Shared social identity and group identification are typically viewed as positive elements of social life, with benefits to group cohesion and to the individuals in those groups (e.g., Turner & Tajfel Reference Turner and Tajfel1982). Baumeister et al. suggest that too much identification – too much shared identity – can come with costs. When group members lack differentiation, group pathologies are more likely to emerge, such that a shift away from similarity can be beneficial for the group in general. We suggest that this model has interesting implications for the study of vicarious processes in groups, with vicarious processes often serving as an intermediate step between the individual and the group: When an individual member of a group “catches” the attitudes, emotions, and preferences of another group member, all individuals in those groups become more similar over time. Such vicarious contagion is most likely to occur for group members who are highly identified with that group, such that vicarious processes have been viewed as one means to ensure that groups are in sync.

Below, we review the literature on vicarious processes – focusing on attitudes, emotions, morality, and self-control – and discuss the implication of the Baumeister et al. model, that vicarious processes can in fact come with costs: As vicarious contagion leads group members to become less differentiated, negative consequences can accrue.

Several research paradigms have documented the role of group identification in vicarious attitude change. For example, witnessing an in-group member act against his or her previously stated beliefs can induce vicarious dissonance – that is, vicarious discomfort resulting from imagining oneself in that in-group member's position (Norton et al. Reference Norton, Monin, Cooper and Hogg2003). Individuals highly identified with the group align their own attitudes to the inconsistent behavior of that group member to reduce that discomfort, thereby promoting attitudinal agreement (Norton et al. Reference Norton, Monin, Cooper and Hogg2003; Monin et al. Reference Monin, Norton, Cooper and Hogg2004). Vicarious attitude change can also be induced experimentally: Individuals informed that another person shares their brain-wave patterns experience a merged identity and change their self-perceptions (Goldstein & Cialdini Reference Goldstein and Cialdini2007). These changes can have negative consequences; for example, individuals who believe that a merged other is knowledgeable come to see themselves as more knowledgeable than they are and perform worse on knowledge-oriented tasks (Goldstein & Cialdini Reference Goldstein and Cialdini2007). Identification through psychological connectedness can also become costly in decision-making. When people feel connected to others, they vicariously justify others' initial decisions, and escalate their commitment to earlier investments – as though others' sunk costs are their own (Gunia et al. Reference Gunia, Sivanathan and Galinsky2009). These examples illustrate that vicarious processes may help groups attain attitudinal homogeneity but also hamper individual differentiation, leading group members to behave similarly even when negative consequences accrue.

Association with others not only affects attitudes and behaviors, but also shapes emotional experiences. For example, when an individual engages in wrongful behavior, observers who feel interdependent with the wrongdoer will feel guilty, and, if they share a social identity with the perpetrator, feel shame (Lickel et al. Reference Lickel, Schmader, Curtis, Scarnier and Ames2005). Similarly, people can feel pain by association: Individuals who witness the exclusion of another person with whom they are identified feel the pain of ostracism as their own (Wesselman et al. Reference Wesselmann, Bagg and Williams2009). Indeed, vicarious experience of emotion – such as embarrassment – are subserved by unique brain regions (Krach et al. Reference Krach, Cohrs, de Echeverria Loebell, Kircher, Sommer, Jansen and Paulus2011). Vicarious experience of negative emotions is only a portion of the cost, as these feelings may also lead individuals to misjudge situations. For example, individuals feel more powerful when associated with a more powerful other, an association that increases their risk-taking even when they cannot leverage that power (Goldstein & Hays Reference Goldstein and Hays2011).

Vicarious processes can also impair self-control. Acts of self-control ensure group cohesion and enable social functioning (Finkel et al. Reference Finkel, Campbell, Brunell, Dalton, Scarbeck and Chartrand2006; Heatherton & Vohs Reference Heatherton and Vohs1998). However, taking the perspective of another person who exerts self-control leads individuals to experience vicarious depletion and therefore exhibit less restraint (Ackerman et al. Reference Ackerman, Goldstein, Shapiro and Bargh2009). Although self-control resources can also be vicariously replenished, observers must feel they are similar to the actor who engages in self-regulatory restoration (Egan et al. Reference Egan, Hirt and Karpen2012). These studies demonstrate that when group members lack sufficient differentiation, self-control depletion of one group member can have detrimental effects on the self-regulatory abilities of others in the group.

Finally, vicarious processes can have consequences for justification of and engagement in unethical behavior among highly identified groups. When observers feel psychologically close to a selfish actor, they are more likely to ignore the ethical elements of the decision through vicarious justifications – in turn causing observers to act unethically themselves (Gino & Galinsky Reference Gino and Galinsky2012). Furthermore, witnessing others' successful moral behavior can also lead to vicarious moral licensing: Individuals strongly identified with a group can gain moral credentials when observing a nonprejudiced decision by an in-group member, leading them to engage in unethical behavior in subsequent tasks (Kouchaki Reference Kouchaki2011).

Baumeister et al. propose that individual differentiation is a crucial element of group success: Sharing a common identity is necessary, but it can be harmful when differentiation is lacking. We suggest that their model holds insight into the study of processes lying in the middle ground between individual and group – vicarious processes: Vicarious experiences align group members, but lack of differentiation causes vicarious contagion to come with costs.