Word-learning trajectories influence long-term recall in children with developmental language disorder and typical development

Introduction: Children with developmental language disorder (DLD) have difficulties learning words. However, the severity of these difficulties can be reduced through word learning procedures that incorporate repeated spaced retrieval (RSR). Previous studies have shown positive outcomes with RSR but we still know very little about how learning unfolds with this procedure. In this study, we focus on the process of learning under RSR. Methods: We analyze the learning data from children with DLD and with typical development (TD) from three recent studies using RSR. We fit growth curves to the trial-by-trial learning data for immediate and spaced retrieval trials and use the characteristics of children's individual wordlearning trajectories to predict their long-term recall. Results: We found that children in both groups demonstrated linear growth during learning, despite breaks within and across days. Success on early immediate retrieval trials promoted success on subsequent spaced retrieval trials. Children's trial-by-trial RSR learning trajectories were related to their long-term recall: both cumulative success and growth over time on the spaced retrieval trials positively predicted long-term recall. Consecutive success was also highly correlated with growth over time. Conclusions: Repeated spaced retrieval supplemented with immediate retrieval trials during learning promotes long-term recall.