The Role of Self-Directed Speech in Executive Functioning and Theory of Mind in Children with and without DLD

This project investigates why children with developmental language disorder (DLD) often struggle not only with language but also with executive functioning (EF), theory of mind (ToM), and social-emotional functioning. More specifically, it assesses whether these difficulties can be explained in terms of self-directed speech. Young children start talking to themselves in early childhood; this self-directed speech gradually internalizes (i.e., becomes more silent, condensed, and integrated in cognition) and helps them regulate behavior (EF) and form hypotheses about mental states (ToM). The study uses three complementary methods for measuring self-directed speech: coding overt self-directed speech (i.e., private speech) during problem-solving, assessing silent forms of self-directed speech (i.e., inner speech) using EMG, and examining the phonological similarity effect as a marker of speech-based strategies in working memory. Because self-directed speech draws on the underlying language system, aspects of word meaning structure, syntax, and vocabulary were measured. Experiment 1 examines younger and older typically developing children to validate the measures and assess whether self-directed speech can indeed be shown to play a role in EF and ToM. Experiment 2 focuses on self-directed speech in children with DLD and compares these children to the other (now control) groups. The collection contains all data (at item, individual, and combined levels), R scripts, and documentation needed to reproduce the analyses.