UC Davis

Faces are among the most important sources of social information in early childhood, providing cues about others' emotions, intentions, and mental states that support children's developing social understanding and behavior. The ability to perceive emotional facial expressions has been proposed to play a foundational role in the development of theory of mind (ToM) (Mitchell & Phillips, 2015; O’Brien et al., 2011), yet empirical evidence directly linking emotional face perception and ToM remains limited, particularly during early childhood when both abilities undergo rapid development. Moreover, although theoretical models of prosocial development posit that successful prosocial behavior depends on both children's capacity to reason about others' mental states and their ability to perceive socially relevant cues (Eisenberg & Mussen, 1989; Rahal & Fiedler, 2021), little research has examined how these processes work together to predict children's social behavior.To address these gaps, the present dissertation examined the role of emotional face perception in social-cognitive development using event-related potentials (ERPs), which provide a temporally precise measure of neural responses to emotional facial expressions (Luck, 2014). Across two studies of preschool-aged children, neural indices of early, automatic attentional orienting (P1) (Batty & Taylor, 2006), structural face processing (N170) (Blau et al, 2007), and attentional allocation to faces (Nc) (de Haan et al., 2002) were used to characterize individual differences in emotional face perception and their relations with behavioral measures of ToM and prosocial tendencies.The first study investigated whether individual differences in preschool children's neural responses to emotional facial expressions (as indexed by N170 and Nc) were associated with individual differences in behavioral ToM. Findings revealed a specific role for the Nc component, such that a greater Nc amplitude to negative (fear and anger) relative to neutral facial expressions were associated with more advanced mental-state reasoning, suggesting that individual differences in the allocation of attention to emotional faces are meaningfully related to emerging ToM abilities.The second study examined whether emotional face perception and ToM jointly predicted preschool children's prosocial tendencies. Results indicated that ToM was positively associated with prosocial behavior only among children who exhibited enhanced P1 amplitudes to emotional facial expressions, suggesting that early attention to emotional cues may facilitate the translation of social-cognitive inferencing into prosocial action.Together, these findings provide novel evidence that individual differences in neural responses to emotional faces contribute to variability in preschoolers' social cognition and prosocial behavior. By integrating developmental neuroscience with existing empirical and behavioral theories, this dissertation advances understanding of the mechanisms linking emotional face perception, mental-state inferencing, and prosocial development during a critical period of early childhood.