Dyslexia is a specific type of learning difficulty where a person has trouble with written language, such as reading and writing. These problems often becomes most evident in early school age children, who have difficulty developing word-level reading skills and struggle with spelling. Dyslexia is estimated to affect around 5-9% of school-aged children, however some researchers suggest that its prevalence is as high as 17%. Dyslexia is not an intellectual disability and people with the condition are often very intelligent, and able to achieve well in other areas where language is less important.
There are two different types of dyslexia, which include:-
People with surface dyslexia have poor lexical dexterity, which means they have poor skills relating to words. For example, an individual with this condition may find it difficult to decipher new or irregular words. These problems arise from the individuals difficulty with sounding out new words by using old words that were learnt in the past (lexical procedure).
People with phonological dyslexia have difficulty converting sounds (phonemes) into letters (graphemes). Individuals with this condition have trouble with connecting sounds to symbols. This is the most predominant type of dyslexia.
There is no cure for dyslexia, and people with the condition often require a high level of support or specialised education to allow them to read and write correctly. The best way to help a child or adult overcome reading and writing obstacles in through strong encouragement and mentorship, and by providing lots of motivation during treatment programs and language practice. Most people with dyslexia overcome their early difficulties with literacy and pursue successful careers. Often, individuals with dyslexia are very creative and can have excellent spatial memory and spatial reasoning, which means they are very good at retaining information about their environment and are able to visualise spatial patterns well.
Written words represent spoken words, and in order to read and write, the sound of a letter must be linked with its written symbol. Correctly associating visual symbols with verbal sounds is a procedure known as phonological coding, and is crucial to reading and writing. Learning to read and write is a slow process, because written letters do not have a direct or obvious correlation to their sound. For example, it is impossible to guess how to correctly pronounce the letter ‘t’ just by looking at it – we rely upon our memories to remember the sound that the letter ‘t’ represents, and apply this memory to the sounding out of new words. It is thought that dyslexia could be a problem with phonological coding. This is thought to be linked to certain neurological differences in how the brain processes written and/or spoken language, and can affect different structural parts of the brain. Despite intensive research, scientists have been unable to pin-point the exact causes of dyslexia, but factors that may contribute to the condition include genetics and physiology, as dyslexia appears to run in families and has been linked to structural differences in the brain.
The most common symptoms associated with dyslexia are problems with reading and spelling. People with dyslexia often have difficulty understanding the association between a letter and the sound that it makes. Because of this difficulty in learning letter-sound correspondences, individuals with dyslexia might misspell words or leave vowels out of words. Because people with dyslexia find it difficult to remember the sound that a particular letter makes, when spelling words, they often write letters in the wrong order. They also often confuse letters that look similar such as ‘p’ and ‘q’ or‘d’ and ‘b’. People with the condition also commonly spell words inconsistently within the same body of text, in a highly phonetic way, such as writing ‘wud’ instead of ‘would’. Dyslexic individuals also typically have difficulty distinguishing among homophones such as ‘weather’ and ‘whether’. People with dyslexia may also reverse the order of two letters when they are trying to spell out a word, especially when the final, incorrect, word looks similar to the intended word (e.g., spelling ‘tose’ instead of ‘toes’).
Often, dyslexia also makes mathematics difficult because people mix numbers up in the same way they confuse letters. Many individuals with dyslexia have problems in other areas such as poor short term memory and organisational skills. As a consequence of these literacy problems, an individual with dyslexia often has difficulty with handwriting, and can have a small written vocabulary, even if they have a large spoken vocabulary.
The symptoms experienced by individuals with dyslexia can differ, depending on the age of the sufferer. In young children, speech delays or stuttering may be early warning signs of dyslexia, which can lead to reading problems later on. Other symptoms in young children include:-
- Trouble with pronouncing words correctly. For example they may say ‘gween’ instead of ‘green’
- Difficulty with identifying or generating rhyming words or learning rhymes
- Difficulty learning the alphabet or the sounds of letters
- Problems with writing, such as not being able to write their own name
- Difficulty with learning colours and shape
- Trouble retelling a series of events or a story in the correct order
Symptoms in primary-school aged children can include:-
- Trouble with grammar, such as learning nouns and verbs or prefixes and suffixes
- Frequent misspelling or writing words backwards such writing ‘pat’ instead of ‘tap’
- Regular confusion of letters that look similar when writing such as ‘n’ and ‘v’ or ‘w’ and ‘m’
- Low reading level, especially compared to other areas
- Trouble reading single words
- Dislike of reading or reading aloud
- Difficulty counting syllables in words
- Difficulty with time keeping and concept of time
- Difficulty associating individual words with their correct meanings
Symptoms in teenagers include:-
- Generally poor spelling, especially when the same word is misspelt differently in one assignment.
- Difficulty with reading
- Trouble writing a summary
- Difficultly with trying to learn a foreign language
Symptoms in adults include:-
- Reading and spelling difficulties
- Dislike towards reading books
- An avoidance of writing-based tasks such as writing letters, or may ask someone else to do these tasks for them
People with dyslexia often have very good long term memory, and they can also be very gifted in areas where language based skills are less important, such as art, design or engineering.
Dyslexia can be hard to diagnose, unless the problem is quite severe. It can be diagnosed by a qualified professional, such as an educational psychologist or a neurologist. Reaching a diagnosis generally involves a series of tests such as reading ability, short term memory, vocabulary and literacy skills, which are assessed together as a means of evaluating phonological coding skills. Specific tests that may be included as part of the diagnosis include:-
Intellectual ability is measured by performance on an intelligence test, such as an IQ test, which can determine learning strengths and weaknesses.
Information processing looks at how the brain gathers, manipulates, stores and retrieves information.
Cognitive skills are mental skills that are used in the process of acquiring knowledge. Reading and writing rely on a specific set of cognitive skills such as attention, memory, symbolic thinking, and self-regulation.
Psycholinguistic processing assesses the brain processes that make it possible to generate a grammatical and meaningful sentence out of vocabulary and grammatical structures, as well as the processes that make it possible to understand words.
Diagnosis often includes interdisciplinary testing to exclude other possible causes for reading difficulties, such as other forms of cognitive impairment or physical causes such as problems with hearing or vision, and may also be assisted by evaluation by a speech therapist. Understanding the different types of dyslexia (surface and phonological) is also useful in diagnosing learning patterns and developing treatments for overcoming reading and writing difficulties.
There is no cure for dyslexia, but a person with the condition can learn to read and write with specialised education and support. For children, effective training can also be given by teachers at school or at kindergarten. Different forms of treatment may include:-
- One-to-one tutoring from a specialist educator to provide extra practice at certain reading and writing tasks
- A phonics-based reading program, which teaches reading by training beginners to associate letters with their sound values. This teaches children with dyslexia the link between spoken and written sounds and encourages a word to be recognised through the building of its constituent sounds
- Concessions may also be made while children are learning to overcome their reading and writing difficulties. For example, arrangements can be made with a child’s school for them to take oral examinations instead of written tests. In this way they are not disadvantaged by their reading and writing deficits
- Using visual or audio aids to learn the alphabet and the sounds each letter make
Individuals with dyslexia require more practice to master skills in their area of reading and/or writing difficulty compared to other children. For example, a child with no learning difficulties may require 30 to 60 hours of practice to master a certain skill, while a child with dyslexia may require 80 to 100 hours of practice to master the same skill.