An ERP Study Of Hemispheric Asymmetry Effects In Global/Local Processing

Blocked and random hierarchical processing tasks are used to investigate hemispheric asymmetry effects under different attention filtering condition and to examine how attention filtering mechanism,perceptual conflict and response conflict factors modulate the hemispheric asymmetry effects as well. Attention filtering mechanism in Experiment One is effective to exclude the inference from unrelated information, and there are no response conflict effects in local processing tasks; but P2 and N2 components still show hemispheric difference effects in this situation, which can't be explained with the "integration theory". Attention filtering mechanism in Experiment Two is ineffective to exclude the inference of unrelated information, so more response conflict effects emerge. Under this condition, P2 component is modulated by perceptual factors, and hemispheric asymmetry effects of P2 only appear when processing stimulus with perceptual conflicts, while response factors show influence on P3 component, and brain asymmetry effects just appear in response conflict processing. Hemispheric difference of P3 component only appears when attention filtering mechanism is ineffective (Experiment Two), indicating that attention can modulate the mode of hemispheric asymmetry effects. In brief, our results show that hemispheric asymmetry effects in global/local processing are complexly dynamic systems which may be modulated by attention filtering mechanism,perceptual conflict and response conflict; stages in which the effects emerge would change with experiment conditions.