Size determines whether specialized expert processes are engaged for recognition of faces

Many influential models of face recognition postulate specializedexpertprocessesthatareengagedwhenviewing upright, own-race faces, as opposed to a general-purpose recognition route used for nonface objects and inverted or other-race faces. In contrast, others have argued that empirical differencesdonot stemfromqualitativelydistinct processing.We offer a potential resolution to this ongoing controversy.We hypothesize that faces engage specialized processes at large sizes only. To test this, wemeasured recognitionefficienciesforawiderangeofsizes.Uprightface recognition efficiency increased with size.This was not due to better visibility of basic image features at large sizes.We ensuredthisbycalculatingefficiencyrelativetoaspecialized ideal observer unique to each individual that incorporated size-related changes in visibility and by measuring inverted efficienciesacrossthesamerangeof facesizes. Invertedface recognition efficiencies did not change with size. A qualitative face inversion effect, defined as the ratio of relative upright and inverted efficiencies, showed a complete lack of inversion effects for small sizes up to 68. In contrast, significant face inversion effectswere found for all larger sizes. Size effects may stem from predominance of larger faces in the overall exposure to faces, which occur at closer viewing distances typical of social interaction. Our results offer a potential explanation for the contradictory findings inthe literatureregardingthespecial statusoffaces