The relationship between phonological short-term memory, receptive vocabulary, and fast mapping in children with specific language impairment

Abstract

© 2015 Royal College of Speech and Language Therapists. Background: Children with specific language impairment (SLI) often experience word-learning difficulties, which are suggested to originate in the early stage of word learning: fast mapping. Some previous research indicates significantly poorer fast mapping capabilities in children with SLI compared with typically developing (TD) counterparts, with a range of methodological factors impacting on the consistency of this finding. Research has explored key issues that might underlie fast mapping difficulties in children with SLI, with strong theoretical support but little empirical evidence for the role of phonological short-term memory (STM). Additionally, further research is required to explore the influence of receptive vocabulary on fast mapping capabilities. Understanding the factors associated with fast mapping difficulties that are experienced by children with SLI may lead to greater theoretically driven word-learning intervention. Aims: To investigate whether children with SLI demonstrate significant difficulties with fast mapping, and to explore the related factors. It was hypothesized that children with SLI would score significantly lower on a fast mapping production task compared with TD children, and that phonological STM and receptive vocabulary would significantly predict fast mapping production scores in both groups of children. Methods & Procedures: Twenty-three children with SLI (mean = 64.39 months, SD = 4.10 months) and 26 TD children (mean = 65.92 months, SD = 2.98) were recruited from specialist language and mainstream schools. All participants took part in a unique, interactive fast-mapping task whereby nine novel objects with non-word labels were presented and production accuracy was assessed. A non-word repetition test and the Peabody Picture Vocabulary Test-Fourth Edition (PPVT-IV) were also administered as measures of phonological STM capacity and receptive vocabulary, respectively. Outcomes & Results: Results of the fast-mapping task indicated that children with SLI had significantly poorer fast mapping production scores than TD children. Scores from the non-word repetition task were also significantly lower for the SLI group, revealing reduced phonological STM capacity. Phonological STM capacity and receptive vocabulary emerged as significant predictors of fast mapping performance when the group data were combined in a multiple regression analysis. Conclusions & Implications: These results suggest that the word-learning difficulties experienced by children with SLI may originate at the fast mapping stage, and that phonological STM and receptive vocabulary significantly predict fast mapping ability. These findings contribute to the theoretical understanding of word-learning difficulties in children with SLI and may inform lexical learning intervention.