Theory of mind in children with autistic disorder: evidence of developmental progression and the role of verbal ability.

The present study investigated theory of mind in two groups of autistic children with markedly different verbal mental ages but comparable nonverbal ability and chronological ages, using a range of theory of mind belief tasks. The aims were to look for evidence of developmental progression of theory of mind ability in autistic children and to examine the role played by verbal ability in task performance. The results showed hierarchical patterns of performance across tasks, suggesting a developmental sequence of emerging aspects of theory of mind ability. There was clear evidence that verbal ability is an important contributor to successful task performance.