Proceedings of the Annual Meeting of the Cognitive Science Society

While it is straightforward to compare the costs of differentvariants of the same action (e.g., walking to a coffeeshop at theend of the block will always be less costly than walking to acoffeeshop three blocks away), the relative costs of differentactions are not directly comparable (e.g., would it be easier tojump over or walk around a fence?). Across two experimentswe demonstrate that 10-month-old infants spontaneouslyencode the manner of different goal-directed actions (jumpingover an obstacle vs. detouring around it, Experiment 1) and usethe principle of cost-efficiency to infer their relative costs(jumping is less costly to bypass low walls, but detouring isless costly to bypass high walls, Experiment 2). By relatingaction choices to the physical parameters of the environment,infants identify the least costly actions given thecircumstances, which allows them to make behavioralpredictions in new environments and may also enable them toinfer others’ motor competence.