期刊
VISION RESEARCH
卷 50, 期 14, 页码 1312-1320出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.visres.2010.01.015
关键词
Visual attention; Visual search; MEG; Human
The spatial focus of attention has been suggested to resemble a spotlight, a zoom-lens, a simple gradient, or even a more complex center-surround profile. Here we review evidence from neuromagnetic recordings indicating that the spatial profile is not fixed but depends on the particular perceptual demands of the attention task. We show that visual search requiring spatial scrutiny for target discrimination produces a zone of neural attenuation in the target's immediate surround, whereas search permitting target discrimination without spatial scrutiny is associated with a simple gradient. We provide new evidence indicating that increasing the demands on target discrimination without changing the spatial scale of discrimination does not influence surround attenuation, and that surround attenuation is also not influenced by the type of features involved in forward processing, that is whether the target location is defined by color or luminance contrast in visual search. An assessment of the time-course of attentional selection reveals that, when present, surround attenuation onsets with a substantial delay relative to the initial feed-forward sweep of processing in the visual system. The reported observations together suggest that the more complex center-surround profile arises as a consequence of top-down attentional selection in the visual system. The reviewed neuromagnetic evidence is discussed with respect to key notions of the Selective Tuning model of visual attention for which strong support is provided. (C) 2010 Elsevier Ltd. All rights reserved.
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