title: How to make the word-length effect disappear in letter-by-letter dyslexia: implications for an account of the disorder.
abstract: The diagnosis of letter-by-letter (LBL) dyslexia is based on the observation of a substantial and monotonic increase of word naming latencies as the number of letters in the stimulus increases. This pattern of performance is typically interpreted as indicating that word recognition in LBL dyslexia depends on the sequential identification of individual letters. We show, in 7 LBL patients, that the word-length effect can be eliminated if words of different lengths are matched on the sum of the confusability (visual similarity between a letter and the remainder of the alphabet) of their constituent letters. Additional experiments demonstrate that this result is mediated by parallel letter processing and not by any compensatory serial processing strategy. These findings indicate that parallel processing contributes significantly to explicit word recognition in LBL dyslexia and that a letter-processing impairment is fundamental in causing the disorder.
authors: Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, CP 6128, Succ. Centre-ville, Montreal, Quebec H3C 3J7, Canada.
authors: Daniel
authors: D
authors: Fiset
authors: Martin
authors: M
authors: Arguin
authors: Daniel
authors: D
authors: Bub
authors: Glyn W
authors: GW
authors: Humphreys
authors: M Jane
authors: MJ
authors: Riddoch
mesh_terms: D004411:Dyslexia, Acquired / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D021641:Recognition, Psychology