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Developmental delays in speech coding among children with Down syndrome and William’s syndrome

Danielsson, H., Henry, L., Messer, D.M. , Carney, D.P.J. & Ronnberg, J. (2016). Developmental delays in speech coding among children with Down syndrome and William’s syndrome. Research in Developmental Disabilities, 55(August), pp. 64-76. doi: 10.1016/j.ridd.2016.03.012


This study examined the development of phonological recoding in short-term memory (STM) span tasks among two clinical groups with contrasting STM and language profiles: those with Down syndrome (DS) and Williams syndrome (WS). Phonological recoding was assessed by comparing: 1) performance on phonologically similar and dissimilar items (phonological similarity effects, PSE); and 2) items with short and long names (word length effects, WLE). Participant groups included children and adolescents with DS (n=29), WS (n=25) and typical development (n=51), all with average mental ages around 6 years. The group with WS, contrary to predictions based on their relatively strong verbal STM and language abilities, showed no evidence for phonological recoding. Those in the group with DS, with weaker verbal STM and language abilities, showed positive evidence for phonological recoding (PSE), but to a lesser degree than the typical group (who showed PSE and WLE). These findings provide new information about the memory systems of these groups of children and adolescents, and suggest that STM processes involving phonological recoding do not fit with the usual expectations of the abilities of children and adolescents with WS and DS.

Publication Type: Article
Publisher Keywords: Down syndrome, Williams syndrome, phonological recoding, phonological similarity effect, word length effect, visual similarity effect, short-term memory
Subjects: P Language and Literature
Departments: School of Health & Psychological Sciences > Language & Communication Science
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