Developmental Dyslexia: a diagnostic tool.
The diagnosis of developmental dyslexia is a long and convoluted journey, complicated by the various different theories concerning its development, causes and treatment. As a condition, it affects approximately between 10 to 20% of the population, with 4% being affected severely, and is generally perceived as being caused by abnormalities in visual and auditory processing. This, in turn, is what directly affects the sufferer’s ability to process words, numbers and have the occasional bought of poor co-ordination. Three key types of dyslexia are deep dyslexia, surface dyslexia, and pure alexia; these refer to the level of severity and specific difficulties. Deep dyslexia affects the sufferer’s ability to comprehend semantics, which indicates damage to the left hemisphere of the brain; surface dyslexia can cause problems with the sufferer’s ability to distinguish between similar-sounding and spelling words; pure alexia causes the reader to have trouble distinguishing between letter to letter. (New York University). The purpose of this essay is to critically review the important factors in diagnosing developmental dyslexia in the development of an effective diagnostic tool.
The neuropsycholinguistic criteria for the diagnosis of dyslexia, revolves around the assessment of the child’s functional reading level, their potential reading ability, the extent of their deficiency in reading, the specific reading deficiencies, the neuropsychological dysfunction (which part of the brain is causing the problem), the factors associated, and finally methods of development and recovery. (Capellini, 2007, p 7) The time between the 1950s and the 1990s showed an increase in the diagnostic tools used in connection with children who were suspected of having dyslexia: “researchers started to associate psychological, neurological, psycholinguistic and neuropsycholinguistic diagnostic instruments which could provide intellectual and cognitive-linguistic development data from the children with such a problem” (Capellini, 2007, p 7). The implication here is that it was a great time for developing diagnostic tools in connection with dyslexia. These methods have been slimmed down for modern use to tests which focus on the assessment of the child’s ability to read quickly and accurately (aloud and silently), spoken and written diction concentrating on both made up and real words, textual production, phonological awareness, the ability to name things correctly (and with a level of automacity), the ability to sustain attention, short and long term memory tests, and mathematic and calculus tests. Arguably, this is still extremely comprehensive but time consuming. Tests that ascertain the subject’s ability to spell made up words correctly are, arguably, quite damning. Whilst this type of test may make a sound assessment of the subject’s ability to recognise phonemes, it seems quite unfair to expect anyone to be able to spell non-existent words. Whilst recognising that this is an imperative test to assess a subject’s ability to pick out key letters and sounds, it does seem like it might be quite an unreasonable expectation to have, of anyone; much less a dyslexic child. However, this approach does directly address the neurological implications of dyslexia through the assessment of both linguistic and cognitive abilities whilst also assessing the effect of dyslexia on academic capabilities (Capellini, 2007, p 7).
The Magnocellular Theory, however, focuses more on the visual impairment-based definitions of dyslexia: “The visual magnocellular system is responsible for timing visual events when reading.” (Stein, 2001, p 12). This means that the magnocellular part of the brain is what allows us to read a word and process its meaning efficiently enough to move on to the next word, allowing for a natural ‘flow’ when reading. For dyslexia sufferers, this part of the brain is impaired which means that they struggle to read with any sense of natural speed; they take too long to process individual words, or in extreme cases; letters, and therefore do not process a chunk of text quickly nor accurately. Understandably, for dyslexic sufferers, reading loses any sense of pleasure and it immediately becomes a daunting task – especially at school, in front of their peers. The discussion in this approach addresses the fact that frequently, there is little to distinguish people with dyslexia from those who simply have poor reading ability due to having a low IQ, but that there are a number of other factors to consider as well: “We therefore define a person as dyslexic if their reading is 2 standard deviations behind what would be expected on the basis of their IQ” (Stein, 2001, p 14). This presumably entails that the subject is assessed for their level of IQ before any specific dyslexia-based testing is considered. In a child, especially one who potentially has other issues too, these level of strenuous testing could be considered to be intrusive, exhausting and time-consuming (with regard to a child’s ability to concentrate for an extended period of time). However, they also assess other traditional dyslexia symptoms: “incoordination, mis-sequencing and left-right confusions” (Stein, 2001, p 14). The magnocellular approach assesses children from dyslexia with their academic ability as a baseline with which to measure their discrepancies against. It also places importance on the understanding that for more academically able children with dyslexia, it can be especially frustrating because they want to learn but are fundamentally incapable of learning at the correct speed and are dubbed as ‘lazy’ as a result. Arguably, their theory reflects the child very accurately without resorting to solely just labelling them. Whilst the assessment may seem lengthy, it certainly seems to reflect the individual rather than working to a generic set of symptoms.
