Fourteen- to Eighteen-Month-Old Infants Use Explicit Linguistic Information to Update an Agent’s False Belief

The current research examined how infants exploit linguistic information to update an agent's false belief about an object's location. Fourteen- to eighteen-month-old infants first watched a series of events involving two agents, a ball, and two containers (a box and a cup). Agent1 repeatedly acted on the ball and then put it in the box in the presence of agent2. Then agent1 disappeared from the scene and agent2 switched the ball's location from the box to the cup. Upon agent1's return, agent2 told her, "The ball is in the cup!" Agent1 then reached for either the cup (cup event) or the box (box event). The infants looked reliably longer if shown the box event as opposed to the cup event. However, when agent2 simply said, "The ball and the cup!" - which does not explicitly mention the ball's new location - infants looked significantly longer if shown the cup event as opposed the box event. These findings thus provide new evidence for false-belief understanding in infancy and suggest that infants expect an agent's false belief to be updated only by explicit verbal information.