Generalization of mere exposure to faces viewed from different horizontal angles

Evolutionary accounts of the centrality of social interaction for our species might anticipate more efficient affective processing for faces. The current study assessed whether mere exposure to upright faces resulted in greater generalization of liking than mere exposure to inverted faces, as might be predicted by special-process views of face perception. We presented upright and inverted photographs of faces taken from three different horizontal angles (full front-view, 45-degree, and full-profile), then asked participants to rate their liking for front-view photographs of the same faces. For inverted faces, but not upright faces, there was a significant linear trend for liking to decrease as presentation angle increased (from front-view through 45-degree to full-profile). Thus, upright front-view faces that had previously been presented in full-or semi-profile were liked at equivalent levels to upright front-view faces that had previously been presented in front-view. These findings suggest that mere exposure for upright faces presented at any angle may easily generalize to other views of the face, but that generalization is less efficient for perceptually matched inverted faces. These findings are consistent with evolutionary arguments for enhanced affective discrimination.