Does giving behavior in economic games reflect true prosocial preferences or is it due to confusion? Research showing that trait Honesty-Humility accounts for giving behavior suggests the former, whereas research showing that participants give money to a computer might suggest the latter. In three preregistered, well-powered studies, we examined the relation of Honesty-Humility with behavior in the Dictator Game (Study 1, N = 468) and Public Goods Game (Studies 2 and 3, each N = 313), while participants interacted either with humans (“social game”) or with a computer (“non-social game”). We found that (a) decisions in the non-social game predicted decisions in the social game, supporting the confusion hypothesis; (b) the effect of Honesty-Humility differed within and between games; and (b) participants who gave money to the computer reported acting as if they were playing with humans. Overall, the studies suggest that both prosocial preferences and confusion underlie giving behavior.