Mothers’ cognitive state talk during shared book reading and children’s later false belief understanding

• Examined mothers’ cognitive state talk and children’s false belief understanding.
• Examined cognitive state vocabulary, complement syntax, and constrastives.
• Only mothers’ contrastives predicted children’s later false belief understanding.

Mothers’ cognitive state talk was assessed during shared book reading with 50 3- to 5-year-olds in relation to children’s false belief understanding six months later. Mothers’ cognitive state talk was assessed using three hierarchically related variables: (1) mothers’ total use of cognitive state vocabulary (2) mothers’ complement syntax using the verb think and (3) mothers’ complement syntax that directly contrasted thought and reality (i.e., contrastives). There were significant correlations between mothers’ cognitive state vocabulary and contrastives, and children’s later false belief understanding. However, after controlling for children's age, receptive vocabulary, and false belief understanding at Time 1, only mothers’ contrastives significantly predicted children’s Time 2 false belief understanding.