This paper examines the difference between strategic ambiguity as in game theory and ambiguity arising in individual decisions. We identify a new, non-strategic component underlying all strategic ambiguities, called social ambiguity. We recommend controlling for it to better identify strategic causes. Thus, we shed new light on Bohnet and Zeckhauser's betrayal aversion in the trust game. We first show theoretically that, contrary to preceding claims in the literature, ambiguity attitudes can play a role here. We then show experimentally that social ambiguity, rather than betrayal aversion, can explain our empirical findings. Using our new control, we identify the unique effect of strategic ambiguity. Strategic complexity increases ambiguity...