The nature of synthetic face adaptation

Recent evidence demonstrates that adapting to a face will systematically bias the perception of faces that lie along the same identity trajectory in geometric face space but not faces that lie along different identity trajectories [Leopold, D.A., O'Toole, A. J., Vetter, T., & Blanz, V. (2001). Prototype-referenced shape encoding revealed by high-level aftereffects. Nature Neuroscience, 4(1), 89-94]. We explored this configural aftereffect using synthetic face stimuli developed to measure face-specific processing. Adapting to synthetic “anti-faces” resulted in an identity-specific aftereffect that was characterized by a marked decrease in the slope of the psychometric functions. Adaptation transferred across different face sizes, but not different face viewpoints nor faces constructed about a non-mean face. Performance was captured by a model where responses were modulated through a divisive gain control and an additive constant reflecting a shift in the origin of perceived face space. Together, these results suggest that face adaptation reflects activity from mechanisms common to various processing stages along the visual pathway.