| Summary: | 碩士 === 臺灣大學 === 心理學研究所 === 98 === To study how the visual system compute 3D shape of faces from shading information, we manipulated the illumination conditions on 3D scanned face models and observed how the face discrimination changes with lighting directions . We used a symmetry algorithm to dissociate surface albedo and illumination component of face images by separating symmetric and asymmetric components of both low and high spatial frequency information of face images. Stimuli were hybrid faces with different combination of symmetric and spatial content. Results show that asymmetric low spatial frequency (shading) information had significant influence on face discrimination, while the symmetric ones have little, if any, effect on face discrimination. The asymmetric low spatial frequency also changed the perceived depth of hybrid faces. Together, these results suggest that (1) the asymmetric low spatial frequency information dramatically affects both perceived face identity and perceived depth; and (2) this effect increased as the lighting direction shifts to the side. Thus, our results provide an evidence for 3D-based face processing.
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