title: Developmental delays in phonological recoding among children and adolescents with Down syndrome and Williams syndrome.
abstract: 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.
authors.affiliation: The Swedish Institute for Disability Research, Linköping, Sweden; Linnaeus Centre HEAD, Linköping University, Sweden; Department of Behavioural Sciences and Learning, Linköping University, Sweden. Electronic address: henrik.danielsson@liu.se.
authors.forename: Henrik
authors.initials: H
authors.lastname: Danielsson
authors.affiliation: City University London, UK.
authors.forename: Lucy
authors.initials: L
authors.lastname: Henry
authors.affiliation: Open University, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Messer
authors.affiliation: London South Bank University, London, UK.
authors.forename: Daniel P J
authors.initials: DP
authors.lastname: Carney
authors.affiliation: The Swedish Institute for Disability Research, Linköping, Sweden; Linnaeus Centre HEAD, Linköping University, Sweden; Department of Behavioural Sciences and Learning, Linköping University, Sweden.
authors.forename: Jerker
authors.initials: J
authors.lastname: Rönnberg
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000503:physiopathology / Q000523:psychology*; D005260:Female; D006801:Humans; D007802:Language; D007804:Language Development; D007805:Language Development Disorders / Q000503:physiopathology / Q000523:psychology*; D008297:Male; D008570:Memory, Short-Term; D018980:Williams Syndrome / Q000503:physiopathology / Q000523:psychology*; D055815:Young Adult
keywords: Down syndrome; Phonological recoding; Phonological similarity effect; Short-term memory; Visual similarity effect; Williams syndrome; Word length effect