Développement de la compétence orthographique : étude des connaissances des frontières lexicales d’élèves sans difficulté à l’écrit et d’élèves dyslexiques du primaire

Reading and writing are two complex activities that contribute to success in all school subjects. For apprentice writers, and particularly for students with learning difficulties (notably students with dyslexia), learning to spell represents a real challenge and often requires years of effort. To be successful, students require knowledge of the orthographic code, which is the foundation upon which spelling ability it built.  To recognize and produce written words, students must develop a set of core skills that are linked to orthographic knowledge, including knowledge of the phonological, morphological and visual properties of the orthographic code. As their spelling skills develop, readers and writers must construct increasingly stable and better defined orthographic representations that reflect the properties of the orthographic code. However, recent empirical research has found that students with dyslexia, who tend to make more errors related to word merging and segmentation than students without writing difficulties, do not seem to have accurate orthographic representations of the words they are trying to spell, particularly of the beginnings and endings of words. Therefore, the general aim of this study is to explain spelling errors occurring at word boundaries in dyslexic children. To our knowledge, no typical trajectory of development has been established for normally-developing readers/writers with regards to knowledge of lexical boundaries. Therefore, using both cross-sectional and longitudinal analyses, this study’s first objective is to describe the performances of normally-developing reader and writers from kindergarten to grade 4 on tasks related to lexical boundary knowledge (Study 1). With this developmental reference having been established, the second study will evaluate lexical boundary knowledge in primary school students with dyslexia (study 2).  To evaluate ability in reading and word production, a reading test from the K-ABC battery and a dictation task requiring students to insert words in the context of a sentence were administered. To evaluate knowledge of lexical boundaries, three tasks (a lexical decision task, a lexical identification task, and a lexical permutation task) were completed by all participants in oral and written form, each of which varied according to the level of cognitive constraint involved in completing the task.  For the first study, results revealed that knowledge of lexical borders appeared to be nearing mastery at the end of grade two and was fully mastered by grades 3-4. A significant part of the variance found in the results for reading and word production could be explained by knowledge of lexical borders measured the previous year. Generally, although certain exceptions must be made for the permutation task, modality (oral or written) did not appear to impact performance. However, results did show an effect for task type according to the level of cognitive constraint. The results for study 2 show a significant delay in the developmental trajectories related to lexical boundary knowledge in children with dyslexia. Like the normo-readers / writers, the results were also correlated with scores on the dictation and reading tasks. In addition, the degree of cognitive constraint as well as modality appeared to influence performance. In light of the results from studies 1 and 2 and taking into account the central role played by lexical boundary knowledge in the establishment of foundational reading and writing skills, explicit teaching of this knowledge to students with dyslexia and to children more generally in kindergarten is recommended. More research is necessary to better understand the role played by orthographic knowledge, especially visual knowledge, in the development of reading and writing abilities.

Keyphrases: spelling ability, orthographic representations, lexical boundaries, developmental dyslexia