Perceptual consequences of face viewpoint adaptation: face viewpoint aftereffect, changes of differential sensitivity to face view, and their relationship.

Adaptation to a visual pattern can alter the sensitivities of neuronal populations encoding the pattern, which usually results in a visual aftereffect. However, the functional role of visual adaptation is still equivocal and its relation to visual aftereffect is largely unknown, especially for high-level visual adaptation. In this study, we took advantage of face view adaptation to investigate these issues. In the first experiment, we measured the angular tuning function of the face viewpoint aftereffect in F. Fang and S. He's (2005) study. As the adapting angle increased from 0 degrees to 90 degrees , the aftereffect magnitude increased quickly, peaked at 20 degrees , and then gradually decreased. In the second experiment, the effects of face viewpoint adaptation on face view discrimination were measured. We found that face view discrimination around the adapting view improved but was impaired when the adapting view was about 30 degrees away. These results suggest that the functional role of face viewpoint adaptation was not only to adjust the boundary of our perceptual categories but also to modulate the performance of our face view discrimination, highlighting the adaptive nature of face coding. Finally, we showed that a computational model proposed by C. W. G. Clifford, A. M. Wyatt, D. H. Arnold, S. T. Smith, and P. Wenderoth (2001) could account for these two phenomena and their relationship in terms of the changes of the tuning function of face view selective neurons.