The infant's concept of agency: the distinction between social and nonsocial objects.

The primary purpose of this study was to examine young infants' discrimination between the abilities of social and nonsocial objects to serve as agents. Thirty-one infants between 8 months and 8 days old and 14 months and 19 days old were studied. The children's communicative skills were evaluated through frustration episodes in which a toy was taken away in order to elicit communicative behaviors toward the mother. Visual fixation time was compared for events in which an inanimate object moved independently and events in which a human being was the agent. Analysis of the magnitude of decrease of attending responses revealed that the older infants took longer to process anomalous events, whereas the younger infants manifested more interest for events in which an animate being played the role of agent. The findings suggest that infants can distinguish between the causal powers of social and nonsocial objects by the end of the first year.