Letter processing in dyslexic subgroups.
Hypothesized cognitive strengths and weaknesses of three dyslexic subgroups (Boder and Jarrico 1982) were examined in two reading related experiments. The first experiment tested the prediction that auditorily presented letter sets should be processed better by dyseidetic than by dysphonetic readers. The prediction was not confirmed. The results did not show any modality of presentation-specific recall differences between the three dyslexic subgroups. Overall, dyslexic children's scores were significantly lower than those of age-matched control groups. The second experiment tested predictions of differential performance of dyseidetic and dysphonetic readers in a task in which the name identity of letters in pairs had to be indicated. Predicted patterns were not confirmed. Compared to the control groups all three dyslexic subgroups (whose means did not differ significantly) made significantly more errors in the condition in which it was essential to activate phonetic representations of the letters. The experimental results of this study suggest a greater similarity in the nature of letter processing problems in dyslexic children than is assumed in Boder and Jarrico's (1982) subtyping test.
Department of Special Education, Groningen State University, The Netherlands.
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van den Bos