The current longitudinal study ( n = 98) utilized a developmental cognitive neuroscience approach to examine whether and how variability in social perception is linked to social behavior in early human development. Cortical responses to processing dynamic faces were investigated using functional near-infrared spectroscopy at 7 months. Individual differences in sociability were measured using the Early Childhood Behavior Questionnaire at 18 months. Confirming previous work with infants and adults, functional near-infrared spectroscopy results show that viewing changing faces recruited superior temporal cortices in 7-month-old infants, adding to the view that this brain system is specialized in social perception from early in ontogeny. Our longitudinal results show that greater engagement of the right superior temporal cortex at 7 months predicts higher levels of sociability at 18 months. This suggests that early variability in social perception is linked to later differences in overtly displayed social behavior, providing novel longitudinal evidence for a social brain–behavior association.

Face evaluation is a key aspect of face processing in humans, serving important functions in regulating social interactions. Adults and preschool children readily evaluate faces with respect to a person's trustworthiness and dominance. However, it is unclear whether face evaluation is mainly a product of extensive learning or a foundational building block of face perception already during infancy. We examined infants' sensitivity to facial signs of trustworthiness (Experiment 1) and dominance (Experiment 2) by measuring ERPs and looking behavior in response to faces that varied with respect to the two facial attributes. Results revealed that 7-month-old infants are sensitive to facial signs of trustworthiness but not dominance. This sensitivity was reflected in infants' behavioral preference and in the modulation of brain responses previously linked to emotion detection from faces. These findings provide first evidence that processing faces with respect to trustworthiness has its origins in infancy and shed light on the behavioral and neural correlates of this early emerging sensitivity.

We measured looking times and ERPs to examine the cognitive and brain bases of perceptual category learning in 6-month-old infants. In Experiment 1, we showed that categorization and exemplar discrimination rely on different cortical processes. Specifically, the repetition of individual exemplars resulted in differential cortical processing at posterior channels at an early stage during object processing (100–300 msec), whereas discriminating among members of different categories was reflected in ERP differences over anterior cortical regions occurring later in time (300–500 msec) than the repetition effects. In Experiment 2, replicating the findings of Study 1, we found that infants engage the same cortical processes to categorize visual objects into basic-level categories, regardless of whether a basic (bird vs. fish) or global level is crossed (birds vs. cars). This pattern of findings is consistent with perceptual accounts of infant categorization [Quinn, P. C., & Eimas, P. D. Perceptual organization and categorization in young infants. In C. Rovee-Collier & L. P. Lipsitt (Eds.), Advances in infancy research ( pp. 1–36). Norwood, NJ: Ablex, 1996] and accords with recent adult neural-level models of perceptual categorization.

Numerous studies investigated physiological correlates of the processing of musical information in adults. How these correlates develop during childhood is poorly understood. In the present study, we measured event-related electric brain potentials elicited in 5and 9-year-old children while they listened to (major–minor tonal) music. Stimuli were chord sequences, infrequently containing harmonically inappropriate chords. Our results demonstrate that the degree of (in) appropriateness of the chords modified the brain responses in both groups according to music-theoretical principles. This suggests that already 5-year-old children process music according to a well-established cognitive representation of the major–minor tonal system and according to music-syntactic regularities. Moreover, we show that, in contrast to adults, an early negative brain response was left predominant in boys, whereas it was bilateral in girls, indicating a gender difference in children processing music, and revealing that children process music with a hemispheric weighting different from that of adults. Because children process, in contrast to adults, music in the same hemispheres as they process language, results indicate that children process music and language more similarly than adults. This finding might support the notion of a common origin of music and language in the human brain, and concurs with findings that demonstrate the importance of musical features of speech for the acquisition of language.