Evaluation of an explicit intervention to teach novel grammatical forms to children with developmental language disorder

Purpose: Unlike traditional implicit approaches used to improve grammatical forms used by children with developmental language disorder, explicit instruction aims to make the learner consciously aware of the underlying language pattern. In this study, we compared the efficacy of an explicit approach to an implicit approach when teaching 3 novel grammatical forms varying in linguistic complexity. Method: The study included twenty-five 5-to 8-year-old children with developmental language disorder, 13 of whom were randomized to receive an implicit-only (I-O) intervention whereas the remaining 12 participants were randomized to receive a combined explicit–implicit (E-I) intervention to learn 3 novel grammatical forms. On average, participants completed 4.5 teaching sessions for each form across 9 days. Acquisition was assessed during each teaching session. Approximately 9 days posttreatment for each form, participants completed probes to assess maintenance and generalization. Results: Analyses revealed a meaningful and statistically significant learning advantage for the E-I group on acquisition, maintenance, and generalization measures when performance was collapsed across the 3 novel targets ( p <.02, Φs > 0.60). Significant differences between the groups, with the E-I group outperforming the I-O group, only emerged for 1 of the 3 target forms. However, all effect sizes ranged from medium to large (Φs = 0.25–0.76), and relative risk calculations all exceeded 0, indicating a greater likelihood of learning the target form with E-I instruction than I-O instruction. Conclusions: Study findings indicate that, as compared to implicit instruction, children are more likely to acquire, maintain, and generalize novel grammatical forms when taught with explicit instruction. Further research is needed to evaluate the use of explicit instruction when teaching true grammatical forms to children with language impairment.