The influence of language on theory of mind: a training study.

This study investigated the role of language in the development of theory of mind. It was hypothesized that the acquisition of the syntactic and semantic properties of sentential complements would facilitate the development of a representational theory of mind. Sixty preschoolers who failed false belief and sentential complement pretests were randomly assigned to training on false belief, sentential complements, or relative clauses (as a control group). All the children were post-tested on a set of different theory of mind tasks, sentential complements and relative clauses. The main findings were that the group trained on sentential complements not only acquired the linguistic knowledge fostered by the training, but also significantly increased their scores on a range of theory of mind tasks. In contrast, false belief training only led to improved theory of mind scores but had no influence on language. The control group, trained on relative clauses, showed no improvement on theory of mind posttests. These findings are taken as evidence that the acquisition of sentential complements contributes to the development of theory of mind in preschoolers.