Infants’ neural processing of emotional faces is affected by ostracism.

Humans can extract multiple behavioral and biological information from processing others’ facial expressions (Leppänen et al., 2007). This ability has been shown to appear at early stages of development (Rayson et al., 2017) and to play a fundamental role in social communication for infants (Kobiella et al., 2008). Many studies have investigated the neural correlates of face processing in infancy (e.g., Leppänen et al., 2007; Kobiella et al., 2008; Quadrelli et al., 2019); however, little is known about whether and how this processing can be affected by social interactions during infancy. The aim of this study is to explore whether being included or ostracized during a triadic playful social interaction (i.e., a ball-tossing game) can influence 13- to 14-month-old infants’ behavioral reactivity during the game and the subsequent neural processing of emotional faces. Therefore, we implemented a live version of the Cyberball Game (Williams & Sommer, 1997; Williams et al., 2000) in which infants participated being either included or excluded while playing with two experimenters. The Cyberball phase was videorecorded to assess whether infants’ behavior was affected by being ostracized as compared to included. Following the participation in the ball-tossing game, event-related potentials (ERPs) of 38 infants (N = 19 excluded) were measured while they observed faces displaying dynamic expressions of anger, fear, and happiness. Results exploring behavioral reactions revealed that ostracism influenced ostracized infants’ negative emotionality and involvement behaviors during the ball-tossing game. Furthermore, analysis on ERP data were conducted via ANOVAs to assess whether the condition in which the infant played the game and the emotional expressions seen had an impact on components’ amplitude and latency. Results revealed a faster P1 to happy faces in the ostracism as compared to the inclusion condition. In addition, in the inclusion condition fearful faces elicited faster responses compared to happy expressions, while no significant differences emerged in the ostracism condition. However, no significant results were found for Nc component, considered as an index of the allocation of infants’ attentional resources (i.e., Dennis et al., 2009) and for the N290 and P400 components (i.e., linked to face processing, and considered the precursors of adults’ N170, de Haan et al., 2003). Current findings demonstrate that ostracism has a direct impact on infants’ behavior and influences the way in which they process emotional faces at the neural level, thus suggesting possible negative cascading effects of ostracism episodes on infants’ affective and cognitive development.