Capuchins (Cebus apella) are limited in their ability to infer others' goals based on context

Recent research suggests that many primate species understand others' actions not only in terms of their physical movements, but also in terms of the actor's underlying goals and intentions. Impressively, apes also have the capacity to incorporate previously acquired contextual information into their goal representations. To date, little work has tested whether other primates demonstrate this level of flexibility when inferring others' goals. To help address this question, we tested capuchin monkeys using a procedure similar to one that Buttelmann, Schütte, Carpenter, Call, and Tomasello (2012) used to test apes. Capuchin subjects were repeatedly shown an experimenter manipulating locking mechanisms on a series of boxes. In an experimental condition, the experimenter gave subjects food retrieved from inside the boxes, whereas in a control condition subjects never received food from inside the boxes. We then explored how capuchin subjects would interpret the experimenter's ambiguous manipulation of a novel box. In contrast to apes, subjects in our experiment showed little evidence of being able to flexibly use temporally dissociated contextual cues to make inferences regarding others' goals. This result may point to a crucial difference in the sophistication with which ape and nonape primates understand others' actions.