Abstract
In a recent study by Huang, Kingdom, and Hess, (VSS 2005) it was suggested that the visual system has only two phase mechanisms, namely +cosine and -cosine. This suggests rather limited access to the rich distribution of receptive field phase that neurophysiologists tell us are represented in the different response profiles of striate simple cells. While that study has suggested that striate receptive field phase is not directly available to perception for the detection/discrimination of localized stimuli, here we investigate whether such information might be utilized in more integrative texture segmentation and contour integration tasks. Specifically, given that simple cells have different local absolute phase response profiles, we ask whether a network of simple cells with similar phase preferences can interact in such a way as to extract textures and/or contours on the basis of phase alone. Accordingly, we designed two novel 4AFC texture segmentation experiments and one 2AFC contour integration experiment both using random-phase fields of log-Gabors with embedded sub-regions of same-phase elements with the intention of providing an answer to the question of how useful is local absolute spatial phase for texture segmentation and contour integration. The results add further support to the proposition that, at the perceptual level, only two phase mechanisms (±cosine) are available, be it for the detection/discrimination of an isolated feature or the segmentation/integration of globally distributed features.
Canadian Institutes of Health Research (CIHR) grant: MT 108-18 to RFH