Dyslexia is a broad terminology defining an unusual approach to processing information and learning disability that impairs a person's fluency or comprehension accuracy in being able to read, and which can manifest itself as a difficulty with phonological awareness, phonological decoding, processing speed, orthographic coding, auditory short-term memory, language skills/verbal comprehension, and/or rapid naming. However dyslexia can increase the ability to think and perceive multi-dimensionally and can help further utilize the brain’s ability to alter and create perceptions (Vellutino, 1979). Dyslexia is different from reading difficulties resulting from other causes, such as a non-neurological deficiency with vision or hearing, or from poor or inadequate reading instruction. It is believed that dyslexia can affect between 5 and 10 percent of a given population although there have been no studies to indicate an accurate percentage (Vellutino, 1979). There are three proposed cognitive subtypes of dyslexia (auditory, visual and attentional), although individual cases of dyslexia are better explained by specific underlying neuropsychological deficits and co-occurring learning disabilities (e.g. attention-deficit/hyperactivity disorder, math disability, etc.) Reading disability, or dyslexia, is the most common learning disability. Although it is considered to be a receptive language-based learning disability in the research literature, dyslexia also affects one's expressive language skills. Adult dyslexics can read with good comprehension, but they tend to read more slowly than non-dyslexics and perform more poorly at spelling and nonsense word reading, a measure of phonological awareness. Dyslexia and IQ are not interrelated as a result of cognition developing on its own. The World Federation of Neurology defines dyslexia as "a disorder manifested by difficulty in learning to read despite conventional instruction, adequate intelligence and sociocultural opportunity”. The National Institute of Neurological Disorders and Stroke gives the following definition for dyslexia: “Dyslexia is a brain-based type of learning disability that specifically impairs a person's ability to read. These individuals typically read at levels significantly lower than expected despite having normal intelligence. Although the disorder varies from person to person, common characteristics among people with dyslexia are difficulty with spelling, phonological processing (the manipulation of sounds), and/or rapid visual-verbal responding. In adults, dyslexia usually occurs after a brain injury or in the context of dementia. It can also be inherited in some families and recent studies have identified a number of genes that may predispose an individual to developing dyslexia (Vellutino, 1979). Other published definitions are purely descriptive or embody causal theories. Varying definitions are used for dyslexia from researchers and organizations around the world; it appears that this disorder encompasses a number of reading skills, deficits and difficulties with a number of causes rather than a single condition (Smythe, Everatt &Salter). Signs and symptoms
Some early symptoms that correlate with a later diagnosis of dyslexia include delays in speech, letter reversal or mirror writing, and being easily distracted by background noise. This pattern of early distractibility is partially explained by the co-occurrence of dyslexia and attention-deficit/hyperactivity disorder. Although each disorder occurs in approximately 5% of children, 25-40% of children with either dyslexia or ADHD meet criteria for the other disorder. At later ages symptoms can include a difficulty identifying or generating rhyming words, or counting syllables in words (phonological awareness), a difficulty segmenting words into individual sounds, or blending sounds to make words, a difficulty with word retrieval or naming problems (see anomic aphasia), commonly very poor spelling,...
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