The relation between receptive grammar and procedural, declarative, and working memory in specific language impairment

Abstract

What memory systems underlie grammar in children, and do these differ between typically developing (TD) children and children with specific language impairment (SLI)? Whilst there is substantial evidence linking certain memory deficits to the language problems in children with SLI, few studies have investigated multiple memory systems simultaneously, examining not only possible memory deficits but also memory abilities that may play a compensatory role. This study examined the extent to which procedural, declarative, and working memory abilities predict receptive grammar in 45 primary school aged children with SLI (30 males, 15 females) and 46 TD children (30 males, 16 females), both on average 9;10 years of age. Regression analyses probed measures of all three memory systems simultaneously as potential predictors of receptive grammar. The model was significant, explaining 51.6% of the variance. There was a significant main effect of learning in procedural memory and a significant group × procedural learning interaction. Further investigation of the interaction revealed that procedural learning predicted grammar in TD but not in children with SLI. Indeed, procedural learning was the only predictor of grammar in TD. In contrast, only learning in declarative memory significantly predicted grammar in SLI. Thus, different memory systems are associated with receptive grammar abilities in children with SLI and their TD peers. This study is, to our knowledge, the first to demonstrate a significant group by memory system interaction in predicting grammar in children with SLI and their TD peers. In line with Ullman's Declarative/Procedural model of language and procedural deficit hypothesis of SLI, variability in understanding sentences of varying grammatical complexity appears to be associated with variability in procedural memory abilities in TD children, but with declarative memory, as an apparent compensatory mechanism, in children with SLI.

Keywords: compensation; declarative memory; grammar; memory; procedural memory; receptive grammar; specific language impairment; working memory.

FIGURE 1

Histograms showing distribution of scores for the measures of procedural memory (A), declarative memory (B), working memory (C), and receptive grammar (D) reported by group. Shaded bars show the distributions for the SLI group (right side of each panel), while white bars show the distributions for the TD group (left side of each panel).

FIGURE 2

Scatterplots showing the relationship between TROG-2 scores and the measures of procedural memory (A), declarative memory (B), and working memory (C) for SLI and TD groups. Dashed line plots regression equation for TD group and unbroken for SLI group. Recall that the procedural memory task is a non-verbal task.