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Background: Recent studies indicate that school-age children's patterns of performance on measures of verbal and visuospatial short-term memory (STM) and working memory (WM) differ across types of neurodevelopmental disorders. Because these disorders are often characterized by early language delay, administering STM and WM tests to toddlers could improve prediction of neurodevelopmental outcomes. Toddler-appropriate verbal, but not visuospatial, STM and WM tasks are available. A toddler-appropriate visuospatial STM test is introduced., Method: Tests of verbal STM, visuospatial STM, expressive vocabulary, and receptive vocabulary were administered to 92 English-speaking children aged 2-5 years., Results: Mean test scores did not differ for boys and girls. Visuospatial and verbal STM scores were not significantly correlated when age was partialed out. Age, visuospatial STM scores, and verbal STM scores accounted for unique variance in expressive (51%, 3%, and 4%, respectively) and receptive vocabulary scores (53%, 5%, and 2%, respectively) in multiple regression analyses., Conclusion: Replication studies, a fuller test battery comprising visuospatial and verbal STM and WM tests, and a general intelligence test are required before exploring the usefulness of these STM tests for predicting longitudinal outcomes. The lack of an association between the STM tests suggests that the instruments have face validity and test independent STM skills.

Purpose: This study explored whether measures of working memory ability contribute to the wide variation in 2-year-olds' expressive vocabulary skills., Method: Seventy-nine children (aged 24-30 months) were assessed by using standardized tests of vocabulary and visual cognition, a processing speed measure, and behavioral measures of verbal working memory and phonological short-term memory., Results: Strong correlations were observed between phonological short-term memory, verbal working memory, and expressive vocabulary. Speed of spoken word recognition showed a moderate significant correlation with expressive vocabulary. In a multivariate regression model for expressive vocabulary, the most powerful predictor was a measure of phonological short-term memory (accounting for 66% unique variance), followed by verbal working memory (6%), sex (2%), and age (1%). Processing speed did not add significant unique variance., Conclusions: These findings confirm previous research positing a strong role for phonological short-term memory in early expressive vocabulary acquisition. They also extend previous research in two ways. First, a unique association between verbal working memory and expressive vocabulary in 2-year-olds was observed. Second, processing speed was not a unique predictor of variance in expressive vocabulary when included alongside measures of working memory.

Purpose: In this study, the authors examined the diagnostic accuracy of a composite clinical assessment measure based on mean length of utterance (MLU), lexical diversity (D), and age (Klee, Stokes, Wong, Fletcher, & Gavin, 2004) in a second, independent sample of 4-year-old Cantonese-speaking children with and without specific language impairment (SLI)., Method: The composite measure was calculated from play-based, conversational language samples of 15 children with SLI and 14 children without SLI. Scores were dichotomized and compared to diagnostic outcomes using a reference standard based on clinical judgment supported by test scores., Results: Eleven of 15 children with SLI and 8 of 14 children with typical language skills were correctly classified by the dichotomized composite measure. The measure's sensitivity in this second sample was 73.3% (95% confidence interval [CI] 48%-89%); specificity was 57.1% (95% CI 33%-79%); positive likelihood ratio was 1.71 (95% CI 0.87-3.37); and negative likelihood ratio was 0.47 (95% CI 0.18-1.21)., Conclusions: The diagnostic accuracy of the composite measure was substantially lower than in the original study, suggesting that it is unlikely to be informative for clinical use in its present form. The value of replication studies is discussed.

Background: This research explored the relative impact of demographic, cognitive, behavioural, and psycholinguistic factors on vocabulary development in two-year-old children., Methods: Two hundred and thirty-two children (24-30 months) were tested on expressive and receptive vocabulary, cognitive development, word learning and working memory skills. Parents completed a British adaptation (Klee & Harrison, 2001) of the MacArthur-Bates Communicative Development Inventory (CDI; Fenson et al., 1993), a demographic questionnaire and a questionnaire regarding the child's social-emotional behaviour., Results: Several demographic, child and processing variables were significantly correlated with CDI (vocabulary) scores, but the only significant unique predictors of CDI scores were nonword repetition (NWR; R(2) change = .36), sex (R(2) change = .05) and age (R(2) change = .04). Scores were only included when a child completed the entire NWR test (77% of toddlers)., Conclusions: The NWR task used in this experiment maximised participation in this group of toddlers, and was a strong predictor of vocabulary ability. Longitudinal research is warranted to explore the independent and reciprocal growth in working memory and language skills in children.

Since norms for vocabulary acquisition in Maltese children do not yet exist, documentation of productive vocabulary acquisition may contribute to establishing a baseline of lexical development. Clinical implications may thus be derived. The current study is a small-scale investigation of the proportions of Maltese and English lexemes in the vocabularies of ten normally-developing Maltese children aged between 12 and 30 months. The participants were primarily exposed to Maltese within their immediate environments, while receiving indirect exposure to English. Outcomes of parental report and language sampling were analysed for evidence of a bilingual dimension in these children's productive vocabularies. Translation equivalents were reported on by parents, but negligible evidence of equivalents emerged in conversational language use. In contrast, lexical borrowings were both reported and sampled. A substantial proportion of English lexemes were reported by the parents in the absence of Maltese equivalents.

Two studies of children's conversational language abilities are reported. In the first, mean length of utterance (MLU) and lexical diversity (D) were examined in a group of typically developing Cantonese-speaking children in Hong Kong. Regression analyses indicated a significant linear relationship between MLU and age (R = .44) and a significant curvilinear relationship between D and age (R = .73) in children age 27-68 months. MLU and D were moderately correlated with each other (r = .23); however, the two measures showed no statistical relationship when the effect of age was partialled out. In a second study, the utterances of Chinese children with specific language impairment (SLI) were found to be significantly shorter and less lexically diverse than typically developing children matched for age but similar to children matched for comprehension level. Discriminant analyses revealed that the combination of age, MLU, and D could be used to accurately differentiate children with SLI from both age-matched and language-matched children. Based on these findings, we hypothesize that these measures can be used jointly as a marker of SLI in Cantonese-speaking children.