title: The deficit of letter processing in developmental dyslexia: combining evidence from dyslexics, typical readers and illiterate adults.
abstract: To clarify the link between anomalous letter processing and developmental dyslexia, we examined the impact of surrounding contours on letter vs. pseudo-letter processing by three groups of children - phonological dyslexics and two controls, one matched for chronological age, the other for reading level - and three groups of adults differing by schooling and literacy - unschooled illiterates and ex-illiterates, and schooled literates. For pseudo-letters, all groups showed congruence effects (CE: better performance for targets surrounded by a congruent than by an incongruent shape). In contrast, for letters, only dyslexics exhibited a CE, strongly related to their phonological recoding abilities even after partialling out working memory, whereas the reverse held true for the pseudo-letter CE. In illiterate adults, the higher letter knowledge, the smaller their letter CE; their letter processing was immune (to some extent) to inference from surrounding information. The absence of a letter CE in illiterates and the positive CE in dyslexics have their origin in different aspects of the same ability, i.e. phonological recoding.
authors.affiliation: Faculty of Psychology and Education Sciences, Universidade do Porto, Portugal.
authors.forename: Tânia
authors.initials: T
authors.lastname: Fernandes
authors.forename: Ana P
authors.initials: AP
authors.lastname: Vale
authors.forename: Bruno
authors.initials: B
authors.lastname: Martins
authors.forename: José
authors.initials: J
authors.lastname: Morais
authors.forename: Régine
authors.initials: R
authors.lastname: Kolinsky
mesh_terms: D000328:Adult; D000368:Aged; D002648:Child; D003071:Cognition / Q000502:physiology; D004410:Dyslexia / Q000503:physiopathology*; D004522:Educational Status; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D011932:Reading