title: Hemispheric differences in orthographic and semantic processing as revealed by event-related potentials.
abstract: Differences in how the right and left hemispheres (RH, LH) apprehend visual words were examined using event-related potentials (ERPs) in a repetition paradigm with visual half-field (VF) presentation. In both hemispheres (RH/LVF, LH/RVF), initial presentation of items elicited similar and typical effects of orthographic neighborhood size, with larger N400s for orthographically regular items (words and pseudowords) than for irregular items (acronyms and meaningless illegal strings). However, hemispheric differences emerged on repetition effects. When items were repeated in the LH/RVF, orthographically regular items, relative to irregular items, elicited larger repetition effects on both the N250, a component reflecting processing at the level of visual form (orthography), and on the N400, which has been linked to semantic access. In contrast, in the RH/LVF, repetition effects were biased toward irregular items on the N250 and were similar in size across item types for the N400. The results suggest that processing in the LH is more strongly affected by wordform regularity than in the RH, either due to enhanced processing of familiar orthographic patterns or due to the fact that regular forms can be more readily mapped onto phonology.
authors.affiliation: Department of Psychology, University of Illinois at Urbana-Champaign, 603 East Daniel St., Champaign, IL 61820, USA. Electronic address: ddicksn2@illinois.edu.
authors.forename: Danielle S
authors.initials: DS
authors.lastname: Dickson
authors.affiliation: Department of Psychology, University of Illinois at Urbana-Champaign, 603 East Daniel St., Champaign, IL 61820, USA; Program in Neuroscience, University of Illinois at Urbana-Champaign, 505 South Goodwin Ave, Urbana, IL 61801, USA; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 North Mathews Ave, Urbana, IL 61801, USA. Electronic address: kfederme@illinois.edu.
authors.forename: Kara D
authors.initials: KD
authors.lastname: Federmeier
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time; D021641:Recognition, Psychology / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Cerebral hemispheres; ERPs; N400; Orthographic neighborhood; Visual word recognition