The cognitive deficits responsible for developmental dyslexia: Review of evidence for a selective visual attentional disorder

Abstract

There 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 hypothesized deficit needs to be associated with developmental dyslexia independently of additional phonological deficits. Second, the hypothesized 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.

Individual Differences in Adult Reading Are Associated with Left Temporo-parietal to Dorsal Striatal Functional Connectivity

“…Many studies have highlighted abnormalities in visuospatial attention in RD (Facoetti and Molteni 2001;Hari et al 2001;Facoetti et al 2003Facoetti et al , 2006Sireteanu et al 2005;Liddle et al 2009;Facoetti, Corradi et al 2010;Facoetti, Trussardi et al 2010). Converging evidence also suggests that difficulties in visuospatial attention are an important predictor of reading abilities (Valdois et al 2004;Shaywitz and Shaywitz 2008;Franceschini et al 2012Franceschini et al , 2013. Reading remediation (Franceschini et al 2013) may rely largely on alterations in visual or auditory attentional functions of the dorsal attention network (Ronconi et al 2014).…”

Varieties of developmental dyslexia in Greek children

“…Slow nonword reading can also be explained within the multi-trace memory model (Ans et al, 1998). The multi-character simultaneous processing hypothesis holds that both slow nonword reading and impaired irregular word reading can derive from a visual attention span disorder (Valdois et al, 2004; since, in this framework, nonword reading speed is associated with the size of the sublexical units that individuals use to read nonwords. The larger the sublexical unit the faster the reading speed.…”

“…We aimed to investigate not only phonological awareness and rapid automatized naming, as in the Douklias et al study, but also multi-character processing ability (with letter report tasks) and visual memory. Multi-character processing ability, assessed in tasks involving the simultaneous presentation of letters, has been found to be associated with surface dyslexia in English and French dyslexic children (Valdois, Bosse, & Tainturier, 2004). Also, Niolaki and Masterson (2013) recently presented a case of a Greekspeaking child, RF, with surface dyslexia who exhibited a selective difficulty with letter report from arrays, and no evidence of a phonological deficit.…”

The effect of print size on reading speed in dyslexia

“…This theory proposes specific problems with serially focusing attention, either through rapid attentional capture or with attentional disengagement (Valdois, Bosse & Tainturier, 2004). In this regard, Pammer, Lavis, Hansen and Cornelissen (2004) found evidence that problems with attentional focusing contribute to anomalies in relative position coding in dyslexia.…”