Lexical decision with pseudohomophones and reading in the semantic variant of primary progressive aphasia: A double dissociation.
The co-occurrence of semantic impairment and surface dyslexia in the semantic variant of primary progressive aphasia (svPPA) has often been taken as supporting evidence for the central role of semantics in visual word processing. According to connectionist models, semantic access is needed to accurately read irregular words. They also postulate that reliance on semantics is necessary to perform the lexical decision task under certain circumstances (for example, when the stimulus list comprises pseudohomophones). In the present study, we report two svPPA cases: M.F. who presented with surface dyslexia but performed accurately on the lexical decision task with pseudohomophones, and R.L. who showed no surface dyslexia but performed below the normal range on the lexical decision task with pseudohomophones. This double dissociation between reading and lexical decision with pseudohomophones is in line with the dual-route cascaded (DRC) model of reading. According to this model, impairments in visual word processing in svPPA are not necessarily associated with the semantic deficits characterizing this disease. Our findings also call into question the central role given to semantics in visual word processing within the connectionist account.
Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Québec, Canada. Electronic address: mariem.boukadi@gmail.com.
Mariem
M
Boukadi
Département de réadaptation, Faculté de médecine, Université Laval, Québec, Canada.
Karel
K
Potvin
Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Québec, Canada; Département de réadaptation, Faculté de médecine, Université Laval, Québec, Canada.
Joël
J
Macoir
Clinique interdisciplinaire de mémoire (CIME), Centre Hospitalier Universitaire (CHU) de Québec, Québec, Canada; Département des Sciences Neurologiques, Faculté de médecine, Université Laval, Québec, Canada.
Robert
R
Jr Laforce
Clinique interdisciplinaire de mémoire (CIME), Centre Hospitalier Universitaire (CHU) de Québec, Québec, Canada.
Stéphane
S
Poulin
Centre de recherche de l'Institut universitaire de gériatrie de Montréal (CRIUGM), Montréal, Canada.
Simona M
SM
Brambati
Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Québec, Canada; Département de réadaptation, Faculté de médecine, Université Laval, Québec, Canada. Electronic address: maximiliano.wilson@fmed.ulaval.ca.
Maximiliano A
MA
Wilson
D000368:Aged; D018888:Aphasia, Primary Progressive / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004213:Dissociative Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011932:Reading; D012660:Semantics
Lexical decision; Reading; Semantic dementia; Semantics; Surface dyslexia; Visual word processing