Wariness in early childhood manifests as shy, inhibited behavior in novel social situations and is associated with increased risk for developing social anxiety. In youth with childhood wariness, exposure to a potent social stressor, such as peer victimization, may potentiate brain-based sensitivity to unpredictable social contexts, thereby increasing risk for developing social anxiety. To test brain-based associations between early childhood wariness, self-reported peer victimization, and current social anxiety symptoms, we quantified neural responses to different social contexts in low- and high-victimized pre-adolescents with varying levels of early childhood wariness. Measures of early childhood wariness were obtained annually from ages 2-to-7-years. At age 11, participants were characterized as having low (N=20) or high (N=27) peer victimization. To index their neural responses to peer evaluation, participants completed an fMRI-based Virtual School paradigm (Jarcho et al., 2013). In highly victimized, relative to low-victimized participants, wariness was differentially related to right amygdala responsivity based on the valence and predictability of peer evaluation. More specifically, in highly victimized participants, wariness was associated with greater right amygdala responsivity to unpredictably positive peer evaluation. Effects of wariness were not observed in participants who reported low levels of victimization. Moreover, in victimized participants, high wariness and right amygdala response to unpredictably positive peer evaluation was associated with more severe social anxiety symptoms. Results can be interpreted using a diathesis-stress model, which suggests that neural response to unexpectedly positive social feedback is a mechanism by which exposure to peer victimization potentiates the risk for developing social anxiety in individuals exhibiting high levels of early childhood wariness.

Social rejection elicits profound feelings of distress. From an evolutionary perspective, the best way to alleviate this distress is to behave prosocially, minimizing the likelihood of further exclusion. Yet, examples ranging from the playground to the pub suggest rejection commonly elicits aggression. Opposing theoretical perspectives and discordant empirical results have left a basic question unanswered: does rejection more commonly elicit prosocial or aggressive behavior?We conducted three meta-analyses (one with studies measuring aggressive behavior; one with studies measuring prosocial behavior; and one with studies measuring both aggressive and prosocial behavior; N = 3864) to quantify: (1) the extent to which social rejection elicits prosocial or aggressive behavior and (2) potential moderating effects on these relations. Random-effects models revealed medium effects such that social rejection potentiated aggressive behavior (k = 19; d = 0.41, p < .0001) and attenuated prosocial behavior (k = 7; d = 0.59, p < .0001), an effect that remained consistent even when participants were given the option to behave prosocially or aggressively (k = 15; d = 0.71, p < .0001). These results cast doubt on the theory that rejection triggers prosocial behavior, and instead suggest it is a robust elicitor of aggression.Statement of Relevance: To our knowledge, these meta-analyses are the first to directly test whether social rejection elicits aggressive or prosocial behavior. By including a comprehensive collection of both published and unpublished research studies, and examining a wide variety of previously untested moderators, we show that social rejection robustly elicits aggressive behavior and inhibits prosocial behavior. Additionally, we demonstrate that aggressive behavior following social rejection is not simply a function of limited choices in response options. In fact, aggressive behavior was evoked even when the option to engage in prosocial behavior was provided. Furthermore, we conducted a comprehensive narrative review of the neural mechanisms underlying social rejection-elicited aggressive and prosocial behavior to supplement primary analyses. Overall, we believe that our work makes a critical theoretical contribution to the field.