Abstract
Moradi et al. (2005) showed that the face adaptation did not occur when the adaptor was invisible. However, Bahrami et al. (2008) found that spatial attention to the location of invisible adaptor could increase the amount of orientation adaptation. In this study, we investigated whether spatial attention could boost even the amount of adaptation from invisible face. We used the same method as in Moradi et al. (2005) except using a different suppressor. The stimuli were morphed faces in which certain percentage of a female face was intermixed with certain percentage of a male face. Participants' task was to judge whether these morphed faces looked like a female or a male against 5 different levels of femaleness. We first measured PSE of male/female discrimination before adaptation. We then had participants adapt to the female faces. The two adaptors were presented in the left and the right visual field of a non-dominant eye and they were made to be invisible using binocular rivalry. They were suppressed by two pinwheel gratings (suppressors) presented in a dominant eye and participants had to report their percept during adaptation. To modulate attention during adaptation, participants performed the contrast-decrement detection task on the attended suppressor. Contrast decrements were independently occurred in each visual field regardless of participants' locus of attention. For the unattended faces, we found that the PSE before adaptation did not differ from that after adaptation in the invisible condition, whereas the PSE after adaptation shifted towards more femaleness in the partially visible condition, replicating Moradi et al. (2005)'s findings. For the attended faces, however, the PSE after adaptation significantly shifted towards more femaleness even in the invisible condition. These results suggest that attention can modulate the effect of face adaptation even when the adaptor is invisible.
This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MEST) (NO. R01-2008-000-10820-0).