Definition of Dyslexia

The definition of dyslexia created by the International Dyslexia Association is the most widely accepted in the world:

“Dyslexia is a specific learning disability that is neurological in origin. It is characterised 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”.

Let’s break this down and look at each part. The word 'dyslexia' is derived from the Greek 'dys' meaning ‘difficulty' and 'lexia' meaning ‘words’, so it literally translates to “difficulty with words.”

‘Neurological’ relates to the nervous system and the brain. When you have dyslexia, the brain has difficulty processing language.

Decoding is a vital reading skill. It means being able to break a word into its component sounds, e.g. sh-ee-p, then blending those sounds together to read the whole word.

A key element of the Definition of Dyslexia is the recognition that for most people, dyslexia is caused by a problem with 'phonological' (link to phonological page) processing. This is the ability to work with, and manipulate, the sounds that make up a word.

In 2010 the British Dyslexia Association adopted a definition of dyslexia contained in the influential Rose Report. This definition agrees that the root cause of dyslexia is a phonological difficulty.

“Dyslexia is a learning difficulty that primarily affects the skills involved in accurate and fluent word reading and spelling. Characteristic features of dyslexia are difficulties in phonological awareness, verbal memory and verbal processing speed. Dyslexia occurs across the range of intellectual abilities. It is best thought of as a continuum, not a distinct category, and there are no clear cut-off points.

Co-occurring difficulties may be seen in aspects of language, motor co-ordination, mental calculation, concentration and personal organisation, but these are not, by themselves, markers of dyslexia. A good indication of the severity and persistence of dyslexic difficulties can be gained by examining how the individual responds or has responded to well-founded intervention”.

The Rose Report definition makes it clear that dyslexia is not connected to intelligence. Some people with dyslexia will be very intelligent but others will be average.

In addition to these characteristics, the British Dyslexia Association go on to say that dyslexic readers can show a combination of abilities and difficulties that affect the learning process. They acknowledged that children might also experience related difficulties in visual and auditory processing but also may have strengths in other areas, such as design, problem solving, creative skills, interactive skills and oral skills.