Unpacking the role of working memory in reading comprehension: linear and non-linear perspectives in a transparent orthography

This study examines the direct and indirect effects of working memory on reading comprehension in a sample of 395 Chilean fourth-grade students (Mean age 9.97, SD = 0.51; 46% are females) within the context of Spanish, a transparent orthographic system. Using both linear and non-linear approaches, the research investigates the relation between working memory and reading comprehension, as well as whether this relation is mediated by a set of linguistic variables. The linear component was analyzed using path analysis, and the results showed that working memory has a significant direct effect on reading comprehension, as well as indirect effects through vocabulary, word reading, and reading speed. The indirect effect via vocabulary was the most substantial. The non-linear component was assessed using latent profile analysis, and the results revealed three distinct working memory cognitive profiles defined by child performance, which were associated with significantly different outcomes in reading comprehension and its predictors. These findings suggest that working memory is not only foundational for the development of fluent and meaningful reading but also interacts with language-related skills to support comprehension. The study highlights the importance of considering both inter and intra-individual differences in cognitive functioning to understand better the mechanisms underlying reading development in transparent orthographies.