Understanding knowledge as a mental state in normal and autistic children.

This thesis examines the cognitive-psychological theory of autism, specifically the "theory of mind" account. According to this theory, autistic people lack the ability to attribute mental states to other people and this underlies their social communication difficulties. In the introductory chapters, autism is described, followed by a consideration of different theoretical accounts of the normal child's theory of mind and empirical evidence on the autistic child's theory of mind. Finally, the introduction discusses whether the different theoretical accounts can explain autism. A series of experiments are then described which investigated normal and autistic children's ability to understand knowledge as a mental state. Experiment 1 established a baseline for the subsequent experiments and included three groups of normal children with mean ages of four years nine months, five years nine months and six years nine months. In this experiment the children's ability to differentiate the cognitive mental terms "know" and "guess" with reference to their own and another person's mental states was examined. Results of this experiment indicated that all three groups of children could differentiate "know" and "guess" in reference to their own and another person's mental state. Experiments 2 and 3 compared the ability to differentiate "know" from "guess" with reference to their own and another persons mental state of high language level autistic children, low language level autistic children, children with Down's syndrome, four-year- old and five-year-old normal children. Results of these experiments showed that the high language level autistic children were able to refer to their and another person's mental state of knowledge. In addition the results were related to a number of measures of language ability. Experiment 4 compared the ability to attribute knowledge and ignorance to themselves and another person of high language level autistic children, low language level autistic children, four-year-old and five-year-old normal children. In one task the experimental question involved the mental term "know", in another task, the term "could help" was used. Results of this experiment showed that all four groups of children performed significantly better in the "know" task than in the "help" task. Performances on the tasks was again related to the children's language skills. The thesis reaches two main conclusions. First that autistic children do not totally lack a theory of mind, since high language level autistic children were able to refer to their and another person's knowledge state. Second, autistic children's language level is a strong predictor of their performance on theory of mind tasks. The thesis concludes by discussing a number of issues involved in autism research and indicating future directions for research.