It is well-established that children with dyslexia and/or Developmental Language Disorder (hereafter children with DDLD) perform poorly on phonological tasks compared to typically developing (TD) children. However, there has been some debate as to whether their phonological deficit arises directly from an impairment in phonological representations, or instead from deficient access to (intact) phonological representations. This study tested the Degraded Phonological Representations Hypothesis and the Deficient Phonological Access Hypothesis using a task that is not often used with children with DDLD, namely phonological fluency. Both hypotheses predict that children with DDLD will retrieve fewer items than their TD peers in the phonological fluency task. However, while the Degraded Phonological Representations Hypothesis predicts smaller clusters of phonologically related items in children with DDLD, the Deficient Phonological Access Hypothesis predicts that the two groups will not differ in cluster size. How phonological fluency performance related to children’s language, literacy, and phonological skills was investigated. Further, the specificity of a phonological fluency deficit in children with DDLD was tested using a nonverbal (design) fluency task. Sixty-six children with DDLD aged 7–12 years and 83 TD children aged 6–12 years, all monolingual Greek speakers, were tested on three phonological fluency categories, on nonverbal IQ, language, literacy, and phonological tasks, and on a design fluency task. The DDLD group produced significantly fewer correct responses and fewer switches compared to the TD group, but the two groups showed similar clustering and average cluster size. After controlling for age, children’s language, literacy, and phonological skills significantly predicted the number of correct responses produced. The two groups did not differ significantly on the number of unique designs generated in the design fluency task. Furthermore, children with DDLD showed poorer phonological fluency performance relative to their TD peers even after design fluency performance was controlled, demonstrating the specificity of their phonological fluency deficit. This study adds to the theoretical debate on the locus of the phonological deficit in dyslexia and DLD. The findings support the hypothesis that the phonological deficit in dyslexia and DLD lies in deficient explicit access to intact phonological representations.

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.

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