Different types of dyslexia

While there are key characteristics of dyslexia, every person with dyslexia has a slightly different cluster of difficulties.  This is why individual intervention and support is most effective.

Anyone who works with dyslexic students or parents who have more than one child with dyslexia will tell you that there are different types of dyslexia.  While cumulative, systematic multisensory teaching benefits all dyslexic students, there are different materials and approaches which can be used depending on the type of dyslexia.  In any intervention, it makes sense to utilise a child’s strengths and work on improving areas of weakness.

Different websites and authors explain these differences in their own way and use different terminology. Some choose to split the main areas of difficulty while others group certain difficulties together. Some sources mention 4 types of dyslexia, while others list 7 or even 12 types. This can be confusing and is perhaps unnecessarily complicated. Nessy.com is one of the clearest and lists different types of difficulties and explains how these impact a learner.  

In essence, there are 3 main types of dyslexia.   Nearly all dyslexics struggle with working memory however some have more visual difficulties and some have more auditory difficulties and some have equal difficulties in both areas. In addition, all of these groups may have slow processing (this may be identified as rapid naming deficit) and motor skills difficulties (this may include dysgraphia or dyspraxia).

1.    Those dyslexics who have more difficulty with processing auditory information but have strong visual skills have dysphonetic dyslexia (it is also called phonological dyslexia.) This group also includes double deficit dyslexia which is children with difficulties with phonological awareness and rapid naming. 

These are the children who muddle words that sound similar like ‘bag’ and ‘back’ or ‘rag’and ‘rug’. They will have trouble identifying all the sounds in a word when they try to segment a word for spelling. They will try to use their visual memory and could spell chased as ‘cashed’ or farmer as ‘framer’. They often miss sounds or syllables or suffixes from longer words like ‘epty’ for empty, swim for 'swimming'.  These children will have trouble reading names or sounding out polysyllabic words. They can often say the sounds in a word but have trouble blending them together and they may swap over the order of the letters.

When the child starts to learn to read they may initially do quite well as they use their strong visual skills to learn key sight vocabulary and use picture cues to decipher simple texts. However, their decoding skills do not develop in the same way.  If the school uses a scheme that is based on introducing sight vocabulary a little at a time, with predictable sentence structure like Oxford Reading Tree then the child will appear to be learning read. However, as texts become more varied, complex and less predictable they will have no skills to work out new words. Suddenly, the teacher and/or the parents will realise the child has reading difficulties. If the school uses a phonic based scheme like Read Write Inc then these reading difficulties will be evident earlier.

These children also tend to be good at maths as they recognise patterns and so do not rely on memory for number bonds and times tables. 

2. Other dyslexics struggle more with visual perception and are said to have dyseidetic dyslexia (this may also be called surface dyslexia or visual dyslexia.) These children often struggle with Maths as well as reading and writing. They find it hard to visualise maths concepts and develop a concept of number. They do not notice visual patterns and rely on their weak working memory skills to try to remember number facts and calculation methods.

These are the children who struggle to learn irregular high frequency which make up so much of our early reading (in more transparent languages these children would have fewer difficulties.) If the school uses a phonic based reading scheme these children will learn to decode simple 3 or 4 letter words but it will be noticeable that they will sound out words again and again. They do not commit words to memory. In their writing, high frequency words are spelt phonetically like ‘becos’ and ‘sed’ and they may reverse letters and words. These difficulties are considered normal in the early stages of writing. However, as other children begin to master letter formation and key vocabulary these errors will persist. Verbalising what is tricky about a word is helpful in learning spellings, as are mnemonics.

3. Some dyslexics have both visual and auditory difficulties.  These tend to be the children who are noticed early on and are most readily identified as dyslexic by teachers and parents. They struggle to develop reading and writing skills at all in a normal school context as they cannot use stronger skills to compensate. Practical, hands on activities are needed for them to learn to read and grasp basic maths skills. They will have difficulty accessing and processing information that is presented verbally or visually. In essence, they will learn through doing. It is vital that these children receive structured, cumulative, multisensory support.