Snowling MJ., Caravolas M.
© Oxford University Press 2007. All rights reserved. In spite of the complexities of written language systems, the majority of children learn to read easily. However, a minority have difficulty acquiring literacy skills even though they master other tasks well. These children are sometimes described as dyslexic. This article presents current scientific understanding of dyslexia from a developmental perspective. First, it considers the definition of dyslexia in behavioural terms and, with the normal development of literacy as a framework, discusses how its manifestation differs according to the language in which the child is learning to read. The article then examines cognitive explanations of dyslexia and evidence concerning sensory, biological, and environmental factors in its aetiology; behavioural manifestations of dyslexia (dyslexia in English, dyslexia in consistent orthographies, dyslexia in Chinese); theories of dyslexia (cognitive theories, automatization deficit hypothesis, auditory processing impairments, visual processing deficits, speech perception); and reading intervention programs. It concludes by looking at how theoretical advances in the field of dyslexia provide the rationale for effective interventions.