Reading mechanisms and the organisation of the lexicon: Evidence from acquired dyslexia

Abstract

Abstract Two patients with a highly selective disruption of nonword reading are described. Both patients were able to read all types of words, made no morphological paralexic errors, but could read only about 70% of the nonwords presented. Errors in reading nonwords resulted mostly in nonword responses. An analysis of the ability of one of the two patients (LB) to read nonwords that differed in terms of whether or not they could be parsed into root morpheme plus affix, revealed major differences in processing of the two types of stimuli. The complete dissociation of nonword- from word-reading performance, and various features of the reading errors made by our patients, are discussed in relation to current models of reading and lexical organisation. It is proposed that words are represented in the lexicon in morphologically decomposed form—root morphemes are represented separately from affixes and function words. It is further proposed that morphemic representations in the lexicon are addressed from whole word addresses for known words but that new words are processed by a morphological parsing device.