Dyslexia usually arises from a weakness in the processing of language-based information. Biological in origin, it tends to run in families, but environmental factors also contribute. Dyslexia can occur at any level of intellectual ability, it is not due to the individual's ability to learn and develop these skills. It is not the result of poor motivation, emotional disturbance, sensory impairment or lack of opportunities, but it may occur alongside any of these.
Dyslexia is to do with the way people process information and how that affects their ability to learn. This processing difficulty can be due to a number of reasons, but it is this which causes problems with acquiring literacy skills. Most dyslexic students have been identified to have one or more of the following deficiencies in the sub-skills that are required to acquire and use adequate literacy skills: