Interrelationships between Theory of Mind and language development: A longitudinal study of Dutch-speaking kindergartners

Research on the relationship between language acquisition and Theory of Mind (ToM) has been largely confined to English-speaking populations and has yielded conflicting results regarding which domains of language are most relevant. The current study assessed 101 Dutch-speaking kindergartners on ToM and various potentially relevant domains of language (general and mental vocabulary, sentence comprehension and sentential complementation understanding). Results show a bidirectional relationship between ToM and both vocabulary measures and a unidirectional relationship from sentence comprehension to ToM. Sentence comprehension was the best ToM predictor out of the language measures. No evidence was found for a relationship between ToM and sentential complementation understanding, likely due to the use of a novel, and potentially purer, sentential complementation measure. Comprehension of language at the sentential level is thus fundamental for explicit ToM development. Finding this result in a Dutch-speaking population suggests that similar outcomes from previous studies can be generalised more broadly.