In the recognition heuristic (Goldstein & Gigerenzer, 2002), people’s knowledge of objects is defined as “recognized” or “not recognized.” Thus the subjective knowledge levels for recognized objects are regarded as identical. However, subjective knowledge levels for recognized objects can differ, based on differences in their familiarity. In the current study, we assume that subjective knowledge levels for recognized objects differ in familiarity, and we examine effects of familiarity on inference. Results of an experimental study show that participants infer on the basis of familiarity, and that participants adopt some inference strategies depending on the situation.