ScienceDirect - Cognition : A case study of an English-Japanese bilingual with monolingual dyslexia
Here is a very interesting report, the case of AS, a 16 year-old English/Japanese bilingual boy, whose reading/writing difficulties are confined to English only.
AS was born in Japan to a highly literate Australian father and English mother, and goes to a Japanese selective senior high school in Japan. His spoken language at home is English.
AS's reading in logo-graphic Japanese Kanji and syllabic Kana is equivalent to that of Japanese undergraduates or graduates.
In contrast, his performance in various reading and writing tests in English as well as tasks involving phonological processing was very poor, even when compared to his Japanese contemporaries.
Yet he has no problem with letter names or letter sounds, and his phoneme categorisation is well within the normal range of English native speakers.
The data show a clear dissociation between AS's ability to read English and Japanese, and the research study put forward the ‘hypothesis of granularity and transparency'.
The Orthography of a language specifies the correct way of using a specific writing system to write the language and Phonology is the systematic use of sound to encode meaning in any spoken human language.
It is postulated that any language where orthography-to-phonology mapping is transparent, or even opaque, or any language whose orthographic unit representing sound is coarse (i.e. at a whole character or word level) should not produce a high incidence of developmental phonological dyslexia.