Dyslexia In Different Countries

Why is it that there is such a disparity between individuals when it comes to learning to read? Reading is a cultural and taught activity and its success depends on two important factors - possessing the precursor skills and the nature of the orthography in question.

English is one of the hardest languages to learn to read. English children start learning to read much earlier than Scandinavian children, for instance, yet cross-language comparisons of simple word and non-word reading show that English children score much lower than their European counterparts. This is because the English language presents children with a much more difficult learning problem. Despite the importance of phonics, simply giving a child good phonics skills will not make them a good reader because of the many inconsistencies in the English spelling system.

Phonological awareness, usually measured by rhyme recognition, is the most accurate predictor of later reading and spelling acquisition, even for languages that do not use the western alphabet (Ho & Bryant 1997). According to Snowling (2000), dyslexic children have trouble with phonological representation, which therefore makes it difficult for them to learn letter-sound relationships. However if the dyslexic children are being taught to read languages with highly consistent spelling systems, then a deficit in accuracy disappears very quickly, although the dyslexic children's performance is much slower than non-dyslexics. Dyslexic children in Greece, Germany and Spain perform phonological awareness tasks with a high degree of accuracy, but very slowly. In England, however, dyslexic children are slow as well as inaccurate in phonological awareness tasks.

The difference in spelling consistency explains the cross-language difference in the manifestation of dyslexia. Dyslexic readers of consistent spelling systems can use letters to solve phonological awareness tasks. Letters provide an anchor to the variability of sound because for such languages the anchor is 1:1. However, spelling rarely becomes highly accurate in dyslexia because few languages have 1:1 correspondence from sound to spelling. Therefore, persistent problems with spelling is the usual basis for the diagnosis of dyslexia in languages other than English.

Another important factor for the different manifestations of dyslexia lies in the phonological structure of different languages. On the whole, when children start learning to read, they are able to segment their phonological representations for familiar words to at least the onset-rime level. For languages like Spanish and Italian, most of the words have a simple CVCV structure. This makes the reading task much easier for these children. But this is not the case for languages like English and German.

Onset-rime processing of syllables is deficient in dyslexic children across languages and this is probably caused by a deficit in their perceptual experience of regularity or rhythmic timing. Goswami et al (2002) showed that dyslexic children were significantly less sensitive than the precocious readers to the auditory parameters that yield the 'stress beats' in speech. They also found that individual differences in sensitivity to these auditory parameters accounted for 25 percent of the variance in reading and spelling acquisition.

The hypothesis about beat detection suggests it may be important to develop children's informal knowledge about syllables and rhymes from an early age through traditional nursery rhymes and clapping games, as well as through other forms of rhythm. The neural pathway underpinning beat detection is probably the posterior stream of processing involved in mapping speech sounds on to motor representations of articulation (Scott & Wise, in press). As this is the pathway underlying the motor production of sounds, other forms of practice in mapping motor production to sound may also be helpful for the development of rhythm perception.

References Goswami et al (2002). Amplitude envelope onsets and developmental dyslexia: A new hypothesis. Proceedings of the National Academy of Sciences, 99(16), 10911-10916 Ho & Bryant (1997). Phonological skills are important in learning to read Chinese. Developmental Psychology, 33. 946-951 Scott & Wise (in press). The functional neuroanatomy of prelexical processing in speech perception. Cognition Snowling (2000). Dyslexia (2nd edn.) Oxford: Blackwell.