It is:

• Dyslexia is a set of processing difficulties that affect the acquisition of reading and spelling.
• In dyslexia, some or all aspects of literacy attainment are weak in relation to age, standard teaching and instruction, and level of other attainments.
• Across languages and age groups, difficulties in reading fluency and spelling are a key marker of dyslexia.
• Dyslexic difficulties exist on a continuum and can be experienced to various degrees of severity.
• The nature and developmental trajectory of dyslexia depends on multiple genetic and environmental influences.
• Dyslexia can affect the acquisition of other skills, such as mathematics, reading comprehension or learning another language.
• The most commonly observed cognitive impairment in dyslexia is a difficulty in phonological processing (i.e. in phonological awareness, phonological processing speed or phonological memory). However, phonological difficulties do not fully explain the variability that is observed.
• Working memory, processing speed and orthographic skills can contribute to the impact of dyslexia.
• Dyslexia frequently co-occurs with one or more other developmental difficulties, including developmental language disorder, dyscalculia, ADHD, and developmental coordination disorder.

It is not:

• Feeling that text blurs or ‘moves’ when reading. These are visual issues which can exist separately from dyslexia. A registered optometrist who can make medical referrals should be consulted.
• Physical coordination problems, e.g. falling over, dropping objects, difficulties with catching/throwing balls, problems with learning to ride a bike or bumping into things more than usual. If these difficulties are severe, a referral to an Occupational Therapist should be made, as these are medical issues.

Carroll, J., Holden, C., Kirby, P., Snowling, M. J., & Thompson, P.A. (2025) Journal of Child Psychology and Psychiatry.

The ‘Delphi’ Definition of Dyslexia