Dissertation

Psycholinguistic subtype profiles of children with specific language impairment

Simkin, Zoë Victoria

2001

Overview

Three subgroups of 11-year-old children with Specific Language Impairment (SLI) were identified, characterised by selective or joint impairment of receptive and expressive language or resolution of previous SLI in both of these modalities. All subgroups demonstrated normal range non-verbal IQ. The subgroups comprised 30 children with current expressive-only language impairment (E-SLI subgroup), 32 with a combination of current expressive and receptive language impairment (ER-SLI subgroup) and 28 with a history of now-resolved language impairment (Resolved-SLI subgroup). Subtype profiles were investigated through standardised tests of language, literacy and cognition. Following a secondary study to provide norm-referenced standardised data on measures of grammatical morphology and nonword repetition, subgroup profiles were investigated relative to each other and also relative to typically developing age-matched controls. The results indicated that, at 11 years, distinct subgroup profiles can identified along the receptive/expressive language distinction, although these subgroups are not homogeneous. The E-SLI subgroup displayed normal-range receptive syntax and receptive vocabulary coupled with clinical impairment in tests of expressive syntax (past tense and third-person singular), expressive vocabulary, expressive sentence recall and nonword repetition. The ER-SLI subgroup displayed impairment in receptive and expressive vocabulary, receptive and expressive syntax, sentence recall and nonword repetition. Normal range functioning for both subgroups on a test of word associations/fluency was inconsistent with other expressive language areas, indicating that this domain of language functioning is not a key area of difficulty in the profiles of children with SLI at 11 years. The Resolved SLI subgroup displayed residual difficulties (based on mean group score) only in phonological short-term memory, as measured by a nonword repetition test. However, small proportions of this subgroup also displayed difficulty with vocabulary, regardless of the modality tested. Previous language characteristics at 7 were also investigated for each subgroup. A measure of narrative-retelling at 7 years was found to be the best predictor of membership of the E-SLI vs. ER-SLI subgroups and resolved outcome generally, whereas a measure of expressive syntax additionally predicted outcome into the Resolved-SLI subgroup. Subtypes of SLI identified along the expressive/receptive distinction were not consistent with age during primary schooling, as changes in comprehension and production abilities were observed which impacted on subgroup diagnosis. The Resolved-SLI and ER-SLI subgroups were relatively stable however, compared to the E-SLI subgroup. Diagnosis based on dichotomous impairment of mean group comprehension and expression had 100% success rate for the Resolved- SLI and ER-SLI subgroups with age. The E-SLI subgroup however showed a decline from previous normal-range expressive ability at 7 years to be classed as expressive- only impaired at 11 years. Despite a subgroup criteria for non-verbal IQ in the normal range at subgroup formation (11 years old), a significant decline was observed in nonverbal IQ from 7 years to 11 years for all subgroups, suggesting that the general decline in IQ generally documented in children with SLI, is not dependent on subtype and thus not causally related to patterns of impairment in the domains of comprehension and expression. However, although no between-group differences were evident in non-verbal cognitive abilities at 7 years, by 11 years a significant difference had emerged between the ER-SLI and Resolved-SLI subgroups. The present study further found evidence of distinctive reading profiles as a function of subtype. Children displaying language impairment in the domains of both comprehension and expression also demonstrated reading difficulties in both single word reading and reading comprehension. In contrast, children with impairment in language production but not language comprehension presented with normal range ability in single word reading but had difficulties with reading comprehension. In further contrast, children whose overt language impairments appear resolved by age 11 years, also demonstrated unaffected reading skills at this time in terms of both decoding skills and reading comprehension. All subgroups showed consistent ability with age in single word reading decoding skills, suggesting that presence or absence of associated reading impairment is stable in children with SLI between age 7 and 11 years, dependent on subtype. The finding that reading problems manifest at the beginning of primary schooling are likely to be still apparent at the end of primary schooling is likely to have educational implications. The results from the study overall have implications for both research and clinical practice.

• Publisher: ProQuest Dissertations & Theses
• Subject: Cognitive psychology / Special education / Speech therapy
• ISBN: 9780355609851, 0355609851