Abstract
Rituals are ubiquitous in organizations and society. Ritual conformity can signal one's commitment to the group and in turn engender trust. However, its signaling effect is elusive as cooperative individuals might self-select into groups that demand more conformism, as groups inculcate rituals promoting prosocial values and norms, or as it induces group biases in altruism and fairness. We experimentally test the causal signaling effect of rituals by manipulating the observability of conformity to synthetic minimal rituals across minimal groups in the laboratory. We find that only perfect and observable conformity in groups engenders increased trust. Non-conformity by group members erodes the trust of perfect conformists. Observing perfect conformity also increases ingroup sharing if reciprocity by co-players yields mutual benefit even when it is costless to unilaterally benefit others, but not when it yields neither mutual benefit nor welfare gains. Thus, we confirm that perfect conformity to observable rituals signals a commitment to mutual beneficence and in turn engenders trust.