Visual and Phonological Processing in Developmental Dyslexia: a Cross-Linguistic Investigation
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| Publicado en: | PQDT - Global (2021) |
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ProQuest Dissertations & Theses
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| Acceso en línea: | Citation/Abstract Full Text - PDF Full text outside of ProQuest |
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| Resumen: | This thesis aimed to investigate the extent to which visual processing is impaired in individuals with developmental dyslexia (henceforth DD) across orthographies varying in orthographic transparency. Contrasting the prevailing account, it was proposed that a phonological deficit per se may not to be sufficient to explain the difficulties shown by individuals with reading disorders.Chapter 2 (Study 1) examined the reading performance of a group of adult participants with DD which was contrasted with that of a group of typical developing readers (TDR) in an opaque/inconsistent orthography. The word length effect (WLE), slower reading of lengthier words, a phenomenon which has received more attention in DD in transparent than in opaque orthographies, was investigated. The results revealed that a WLE indexed as reading reaction times (RT) persisted in DD even in a population of highly educated individuals. This evidence suggests that speed might be a more sensitive measure of reading difficulties than reading accuracy when assessing reading by DDs, even in opaque orthographies such as English. Moreover, such an effect might be related to impaired visual processing that in turn affected fast visual word recognition in the DD sample.Chapter 3 (Study 2) explored the contention of visual processing impairments in DD. Visual processing and visuo-spatial working memory (VSWM) were evaluated in a group of English individuals with DD, whose performance was contrasted to that of TDRs. Two visual matching tasks adopting visual stimuli that differed in the degree of complexity and similarity, and three VSWM tasks were administered to each participant. In line with the dominant hypothesis of phonological deficits in DD, phonological processing was evaluated using the digit span task. Results revealed impaired visual and phonological processing in DD participants. Furthermore, in a discriminant function analysis, conducted to establish which tasks most effectively discriminate between DD and TDRs, group membership was predicted by one visual and one phonological task. This evidence provides support for the contention that the processing of both visual and phonological stimuli may be deficient in DD.In Chapter 4 (Study 3) a direct comparison between English and Italian individuals with DD and TDRs was conducted on visual and phonological processing, with the view to investigate differences in visual processing in DD in the two orthographies. The performance of the Italian DD and the English DD samples was compared to each other and with that of two groups of TDRs by using the two visual matching tasks described in Study 2 and the digit span task. The results showed that the two TDR groups did not differ from each other in all tasks. Unsurprisingly, they outperformed both DD groups. More critically, the Italian DD group performed worse than the English DD group on the visual matching tasks, in particular in the visually complex conditions. No significant difference was found in the phonological task between the two DD groups.Taken together, the findings of this thesis confirm a) phonological processing is pivotal in reading disability irrespective of orthographic consistency/transparency; b) phonological processing impairments alone do not fully account for reading difficulties when visual processing deficits are evident across languages; c) visual processing deficits vary according to orthographic consistency with readers of a consistent/transparent orthography being more impaired in visual processing than readers of an inconsistent/opaque orthography. |
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| ISBN: | 9798522948733 |
| Fuente: | ProQuest Dissertations & Theses Global |