The role of gaze direction in face viewpoint aftereffect

Face viewpoint aftereffect is a visual illusion that, after adaptation to a face side view, the perceived view direction of the same face subsequently presented near its front view is biased in a direction opposite to that of the adapted view. Eye gaze is a unique component in face not only because its direction is relatively independent of face view direction, but also because it is a primary cue for conveying social attention. Here, we studied the contribution of gaze direction adaptation to the formation of face viewpoint aftereffect. We found that a tiny (in terms of relative area) change of gaze direction in adapting face stimuli could induce a dramatic reduction in the magnitude of face viewpoint aftereffect. However, vertical inversion of the face stimuli almost abolished the reduction. Implications of these findings about face view representation and gaze direction representation are discussed.