Phoneme Categorisation in 20-Month-Old Infants with a Familial Risk of Dyslexia

Abstract

One of the leading hypotheses in the research towards developmental dyslexia – a learning disability that is mostly visible in problems with reading and writing, despite normal intelligence – is the allophonic representation hypothesis. It states that the underlying cause of dyslexia is a phonological one: the phoneme categories that develop during early childhood are less categorical in dyslexic individuals than in normal readers, which results in impaired phoneme categorisation abilities. This study looks at the difference in phoneme categorisation abilities between 20-month-old infants with a familial risk of dyslexia and typically developing age-matched controls. EEG recordings were made while the infants listened to two pseudowords with a CVC-structure that differed only in the vowel, using an oddball paradigm in which a standard (80%) was alternated with a deviant (20%). The results show that the at-risk children differ from the typically developing children in their response towards the deviant stimulus. However, the results are not yet conclusive enough to say they support or contradict the allophonic representation hypothesis. Further research is necessary.