by Joalida Smit
Dyslexia is well-known to the general public, but unlike what most people think, it is not just about poor spelling!
From a neuropsychological perspective, dyslexia can be understood as a neurodevelopmental difficulty in how children (and adults) process information. It is characterised by the following cognitive difficulties:
- Phonological awareness: Dyslexics have difficulty processing certain speech sounds and mapping sounds onto letters, a process call phonological awareness. This is considered the main reason for poor spelling skills.
- Decoding skills: Refers to recognising the letters and sound that construct words. In dyslexia this is particularly difficult resulting in poor reading skills. It also results in a reduced vocabulary as the effort in decoding a word detract from learning the meaning. Not knowing what words mean impacts on understanding what you read. Thus poor decoding skills results in a poor vocabulary and in turn poor reading comprehension.
- Poor working memory / short-term memory: Working memory is a specific brain process which holds information in mind to be used and manipulated without storing it as long term memory. Word decoding requires working memory. Over time, from repeated decoding a word is recognised and then stored as long term memory. This does not occur in dyslexia with words not recognised and thus not learnt (memorised). Interestingly memory for events, names of objects and friends may be perfectly intact!
- Organising information: People with dyslexia may find it hard to sequence and organise information on a sound, word and paragraph level. This may be due to the effort in letter-sound decoding, but may be due to an additional difficulty in organisation more generally, often making it hard for dyslexics to express themselves eloquently, despite high intelligence and creativity.
- Poor writing skills: Poor handwriting are perhaps because letter-sound mapping is so effortful it uses up the available brain resources! However, it may also be due to associated difficulties with planning motor output (dyspraxia), fine motor skills and pencil grip (dysgraphia) or poor proprioception (visual-spatial disorientation). Often these difficulties can go together making the mechanics of writing very hard indeed.
Dyslexia is thus a term that describes a range of cognitive difficulties. This is because reading and writing uses multiple brain mechanisms that need to work together.
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