Thursday, October 27, 2011

Precursors to numeracy in kindergartners with specific language impairment

Kleemans, T., Segers, E., & Verhoeven, L. (2011). Precursors to numeracy in kindergartners with specific language impairment. Research in Developmental Disabilities, 32, 2901-8.

Kleemans et al. examined whether children with SLI significantly differed on measures of numeracy in comparison to typically developing children and which precursors were more closely related to numerical processing skills in children with SLI. A group of 111 typically developing children and 61 with SLI completed measures of working memory, naming speed, phonological awareness and grammatical ability, as well as measures of logical operations, numeral representations and numeral estimations. The researchers found that phonological awareness and grammatical ability predicted logical operations and numerical representations. Furthermore, there was an interaction between group and naming speed, with naming speed being significantly correlated with logical operations and numerical representations in the SLI group, but the typically developing group.

These findings are consistent with the Triple Code Model proposed by Dehaene et al. (2003). This model predicts that depending on the tasks, there are three distinct systems of representation that may be recruited: the quantity system (nonverbal), a verbal system (where numerals are represented lexically, phonologically and syntactically) and visual system. The verbal system is associated with activating the left angular gyrus (located in the parietal lobe), which has been found to be associated with arithmetic fact retrieval, but also other language mediated processes such as verbal STM and reading. The findings of a relationship between language abilities and the verbally based numerical tasks in the Kleemans et al. study are consistent with the verbal numeracy system proposed in the Triple Code Model.

Although the paper is consistent with previous findings, the hierarchical regression analysis reported was confusing. Furthermore, multiple t-tests were conducted increasing the chance of finding a type I error. The correlation analyses would have been stronger if partial correlations controlling for age were reported. As well, the numeracy tasks that measured numerical operations and numerical representations were very similar to one another and relied heavily on language processes to perform. Given the fact that the numeracy tasks were not independent of language skills, the results are not surprising.

These findings may have clinical and diagnostic implications. Although further research is necessary, the rapid naming may be related to number deficits in children with SLI. However, given the statistical methods used, the results should be interpreted with caution.

Blogger: Stephanie Bugden is our guest blogger and a PhD candidate working in the lab of Dr. Daniel Ansari, Canada Research Chair in Developmental Psychology at the University of Western Ontario. Stephanie’s research examines the developmental trajectories of cognitive impairments in children with math learning disabilities. Stephanie currently holds the record for the shortest time between finishing our lab meeting and writing her post for this blog!

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