structural:scholar_edition
Social identity approach

The social identity approach explains a person's trust in strangers as a function of their group-based stereotypes or in-group favoring behaviors which they base on salient group memberships. With regard to ingroup favoritism, people generally think well of strangers but expect better treatment from in-group members in comparison to out-group members. This greater expectation translates into a propensity to trust a member of the in-group more than a member of the out-group. It is only advantageous for one to form such expectations of an in-group stranger if the stranger also knows one's own group membership.

The social identity approach has been empirically investigated. Researchers have employed allocator studies to understand group-based trust in strangers. They may be operationalized as unilateral or bilateral relationships of exchange. General social categories such as university affiliation, course majors, and even ad-hoc groups have been used to distinguish between in-group and out-group members. In unilateral studies of trust, the participant is asked to choose between envelopes containing money that an in-group or out-group member previously allocated. Participants have no prior or future opportunities for interaction, thereby testing Brewer's notion that group membership is sufficient to bring about group-based trust and hence cooperation. Participants could expect an amount ranging from nothing to the maximum value an allocator could give out. Bilateral studies of trust have employed an investment game devised by Berg and colleagues in which people choose to give a portion or none of their money to another. Any amount given would be tripled and the receiver would then decide whether they would return the favor by giving money back to the sender. This was meant to test trusting behavior on the sender's part and the receiver's eventual trustworthiness.

Empirical research demonstrates that when group membership is salient to both parties, trust is granted more readily to in-group members than out-group members. This occurs even when the in-group's stereotype was comparatively less positive than the out-group's (e.g. psychology versus nursing majors), in the absence of personal identity cues, and when participants had the option of a sure sum of money (i.e. in essence opting out of the need to trust a stranger to gain some monetary reward). When only the recipient was made aware of group membership, trust becomes reliant upon group stereotypes. The group with the more positive stereotype was trusted (e.g. one's university affiliation over another's) even over that of the in-group (e.g. nursing over psychology majors).

Another explanation for in-group-favoring behaviors could be the need to maintain in-group positive distinctiveness, particularly in the presence of social identity threat. Trust in out-group strangers increased when personal cues to identity were revealed.