Abstract
Several investigations suggest that during the first year of life, face representations become tuned to environmentally relevant faces (e.g., own-race faces) relative to environmentally irrelevant or less frequently encountered faces (e.g., other-race faces), a process called “perceptual narrowing” (Kelly et al., 2007; 2009; Pascalis et al., 2002; 2005; Scott & Monesson, 2009; Sugita, 2008). Recently, this tuning of face representations has been found to be dependent on experience (or lack of experience) learning to match a face with an individual-level proper name during the first year of life (Scott & Monesson, 2009). However, it is unknown how early experience contributes to the neural specialization of structures underlying face processing or whether experience with objects leads to similar discrimination and neural specialization. Here, four groups of infants completed pre-training (at 6 months of age) and post-training (at 9 months) behavioral (Visual-Paired Comparison) and electrophysiological (Event-Related Potentials) assessments, which indexed face and object discrimination. Following the pre-training assessment, two groups of infants were sent home with training books of monkey faces or of objects (strollers), which were labeled at the individual level (i.e. all faces and strollers had individual names). Two more groups of infants were sent home with books of monkey faces or strollers labeled at the category level (i.e. all faces were named “monkey” or “stroller”). Infants returned at 9 months and results revealed both behavioral and electrophysiological (P1; N290; P400; Nc) differences from 6 to 9 months, and across training conditions. Only individual-level training led to behavioral maintenance (monkey faces) or facilitation (strollers) in ability to discriminate stimuli. The electrophysiological results show that infants exhibited greater ERP inversion effects for both monkey faces and strollers after individual-level, but not category-level training highlighting the importance of individual-level learning in the development of perceptual expertise for faces and objects.
University of Massachusetts Faculty Research Grant.