Lexical and semantic access in letter-by-letter dyslexia: A case report

Abstract

Letter-by-letter (LBL) dyslexia is a reading impairment caused by left occipital damage and characterized by significant increase in reading time according to the number of letters in a given string (word length effect). In analogy to Dejerine’s interpretation of pure alexia (1892), this disorder is said to be the consequence of a disconnection of the word-blind right hemisphere (RH) from the left hemisphere (LH) word recognition system (angular gyrus). However, several patients have been found to maintain some reading capacities. Coslett & Saffran (1989) described four LBL patients who performed better than chance either on lexical decision or on semantic judgment tasks with words that could not be explicitly identified (implicit reading). Results are controversial (Behrmann, Black & Bub, 1990) and not consistent with the assumption of a complete RH blindness. Data on pure alexia and LBL reading were mostly obtained on Frenchor English-speaking patients, i.e. patients speaking languages with largely irregular orthography, but similar results were also occasionally reported for languages with shallow orthography, like Italian (Perri, Bartolomeo, & Silveri, 1996). The purpose of the present study is to collect data on the nature of the implicit reading phenomenon, to analyze the explicit and implicit reading abilities of a bilingual English and Italian-speaking patient suffering from LBL dyslexia, and to verify for a possible different reading behavior in the two languages.