Perceptual filling-in from the edge of the blind spot

Abstract

Looking at the world with one eye, we do not notice a scotoma in the receptor-free area of the visual field where the optic nerve leaves the eye. Rather we perceive the brightness, color, and texture of the adjacent area as if they were actually there. The mechanisms underlying this kind of perceptual filling-in remain controversial. To better understand these processes, we determined the minimum region around the blind spot that needs to be stimulated for filling-in by carefully mapping the blind spot and presenting individually fitted stimulus frames of different width around it. Uniform filling-in was observed with frame widths as narrow as 0.05 degrees visual angle for color and 0.2 degrees for texture. Filling-in was incomplete, when the frame was no longer contiguous with the blind spot border due to an eye movement. These results are consistent with the idea that perceptual filling-in of the blind spot depends on local processes generated at the physiological edge of the cortical representation.

Appearance of an Illusory Object in the Blind Spot

“…Two and three objects below the blind spot appear as three and four objects, respectively. The phenomenon differs in the following two unique aspects from perceptual filling-in of dots at the blind spot reported in previous studies (Brown and Thurmond 1993;Kawabata 1982;Spillmann et al 2006): it occurred even when (a) the objects were large enough to be counted, and (b) the objects were presented on only one side of the blind spot.The first aspect suggests that the visual system produces an independent illusory object in the blind spot. The previous studies have shown that visual information consisting of small dots of an uncountable size, which could be considered as a texture, filled-in the blind spot (Brown and Thurmond 1993;Spillmann et al 2006).…”

“…Two and three objects below the blind spot appear as three and four objects, respectively. The phenomenon differs in the following two unique aspects from perceptual filling-in of dots at the blind spot reported in previous studies (Brown and Thurmond 1993;Kawabata 1982;Spillmann et al 2006): it occurred even when (a) the objects were large enough to be counted, and (b) the objects were presented on only one side of the blind spot.…”

“…There has been no previous report that visual information presented only on one side of the blind spot is perceived in the blind spot. In the previous studies which reported that the dots appeared in the blind spot, the dot pattern covered the whole of the blind spot (Brown and Thurmond 1993;Spillmann et al 2006) or the dotted lines were presented on opposite sides of the blind spot (Kawabata 1982). The previous studies suggest that the visual system may produce the filling dots so that they preserve the perceived dot pattern.…”

Fixation Locus in Patients with Bilateral Central Scotomas for Targets that Perceptually Fill In

“…The spanning of the scotoma by the target is thought to be an important prerequisite for perceptual filling-in to occur. 14,15 …”

Preenchimento perceptivo da mancha cega não distorce a percepção do tamanho linear

“…Ela apresentou erros geralmente com grande variabilidade e os erros médios eram desprezíveis em certas condições, sugerindo-se que havia preenchimento perceptivo sem distorção de tamanho. Em outras condições, os erros médios eram significativamente diferentes de zero, sugerindo-se que havia preenchimento perceptivo com distorção de tamanho, similar aos dados relatados por Araragi e Nakamizo (2008) e Spillmann et al (2006). Uma possível explicação para essa variação é a hipótese da interpolação neural da mancha cega proposta por Fiorani, Rosa, Gattass e Rocha-Miranda (1992).…”