depicting two planar surfaces slanted in opposite directions and were asked to judge the sign of the depth discontinuity created where those surfaces met. Although the judgement was focussed on the adjacent edges, the precision of depth discontinuity discrimination depended upon the slant of the two surfaces: increasing surface slants to ±60° increased discontinuity discrimination thresholds by, on average, a factor of 5. Control experiments examining discontinuity discrimination across surfaces with identical slants showed either biases in discontinuity judgements or reduced threshold elevation. These results suggest that sensitivity to depth discontinuities is affected by processing limitations in both local absolute disparity measurement mechanisms and mechanisms selective for disparity differences. As further evidence in support of this conclusion, we show that our results are well-described by a model of discontinuity discrimination based on the encoding of local differences in relative disparity.
双眼视差信号对于视觉场景的三维结构非常重要，包括帮助检测表面之间的深度不连续性。在这里，我们研究了影响对这种表面不连续性的敏感性的因素。参与者被呈现描绘两个平面表面以相反方向倾斜的随机点立体图，并被要求判断这些表面相遇时产生的深度不连续性的符号。尽管判断集中在相邻的边缘，但深度不连续性的辨别精度取决于两个表面的倾斜度：表面倾斜度增加到±60°，不连续性辨别阈值平均增加了 5 倍。检查具有相同倾斜度的表面之间不连续性辨别实验显示出不连续性判断的偏差或阈值升高的降低。这些结果表明，深度不连续性的敏感性受到局部绝对视差测量机制和选择性差异的机制的处理限制的影响。作为支持这一结论的进一步证据，我们表明，我们的结果很好地由基于相对视差局部差异编码的不连续性辨别模型描述。
