Working Memory Performance in Children With Developmental Language Disorder: The Role of Domain

Purpose: This study examined working memory in children with developmental language disorder (DLD). The overarching goal of this work was to integrate three primary processing-based hypotheses of DLD, (a) limited verbal working memory, (b) slowed processing speed, and (c) inefficient inhibition of interference, by using the serial-order-in-a-box-complex span (SOB-CS) computational model as our theoretical framework. We also examined the role of domain in working memory performance by varying the domain of interference and recall (i.e., verbal vs. nonverbal) task demands. Method: Participants were 55 school-age children, 21 children with DLD and 34 age-matched typically developing (TD) peers (9-13 years old). Results: Findings indicated that verbal and nonverbal working memory performance was poorer in the DLD than TD group. There was a modest benefit of dispersing interference and recall task demands across domains relative to task demands being within one domain, yet verbal interference affected performance to a greater degree than nonverbal interference in the DLD group. Conclusions: Overall findings supported a role for each of the processing based hypotheses of DLD, albeit an incomplete role. In contrast, the SOB-CS model accounted for interrelationships among these processing-based factors and provided an explanation across patterns of findings. Thus, the SOB-CS model represents a useful step forward in explaining processing in children with DLD.