Tuesday, October 4, 2011

Domain-specific treatment effects in children with language and/or working memory impairments: A pilot study

Wener, S.E., & Archibald, L.M.D. (2011). Domain-specific treatment effects in children with language and/or working memory impairments: A pilot study. Child Language Teaching and Therapy, 27, 313-330.

Archibald & Joanisse (2009) identified three groups of children: (1) Those with a Specific Language Impairment (SLI), an impairment in language development but not working memory; (2) those with a Specific Working Memory Impairment, an impairment in working memory but not language; and (3) those with both language and working memory impairments (L&WMI). Given these separable groups, it would be reasonable to hypothesize that these children may respond differently to treatment aimed either at improving language or working memory. It was the purpose of this pilot study to evaluate this hypothesis.

We employed a single subject design with 9 participants, 3 with SLI, 2 with SWMI, and 4 with L&WMI. Performance was measured using 3 probes (picture recall, sentence formulation, geometric puzzle completion) throughout the baseline phase (2 wks), treatment phase 1 (4 wks), no treatment (4 wks), and treatment phase 2 (4 wks). Standardized tests of language and working memory were completed before and after each treatment phase, and at 4 months post treatment. The treatment in the 2 phases involved 4 tasks (word recall, n-back, story retelling, memory updating) but differed in the strategies taught. For the language-based intervention, verbal strategies were targeted whereas for the working memory-based intervention, imagery strategies were taught as a memory strategy. Five of the participants did the language-based intervention first followed by the working memory intervention.

Results revealed that performance improved on the picture recall probe after the language-based intervention, and on the geometric puzzle completion probe after the working memory-based intervention. No reliable effects were found for the sentence formulation probe. Improvements of 10 points on standard scores were considered clinically significant. Based on this criterion, 6 of 7 of the children with a language impairment (SLI or L&WMI) showed an improvement on a language measure and 3 of 5 (SWMI or L&WMI) on a working memory measure at 4 months post onset.

This study provides some preliminary evidence of a domain-specific treatment effect in that performance on a language task improved after language-based intervention and on a visuospatial task after working memory-based intervention focusing on imagery strategies. The findings also suggest a profile-specific effect in that children with a language impairment tended to improve on a language measure and children with a working memory impairment on a working memory test. Given the small sample size, these results must be interpreted with caution.

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