We examined the contribution of working memory capacity to the development of children's reading comprehension. We present data from three waves of a longitudinal study when the children were 7 years (Grade 1), 8 years (Grade 2) and 9 years (Grade 3). Two questions were raised: The first question concerned the developmental changes of the relative contribution of working memory in predicting reading comprehension compared to vocabulary and decoding skills. The second question explored to what extent reading comprehension could be predicted by working memory capacity measured at a prior time. At the end of each grade, reading comprehension, nonword reading, vocabulary knowledge and working memory capacity were assessed. To test the first question, the predictive power of working memory capacity was compared to vocabulary and decoding skills by performing concurrent multiple-regression analyses in each grade. The results showed that working memory capacity emerged as a direct predictor of reading comprehension in Grade 3. To address the second question, we performed multiple-regression analyses predicting reading comprehension from working memory, nonword reading, and vocabulary measured at a prior time. In these analyses, the autoregressive effect was taken into account to separately assess the unique contribution of each predictor to the development of later reading comprehension. The results showed that Grade 1 vocabulary and Grade 2 working memory had additional effects on Grade 3 reading comprehension after the autoregressive effect of reading comprehension had been accounted for. These findings support the idea that, as word recognition becomes automated throughout the early grade levels, working memory becomes an important determinant of reading comprehension. There is also evidence that working memory capacity directly influences the development of reading comprehension skills. The direction of the causal flow is discussed.

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The dual-task paradigm was used to show how visuospatial working memory and the phonological loop are involved in processing scientific texts and illustrations presented via computer. In experiment 1, two presentation formats were compared: text-only and text-with-illustrations. With a concurrent tapping task, the beneficial effect of illustrations disappeared, while a concurrent articulatory task impaired performance similarly in both presentation formats. An analysis of individual differences revealed that this pattern of results was present in high, but not low spatial span subjects. These results support the selective involvement of visuospatial working memory in processing illustrated texts. In Experiment 2, the text-only presentation format was compared to an illustrations-only format. The concurrent articulatory task selectively impaired text-only processing, compared with processing illustrations-only. In addition, this pattern of results was found for high, but not low digit span subjects. These results suggest that individual differences define the extent to which the two subsystems of working memory are involved in learning from multimedia. These two subsystems would be mainly involved in the maintenance of a visual trace of illustrations and of a verbatim representation of linguistic information respectively, these representations being the basis for higher-level comprehension processes.