Motor system activation reveals infants' on-line prediction of others' goals.

Despite much research demonstrating infants' abilities to attribute goals to others' actions, it is unclear whether infants can generate on-line predictions about action outcomes, an ability crucial for the human propensity to cooperate and collaborate with others. This lack of evidence is mainly due to methodological limitations restricting the interpretation of behavioral data. Here, we exploited the fact that observers' motor systems are recruited during the observation of goal-directed actions. We presented 9-month-old infants with part of an action. For this action to be interpreted as goal directed, the infants would need to predict an outcome for the action. Measuring the attenuation of the sensorimotor alpha signal during observation of action, we found that infants exhibited evidence of motor activation only if the observed action permitted them to infer a likely outcome. This result provides evidence for on-line goal prediction in infancy, and our method offers a new way to explore infants' cognitive abilities.