Selectivity of Facial Aftereffects for Changes in Gender and Expression
AdvisorWebster, Michael A.
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The ability to perceive and distinguish faces is a fundamental role of the visual system, though how the visual system accomplishes this goal remains poorly understood. A common method used to explore the neural mechanisms underlying face perception is to examine face adaptation aftereffects. For instance, when an observer views a distorted face (e.g. contracted) for a prolonged period of time, a normal face will appear to be distorted in the opposite direction (e.g. expanded). Several studies have utilized these adaptation aftereffects in order to investigate how adaptation transfers across different types of faces, to test whether common or separate neural pathways code different facial attributes. Two attributes that are thought to be processed by largely separate neural subsystems are the expression and identity of the face. In the present study, we examined the selectivity of face aftereffects for differences in gender or expression, in order to further elucidate how expression and identity are encoded in the brain. We tested the prediction that adaptation should show stronger transfer across changes in facial expression because expression changes do not alter the perceived identity of faces. The results of this study showed weak selectivity for changes in expression or gender, as well as modest differences between these two forms of natural facial variation. The results thus were inconsistent with the proposal that variant features of the face, like an expression change, will have less influence on adaptation than an invariant change, like gender or identity. Instead, the results suggest that changes in expression or gender have comparable effects, and may be represented in similar ways at least with regard to the mechanisms mediating face adaptation.