Proceedings of the Annual Meeting of the Cognitive Science Society

Our ability to make sense of goal-directed behavior is central to social reasoning. From infancy, this capacity is structuredaround an assumption that agents act efficiently. But agents are often inefficient and how we move is affected by ouremotional states and personal idiosyncrasies. How, then, does an assumption of efficiency allow us to accurately interpretpeople’s actions? We hypothesized that people expect agents to move efficiently relative to an agent-specific baselinerather than to an objective notion of efficiency. Consistent with this, we found that people can quickly learn and subtractagent-idiosyncratic movements when interpreting goal-directed action (Experiment 1). Moreover, in a free-response task,people’s propensity to explain superfluous movement in terms of goals depended on the agent’s relative efficiency ratherthan on the path’s objective efficiency (Experiment 2). Our results show that people flexibly adjust their expectations ofefficiency by attending to how agents typically move.