Reading development from age 2 to 16: Divergent developmental pathways and their early identification

Abstract

The overall aim of the current dissertation is to examine reading development over time (from age 2 to 16) and investigate the key factors for the early identification and resolution of reading difficulties. It aims to identify ways to predict the development of reading skills and reading difficulties at different ages with the use of very early skills. In particular, the dissertation seeks to increase understanding of how family risk, cognitive skills, and environmental effects affect reading development and reading difficulties. This dissertation builds on data from the Jyväskylä Longitudinal Study of Dyslexia and The First Steps Study. The results of this dissertation suggested that for most children with reading difficulties, the difficulties are persistent from Grades 1 to 9. However, some participants manifested instability in their reading difficulties, and resolving and late-emerging pathways were identified. The results demonstrate that how reading difficulties are identified affects their stability. In particular, the use of single cut-offs can contribute to false impressions, such as how distinct the reading difficulty groups are. The use of different methodologies such as person- vs. variable-oriented approaches may yield differences in the results. The use of latent profile analysis (a person-oriented approach) revealed higher stability in reading skills compared to the use of cut-offs on continuous variables (a variable-oriented approach). The examination of the longitudinal stability of reading difficulties with the use of cut-offs on continuous variables showed that the use of measures with measurement error and the use of single cut-offs affect the longitudinal stability of reading difficulties identification across two time points by causing misclassifications. Furthermore, the examination of the factors that can be used for the early identification of the differential developmental pathways of reading development suggested multiple risk and protective factors. Family risk for reading difficulties, being a boy, and lower performance in cognitive skills (slow rapid automatized naming, difficulty in reading easy words, and low scores in phonological skills, letter knowledge, number counting, and vocabulary) in kindergarten increased the odds of developing reading difficulties. Factors such as being a girl, and good number counting and vocabulary skills in kindergarten seemed to be good markers for the resolution of reading difficulties. A profile with risk factors did not inevitably lead to reading difficulties.