Semantic fluency difficulties in developmental dyslexia and developmental language disorder (DLD): poor semantic structure of the lexicon or slower retrieval processes?

Abstract

Background Children with dyslexia and/or developmental language disorder (hereafter children with DDLD) have been reported to retrieve fewer words than their typically developing (TD) peers in semantic fluency tasks. It is not known whether this retrieval difficulty can be attributed to the semantic structure of their lexicon being poor or, alternatively, to words being retrieved more slowly despite semantic structure being intact. Aims To test two theoretical models that could potentially account for retrieval difficulties in semantic fluency tasks, namely, the Poor Lexical–Semantic Structure Model and the Slow‐Retrieval Model. Both models predict that children with DDLD will retrieve fewer items compared with TD children. However, while the Poor Lexical–Semantic Structure Model predicts a less sophisticated network of semantic connections between words in the lexicon, as evidenced by smaller clusters of related items in children with DDLD, the Slow‐Retrieval Model predicts intact inter‐item associations in the lexicon, as evidenced by the two groups’ clusters being of a similar size. The groups’ semantic fluency performance was therefore compared. How semantic fluency performance related to children's language, literacy, and phonological skills was also investigated. Methods & Procedures A total of 66 children with DDLD aged 7–12 years and 83 TD children aged 6–12 years, all monolingual Greek speakers, were tested on semantic fluency, using the categories ‘animals’, ‘foods’ and ‘objects from around the house’. The numbers of correct and incorrect responses, clusters and switches, and the average cluster size were computed. Children were also assessed on non‐verbal IQ, language, literacy and phonological tasks. Outcomes & Results In both groups, productivity in semantic fluency tasks correlated strongly with the numbers of clusters and switches, but not with average cluster size. The DDLD group produced significantly fewer correct responses and fewer clusters compared with the TD group, but the two groups showed similar switching and average cluster size. Children's language, literacy and phonological skills significantly predicted the number of correct responses produced, beyond the significant effect of age. Conclusions & Implications We conclude that poorer semantic fluency performance in children with DDLD results not from a lexicon with poor semantic structure, but rather from slower retrieval processes from a lexicon with intact semantic structure. The underlying causes of slow lexical retrieval still need further investigation.

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

“…Moreover, findings remain limited to languages other than English, although language characteristics can affect performance in tasks tapping on lexical access and vocabulary development [ 63 ]. In line with our results on semantic fluency (yet, contrast to findings in studies with English-speaking children [ 100 , 101 ]), a recently published study [ 102 ] found poorer semantic fluency in Greek-speaking school-age children with DLD relative to TD peers. However, researchers did not additionally obtain a phonological fluency measure.…”

“…Besides, controversial findings remain limited in languages other than English. A recently published study in the language of the present sample (one of the very few in Greek; see Mengisidou et al [ 102 ]) found poorer semantic fluency performance in school-age children with DLD relative to TD peers; yet, researchers have not also used a phonological fluency measure.…”

“…Children were also given a verbal fluency task [ 136 ], which consisted of two assessment sessions: a semantic fluency and a phonological fluency session (see relevant assessments with children with DLD [ 38 , 39 , 68 , 102 ]). In the semantic fluency test, participants are asked to produce as many different words as they can for each of three semantic categories (animals, fruit, objects).…”

Written Language Production in Children With Developmental Language Disorder

“…According to researchers, children with DLD do not present a consistent language profile since their language characteristics show great heterogeneity ( Pijnacker et al, 2017 ). Previous studies have documented difficulties on the part of the DLD population in non-word repetition ( Bishop et al, 1996 ; Baddeley et al, 1998 ; Larkin et al, 2013 ; Lalioti et al, 2016 ; Mengisidou et al, 2020 ), in verbal short-term memory ( Hill, 2001 ; Girbau and Schwartz, 2007 ) as well as impairments in terms of working memory and processing speed ( Archibald and Gathercole, 2006 ; Leonard, 2014 ). In addition, they face problems in phonological awareness and in oral language production, including many grammatical errors.…”

Reading and Children With Developmental Language Disorder: A Case of Greek Students

“…The difficulties individuals with DLD face concern nonword repetition (Baddeley, Gathercole, & Papagno, 1998;Bishop, North, & Donlan, 1996;Lalioti, Stavrakaki, Manouilidou, & Talli, 2016;Mengisidou, Marshall, & Stavrakaki, 2020), phonological awareness, oral speech production (Catts & Kahmi, 1986), reading and verbal short-term memory (Girbau & Schwartz, 2007;Hill, 2001). Deficits are also observed in morphology (Abel, Rice, & Bontempo, 2015;Rice, Wexler, & Cleave, 1995;van der Lely & Ullman, 2001), and especially in the use of passive voice (van der Lely, 1996) and in question clauses (Stavrakaki, 2019;van der Lely & Battell 2003).…”