 Xiao and Bicchieri (2010) designed an experiment to investigate the impact on trust games of two potentially applicable—but conflicting—principles of conduct, namely, equality and reciprocity. Note that the former can be broadly defined as a rule that recommends minimizing payoff differences, whereas the latter recommends taking a similar action as others (regardless of payoff considerations). The experimental design involved two trust game variants: in the first one, players started with equal endowments; in the second one, the investor was endowed with twice the money that the trustee was given. In both cases, the investor could choose to transfer a preset amount of money to the trustee or keep it all. Upon receiving the money, the trustee could in turn keep it or else transfer back some of it to the investor: in the equal endowment condition (“baseline treatment”), both equality and reciprocity dictate that the trustee transfer some money back to the investor; by contrast, in the unequal endowment condition (“asymmetry treatment”), equality and reciprocity dictate different actions as the trustee could guarantee payoff equality only by making a zero back-transfer. Xiao and Bicchieri elicited subjects’ first- and second-order empirical beliefs (“how much do you think other participants in your role will transfer to their counterpart?”; “what does your counterpart think you will do?”) and normative expectations (“how much do you think your counterpart believes you should transfer to her?”). The experimental results show that a majority of trustees returned a positive amount whenever reciprocity would reduce payoff inequality (in the baseline treatment); by contrast, a majority of trustees did not reciprocate the investors’ transfer when doing so would increase payoff inequality (in the asymmetry treatment). Moreover, investors correctly believed that less money would be returned in the asymmetry treatment than in the baseline treatment, and most trustees correctly estimated investors’ beliefs in both treatments. However, in the asymmetry treatment empirical beliefs and normative expectations conflicted: this highlights that, when there is ambiguity as to which principle of conduct is in place, each subject will support the rule of behavior that favors her most.