Global interactions in perceptual completion at the blind spot

Nonlinearity and asymmetrical property in the filling-in process at the blind spot are investigated. Perceptual completion of a pattern with a gap is deteriorated, i.e. gap information inhibits completion across the gap. Filled-in patterns, observed from complementary patterns, are not the same in complementary sense. These suggest that perceptual completion cannot simply be predicted from a superimposition of completions, obtained from local stimulus conditions, and seems to be mediated by global processes.