Abstract
Previous studies have shown that the speed of visual information processing increases with eccentricity. Researches have also demonstrated that the visual system is sensitive to topological changes, such as the appearance and disappearance of holes in a figure. Our results suggest that, compared to foveal vision, the peripheral vision is more engaged in the rapid detection of topological changes. We employed a change detection task with eye movement monitoring. One of the moving figures underwent an abrupt shape change either with a change of hole number ("HC") or without ("nHC"). In 7 experiments, many local features (e.g. luminance, similarity, spatial frequency, perimeter and shape of the contour) were well controlled. The detection performance was quantified as d'. The results showed that the d' under the "HC" condition was significantly larger in the periphery than it in the fovea, whereas the "nHC" condition manifested significantly larger d' in fovea than in periphery. The luminance contrast was manipulated to control for the task difficulty. There were 6 experiments consistently showed the advantage of "HC" detection in the periphery. And the consistent finding was also revealed by a random motion paradigm. When the stimulus size was scaled in the periphery according to the cortical magnification theory, the topological advantage cannot be diminished. Moreover, measuring at more eccentricities and even at the eccentricity of 30°, the performance of "HC" retained its sensitivity while "nHC" deteriorated with eccentricity increased. Further, in our fMRI experiment, the response to the "HC" at periphery condition was contrasted with the activation in response to the "nHC" at periphery condition. The result revealed a major activation in the anterior temporal lobe. The observed sensitivity advantage in periphery may support the view that topological definition of objects provides a coherent account for the object perception in the peripheral vision.
Meeting abstract presented at VSS 2017