DYSLEXIA

Dyslexia

Dyslexia

Introduction

Dyslexia is one of several types of learning disabilities that occur in children who, despite strengths in other academic and cognitive abilities, experience extreme difficulty in learning to decode and spell printed words (Fletcher, Lyon, Fuchs & Barnes, 2007). This problem at the level of the single word impedes their ability to fluently read and comprehend connected text. Importantly, their reading difficulties do not stem from lack of educational opportunity, sensory acuity deficits, or socioeconomic disadvantage, although educational opportunity and socioeconomic status may interact with dyslexia to either reduce or exacerbate its severity. The International Dyslexia Association defines dyslexia as follows:

A specific learning disability that is neurological in origin. (Stanly, Smith & Howell, 1983) It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede the growth of vocabulary and background knowledge.

Estimates suggest that dyslexia occurs in 6% to 17% of the school-age population depending on how it is defined. Regardless of prevalence estimates, children with dyslexia comprise the bulk of children receiving special education services in the United States for students with learning disabilities. Although dyslexia manifests in childhood with the onset of formal reading instruction, it has definable precursors that permit early detection before formal schooling. In the absence of targeted intervention, the deficiencies observed in childhood continue to be evident in the same individuals well into adulthood. Dyslexia may also occur concomitantly with other conditions, including other learning disabilities involving mathematics (dyscalculia) and written expression (dysgraphia), oral language disorders, and attention deficit disorder with or without hyperactivity. These co-occurrences are usually comorbid, meaning that the child has more than one problem.

Scientific understanding of dyslexia has dramatically increased in the past four decades. It is now widely accepted that dyslexia occurs on a continuum in much the same way as obesity or high blood pressure. What this means in practice is that dyslexia is not an all-or-nothing categorical disability. Instead, it occurs in degrees of severity. Establishing the cut point on the continuum at which word reading difficulties constitute a disability is not well established and accounts for the variability in prevalence estimates. Current classification schemes vary by state and by program type. In the United States, children can receive services for dyslexia as part of special education under the Learning Disabilities (LD) category in the Individuals with Disabilities in Education Act (IDEA), where problems with basic reading skills are one of the eight domains in which LD can occur. A few states, such as Texas and Louisiana, also provide dyslexia services outside of special education. In most states, qualification for dyslexia services under the LD category would be based on an achievement/ IQ test discrepancy, with a number of discrepancy models in use from state to ...