Home Health Dyslexia and other learning difficulties
The deficit in specific spelling difficulty
Reading and writing are opposite processes. In reading, printed symbols (graphemes) are converted into their corresponding sounds (phonemes); in writing, phonemes are converted into their corresponding graphemes.
Spelling in the English language requires knowledge of the inconsistent rules for converting phonemes into the appropriate graphemes. The poem at the beginning of the previous chapter (p. 43) demonstrated how variable these rules are. A particular phoneme may be represented by different graphemes (for example, snuff and enough), and the same grapheme may correspond to different phonemes (for example enough, hiccough, and cough). Words with the same phoneme, but different graphemes, are called homophones (for example, shoot and shute).
Correct spelling is not usually possible until the child reaches the phonological stage (which was described in the last chapter). It is only at this stage that awareness of grapheme-phoneme correspondence begins. There is some evidence that children enter this phase earlier for reading than writing.
It has been postulated that the spelling process consists of the steps shown in Figure 6.2. The word is first thought of in a part of the brain (cognitive system), and needs to enter a graphemic buffer, which will control the way it is spelt when written.
There are two different paths that the process can follow from the cognitive system to the graphemic buffer. If the word is familiar, it follows route A, if it is unfamiliar, route B must be followed.
Route A, for familiar words, involves matching the word to a store of words whose spelling is already known. This is a dictionary or ‘lexicon’ system, analogous to that used when familiar words are read.
Route B, for unfamiliar words, involves a phonological system where the word is broken down into its component sounds (phonemes), which are then
Figure 6.2 The spelling process in the brain.
processed by a phoneme-to-grapheme converter, prior to entering the graph- emic buffer. The buffer controls the way the word is written down.
Once we see a word we have written down, after processing it through route B, we may realize that we have seen it before: we can then process it again, this time through route A, and correct it. This is probably the reason that we find it easier to spell words if we write them down first.
There is evidence that children with isolated spelling difficulty differ from children with combined reading and spelling difficulty on tests that identify the underlying cognitive deficit. Studies show that children with isolated spelling defects have relatively better language skills and that their difficulties lie in the phonological pathway (route B). Children with combined reading and specific spelling difficulty seem to have weaker language skills and have phonetic (phonological), as well as non-phonetic (lexical), deficits in spelling (routes A and B).
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