Horizontal tuning of face-specific processing from childhood to elderly adulthood.

Face recognition in adults recruits specialised mechanisms that are selectively driven by horizontal information. This range indeed conveys the most optimal and stable cues to identity. Whether the horizontal tuning of adult face recognition reflects horizontal bias already active at infancy and/or whether it also results from the extensive experience acquired with faces over the lifespan is elusive. Answering these questions is crucial to determine the information constraining the developmental specialisation of core visual functions such as face perception. Participants aged between 6 and 74 years matched unfamiliar faces that were filtered to retain information in narrow ranges centred on horizontal (H), vertical (V), or both orientation ranges (HV). H and V ranges respectively maximize and minimize the recruitment of face-specific mechanisms (Goffaux and Dakin, 2010). Stimuli were presented at upright and inverted planar orientations and the face inversion effect (FIE; i.e., better performance for upright than inverted faces) was taken as a marker of face-specific processing. In H and HV conditions, FIE size increased linearly from childhood to adulthood, manifesting the progressive specialization of face perception. FIE emerged earlier when processing HV than H faces (FIE onset: 6 and 12 years, respectively) indicating that until 12 years horizontal information is necessary but not sufficient to trigger face-specialised processing. Partial correlations further showed that FIE development in HV condition was not fully explained by FIE development in H condition. Besides a progressive maturation of horizontal processing, the specialization of the face processing system thus also depends on the improved integration of horizontal range with other orientations. In contrast, FIE size was small and stable when processing V information. These results show that the face processing system matures over the life span based on the refined encoding of horizontally-oriented (upright) face cues. Meeting abstract presented at VSS 2015.