Purpose: This systematic review and meta-analysis critically evaluated the research evidence on the effectiveness of conversational recasts in grammatical development for children with language impairments.
Method: Two different but complementary reviews were conducted and then integrated. Systematic searches of the literature resulted in 35 articles for the systematic review. Studies that employed a wide variety of study designs were involved, but all examined interventions where recasts were the key component. The meta-analysis only included studies that allowed the calculation of effect sizes, but it did include package interventions in which recasts were a major part. Fourteen studies were included, 7 of which were also in the systematic review. Studies were grouped according to research phase and were rated for quality.
Results: Study quality and thus strength of evidence varied substantially. Nevertheless, across all phases, the vast majority of studies provided support for the use of recasts. Meta-analyses found average effect sizes of .96 for proximal measures and .76 for distal measures, reflecting a positive benefit of about 0.75 to 1.00 standard deviation.
Conclusion: The available evidence is limited, but it is supportive of the use of recasts in grammatical intervention. Critical features of recasts in grammatical interventions are discussed.