Chinese mothers use idioms in shared book reading: A predictor for children’s Chinese vocabulary growth?

Idioms play an important role in language; however, little research has examined idioms in children's natural language settings. This study explored idioms usage in maternal talk during mother-child shared book reading and its relation to children's vocabulary development. Thirty-three Chinese children in Norway (aged 3;0-5;5) and their mothers participated. We observed shared reading at the onset of the study and assessed children's receptive and expressive vocabulary in Chinese three times across one year. Results demonstrated that mothers used an average of 1.8 idioms and explained one-third of the idioms. Maternal idiom usage was correlated with their talk amount and lexical diversity. Individual growth modeling revealed that the number of idioms mothers used predicted the growth of children's receptive vocabulary in Chinese. We speculate that idiom usage could be an effective and understudied marker of parental linguistic sophistication. This study underscores the importance of idiom exposure in children's language environment.