Dosage and Distribution in Morphosyntax Intervention: Current Evidence and Future Needs

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This article reviews the effectiveness of dose forms and the efficacy of dosage and distribution in morphosyntax intervention for children. Dose forms include the commonly used techniques, procedures, and intervention contexts that constitute teaching episodes; dosage includes the quantitative measures of dose, dose frequency, total intervention duration, and cumulative intervention intensity (S. F. Warren, M. E. Fey, & P. J. Yoder, 2007). Based on the literature, this article first outlines and evaluates the range of dose forms and intervention contexts that clinicians and researchers can employ to facilitate morphosyntactic acquisition. Then, it defines and evaluates research outcomes and provides examples of the dosage components. Current evidence, which focuses primarily on young children and early-developing morphology and sentence structures, suggests that some dose forms and dosage levels are more effective with some populations and some morphosyntactic forms than with others. Distributed practice within sessions and throughout the total period of treatment appears to be more facilitative than massed practice, at least for children with typical language development. The scant research concerning total intervention duration suggests that it affects children's developmental trajectory and that treatment attendance matters. What is missing from the research base is detailed information about the effectiveness and efficacy of intervention for the acquisition of particular morphosyntactic forms in specific populations. The article summarizes these gaps in 3 research goals that reflect the argument of S. F. Warren et al. that it is time to conduct systematic comparisons of specific dose forms while testing how each measure of dosage affects outcomes.