Variability in comprehension strategy use in children with SLI: a dynamical systems account.

The aim was to investigate the stability of comprehension strategy use in children with specific language impairment (SLI). According to principles of Dynamic Systems Theory, behaviour is both unstable and more easily affected by changes in external variables during developmental transitions. The study examined this prediction directly by comparing the comprehension strategy use of children with SLI in two different conditions. The subjects included 16 school-aged children with SLI (ages 6;8-8;5), and eight chronologically age-matched (CA) controls. One group of children with SLI (n = 8) was in a development transition between animacy and word-order comprehension strategy use, demonstrating the emerging use of word-order sentence comprehension strategies (SLI-T). The second group of children with SLI (n = 8) was not in a developmental transition (SLI-N), demonstrating the use of only animacy comprehension strategies characteristic of younger typically developing children. Children were asked to determine the agent in 54 sentences of the forms (NVN, NNV, VNN) with animacy of the noun as a second factor in each of two different conditions designed to vary external processing demands. Analysis of variance and maximum likelihood estimate analysis revealed that comprehension strategies for both groups of children with SLI differed qualitatively from CA controls. In particular, the findings revealed that comprehension strategy use in children with SLI was highly vulnerable to increases in external processing demands as compared with CA controls, suggesting that comprehension strategies in children with SLI are weakly represented regardless of the strategy they use. Findings from the study also illustrate the impact of intrinsic as well as extrinsic contextual factors on the stability and instability of language processing performance in children with SLI.