Abstract
A positive color is perceived when only the contour of the adapting figure was presented to the opposite eye following color adaptation to one eye. We have reported a similar positive aftereffect with van Lier's display (ECVP, 2010), but it involves simultaneous adaptation to two complementary colors, and the selection of aftereffects. The present aftereffect is very simple and free from such complicating factors and is quite parallel to the ordinary negative color aftereffect. In this study, we examined the temporal aspect of this new aftereffect to elucidate the site of adaptation. In Exp. 1, we measured the duration of the aftereffect in binocular (same eye) and dichoptic (opposite eyes) conditions. The adaptor was a star shaped figure colored either in red or green against a gray background. Following 1 sec adaptation, the test figure, a black contour of the same shape was presented. The aftereffect lasted for 1.5 sec in average for both conditions. In Exp. 2, we delayed the presentation of the test for 10 to 1000 ms in 7 steps and asked the occurrence and color of aftereffect to see the persistence of the adaptation effect. In the binocular condition, observers perceived negative aftereffect for more than 75% of trials up to 170 ms delay, and the percentage went down to chance level at around 300 ms. The positive aftereffect was almost never perceived. In the dichoptic condition, positive color was perceived in approximately 70% of the trials up to 170 ms, and it went down to chance level at around 300 ms. The negative aftereffect was almost never perceived. These results indicate that the duration of the dichoptic aftereffect is quite short and similar to that of ordinary negative aftereffect, and suggest that the dichoptic adaptation occurs at a relatively low level in the visual system.
Ministry of Education, Science, Sports and Culture, Grant-in-Aid 21330167.