The face size illusion is specific to whole faces

Abstract

Faces are critical stimuli used for many social cognitive processes, believed to be served by specialised neural processes in the visual system. A recently described face size illusion shows that upright faces are perceived as physically smaller than inverted faces, and may provide insight into the neurocognitive mechanisms underlying human face perception. In this study, we investigated whether the face size illusion is specific to whole faces or whether it occurs as well for isolated face parts. The results provided a clear replication of the face size illusion for whole faces. In striking contrast, no comparable illusion was found for isolated noses, mouths, and eyes. For eyes, there was in fact an illusion in the opposite direction. These results provide further evidence for the specificity of the face size illusion and suggest that it may arise from the holistic processing of the face as an entire unit, rather than localised processing of individual face parts.