Department of Computer Science, Tokyo University of Technology, Hachioji, Tokyo, Japan.
Department of Logistics and Information Engineering, Tokyo University of Marine Science and Technology, Koto, Tokyo, Japan.
PLoS One. 2020 Apr 2;15(4):e0230847. doi: 10.1371/journal.pone.0230847. eCollection 2020.
The number of elements in two stereo-surfaces parallelly overlapped in depth is overestimated compared to that in a single flat surface, even when both have the same number of elements. Using stereoscopic pairs of elements, we evaluated two hypotheses on the overestimation: one that a higher-order process, forming a background surface, increases the number of perceived elements, and the other that the number of elements potentially occluded by the elements on a front surface is taken accounted for. The data from four experiments showed that (a) when binocular disparity between (or among) stereoscopic elements was small, the overestimation occurred for the stimuli we used-a two-surface-overlapping stimulus, where the likelihood for the process to operate was manipulated by changing the averaged luminance of each surface, a volumetric stimulus, where the likelihood for the background surface to be formed would decrease, and a two-non-overlapping-surface stimulus, where the surfaces in depth were not overlapped-, and (b) when binocular disparity was large, the overestimation occurred for the two-surfaces-overlapping stimulus, when the averaged luminance of the two surfaces were the same, and for the volumetric stimulus, but diminished for the surface-overlapping stimulus, when the averaged luminance differed between the surfaces and for the surfaces-non-overlapping stimulus. These results cannot be explained either hypothesis only. We explain the results by postulating that the sensory system processing disparities of elements interferes with that estimating the number of elements, resulting in an overestimation of the elements in a stereo-stimulus, and the disparity range within which the interference occurs may depend on the stimulus depth structure.
当两个深度上平行重叠的立体面中的元素数量与单个平面中的元素数量相同时，与单个平面相比，这些元素的数量会被高估。使用立体元素对，我们评估了关于高估的两个假设：一个假设是，形成背景表面的更高阶过程会增加感知到的元素数量，另一个假设是，前表面上的元素潜在遮挡的元素数量被考虑在内。四项实验的数据表明：(a) 当立体元素之间的双眼视差较小时，高估现象会出现在我们使用的刺激物中——一个两层重叠的刺激物，通过改变每个表面的平均亮度来操纵背景表面形成的可能性，一个体积刺激物，其中形成背景表面的可能性会降低，以及一个两层不重叠的刺激物，其中深度上的表面不重叠；(b) 当双眼视差较大时，高估现象仅出现在两层重叠的刺激物中，当两个表面的平均亮度相同时，以及体积刺激物中，但在重叠的表面刺激物中减少，当两个表面的平均亮度不同时，以及在不重叠的表面刺激物中。这两个假设都不能解释这些结果。我们通过假设来解释这些结果，即处理元素视差的感觉系统会干扰估计元素数量的过程，从而导致对立体刺激中元素数量的高估，并且干扰发生的视差范围可能取决于刺激的深度结构。
