Talking while thinking about another's mind in preschoolers: Evidence of getting Vygotskian about social cognition

•Chinese preschoolers’ private speech during social cognitive processing was examined.•Private speech was correlated with belief understanding in younger preschoolers.•Private speech was correlated with manipulating minds in older preschoolers.•The correlations remain significant after controlling for age and verbal ability.•Results suggest that language (private speech) regulated social cognitive processing.

The study was the first to investigate language use during social cognitive processing in preschoolers. The private speech of 42 Cantonese-speaking 3- to 5-year-olds in a social cognitive context that required preschoolers to encode, understand, and use the psychological properties of others in order to cooperate and compete with them was observed. Task performance was indexed by preschoolers’ ability in manipulating and understanding another's mind, including belief understanding. Results showed that private speech was correlated with belief understanding in younger preschoolers and with manipulating minds in older preschoolers, even after controlling for age and verbal ability. This finding suggests that language, in the form of private speech, could regulate social cognitive processing.