LEXICAL DECISION PERFORMANCES IN P-TYPE DYSLEXIC, L-TYPE DYSLEXIC, AND NORMAL READING BOYS

Lexical decision performances in P-type dyslexic, L-type dyslexic, and normal reading boys were investigated using three-letter and four-let ter words (familiar words) and nonwords presented in the central visua l field. For words, P-type dyslexics displayed significantly longer la tencies for four-letter than for three-letter word decisions, whereas L-type dyslexics and normal readers did not. For nonwords, all subject groups showed significantly larger mean latencies for four-letter tha n for three-letter nonword decisions. In general, the error data corre sponded to the latency data. L-type dyslexics, however, made more erro rs during four-letter words than during three-letter words, although t hey had similar latencies in both conditions. The results are discusse d with reference to the hypothesis that P-type dyslexics would use a s equential processing mode for reading familiar words, whereas L-type d yslexics would employ a parallel processing mode for reading familiar words.