Most children with dyslexia and dysorthography shows phonological difficulties which are manifested by the difficulty in processing and remembering sound sequences and the relationship between phoneme and grapheme.
However, although language and learning are closely related, there are children with a clear language disorder who can write without errors. Why?
On the relationship between language and learning exist four main models:
- Single factor severity model (Tallal ): there is a basic deficit that manifests itself as a language disorder (if severe) and a learning disorder (if mild). It may even be the same deficit that manifests itself differently over time.
- Two-factor model (Bishop ): the two disorders share the same deficit, but the language disorder also has impairments in the level of oral language
- Comorbidity model (Catts ): the two ailments derive from two different deficits, which co-occur very often
- Multiple deficit model (Pennington ): both disturbances are influenced by numerous factors, some of which are partially overlapping
Even those who do not support a frankly multidimensional approach recognize the presence of other factors beyond language and learning. Bishop , for example, suggests that rapid naming (RAN) could have a protective role against dyslexia in children with speech disorder, that is, it could overcome some linguistic difficulties through a faster visual processing. Of course, more than the RAN itself could be the skills involved in the RAN, but the concept remains equally fascinating.
A Russian study  tried to understand better the role of phonological awareness and RAN in the development of speech and / or learning disorder.
A systematic review
The study recruited 149 Russian children aged between 10 and 14 years. The experimental group consisted of 18 children with only the language disorder, 13 with writing difficulties and 11 with language disorder and writing difficulties.
- For the evaluation of expressive narrative language silent books have been used since there is no standardized proof of narrative language in Russian
- For the evaluation of the writing a dictation of 56 words was used
- Non-verbal intelligence tests were also administered
- Other tests related to phonological and morphological awareness were administered, as well as a non-word repetition test
- Finally, performance at a quick naming task was measured
A very interesting fact that emerged from the administration of the tests is that:
- Only the 42% of children with speech disorder had the requirements for a diagnosis of dysorthography
- Only the 31% of dysorthographic children had the requirements for a diagnosis of speech disorder.
Children with writing difficulties showed difficulties in spelling, morphological and phonological awareness as well as in the rapid naming of objects, numbers and letters. Children with only the language disorder manifested difficulties only in phonological awareness, in the rapid naming of letters and in that of colors. The mixed group, however, showed difficulties in all activities.
From the point of view of cognitive profiles, while the difficulties in phonological awareness and rapid naming of letters seem to belong to both groups, there are peculiar characteristics for each of the two:
- Language disorder: slower and more inaccurate naming of colors (although this aspect seems to be affected by the characteristics of the Russian language)
- Writing Disorder: slower digit and color naming of ids, as well as less accuracy in repetition of non-words and orthographic and phonological awareness
Ultimately, although there are some aspects of this study to be replicated in the Italian language, the results seem to go towards a multidimensional model. The relationship between language and writing is certainly very close, but not to the point of predicting the second starting from the first. Numerous other factors intervene, positively and negatively, in the formation of a correct spelling competence. As always, therefore, it is necessary know and apply a wide range of evaluation tools to identify factors that can explain the difficulties shown in school.
You may also be interested in:
- In GameCenter Writing you will find dozens of interactive and free web-apps on writing
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- Article: Verbal working memory and rapid naming as indicators of dyslexia in university students
 Rakhlin N, Cardoso-Martins C, Kornilov SA, Grigorenko EL. Spelling well despite developmental language disorder: what makes it possible?. Ann Dyslexia. 2013;63(3-4):253-273. doi:10.1007/s11881-013-0084-x