To test theories that posit differences in how semantic information is represented in the cerebral hemispheres, we assessed semantic priming for associatively and categorically related prime-target pairs that were gra...
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To test theories that posit differences in how semantic information is represented in the cerebral hemispheres, we assessed semantic priming for associatively and categorically related prime-target pairs that were graded in relatedness strength. Visual half-field presentation was used to bias processing to the right or left hemisphere, and event-related potential (ERP) and behavioral responses were measured while participants completed a semantic relatedness judgement task. Contrary to theories positing representational differences across the cerebral hemispheres, in two experiments using (1) centralized prime presentation and lateralized targets and (2) lateralized primes and targets, we found similar priming patterns across the two hemispheres at the level of semantic access (N400), on later measures of explicit processing (late positive complex;LPC), and in behavioral response speeds and accuracy. We argue that hemispheric differences, when they arise, are more likely due to differences in task demands than in how the hemispheres fundamentally represent semantic information.
The coarse coding hypothesis postulates that the cerebral hemispheres differ in their breadth of semantic activation, with the left hemisphere activating a narrow, focused semantic field and the right weakly activatin...
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The coarse coding hypothesis postulates that the cerebral hemispheres differ in their breadth of semantic activation, with the left hemisphere activating a narrow, focused semantic field and the right weakly activating a broader semantic field. In support of coarsecoding, studies investigating priming for multiple senses of a lexically ambiguous word have reported a right hemisphere benefit. However, studies of mediated priming have failed to find a right hemisphere advantage I-or processing distantly linked, unambiguous words. To address this debate, the present study made use of a multiple priming paradigm in which two primes either converged onto the single meaning of an unambiguous, lexically associated target (LION-STRIPES-TIGER) or diverged onto different meanings of an ambiguous target (KIDNEY-PIANO-ORGAN). In two experiments, participants either made lexical decisions to lateralized targets (Experiment 1) or made a semantic relatedness judgment between primes and targets (Experiment 2). in both tasks, for both ambiguous and unambiguous triplets we found equivalent priming strengths and patterns across the two visual fields, counter to the predictions of the coarse coding hypothesis. Priming patterns further suggested that both hemispheres made use of lexical level representations in the lexical decision task and semantic representations in the semantic judgment task. (c) 2007 Elsevier B.V. All rights reserved.
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