Executive Function, Working Memory, and Verbal Fluency in Relation to Non-Verbal Intelligence in Greek-Speaking School-Age Children with Developmental Language Disorder

Abstract

Developmental Language Disorder (DLD) is often associated with impairments in working memory (WM), executive functions (EF), and verbal fluency. Moreover, increasing evidence shows poorer performance of children with DLD on non-verbal intelligence tests relative to their typically developing (TD) peers. Yet, the degree and generality of relevant difficulties remain unclear. The present study aimed at investigating WM capacity, key EFs and verbal fluency in relation to non-verbal intelligence in Greek-speaking school-age children with DLD, compared to TD peers (8-9 years). To our knowledge, the present study is the first to attempt a systematic relevant assessment with Greek-speaking school-age children, complementing previous studies mostly involving English-speaking participants. The results showed that children with DLD scored lower than TD peers on the non-verbal intelligence measure. Groups did not differ in the inhibition measures obtained (tapping resistance to either distractor or proactive interference), but children with DLD were outperformed by TD peers in the WM capacity, updating, monitoring (mixing cost), and verbal fluency (phonological and semantic) measures. The effects showed limited (in the case of backward digit recall) or no dependence on non-verbal intelligence. Findings are discussed in terms of their theoretical and practical implications as well as in relation to future lines of research.

Keywords: Developmental Language Disorder; executive functions; non-verbal intelligence; school-age children; verbal fluency; working memory.

Figure 1

The group by shifting interaction (RT-estimated marginal means and error bars in msecs).