Piloting building early sentences therapy for pre-school children with low language abilities: An examination of efficacy and the role of sign as an active ingredient.

What is already known on the subject Robust language skills are crucial for positive social, emotional, academic and economic outcomes across the lifespan. There is a paucity of robustly evaluated interventions for preschool children with language difficulties. The development of such interventions is crucial for ameliorating language difficulties and promoting positive educational and psychosocial outcomes. What this study adds to the existing knowledge This paper evaluates BEST, a novel usage-based language intervention targeting children with language difficulties in the early years. Findings indicate that a usage-based intervention is efficacious for treating language difficulties. In particular, BEST benefited expressive language development, bringing benefits to both treated and untreated language structures and improving standard scores. The role of sign as an active ingredient is also supported. Further evaluation is warranted. What are the practical and clinical implications of this work? Findings suggest that BEST may be effective for targeting children who have been identified as having language difficulties. In particular, expressive language may be improved when the intervention is delivered as it was originally manualized, including a signing system to represent content and grammatical morphology. More broadly, these findings also provide preliminary evidence that the use of a signing system does not hinder oral language development in children with language difficulties and may conversely support their expressive language. Future research exploring the role and underpinning mechanisms of sign in language intervention is warranted.