Giving decision-makers nondiagnostic person information promotes trust within and across nations

Humans trust others, enabling them to negotiate agreement and to create long-term bonds (1). However, because trusting others makes people vulnerable to exploitation, it is difficult to see how indiscriminate trust could have evolved (2–4). Romano et al. (2) suggest a solution to this conundrum. Fitting evolutionary theory (3, 4), Romano et al. (2) propose that humans (i) trust ingroup members more than outsiders because they (ii) expect ingroup members to reciprocate trust more than strangers and members of demarcated outgroups. Romano et al. examine this possibility with over 3,000 individuals from 17 countries who played incentivized trust games with three targets: individuals from one’s own country (“ingroup”), individuals from another country (“outgroup”), and individuals from a country not given (“strangers”).

Romano et al. (2) report results for two contrasts: (C1) trust(worthiness) for [ingroup] vs. [outgroup + stranger], and (C2) trust(worthiness) for [outgroup] vs. [stranger]. Both contrasts are significant and suggest, combined, that trust(worthiness) rank-ordered as ingroup ≥ outgroup > stranger. This is a puzzling result in light of existing theory on intergroup relations, and inconsistent with studies looking at ingroup bias in cooperation (3–5). The result is, however, understandable in light of extant work on individuation and social judgeability (6–9). These studies on individuation show two things. First, interpersonal interdependence and possibilities for (in)direct reciprocity motivate people to individuate their partner and to see them as a person rather than interchangeable members of an abstract social category (8, 9). Second, being provided with information about their partner, however nondiagnostic it is, facilitates decision-makers in such individuation and helps them to construe the justifications needed to act toward the partner (6, 7).

Whereas theory on intergroup relations (3–5) implies that Romano et al. (2) should find more trust for ingroups (own country) than for both outgroups (another country) and strangers (country not given), the work on individuation and social judgeability would expect them to find similar levels of trust toward ingroup and outgroup, that both differ from trust invested in strangers. As it stands, the latter is what Romano et al. show. Accordingly, I suggest abandoning the idea that Romano et al. is about trust within and between the groups that people live in and sometimes for (10). I suggest, instead, interpreting Romano et al.’s (2) finding in light of individuation and social judgeability: When individuals are asked to trust someone and realize they know nothing about their target, they feel neither justified nor entitled to judge and, accordingly, withhold trust. Providing nondiagnostic person information—such as the target’s country—allows participants to individuate their targets and to trust their money with them. If correct, the study by Romano et al. (2) raises the intriguing possibility that providing people with bits of individuating information about an interaction partner enables them to build interpersonal trust and trustworthiness both within and across nation states.