Understanding Dyslexia through the Dual-Route Model
Dyslexia is an impairment that severely restricts the ability to read, spell and write.
It can be developmental or acquired after brain damage. Both forms entail basic cognitive disability, which in turn affects performance in school and the workplace (Giannouli and Pavlidis, 2014). Despite the plethora of research and literature on the subject, misconceptions regarding the symptoms persist – a common and simplistic notion being that dyslexia means letters appear jumbled to the reader.
Even amongst those researching this field, the exact nature of the dysfunction is polarising. The important thing to address before exploring it is that – like with all cognitive impairments – there is no solitary definition one can attribute to it.
Dyslexia can affect someone in multiple ways. It is highly elusive when one attempts to categorise it. The purpose of this essay is to explore dyslexia through one of the more accepted theories: the Dual-Route Model. In the context of this theory, however, the mental process of reading must first be addressed, as well as the basic effects dyslexia has on this process.
For the human brain to decipher written text, it engages on multiple levels: visual clarification, orthographic recognition of the letters within each word, the phonological translation of letter to sound, and finally semantic comprehension, with both solitary words and within the context of the accompanying sentence (Ziegler et al, 2008).
These processes work simultaneously and are developed from the earliest stages of reading. It has been observed in children that visual recognition comes first - semantic and orthographical knowledge not being required though the child can read and pronounce words by memory. People with dyslexia - particularly children - exhibit great difficulty in phoneme elision, blending and segmentation, in conjunction with having "less sensitivity to rhyming and alliteration" patterns (Desroaches et al, 2013, p. 250).
As explained by Schickedanz (2013), reading at its most basic level involves two dual processes: decoding and comprehension. As a reader decodes printed words, they also must comprehend the meaning. This process relies on an intricate neural system involving multiple regions of the brain (Sela et al, 2014) - specifically, the frontal lobe, which provides "higher executive functionality such as memory and attention to the process of reading" (p. 279).
The simplest definition of dyslexia is that these four major processes – visual, orthographic, phonological and semantic – are hindered to rates of varying degree, resulting in sometimes severe reading difficulties. The Dual-Route Model will be applied here to demonstrate the bilateral means through which reading is accomplished.
The lexical route (shown above) involves the process whereby words are recognised by memory. The lexical route is crucial in allowing readers access to their orthographic lexicon, enabling them to comprehend phonetic rules of irregular words (e.g. paradigm, asthma and colleague to list but three). Damage to the lexical route results in difficulty remembering and applying these rules when reading or trying to decode words.
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Herein lies a collection of essays which will have been written either for my undergraduate studies or through personal instigation. The first five essays are of the former, but most (unless about pedagogy) beyond that will be on my own initiative...