The effect of a looker's past reliability on infants' reasoning about beliefs.

We investigated whether 16-month-old infants' past experience with a person's gaze reliability influences their expectation about the person's ability to form beliefs. Infants were first administered a search task in which they observed an experimenter show excitement while looking inside a box that either contained a toy (reliable looker condition) or was empty (unreliable looker condition). The infants were then administered a true belief task in which they watched as the same experimenter hid a toy in 1 of 2 locations. In the test trial, the infants witnessed the experimenter search for the toy in a location that was consistent or inconsistent with her belief about the toy's location. Results for the true belief task indicated that only the infants in the reliable looker condition looked longer at the incongruent than at the congruent search behavior. These findings are consistent with evidence suggesting that infants encode the identity of agents based on past reliability and implicitly attribute beliefs to others during the 2nd year of life.