Moving away from more abstract diagnostic approaches, the biological approach has increased in popularity in recent years, presumably because of its quantifiable results as opposed to the qualitative opinions of other approaches, and also due to the significant advances that have been made in recent years with regard to our understanding of the human brain. This is largely due to ‘brain imaging’: “involves imaging a brain while a task is carried out, in order to visualise the changes in cerebral blood flow and metabolism which occur during performance of the task.” (Stackhouse, 2006, p 42). This, basically, involves the subject carrying out a number of tasks (usually ones to test the visual, auditory and linguistic centres of the brain) whilst the doctor maps out their brain’s reactions. An early example of this sort of dyslexia assessment was carried out in 1991 and involved a number of adults with a history of dyslexia, undertaking a spelling test. This showed that their ability to complete the test accurately was “related to the amount of [blood] flow in the Wernicke’s region [of the brain].” (Stackhouse, 2006, p 42). This means that doctors were able to demonstrate a clear correlation between blood flow to this region and the subject’s ability to carry out a simple spelling test accurately and efficiently. The biggest positive about the biological approach is its ability to “side-step the difficulties inherent in studying symptoms in a vacuum” (Stackhouse, 2006, p 36). This refers to the requirement of other approaches that need a standard to measure results against. In the biological approach, subjects can easily be assessed based on the results directly from the study. Ultimately, this approach is less time-consuming and arguably, a little less intrusive for the child (although there will be measurements made of their brain) in the sense that, the testing is less extensive. However, some may argue that the biological approach forgets to view the child as an individual and does not allow for a holistic view: there is only a measurement of one specific aspect of the child’s ability and does not allow for environmental issues or for their potential academic ability, if they did not have dyslexia.
The three approaches discussed here, provide an overview of the current developmental dyslexia diagnostic tools. There are a number of other approaches which pertain to similar methods as these. However, the central ideas that come across when researching these tools, is the importance of the child in proceedings. Ultimately, it is their brain, their education, their problem and their life that is being assessed and it is vital to maintain that thought at all times. Otherwise, the real reason for carrying out such tests is lost forever. From the magnocellular theory, the importance placed on the child’s academic ability and IQ, regardless of their dyslexic status, is something which should be carried across all diagnostic tools. The ‘dyslexic’ label should not automatically denote a lack of intelligence, but rather it should implement an immediate recognition that the child make need extra assistance to achieve their potential but that their potential remains as high as their peers’: “specific dyslexia can occur at all levels of intelligence” (Beaton, 2004, p 11). By establishing an IQ level (independent of the subject’s reading level), the assessor is able to measure the subject’s differing ability with regard to their peers whilst being able to distinguish between a dyslexic child and a child who is not academically bright. In any dyslexia diagnosis, it is important to maintain this difference – if only for the self-esteem and confidence of the subject.
The biological approach poses an interesting question of whether simply proving a child is biologically dyslexic also proves that their disability will affect areas of their life. Ultimately, human beings must be perceived individually and holistically to get a true measure of who they are, what their intelligence level is, and whether they have a learning difficulty or disability, such as dyslexia. Whilst the merits of such a quantifiable set of data are obvious, it is also important to recognise that they must occur within relation to other approaches – such as the neuropsycholinguistic approach which measures the child’s abilities on all manner of levels. Its extensive testing of the traditional symptoms of dyslexia demonstrates a comprehensive approach to development dyslexia diagnosis. Maintaining that some of the tests seem unimportant (for example, the assessment of the child’s co-ordination which arguably could mean that they are simply just clumsy), they are designed to analyse all aspects of the dyslexic child. With that in mind, the ideal diagnostic tool would approach the child holistically whilst assessing the biological symptoms of blood flow in the brain, the child’s academic level and drive, and also the child’s ability to process words, letters and numbers efficiently and at speed. The ultimate aim is to improve the child’s standard of living and education and by taking a holistic view, we are able to best assess how to meet the child’s needs and enhance their abilities.
References
1. Beaton, A. (2004). Dyslexia, reading and the brain: a source book of psychological and biological research. East Sussex: Psychology Press.
2. Capellini, S. A. (2007). Neuropsycholinguistic Perspectives on Dyslexia and Other Learning Disabilities. New York: Nova Science Publishers, Inc.
3. Frith, U. (1985). Beneath the Surface of Developmental Dyslexia. Retrieved from http://www.icn.ucl.ac.uk/dev_group/ufrith/documents/Frith,%20Beneath%20the%20surface%20of%20developmental%20dyslexia%20copy.pdf
4. New York University. (N.d.). Developmental Dyslexia. Retrieved from http://www.psych.nyu.edu/pylkkanen/Neural_Bases/07_slides/09_Dyslexia.pdf
5. Stackhouse, J. (2006). Dyslexia, speech and language: a practitioner’s handbook. Chichester: Whurr Publishers Ltd.
6. Stein, J. (2001). The Magnocellular Theory of Developmental Dyslexia [Electronic version]. Dyslexia, 7, pp. 12-36.
7. Thomson, M. E. (1989). Developmental Dyslexia. Virginia: Cole and Whurr.
