title: Evaluating cognitive models of visual word recognition using fMRI: Effects of lexical and sublexical variables.
abstract: In this study predictions of the dual-route cascaded (DRC) model of word reading were tested using fMRI. Specifically, patterns of co-localization were investigated: (a) between pseudoword length effects and a pseudowords vs. fixation contrast, to reveal the sublexical grapho-phonemic conversion (GPC) system; and (b) between word frequency effects and a words vs. pseudowords contrast, to reveal the orthographic and phonological lexicon. Forty four native speakers of Greek were scanned at 3T in an event-related lexical decision task with three event types: (a) 150 words in which frequency, length, bigram and syllable frequency, neighborhood, and orthographic consistency were decorrelated; (b) 150 matched pseudowords; and (c) fixation. Whole-brain analysis failed to reveal the predicted co-localizations. Further analysis with participant-specific regions of interest defined within masks from the group contrasts revealed length effects in left inferior parietal cortex and frequency effects in the left middle temporal gyrus. These findings could be interpreted as partially consistent with the existence of the GPC system and phonological lexicon of the model, respectively. However, there was no evidence in support of an orthographic lexicon, weakening overall support for the model. The results are discussed with respect to the prospect of using neuroimaging in cognitive model evaluation.
authors.affiliation: Department of Philosophy & History of Science, University of Athens, Greece. Electronic address: aprotopapas@phs.uoa.gr.
authors.forename: Athanassios
authors.initials: A
authors.lastname: Protopapas
authors.affiliation: Department of Psychology, University of Crete, Greece.
authors.forename: Eleni
authors.initials: E
authors.lastname: Orfanidou
authors.affiliation: Department of Psychology, Royal Holloway University of London, UK.
authors.forename: J S H
authors.initials: JSH
authors.lastname: Taylor
authors.affiliation: Radiology and Medical Imaging Research Unit, University of Athens, Greece.
authors.forename: Efstratios
authors.initials: E
authors.lastname: Karavasilis
authors.affiliation: Department of Psychology, University of Iowa, USA.
authors.forename: Efthymia C
authors.initials: EC
authors.lastname: Kapnoula
authors.affiliation: School of Electrical and Computer Engineering, National Technical University of Athens, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Panagiotaropoulou
authors.affiliation: Radiology and Medical Imaging Research Unit, University of Athens, Greece.
authors.forename: Georgios
authors.initials: G
authors.lastname: Velonakis
authors.affiliation: Radiology and Medical Imaging Research Unit, University of Athens, Greece.
authors.forename: Loukia S
authors.initials: LS
authors.lastname: Poulou
authors.affiliation: Department of Psychiatry, Eginition Hospital, School of Medicine, University of Athens, Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Smyrnis
authors.affiliation: Radiology and Medical Imaging Research Unit, University of Athens, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Kelekis
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; 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; D021641:Recognition, Psychology / Q000502:physiology; D055815:Young Adult
keywords: Cognitive models; Greek; Lexical decision; Reading; Visual word recognition; fMRI