Children's Sentential Complement Use Leads the Theory of Mind Development Period: Evidence from the CHILDES Corpus

Converging evidence suggests that children’s linguistic and theory of mind (ToM) development are linked. Specifically, learning the sentential complement grammatical structure has been shown to play a causal role in the development of some false belief reasoning skills. Here, we extend this line of work to examine this relationship in the wild by means of a corpus analysis of children’s speech during the typical period of ToM development. We show that children’s use of the sentential complement grammatical structure increases immediately preceding the ToM development period and plateaus shortly thereafter. Furthermore, we find that parents’ child-directed speech follows a similar pattern.