Visual information processing at the blind spot.

The perceptual completion at the blind spot was studied by presenting test patterns around the blind area of 3 subjects with normal acuity, and conditions generating the perceptual completion were investigated. To be filled in, a stimulus must fall on at least two quadrants around the blind spot. Both a region between 3.0 and 3.9 degrees in radii around the blind spot, which can generate white homogeneous completion, and the region between 4.3 and 5.2 degrees, which can not generate any completion solely, play important parts in provoking completion. Periodic stimuli were more effective than non-periodic ones.