Patterns of developmental dyslexia according to a multi-trace memory model of reading.

International audienceThe reading performance of two groups of dyslexic children with either a phonological (PH) or a visual-attentional (VA) deficit was compared to that of control groups matched on chronological age (CA) and reading age (RA). In both groups and on all the reading measures, the dyslexic children performed worse than the CA-controls but similarly to the RA-controls. Performance of the VA dyslexic participants in exception word reading was lower than that of the PH-dyslexics but the two dyslexic groups exhibited a similarly low performance in pseudo-word reading. These findings constitute arguments against the delay hypothesis and question the current methods used to identify dyslexia subtypes. They are in support of the multi-trace memory model of polysyllabic word reading (Ans, Carbonnel & Valdois, 1998)

Influence of the visual attention span on child reading performance: A cross-sectional study

International audienceThe visual attention (VA) span deficit hypothesis was found successfully to account for variability in developmental dyslexia (Bosse, Tainturier & Valdois, 2007). We conducted a cross-sectional study on 417 typically developing children from first, third and fifth grades examining the role of VA span on the development of reading skills. A battery including reading, phoneme awareness and VA span tasks was administered. Results show that VA span predicts variations in learning to read independent of the influence of phoneme awareness. Moreover, whereas the specific influence of VA span on pseudoword reading declines from first to third grade, VA span has a significant and sustained influence across grades for the irregular words. In addition to phoneme awareness, the VA span contributes to reading performance from the beginning of literacy instruction, suggesting that it might have a long-term influence on specific orthographic knowledge acquisitio

Bayesian modeling of human performance in a visual processing training software

International audienceDyslexia is a deficit of the identification of words, which is thought to be a consequence of different possible cognitive impairments. Recent data suggest that one of these might be a specific deficit of the visual attention span (VAS). We are developing a remediation software for dyslexic children that focuses on the VAS and its training. A central component of this software is the estimation of the performance of a given participant for all possible exercises. We describe a preliminary probabilistic model of participant performance, based on Bayesian modeling and inference. We mathematically define the model, making explicit underlying generalization hypotheses. The model yields a computation of the most probable predicted performance space, and, as a direct extension, an exercise selection strategy

Acquisition du langage écrit et empan visuo-attentionnel : une étude longitudinale

La présente étude s'inscrit dans le prolongement direct des études précédemment décrites sur les relations entre l'EVA et l'acquisition de la lecture. Alors que les études précédentes ne décrivent qu'une co-variation entre EVA et lecture, mesurés au même moment chez l'enfant, la recherche présentée ici vise à préciser la nature du lien qui les relie. L'objectif est de tester l'hypothèse selon laquelle l'EVA, mesuré au début de l'acquisition de la lecture, prédit une part significative de variance en lecture, un an après. La confirmation de cette hypothèse apporte un élément supplémentaire en faveur de l'idée que le traitement visuo-attentionnel est directement impliqué dans l'acquisition du langage écrit et qu'un déficit de l'EVA peut générer des difficultés particulières dans l'acquisition de la lecture

Developmental dyslexia: The visual attention span deficit hypothesis

International audienceThe visual attention (VA) span is defined as the amount of distinct visual elements which can be processed in parallel in a multi-element array. Both recent empirical data and theoretical accounts suggest that a VA span deficit might contribute to developmental dyslexia, independently of a phonological disorder. In this study, this hypothesis was assessed in two large samples of French and British dyslexic children whose performance was compared to that of chronological-age matched control children. Results of the French study show that the VA span capacities account for a substantial amount of unique variance in reading, as do phonological skills. The British study replicates this finding and further reveals that the contribution of the VA span to reading performance remains even after controlling IQ, verbal fluency, vocabulary and single letter identification skills, in addition to phoneme awareness. In both studies, most dyslexic children exhibit a selective phonological or VA span disorder. Overall, these findings support a multi-factorial view of developmental dyslexia. In many cases, developmental reading disorders do not seem to be due to phonological disorders. We propose that a VA span deficit is a likely alternative underlying cognitive deficit in dyslexia

Lexical orthographic acquisition: Is handwriting better than spelling aloud?

International audienceLexical orthography acquisition is currently described as the building of links between the visual forms and the auditory forms of whole words. However, a growing body of data suggests that a motor component could further be involved in orthographic acquisition. A few studies support the idea that reading plus handwriting is a better lexical orthographic learning situation than reading alone. However, these studies did not explore which of the cognitive processes involved in handwriting enhanced lexical orthographic acquisition. Some findings suggest that the specific movements memorized when learning to write may participate in the establishment of orthographic representations in memory.The aim of the present study was to assess this hypothesis using handwriting and spelling aloud as two learning conditions. In two experiments, fifth graders were asked to read complex pseudo-words embedded in short sentences. Immediately after reading, participants had to recall the pseudo-words' spellings either by spelling them aloud or by handwriting them down. One week later, orthographic acquisition was tested using two post-tests: a pseudo-word production task (spelling by hand in Experiment 1 or spelling aloud in Experiment 2) and a pseudo-word recognition task. Results showed no significant difference in pseudo-word recognition between the two learning conditions. In the pseudo-word production task, orthography learning improved when the learning and post-test conditions were similar, thus showing a massive encoding-retrieval match effect in the two experiments. However, a mixed model analysis of the pseudo-word production results revealed a significant learning condition effect which remained after control of the encoding-retrieval match effect. This later finding suggests that orthography learning is more efficient when mediated by handwriting than by spelling aloud, whatever the post-test production task

The cognitive deficits responsible for developmental dyslexia: Review of evidence for a visual attentional deficit hypothesis.

International audienceThere is strong converging evidence suggesting that developmental dyslexia stems from a phonological processing deficit. However, this hypothesis has been challenged by the widely admitted heterogeneity of the dyslexic population, and by several reports of dyslexic individuals with no apparent phonological deficit. In this paper, we discuss the hypothesis that a phonological deficit may not be the only core deficit in developmental dyslexia and critically examine several alternative proposals. To establish that a given cognitive deficit is causally related to dyslexia, at least two conditions need to be fulfilled. First, the hypothesised deficit needs to be associated with developmental dyslexia independently of additional phonological deficits. Second, the hypothesised deficit must predict reading ability, on both empirical and theoretical grounds. While most current hypotheses fail to fulfil these criteria, we argue that the visual attentional deficit hypothesis does. Recent studies providing evidence for the independence of phonological and visual attentional deficits in developmental dyslexia are reviewed together with empirical data showing that phonological and visual attentional processing skills contribute independently to reading performance. A theoretical model of reading is outlined in support of a causal link between a visual attentional disorder and a failure in reading acquisition

Orthographic learning during reading: the role of whole-word visual processing

International audienceThe self-teaching hypothesis suggests that knowledge about the orthographic structure of words is acquired incidentally during reading through phonological recoding. The current study assessed whether visual processing skills during reading further contribute to orthographic learning. French children were asked to read pseudowords. The whole pseudoword letter string was available at once for half of the targets while the pseudoword's sub-lexical units were discovered in turn for the other half. Then memorisation of the targets orthographic form was assessed. Although most pseudowords were accurately decoded, target orthographic forms were recognised more often when the pseudowords entire orthographic sequence was available at once during the learning phase. The whole-word presentation effect was signifi cant and stable from third to fifth grades. This effect was affected neither by target reading accuracy nor by target reading speed during the learning phase. Results suggest that beyond recoding skills, the ability to process the entire orthographic letter string at once during reading contributes to efficient orthographic learning