Seven- to 12-month-olds were trained to press levers that contingently activated lights. Infants had the choice of turning on either a light an adult interaction partner was looking at or a light that she turned away from. By 9 months, infants reliably turned on the light that the adult was looking at. In a second study, 9- and 12-month-old infants could see the adult's upper body but not her face during the test. Nine-month-old infants showed the same pattern of results as in Study 1. However, turning on the light that the adult looked at dropped to chance level for 12-month-olds. Results suggest that feedback from movement cues might influence infants' behaviour at 9 and 12 months of age but that shared visual attention with others may drive infants' behaviour by 12 months. The new paradigm provides a new method to assess the development of social cognitive skills among infants.