Abstract
Face recognition is thought to rely on "holistic processing" – a style of perceptual mechanisms that bind facial features together for face identification. Many researchers propose that disruption of holistic processing is causally implicated in developmental prosopagnosia, but whether holistic processing in developmental prosopagnosia is reduced or completely abolished remains unclear. Here we report a large and comprehensive online study of holistic processing in developmental prosopagnosia. We tested 124 prosopagnosics and 124 sex/age-matched controls with three classic tasks of holistic processing: the inversion task, where identification of a face is much more difficult when the face is shown upside-down; the composite task, where matching two top-halves of faces is more difficult when they are paired with different bottom-halves; and the part-whole task, where discrimination of a target feature (eyes, nose, or mouth) is more difficult when the feature is shown alone than in a whole face. Prosopagnosics showed significant holistic effects across all tasks (inversion: 16.6%; composite: 15.2%; part-whole: 2.5%), but they were reduced compared to the effects in controls (inversion: 26.0%; composite: 20.2%; part-whole: 8.6%). Interestingly, the size of the reduction varied depending on task (inversion: 36.1% reduction relative to controls; composite: 24.8%; part-whole: 71.4%), suggesting that disruption of holistic processing in developmental prosopagnosia is not a unitary phenomenon. The reduced holistic effects in prosopagnosics appear to originate in typical mechanisms, because prosopagnosics showed little or no holistic effects with inverted faces in the composite and part-whole tasks. Our study provides robust evidence that developmental prosopagnosia is associated with reduced, not abolished, holistic processes, and sheds light on the nature and role of holistic processing in normal face recognition. Our study also demonstrates the value of online studies testing large numbers of participants in neuropsychology research.
Meeting abstract presented at VSS 2018