Abstract
It is generally acknowledged that familiar faces are processed in a qualitatively different manner to unfamiliar ones. However, since the majority of previous investigations have employed either famous faces or simply familiarized subjects with stimuli, little is known about how personal familiarity influences face perception. We investigated the effect of personal familiarity on the discrimination of single inter-feature distances within both upright and inverted faces (experiment 1) as well as on the discrimination of the geometric configuration of features within upright faces (experiment 2). Inversion led to poorer discrimination of vertical changes within faces but only for subjects familiar with the stimuli. Furthermore personal familiarity was associated with superior discrimination of subtle changes in facial geometry. Both experiments point towards familiarity increasing sensitivity for information considered to rely on holistic processing. We exploited the fact that subjects can name personally familiar faces to overcome response biases traditionally associated with same-different judgments in the composite paradigm. Specifically we examined the hemisphere dependence of holistic processing by presenting misaligned and aligned composite stimuli in the left or right visual field (experiment 3). Poorer performance—associated with alignment of top and bottom parts—was observed only for stimuli presented within the left visual field. To our knowledge this is the first demonstration of right hemisphere involvement in holistic processing without any contribution of performance bias.