Abstract

The objective of the present thesis was to examine infants' understanding of other people's mental states, such as visual perception and beliefs. The first paper was designed to systematically investigate whether 14-month-olds would follow the gaze of a person to a target hidden behind a barrier when the person's perception was previously unreliable. Infants were first trained on a search task to either expect a person's gaze to be either reliable or unreliable. Then, their gaze following behavior was observed in a gaze following task during which an experimenter looked at a target in front (control condition) and in back of a barrier (experimental condition). In Study 1, infants were more likely to follow the gaze of the reliable looker than infants in the unreliable looker group. In contrast, no differences in gaze following were observed across groups in the control condition. In study 2, when a naïve experimenter administered the gaze following task following training with an unreliable looker in the search task, infants treated the naïve experimenter as though she was a reliable looker and were more likely to follow her gaze behind the barrier than infants in the unreliable looker group in the first study. In the second paper, infants' ability to generalize their knowledge about the reliability of a person's gaze to another context was explored. This paper examined whether 16-month-olds' past experience with the reliability of what a person sees influences their expectation regarding where the person should look for a toy that was previously hidden. Results showed that only infants in the reliable looker group were surprised and therefore looked longer when the experimenter searched for the hidden toy in the incorrect location as compared to the correct location; whereas infants who were previously exposed to an unreliable looker looked equally long at both search locations. Taken together, these results demonstrate for the first time that infants as young as 14 months of age encode the identity of a person based on their past gaze reliability and use this information to decide whether or not to follow her gaze and implicitly attribute beliefs