Authors: R Duncan Milne, Tom Nicholson, Michael C Corballis.
Publication: Neuropsychology (American Psychological Association). 17(3), 362–368 2003 | DOI: 10.1037/0894-4188.8.131.522
Lexical access and phonological decoding were tested in 100 normal adult readers and 21 adult dyslexic individuals. Within the dyslexic sample, 11 dysphonetic dyslexic and 10 dyseidetic dyslexic participants were classified on the basis of spelling patterns. In the 1st experiment, adult dyseidetic readers showed a marked deficit on the lexical-access decision task in comparison with adult dysphonetic readers. In the 2nd experiment, the phonological-decoding decision task did not separate the subtypes. A lexical-access deficit in adult dyseidetic dyslexia cannot be explained in terms of a developmental delay. A phonological-decoding deficit in adult dyseidetic dyslexia may be explained by increased involvement of the lexical procedure in phonological assembly under an analogy strategy.
We found evidence of dyseidetic dyslexia in an adult sample of dyslexic individuals who were distinguishable from dysphonetic individuals on the lexical-access decision task. Furthermore, almost one half of the sample was classified with dyseidetic dyslexia, a considerably higher rate than observed in children (Flynn et al., 1992). Surface dyslexia has been accounted for as a developmental delay resulting from a general resource limitation within a connectionist network (Manis et al., 1996). As the dyseidetic group in our study are adults, poorer performance and longer response time for the lexical-access decision task cannot easily be attributed to a developmental delay. The lexical-access deficit in dyseidetic dyslexia appears more
recognizable at higher levels of reading attainment. In normal reading, the sublexical procedure develops after acquiring the alphabetic principle, whereas the lexical procedure requires considerable print exposure before it learns to process rapidly and efficiently. In this respect, the relative
disability of dysphonetic dyslexia may diminish over time, whereas the relative disability of dyseidetic dyslexia maycontinue to manifest.
Milne, R. D., Nicholson, T., & Corballis, M. C. (2003). Lexical access and phonological decoding in adult dyslexic subtypes. Neuropsychology, 17(3), 362–368. https://doi.org/10.1037/0894-4184.108.40.2062