A neuroimaging study examined the neural correlates of social exclusion and tested the hypothesis that the brain bases of social pain are similar to those of physical pain. Participants were scanned while playing a virtual ball-tossing game in which they were ultimately excluded. Paralleling results from physical pain studies, the anterior cingulate cortex (ACC) was more active during exclusion than during inclusion and correlated positively with self-reported distress. Right ventral prefrontal cortex (RVPFC) was active during exclusion and correlated negatively with self-reported distress. ACC changes mediated the RVPFC-distress correlation, suggesting that RVPFC regulates the distress of social exclusion by disrupting ACC activity.

Ostracism is such a widely used and powerful tactic that the authors tested whether people would be affected by it even under remote and artificial circumstances. In Study 1, 1,486 participants from 62 countries accessed the authors' on-line experiment on the Internet. They were asked to use mental visualization while playing a virtual tossing game with two others (who were actually computer generated and controlled). Despite the minimal nature of their experience, the more participants were ostracized, the more they reported feeling bad, having less control, and losing a sense of belonging. In Study 2, ostracized participants were more likely to conform on a subsequent task. The results are discussed in terms of supporting K. D. Williams's (1997) need threat theory of ostracism.

In this review, I examine the social psychological research on ostracism, social exclusion, and rejection. Being ignored, excluded, and/or rejected signals a threat for which reflexive detection in the form of pain and distress is adaptive for survival. Brief ostracism episodes result in sadness and anger and threaten fundamental needs. Individuals then act to fortify or replenish their thwarted need or needs. Behavioral consequences appear to be split into two general categories: attempts to fortify relational needs (belonging, self-esteem, shared understanding, and trust), which lead generally to prosocial thoughts and behaviors, or attempts to fortify efficacy/existence needs of control and recognition that may be dealt with most efficiently through antisocial thoughts and behaviors. Available research on chronic exposure to ostracism appears to deplete coping resources, resulting in depression and helplessness.

Social loafing is the tendency for individuals to expend less effort when working collectively than when working individually. A meta-analysis of 78 studies demonstrates that social loafing is robust and generalizes across tasks and S populations. A large number of variables were found to moderate social loafing. Evaluation potential, expectations of co-worker performance, task meaningfulness, and culture had especially strong influence. These findings are interpreted in the light of a Collective Effort Model that integrates elements of expectancy-value, social identity, and self-validation theories.