Individual differences in dyslexia
The current research attempted to understand individual differences in dyslexia by
investigating potential sex differences (behavioural, cognitive and remedial), subtypes
and predictors of symptom severity.
The results did not specifically support the hypothesis that behavioural factors were
related to the increased number of male dyslexics reported in the literature. Cognitive
sex differences were identified on the months forwards subtest of the Bangor Dyslexia
Test and on the digit span, coding and symbol search subtests from WAIS-IIIUK. In all
cases, females outperformed males. Although the ACID, AVID and SCAD profiles were
not found to characterise the performance of either sex, performance on the ACID,
AVID and SCAD factor scores appeared more related to dyslexia in males. The findings
indicated that sex differences may affect the manifestation of dyslexia related problems.
Male and female dyslexics did not differ with regard to the level, rate or endurance of
improvement following different methods of spelling instruction. Rather than sex,
reading ability was found to predict spelling improvement following intervention.
The adult dyslexics studied continued to show deficits on a range of tasks usually used
to assessd yslexia in children. Although it was possiblet o divide the adult dyslexics into
phonological and surfaces ubtypes,s ubsequenta nalysesd esignedt o assessth e utility of
this classification system suggestedth at the validity of the subtypesw as questionable.
Similar measures were found to predict the reading ability of dyslexic and non-dyslexic
adults. However, the groups differed with regard to predictors of spelling and reading
comprehension ability. Severity differences in one or several underlying core deficits
were considered a more meaningful way of accounting for individual differences in
dyslexia than the existence of distinct subtypes.