Abstract
The Gestalt psychologists insisted that the whole is other than the sum of its parts. This can be tested using conjoined grouping factors in multi-stable dot lattices where the factors compete or cooperate in producing a global perceptual organization. For example, conjoined factors of spatial proximity and similarity operate additively (Kubovy & van den Berg, 2008), but conjoined factors of spatial and temporal proximity do not (Gepshtein & Kubovy, 2007). Here we studied dot lattices in which we conjoined the factors of spatial proximity and stereoscopic depth by varying inter-dot distances and binocular disparity. The lattices were briefly presented in a mirror stereoscope and the observers reported the perceived orientations of dot groupings. We computed the log-odds of grouping in a given orientation based on the relative strengths of the two grouping factors. We found that binocular disparity strongly modulated effects of spatial proximity, but effects of binocular disparity were highly nonlinear. Increasing the depth separation between dots weakened their grouping for small binocular disparities. For large disparities, however, the trend was reversed: increasing depth separation between dots strengthened their grouping. The effect of binocular disparity was attenuated by surface cues (starry night textures; Zabulis & Backus, 2004) that implied a common surface for all elements of the lattice, indicating that grouping is modulated by the perception of whether the elements belong to the same surface.
Meeting abstract presented at VSS 2014