The deficit of letter processing in developmental dyslexia: combining evidence from dyslexics, typical readers and illiterate adults

Fernandes, Tânia; Vale, Ana Paula; Martins, Bruno; Morais, José; Kolinsky, Régine

doi:10.1111/desc.12102

Cited by 38 publications

(51 citation statements)

References 71 publications

(213 reference statements)

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“…Given that the present ex-illiterate sample comprised only individuals with modest reading skills, it would be especially important to investigate the impact of more extensive adult training on plasticity at the earliest stages of vision. Meanwhile, our present data concur with previous studies (1,31,60,69) in demonstrating that, even when acquired in adulthood, literacy can have a deep impact on early visual processing, radically improving the precision with which we perceive and categorize visual inputs.…”

Section: Discussionsupporting

confidence: 92%

“…2). It may be tentatively proposed that the early-stage effects found here correspond to the impact of learning to efficiently process letters and other high-resolution visual stimuli (60,61), whereas the later-stage effects correspond to the identification of whole words and the interaction of this process with higher cortical language areas (48,49).…”

Section: Discussionmentioning

confidence: 80%

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Timing the impact of literacy on visual processing

Pegado

Comerlato

Ventura

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Learning to read requires the acquisition of an efficient visual procedure for quickly recognizing fine print. Thus, reading practice could induce a perceptual learning effect in early vision. Using functional magnetic resonance imaging (fMRI) in literate and illiterate adults, we previously demonstrated an impact of reading acquisition on both high-and low-level occipitotemporal visual areas, but could not resolve the time course of these effects. To clarify whether literacy affects early vs. late stages of visual processing, we measured event-related potentials to various categories of visual stimuli in healthy adults with variable levels of literacy, including completely illiterate subjects, early-schooled literate subjects, and subjects who learned to read in adulthood (ex-illiterates). The stimuli included written letter strings forming pseudowords, on which literacy is expected to have a major impact, as well as faces, houses, tools, checkerboards, and false fonts. To evaluate the precision with which these stimuli were encoded, we studied repetition effects by presenting the stimuli in pairs composed of repeated, mirrored, or unrelated pictures from the same category. The results indicate that reading ability is correlated with a broad enhancement of early visual processing, including increased repetition suppression, suggesting better exemplar discrimination, and increased mirror discrimination, as early as ∼100-150 ms in the left occipitotemporal region. These effects were found with letter strings and false fonts, but also were partially generalized to other visual categories. Thus, learning to read affects the magnitude, precision, and invariance of early visual processing.reading | brain plasticity | education R eading is a cultural activity in which contemporary humans have considerable training. Fluently accessing the sounds and meanings of written words requires very fast and efficient visual recognition of letter strings, at rates exceeding 100 words/ min. Neuroimaging studies have begun to show how learning to read modulates the functioning of the visual system, from early retinotopic areas (1, 2) to extrastriate occipital and temporal cortex (1, 3, 4). In particular, a restricted region of the left occipitotemporal cortex, the visual word form area (VWFA), is robustly activated when orthographic stimuli are presented to literate subjects.This VWFA activation is reproducible across participants and writing systems (5, 6), even when orthographic stimuli are flashed unconsciously (7). Orthographic processing in the VWFA is thought to be very fast, peaking at ∼170-200 ms (8-10), and is colateralized to the dominant hemisphere for language (11,12). Reading practice enhances activation of the VWFA (1, 13, 14), even in dyslexic children (15). Reading also modulates nonvisual circuits, such as the spoken language network (1,14,16,17).In addition to these positive effects of learning to read, the theory of neuronal recycling (18) proposes that literacy acquisition also may have a negative "unlearning" e...

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 80%

Timing the impact of literacy on visual processing

Pegado

Comerlato

Ventura

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…Studies with illiterate and ex-illiterate control groups offer one particularly useful way to achieve this. A recent study by Fernandes, Vale, Martins, Morais, and Kolinsky (2014) illustrates this point nicely. Using a paradigm introduced by Van Leeuwen and Lachmann (2004) they examined the influence of surrounding contours on letter and pseudo-letter processing by children with dyslexia and adult illiterates and ex-illiterates.…”

Section: Phonological Awarenessmentioning

confidence: 77%

Distinguishing cause from effect – many deficits associated with developmental dyslexia may be a consequence of reduced and suboptimal reading experience

Huettig

Lachmann

Reis

et al. 2017

Language, Cognition and Neuroscience

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(2018) Distinguishing cause from effect -many deficits associated with developmental dyslexia may be a consequence of reduced and suboptimal reading experience, Language, Cognition and Neuroscience, 33:3, 333-350, DOI: 10.1080/23273798.2017 The cause of developmental dyslexia is still unknown despite decades of intense research. Many causal explanations have been proposed, based on the range of impairments displayed by affected individuals. Here we draw attention to the fact that many of these impairments are also shown by illiterate individuals who have not received any or very little reading instruction. We suggest that this fact may not be coincidental and that the performance differences of both illiterates and individuals with dyslexia compared to literate controls are, to a substantial extent, secondary consequences of either reduced or suboptimal reading experience or a combination of both. The search for the primary causes of reading impairments will make progress if the consequences of quantitative and qualitative differences in reading experience are better taken into account and not mistaken for the causes of reading disorders. We close by providing four recommendations for future research.ARTICLE HISTORY

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“…Reading intervention Control period with children with dyslexia and typically reading (RL-and CA-matched) controls in a visual attention task measuring congruence effects 43 . Both letter stimuli and pseudoletter stimuli were presented.…”

Section: Impairments In Visual Attentionmentioning

confidence: 99%

Sensory theories of developmental dyslexia: three challenges for research

Goswami¹

2014

Nat Rev Neurosci

371

391

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Recent years have seen the publication of a range of new theories suggesting that the basis of dyslexia might be sensory dysfunction. In this Opinion article, the evidence for and against several prominent sensory theories of dyslexia is closely scrutinized. Contrary to the causal claims being made, my analysis suggests that many proposed sensory deficits might result from the effects of reduced reading experience on the dyslexic brain. I therefore suggest that longitudinal studies of sensory processing, beginning in infancy, are required to successfully identify the neural basis of developmental dyslexia. Such studies could have a powerful impact on remediation.

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The deficit of letter processing in developmental dyslexia: combining evidence from dyslexics, typical readers and illiterate adults

Cited by 38 publications

References 71 publications

Timing the impact of literacy on visual processing

Timing the impact of literacy on visual processing

Distinguishing cause from effect – many deficits associated with developmental dyslexia may be a consequence of reduced and suboptimal reading experience

Sensory theories of developmental dyslexia: three challenges for research

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