An fMRI study of the effects of caricaturing faces

The ‘caricature effect’ refers to the widely replicated finding that caricatures (formed by distorting a face away from an average face) are treated as good likenesses of the original face, and anticaricatures (distorted towards an average face) as poor likenesses, despite both being equally physically different from the original. In this study we asked what underlies this asymmetric behavioral response at a neural level. Specifically, does the neural activation correspond to the physical differences between the stimuli and the original face (equal for caricatures and anticaricatures), or to the perceived differences (greater for anticaricatures)? Adult participants viewed sequential pairs of unfamiliar photographic quality faces in an event-related fMRI adaptation paradigm with four conditions: (a) original face followed by 50% caricature of the same individual (b) original face followed by 50% anticaricature of the same individual (c) original face followed by an identical image (d) original face followed by a different individual. Baseline activation measures to the different conditions were taken in a separate block design experiment. If the neural response reflected the physical differences between the stimuli, we expected equal adaptation from the original face to both the caricature and the anticaricature. If, however, the response reflected perceived differences between the stimuli, there should be more adaptation to the caricature than the anticaricature. Equivalent adaptation was found (N=7) for both the caricature and anticaricature, supporting the hypothesis that face-related regions (FFA/LOC/STS) are sensitive to changes in the physical properties of the face.