The Influence of Quantitative Intervention Dosage on Oral Language Outcomes for Children With Developmental Language Disorder: A Systematic Review and Narrative Synthesis
Language, Speech, and Hearing Services in Schools
Frizelle, P., Tolonen, A. K., et al. (2021).
Language, Speech, and Hearing Services in Schools, 52(2), 738-754.
This systematic review investigates the effects of dosage, frequency, or intensity of oral language interventions on phonology, vocabulary, or other language outcomes in children, 3 to 18 years of age, with developmental language disorder.
European Cooperation in Science and Technology (European Union); National Health and Medical Research Council fellowship (Australia)
This systematic review is part of a series of documents. See Associated Article section below for more information.
January 2006 - May 2020
Randomized controlled trials; quasi-experimental (nonrandomized) controlled studies; cohort analytical design studies; observational studies
13
For children with developmental language disorder (DLD), two studies investigating global language outcomes found that the best outcomes are achieved when children receive either:<br />
<ul>
<li><span style="color: #333333;">frequent sessions (i.e., approximately 3 times per week) with very short (i.e., 2 min) focus on specific goals, or </span></li>
<li><span style="color: #333333;">less frequent sessions (i.e., approximately weekly) with longer periods (i.e., 20 minutes) of focus on specific goals.</span></li>
</ul>
<span style="color: #333333;"> No studies targeting phonological outcomes were available. Further research investigating the impact of dosage for oral language treatment is needed.</span>
For children with developmental language disorder, three studies investigated a variety of vocabulary outcomes. One study reported a 40% drop in word learning 5-6 days postintervention. Another study found the optimal dose of word learning in 5-6 year old children to be 36-word exposures. The third study concluded that overall dose of word learning is more important than the frequency of treatment. Due to the variability in experimental tasks and definitions of duration and dosage, further research on the delivery of word learning interventions is required.
For children with developmental language disorders, studies investigating morphosyntax outcomes report no difference in treatment effects "between concentrated and distributed conditions if the treatment dose, rate of delivery, total treatment hours, and total intervention duration are controlled" (p. 751). Because of the complexity of controlling dosage components, the limited number of studies available, and the low number of participants included in the studies, further research on optimal dosage and frequency of morphosyntactic interventions is needed.
For children with developmental language disorders (DLD), "more is not always better, and studies show a point of diminishing returns for both vocabulary (number of exposures) and morphosyntax (frequency/total number of intervention sessions). There is some evidence suggesting that younger children may require fewer sessions to achieve the same results (in relation to morphosyntax).... Study findings also suggest that if dose is high (the number of learning opportunities within a session), then frequency can be reduced, particularly in relation to morphosyntax" (p. 752). Due to inconsistent definitions of dosage and frequency, comparison of study results is difficult. Further research on service delivery of oral language interventions for children with DLD is needed.
