The various definitions of dyslexia (of which there are many) do not differentiate between the condition and a delay, or whether they are one and the same. There are discussions as to whether dyslexia is a form of natural difference, a discrete condition or collection of differences.
I am constantly saddened when students walk in declaring dyslexia ‘because a teacher said so’, or similar. Dyslexia should not be assumed or casually given to a student whose reading or spelling ability is below that of their peers, especially when the person 'diagnosing' is not qualified to do so. There are a great many other causes of slow literacy development, including a lack of quality teaching, which are no less distressing or frustrating. The non-consensus of origin or definition of dyslexia is not helpful either.
Rassool (cited in Soler et al, 2010) states that from the perspective of experimental psychology, literacy is viewed as a process involving phonological and graphic, morphology, and technical spelling skills. Understanding where these processes occur in the brain and whether there is atypical processing, could shed light on the origins of dyslexia and/or help inform interventions.
Definitions of dyslexia
"Dyslexia is a specific learning difficulty that mainly affects the development of literacy and language related skills. It is likely to be present at birth and to be life-long in its effects. It is characterised by difficulties with phonological processing, rapid naming, working memory, processing speed, and the automatic development of skills that may not match up to an individual's other cognitive abilities.
It tends to be resistant to conventional teaching methods, but its effect can be mitigated by appropriately specific intervention, including the application of information technology and supportive counseling."
(British Dyslexia Association, 2007)
The following description is quoted in the BDA Code of Practice for Employers:
“Dyslexia is a combination of abilities and difficulties that affect the learning process in one or more of reading, spelling and writing. It is a persistent condition.
Accompanying weaknesses may be identified in areas of speed of processing, short-term memory, organisation, sequencing, spoken language and motor skills. There may be difficulties with auditory and /or visual perception. It is particularly related to mastering and using written language, which may include alphabetic, numeric and musical notation.
Dyslexia can occur despite normal intellectual ability and teaching. It is constitutional in origin, part of one’s make-up and independent of socio-economic or language background.
Some learners have very well developed creative skills and/or interpersonal skills, others have strong oral skills. Some have no outstanding talents. All have strengths.”
(Dr.Lindsay Peer, 2006)
Soler, J., Fletcher-Campbell, F., Reid, G. And Wearmouth J. (2010) E801 Difficulties in Literacy Development Milton Keynes: The Open University