Verbal working memory capacity in DLD (Montgomery et al., 2019) MontgomeryJames W. GillamRonald B. EvansJulia L. SchwartzSarah D. FargoJamison 2019 <div><b>Purpose: </b>The storage-only deficit and joint mechanism deficit hypotheses are 2 possible explanations of the verbal working memory (vWM) storage capacity limitation of school-age children with developmental language disorder (DLD). We assessed the merits of each hypothesis in a large group of children with DLD and a group of same-age typically developing (TD) children.</div><div><b>Method: </b>Participants were 117 children with DLD and 117 propensity-matched TD children 7–11 years of age. Children completed tasks indexing vWM capacity, verbal short-term storage, sustained attention, attention switching, and lexical long-term memory (LTM).</div><div><b>Results: </b>For the DLD group, all of the mechanisms jointly explained 26.5% of total variance. Storage accounted for the greatest portion (13.7%), followed by controlled attention (primarily sustained attention; 6.5%) and then lexical LTM (5.6%). For the TD group, all 3 mechanisms together explained 43.9% of total variance. Storage accounted for the most variance (19.6%), followed by lexical LTM (16.0%), sustained attention (5.4%), and attention switching (3.0%). There was a significant LTM × Group interaction, in which stronger LTM scores were associated with significantly higher vWM capacity scores for the TD group as compared to the DLD group.</div><div><b>Conclusions: </b>Results support a joint mechanism deficit account of the vWM capacity limitation of children with DLD. Results provide substantively new insights into the underlying factors of the vWM capacity limitation in DLD.</div><div><br></div><div><b>Supplemental Material S1. </b>Correlations among verbal working memory capacity (vWM), verbal storage, sustained attention (SA), attention switching (AS), lexical long-term memory (LTM), and age (in months) in the typically developing children.</div><div><br></div><div><b>Supplemental Material S2. </b>Correlations among verbal working memory capacity (vWM), verbal storage, sustained attention (SA), attention switching (AS), lexical long-term memory (LTM), and age (in months) in the children with developmental language disorder.</div><div><br></div><div><b>Supplemental Material S3. </b>Preparation, exploratory data analysis, GLM-TD: typically developing group, GLM-DLD: developmental language disorder group, and GLM: full sample. </div><div><br></div><div>Montgomery, J. W., Gillam, R. B., Evans, J. L., Schwartz, S., & Fargo, J. D. (2019). A comparison of the storage-only deficit and joint mechanism deficit hypotheses of the verbal working memory storage capacity limitation of children with developmental language disorder. <i>Journal of Speech, Language, and Hearing Research, 62, </i>3808–3825. https://doi.org/10.1044/2019_JSLHR-L-19-0071</div>