This study examines whether mothers’ use of Chinese idioms (成语; chengyu) during shared book reading supports children’s vocabulary development through children’s own chengyu knowledge. Building on prior work showing that maternal chengyu input predicts children’s Chinese vocabulary growth (Yang, Grøver, & Lawrence, 2024), we test a mediation account in which maternal idiom use fosters children’s idiom comprehension, which in turn relates to broader receptive vocabulary.
Participants were 35 Mandarin-speaking mother–child dyads; analyses used an analytic sample of 32 after listwise deletion. Maternal chengyu use was coded from Wave-1 storybook interactions. At Wave 3, children completed two idiom measures: a 16-item picture comprehension task and a mimicry/production task. Scores were z-standardised and averaged into a composite chengyu knowledge measure. Receptive vocabulary was assessed with the PPVT at Waves 1–3. Analyses in Stata 18 included correlations, OLS regressions predicting PPVT3 from PPVT1 and chengyu knowledge, and a just-identified SEM mediation model with 5,000 bootstrap draws.
Maternal chengyu use was positively associated with children’s Wave-3 outcomes. The SEM indicated a significant indirect pathway from maternal chengyu use to PPVT3 through children’s chengyu knowledge, with a reduced direct effect, consistent with full mediation at Wave 3. Together, results suggest idiom-rich input during shared reading may support concurrent vocabulary indirectly via children’s idiom mastery.
