Adaptation and Face Perception: How Aftereffects Implicate Norm-Based Coding of Faces

Faces provide vital social information which shapes one's interactions. A response to a person depends on one's perception of their identity, sex, age, attractiveness, health, and ethnicity, as well as their emotional and attentional states. All of this information is read from the face. Although one does this effortlessly, but not always accurately, human visual system must solve a difficult problem because faces are all very similar as visual patterns. How does the visual system solve this problem, computationally and neurally? This chapter considers whether aftereffects in face perception can help one understand these mechanisms. It suggests that high-level and possibly face-specific aftereffects implicate norm-based, or prototype-referenced, coding of faces and discusses how these aftereffects implicate possible opponent coding of faces and indicate the important dimensions in 'face-space'.