Infants' use of object category distinctions in word learning

How do infants initially determine whether a novel object word labels a specific individual (e.g. Madonna) or an instance of a category (e.g., a person)? The research in this dissertation tested the hypothesis that infants assume words for objects from some categories (e.g., people) label individuals (are proper names) but words for objects from other categories (e.g., artifacts) label instances of the category (are count nouns). This assumption could help infants to identify proper names and count nouns in their language, and thereby facilitate the learning of the linguistic proper name/count noun distinction. In a preferential looking task, 16- and 17-month-olds heard a novel word for a target person (a face) or artifact, and their willingness to generalize the word to a non-target object was assessed. In Experiment 1, infants restricted the word to the target object when it was paired with a non-target object from a different category, providing evidence that infants can learn a novel word for the target object in this task. In Experiment 2, infants restricted the word to the target object when both the target and non-target objects were people, but not when they were artifacts from the same category. This finding is consistent with the hypothesis that infants interpret words for people as proper names and words for artifacts as count nouns. In Experiment 3, infants were asked to find the referent of a second novel label in a task identical to Experiment 2. Here, infants restricted their looking to the non-target object when the objects were people, but not when they were artifacts. In Experiment 4, infants did not restrict the novel label to a person (a face) when it was inverted. This result provides evidence that infants’ tendency in Experiment 2 to restrict a label to a particular person was not simply due to the greater perceptual complexity of faces. Together, the findings reveal that infants interpret words for people and words for artifacts differently, raising the possibility that object category distinctions help infants to identify proper names and count nouns in their language and to learn how they are expressed linguistically.Arts, Faculty ofPsychology, Department ofGraduat