How and to what extent is dyslexia a cognitive deficit? Draw on different explanations of dyslexia to build your argument.

Struggling with reading and writing could have an effect on the behaviour of the individual with these difficulties. They could be more disruptive in the classroom for example and give up from learning new tasks easily. The identification of being 'not normal' could have an effect on self-confidence.

So the environment that surrounds the individual is important to how competent they could become with reading and writing skills

Accounts like these are personal examples of behavioural difficulties experienced, but in order to understand dyslexia it is important to try to understand the internal workings. Examining cognitive and biological perspectives are ways to do this and involve theorizing and validation by experiment.

To examine how far dyslexia is a cognitive deficit the cognitive processes that relate to dyslexia need to be explored. Particularly the areas of phonological, visual and automatization. People with dyslexia find tasks where short-term memory processing is required difficult. Short term memory processing is used in mental arithmetic, writing and learning new information. All of these tasks require phonological abilities, which if not developed fully could lead to difficulties in reading and writing skills.

There have been suggestions that in order to learn to read we adopt two strategies, logographic and alphabetic decoding. Logographic is the way that children learn to associate a spoken word with its written form, without being aware of the individual letter sounds.

Alphabetic decoding strategy requires the reader to learn the sounds that each letter of the alphabet makes then to be able to blend the sounds together in order to pronounce them. It is required also during spelling to analyze spoken words and break them down to corresponding letter sounds.

When a reader is skilled they are able to decode letters and rapidly process letters that recur across different words which is known as an orthographic strategy. People with dyslexia find it difficult to move beyond a logographic strategy.

It is not clear however whether phonological deficit is to do with either encoding or retrieval of phonological representations in memory (i.e. in either initial information processing or later retrieval). There has also been speculation that the way the information is stored in long-term memory could also explain difficulties with phonological tasks.

Visual problems have been associated with dyslexia. Samual Orton used the term strephosymbolia (meaning twisted symbols) to describe reading difficulties where children wrote letters back to front, confused similar letters (e.g. b & d), and misplaced letters within a spelling. Such observations suggested there might be some kind of visual processing impairment involving incomplete specialization between the left and right sides of the brain.

The 'word blindness' description mentioned above emphasized a visual perceptual contribution. Recent research has suggested that underlying visual problems would explain the difficulty in learning visual-phonological correspondences (Everett, 1999;Whiteley and Smith, 2001). Seymour (1986) has re-emphasized that cognitive systems needed to write actually lie in the visual domain. His and other research has shown that visual processing weakness in dyslexic people can occur independently of any phonological problems.

Many dyslexic people have shown superior visual-spatial abilities, which aids claims that phonological deficits are more commonplace than visual. Tests used have been less than reliable and differ to the tests that Seymour carried out. It has been proven that mild visual disturbances are present in up to 70 per cent of people with dyslexia and it is usual for them to occur with phonological problems (Lovegrove, 1991).

People with dyslexia have problems with the automatization process. This refers to the gradual reduction in the need for conscious control as a new skill is learned. When a skill is fully automatized it may be carried out at the same time as another task without any disruption to either behaviour. Once reading and writing skills are acquired the tasks should become automatized, however even competent dyslexic readers have shown a lack of fluency in written language skills, reading and writing is laboured, there are many errors and they are unable to concentrate if there are other distractions. The lack of automatization is called a general automatization deficit.

Automatization can be assessed by a rapid automatization task where an individual is presented with fifty pictures (5 rows by 10) in random order and then asked to name each picture as quickly as possible. (This task is known as rapid automatization naming task (RAN). The results have supported the phonological deficit, Wolf and Bowers (1999) suggested that this task is a separate, additional deficit to phonological difficulties and that this deficit alone would explain reading problems even if the person had otherwise a good phonological awareness.

Referring back to Friths three level framework it would suggest that cognitive accounts are only a part of the picture with regards to a developmental difficulty, we also need to consider biological, behavioural input and how an individual's environment can also help or hinder any difficulty.

With regards to biology there are characteristics that are common with people with reading difficulties, these can include left-handedness or mixed handedness, being male and a variety of 'soft' signs and minor physical abnormalities. Also people with dyslexia have been linked with allergic conditions such as asthma and eczema. These can indicate possible biological problems, which could affect/cause dyslexia.

There is evidence that suggests that for every female identified as dyslexic there would be 3 or 4 males identified (James, 1992) however the reason for this is unknown. This would suggest a difference in genetic make up but no X-linked gene has been found that connects with dyslexia. A combination of genes may be involved in the predisposition of these conditions. Studies within extended families and twins have also shown that dyslexia runs in families.

Unusual patterns of cerebral lateralization are connected with dyslexia. Neuroanatomical studies where brain structure is studied from post-mortem samples or MRI scans on living people has supported the view that dyslexia may involve a lack of speculation between the two hemispheres.

Studies of the actual organisation of brain cells from post mortem studies has shown slightly misplaced cells and minor disordering of the usual regular layering of the cortex. This is in an area involved in language processing which can be related to the logographic problems of people with dyslexia.

Highly unsaturated fatty acids (HUFA) are essential for brain development and normality in brain function. These are found in a wide range of natural foods which are lacking in the modern diet, there has been evidence that this may be a factor in the biological predisposition dyslexia (Richardson et al.,1999; Richardson and Ross, 2000). Physical symptoms of deficiency of HUFA have been found in children and adults with dyslexia. This lack of essential fatty acids could have some effect on brain functioning and this would be the result of deficiencies in diet. This is an example of how the environmental factor affects the biology of a person. The deficiency in the biological make up could then produce deficiencies in the cognitive functioning of the brain.

Cognitive and biological theories are not conflicting with each other but in relation to dyslexia they appear to co exist and complement each other.

Cognitive perspectives describe the cognitive processes which can explain how the biological and behavioral accounts are interwoven. One cannot exist without each other. Behaviour identifies the condition and examination of the internal workings of the body and brain can indicate what causes the condition.

Dyslexia cannot be isolated as either a biological, cognitive or behavioral deficit but identified within all three. It is important therefore to examine how they interact with each other to further understand and treat the condition correctly.

References

Wood, C and Richardson A 'Normal' development? The case of dyslexia, in Crooper, T and Roth I (eds), Challenging Psychological Issues Milton Keynes, The Open University