Abstract
The perception of a central stimulus can be affected by the presence of surround stimuli through lateral interactions in the visual system. Xing and Heeger (2000) have demonstrated that surround suppression became markedly stronger as the center-surround stimulus was moved toward the periphery. Moreover, the different center-surround interactions in the fovea and periphery cannot be accounted for by cortical magnification. This report presented further evidence that center-surround interactions in the fovea and periphery are incommensurable. We performed two psychophysical experiments and found that 1) perception of subjective contour diminished in the periphery; and 2) curvature detection with the presence of surround stimuli significantly deteriorated in the periphery. Once again, these differences could not be account for by cortical magnification. The results suggest that fovea and periphery play different functional roles in human vision. To understand the inhomogeneous functions of lateral interaction, we built an image processing model of the primary vision system with lateral connections embedded. We first adjusted model parameters to make the model have the same performance as human subjects had in fovea and periphery respectively. With those parameters, we then analyzed image perception in fovea and periphery. The results showed that lateral interaction resulted in image integration in the fovea but image segmentation in the periphery. The model also predicted the reduced legibility and reading speed in periphery that could not be explained with cortical magnification. The possible impacts of the results on evaluating perceived information complexity of a visual scene were discussed.