Abstract
Previous studies showed that stimuli on the both sides of the blind spot are needed for perceptual completion at the blind spot to occur (Kawabata, 1982; Kobayashi et al., 1999). In this study, we examined whether perceptual filling-in occurs or not in the blind spot when a line segment presented on one side of the blind spot. A test line segment was a horizontal line segment which was presented so that an end of the test line segment coincided with the edge of the blind spot in blind spot condition. Two vertical line segments were also presented above and below the test line segment so that they were horizontally aligned with the end of the test line segment at near side to the blind spot. For comparison, we performed control condition in which the end of the test line segment was detached from the edge of the blind spot. Observer's task was to judge whether the end of the test line segment at the near side to the blind spot was perceived on the right or left side to the two vertical line segments. The results showed that the response of which the end was perceived at the near side to the blind spot in the blind spot condition was significantly more than that in the control condition and the chance level. The results suggest that filling-in of a line segment presented on one side of blind spot occurs in the blind spot.
The present study was supported in part by a Grant-in-Aid for the 21st Century COE Program.