Length effect on reading of kana words and nonwords in fifth or sixth grade normal readers and children with developmental dyslexia

Abstract

We investigated length effect on the reading of Kana words/nonwords in eight children with normal reading ability and seven children with developmental dyslexia. Participants in this study were all Japanese-speaking children in the fifth or sixth grade. Under all word and nonword conditions, reading latency was significantly longer in the dyslexic group than in the control group, while the error rate did not differ between the two groups. Both groups showed main effects of length and lexicality. The control group revealed a significant interaction between length and lexicality, that is, a larger length effect for nonwords than for words, but the dyslexic group did not show such interaction. These results suggested that the fifth and sixth grade primary school children with developmental dyslexia in this study could read neither Kana words nor nonwords fluently. Children with developmental dyslexia appear to fail in the transition from a sub-lexical to a lexical procedure. Furthermore they revealed a capacity to use non-lexical processing but not in a fluent way. These findings suggest that reading speed deficit results from problems in both lexical and non-lexical processing.