Infants' understanding of the epistemic nature of eye gaze during the second year of life

The current thesis explored infants' implicit understanding of mental states during the second year of life. The first paper focused on infants' appreciation of the relationship between visual perception and knowledge. Based on an interactive search task, 24-month-olds demonstrated an understanding that people's eyes need to be unobstructed in order for them to be connected to the external world. Using a preferential looking paradigm, 18-month-olds predicted different behavior as a function of a person's visual experience. The second paper employed the preferential looking paradigm to investigate 18-month-olds' attributions of knowledge or ignorance when looking behavior was displayed by a person or a humanoid robot. Infants predicted different behavior as a function of the person's visual experience, while they did not demonstrate this expectation in the robot condition. The third paper explored infants' understanding of the epistemic nature of eye gaze within the context of a word learning task (Baldwin, 1993). In three experiments 18-month-olds were exposed to either a human or robot speaker who uttered novel labels for unfamiliar objects under two different eye gaze conditions. While infants followed the eye gaze of the non-human speaker, they did not use the robot speaker's eye gaze cues to determine the correct referent of novel words, even when contingent interaction was added. When the speaker was human, infants used the speaker's eye gaze to determine the correct referent. Together, the findings from the studies presented in this dissertation suggest that by 18 months, infants possess an implicit appreciation of the relationship between visual perception and knowledge. The results also provide evidence for the notion that by 18 months, the scope of infants' concept of mentalistic agent has narrowed relative to that demonstrated by younger infant