Abstract
It is well evident that human contrast sensitivity is altered not only by the temporal context such as adaptation but also by the spatial context. In order to examine the spatial contextual effect on blur perception, the present study measured and compared percentages of correct answers to Gaussian blurred Landolt C ring presented in foveal vision over various contextual stimuli. Our results indicated that: 1) the percentage of correct answers improved by the presence of surrounding noise filtered by the identical blur filter used for the Landolt C ring, 2) the improvement with the surrounding blurred noise was restricted in the adjacent area (approximately < 1 deg), and 3) the adaptation to the surrounding blurred noise had no effect on the percentage of correct answers. It is apparent from our results that the perceived blur in foveal vision is mitigated by the blur information presented in the surrounding field. In terms of the extent of the surrounding interaction, horizontal connection in the primary visual cortex is the first candidate for neural mechanism underlying this phenomenon.