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Chia-Ching Wu, Chien-Chung Chen; Background Texture Nonlinearly Modulates Distance Effect on Perceived Size. Journal of Vision 2014;14(10):135. doi: https://doi.org/10.1167/14.10.135.
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The perceived size of an object depends not only on the size of the projected image on the retina but also the perceived distance of the object (size-distance invariance hypothesis). Here we investigated how background texture modulates this perceived size-distances relationship. The target was a disk with 136.8 arcmin diameter on a frontoparallel plane. The background was either blank or with texture filled with small, medium or large disk elements whose diameter was 68.4, 136.8 and 273.6 arcmin respectively. The perceived distance of the display was determined by binocular disparity of -13.4, -7.9, 0, 7.9, and 13.4 arcmin. We used a two interval forced choice paradigm to measure perceived target size at various combinations of disparity and background texture size. In each trial, the target with a background and a particular disparity was presented in one interval while a reference disk on a blank background and zero disparity was presented in another interval. The task of the observer was to determine which interval contained a larger disk. We measured the point of subjective equality (PSE) for the perceived target size with a staircase procedure. With blank background, the perceived target size increased with disparity with a slope 0.35. The presence of a background texture reduced the slope to 0.16-0.24 across background size. The large background texture shifted the perceived size-distance function downward while the small background texture shifted it upward. Hence, while there was a linear relationship between perceived target size and distance and between target size and background texture size, the presence of texture altered the relationship between perceived target size and distance. Such result cannot be explained by the maximum likelihood theory of cue combination but a nonlinear interaction between background size and distance.
Meeting abstract presented at VSS 2014
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