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| Research article summary (published 30 Jul 2003): |
Modulation of neural activities by enhanced local selection in the processing of compound stimuli.
Full Abstract
The global precedence effect refers to the findings that responses are faster to a global structure than to its local parts and local responses are slowed by incongruent global information. We recorded high-density event-related potentials (ERPs) to study the role of enhanced local selection in the global precedence effect. Hierarchical stimuli were compound letters in which the local letters were either identical (homogeneous stimuli) or the central local letter was brighter than (bright stimuli) or different in color from the others (red stimuli). Subjects were asked to attend to the pop-out local letter of the red and bright stimuli during the local task whereas there was no such instruction for the homogeneous stimuli. Top-down attention to the pop-out local item weakened the global reaction time advantage and the interference effect. The enhanced local selection decreased the amplitude of an occipito-temporal negativity between 240-360 msec but increased the amplitude of a frontal-central negativity between 260-320 msec related to local processing. The incongruency between global and local letters enlarged the posterior N2 in the local condition and this effect was eliminated by enhanced local selection. These effects were evident regardless of whether the pop-out local letter was defined by color or luminance difference. The results support the proposal that distinct neural mechanisms over the posterior and anterior areas are engaged in the selection process that contributes to local processing of compound stimuli.Copyright 2003 Wiley-Liss, Inc.
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Author information
Author/s: Han, Shihui (S); He, Xun (X);
Affiliation: Department of Psychology, Center for Brain and Cognitive Sciences, Peking University, Beijing, People's Republic of China. shan(-atsign-)pku.edu.cn
Journal and publication information
Publication Type: Journal Article; Research Support, Non-U.S. Gov't
Journal: Human brain mapping (Hum Brain Mapp), published in United States. (Language: eng)
Reference: 2003-Aug; vol 19 (issue 4) : pp 273-81
Dates: Created 2003/07/22; Completed 2003/09/10; Revised 2006/11/15;
PMID: 12874779, status: MEDLINE (last retrieval date: 11/6/2008)
Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.
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