Abstract
Previous studies have shown that the speed of visual processing increases with eccentricity (Carrasco, 2002). Meanwhile, studies have demonstrated that the visual system is sensitive to topological changes, such as the appearance and disappearance of holes in a figure (Chen, 1982, 2005). Our results of a series of behavioral experiments suggest that, compare to foveal vision, the peripheral vision is more engaged in the rapid detection of topological changes. First, we employed a change detection paradigm to study the sensitivities to changes in foveal and peripheral vision. In each trial, a four-figure stimulus in continuous vertical motion was simultaneously and bilaterally presented at visual angle of 5°and 20°in each side. One of the four figures underwent an abrupt shape change either with a change of hole number ("HC") or without ("nHC"). The luminance contrast between stimuli and background was manipulated to avoid the ceiling effect. Moreover, in 11 experiments, many local features (e.g. luminance, similarity, spatial frequency, perimeter and shape of the contour) and task difficulty were well controlled, and the possibility that a "Hole" figure stimulates an on-center cell was ruled out. The detection performance was quantified as d’. The results showed that the d’ under the "HC" condition was significantly higher in the periphery than it in the foveal, whereas the "nHC" condition manifested significantly higher d’ in foveal than in periphery. And we also investigated the performance of change detection with a random motion paradigm. The topological advantage was still found in the periphery. Last, measuring at more eccentricities, the performance of "HC" retained its sensitivity while "nHC" deteriorated with eccentricity increased. The observed sensitivity advantage in periphery supports the view that topological definition of objects provides a coherent account for the object perception in the peripheral vision.
Meeting abstract presented at VSS 2012