When do infants expect hands to be connected to a person?

A violation-of-expectation paradigm was used to test whether infants infer a person based on the presence of hands alone. Infants were familiarized to a pair of hands that extended out from a curtain to play with a rattle, after which the curtain was opened to reveal either a real person or a mannequin. Infants’ looking at these outcomes was compared with baseline looking at the person and the mannequin. Experiment 1 showed that 9-month-olds looked significantly longer at the mannequin than at the person after familiarization to hands. Experiment 2 ruled out a low-level feature matching interpretation by showing the same looking pattern in 9-month-olds even when the hands were covered with silver gloves. In Experiment 3, 6-month-olds showed no differential looking at the mannequin and person after familiarization to hands. Taken together, these experiments suggest that infants acquire the expectation that hands are connected to a person between 6 and 9 months of age. This finding has implications for how infants’ attribute goals to manual actions.