Infants' Joint Attention Skills Predict Toddlers' Emerging Mental State Language

To assess predictive relations between joint attention skills, intention understanding, and mental state vocabulary, 88 children were tested with measures of comprehension of gaze and referential pointing, as well as the production of declarative gestures and the comprehension and production of imperative gestures, at the ages of 7-18 months. Infants' intention-based imitation skills were assessed at 12,15, and 18 months. At the ages of 24 and 36 months, toddlers' internal state lexicon was evaluated by parents with a German adaptation of the Mental State Language Questionnaire (Olineck & Poulin-Dubois, 2005). Regression analyses revealed that 9-months-olds' comprehension of referential pointing contributed significantly to the prediction of intention-based imitation skills at 15 months, as well as to children's volition and cognition vocabularies at 24 and 36 months, respectively. Moreover, 12-month-olds' comprehension of an imperative motive was shown to selectively predict toddlers' use of volition terms at 24 months. Overall, these results provide empirical evidence for both general and specific developmental relations between preverbal communication skills and mental state language, thus implying developmental continuity within the social domain in the first 3 years of life.