We are aware of nine experimental studies demonstrating vicarious ostracism. These studies find that observers recognize an ostracized individual's distress and also feel ostracized themselves (Over and Carpenter, 2009; Wesselmann et al., 2009; Masten et al., 2010, 2011a, 2013a,b; Beeney et al., 2011; Meyer et al., 2012; Will et al., 2013). Vicarious ostracism has been demonstrated in both child/adolescent (Over and Carpenter, 2009; Masten et al., 2010, 2013a,b; Will et al., 2013) and adult samples (Wesselmann et al., 2009; Beeney et al., 2011; Masten et al., 2011a; Meyer et al., 2012; Will et al., 2013). Vicarious ostracism is enhanced when individuals actively perspective-take (Wesselmann et al., 2009), are higher in trait empathy (Masten et al., 2010, 2011a,b, 2013a), or are closely related to the target (Beeney et al., 2011; Meyer et al., 2012).

These studies used two different paradigms. The primary paradigm is Cyberball—a computer-based ball-tossing game in which participants interact with two computer-controlled confederates (Williams, 2009). These confederate players are programmed to either include all players equally or to ostracize the participant by giving them only two ball tosses at the beginning of the game. Seven studies (Wesselmann et al., 2009; Masten et al., 2010, 2011a,b, 2013a; Beeney et al., 2011; Meyer et al., 2012; Will et al., 2013) adapted this paradigm by programming all of the players' tossing behavior and telling participants they are observing a game already in progress. Over and Carpenter (2009) animated two shapes playing ball together. Eventually, another shape approaches the game—this new shape is either similar to the others (ostracism condition) or dissimilar (i.e., a butterfly; control condition). Regardless of condition, the ball-tossing shapes do not toss to the new shape and ultimately avoid the shape.

These studies have impressive diversity in outcome measures. Wesselmann et al. (2009) measured self-reported psychological need threat. Six studies (Masten et al., 2010, 2011a,b, 2013a,b; Beeney et al., 2011; Meyer et al., 2012) used fMRI measures of brain activity in regions associated with experiencing ostracism oneself (Eisenberger and Lieberman, 2004). Four studies using measures of prosocial/affilitative behavior (Over and Carpenter, 2009; Masten et al., 2010, 2011a,b; Will et al., 2013) found that vicarious ostracism increases prosocial/affiliative behavior much like directly experiencing ostracism does (Williams, 2009).

Observing ostracism increased activity in the dorsal anterior cingulate cortex (dACC) and anterior insula (AI), two brain regions activated by directly experiencing ostracism (Eisenberger and Lieberman, 2004). Observing ostracism also activated the dorsomedial (DMPFC) and medial prefrontal cortexes (MPFC) and precuneus—brain regions associated with mentalizing (i.e., thinking about another's mental state; Masten et al., 2011a,b, 2013b). Individual differences in empathy predicted brain activation in both the mentalizing regions (i.e., bilateral DMPFC, MPFC, and temporal parietal junction) and social pain-related regions (i.e., AI and dACC) during vicarious ostracism (Masten et al., 2011a, 2013a). Vicarious ostracism involves different brain regions depending upon the ostracized target; observing a friend's ostracism activated regions associated with direct ostracism experience (i.e., dACC and insula), whereas a stranger's ostracism involved mentalizing-relevant regions (i.e., DMPFC, precuneus, and temporal pole; Meyer et al., 2012). Finally, brain activation in the AI and MPFC—regions associated with trait empathy—correlated with pro-social responses toward the ostracized target (Masten et al., 2010, 2011a).