The relation between parental language mixing and children's vocabulary outcomes: An evidence synthesis.

Seven studies (total n = 541) have investigated the relation between parental language mixing and bilingual children's (0-10-year-olds) vocabulary outcomes with different research designs. Parental language mixing was either positively, negatively, or not related to children's vocabulary outcomes. Their evidence is aggregated via a novel meta-analytic approach, the GORIC evidence synthesis. Evidence syntheses were conducted for expressive and receptive vocabulary in the majority and minority language. The combined evidence shows that parental language mixing is not related to bilingual children's expressive vocabulary, or to their receptive vocabulary in the minority language. There is a negative relation between parental language mixing and children's receptive vocabulary outcomes in the majority language that ranges from a negligible to small effect size.