Concurrent Relations between inhibitory control, vocabulary, and internal state language in 18-and 24- month-old Italian-speaking Infants.

The aim of this study was to investigate the concurrent relations between 18- and 24-month-olds’ performance on tasks measuring inhibitory control, language and internal state vocabulary. Two tasks were used to measure inhibitory control, the Reverse categorization task (a conflict task), and the Gift task (a delay task). Expressive vocabulary was assessed with the Italian version of the MacArthur Communicative Development Inventory, and internal state vocabulary was assessed with an Italian checklist of 78 mental state terms adapted from previous English Internal State Language Questionnaires (Bretherton and Beeghly, 1982; Poulin-Dubois, Chiarella & Polonia, 2009). Language was associated to Internal State Language and to the Reverse Categorization task, not to the Delay task. Our findings provide an examination of internal language abilities in a sample of 61 Italian speaking children, and show that internal state vocabulary was significantly and specifically related only to performance on the conflict measure of inhibitory control, even when verbal ability was controlled for. Results of our study confirm and extend to an Italian sample of children previous findings on an early association in development between executive function and theory of mind and provide evidence for a link between ‘cool’ inhibitory control processes and internal state language at a very young age.