The Reicher-Wheeler effect and models of deep and phonological dyslexia

Abstract

Current accounts of the functional impairment underlying phonological dyslexia (PD) do not postulate any disturbance of accessing the orthographic lexicon. For deep dyslexia (DD), only the righthemisphere hypothesis involves such a disturbance. However, neither PD nor DD subjects showed the normal word-superiority effects in a Reicher-Wheeler experiment (forced-choice identification of single letters that had been displayed briefly either as single letters or in words or nonwords with a backward mask). Since these word-superiority effects have been argued to lie at the word-specific level, the existing accounts cannot explain the observed results for both PD and DD subjects. Three other accounts are proposed. The most parsimonious account is a degradation hypothesis: as stress is placed on the reading system, reading performance will be seen to degrade gracefully across a number of different tasks and types of stimuli, resulting in symptoms of PD or DD and producing the correlated pattern of performance in oral reading, repetition, lexical decision, and the Reicher—Wheeler task, which was observed for the nine subjects reported here and which is consistent with many previously reported PD and DD subjects.