Electrophysiological correlates of feature analysis during visual search

Authors

  • STEVEN J. LUCK,

    1. Department of Neurosciences. University of California-San Diego, La Jolla
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    • Address reprint requests to: Steven J. Luck, Department of Neurosciences, 0608, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093–0608.

  • STEVEN A. HILLYARD

    1. Department of Neurosciences. University of California-San Diego, La Jolla
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  • This study was supported by ONR Contract N00014–89-J-1806, by grants from NIMH (MH-25594), NINCDS (NS 17778), and the Human Frontier Science Program, and by graduate fellowships from the National Science Foundation and the San Diego McDonnell-Pew Center for Cognitive Neuroscience.

  • We are grateful to Marty Woldorff, Ron Mangun, and Hajo Heinze for helpful discussions of this research and to Jon Hansen and Paul Krewski for excellent technical assistance. This study was included in the doctoral dissertation of the first author.

Abstract

Event-related brain potentials (ERPs) were recorded from normal young adults during visual search tasks in which the stimulus arrays contained either eight identical items (homogeneous arrays) or seven identical items and one deviant item (pop-out arrays). Four experiments were conducted in which different classes of stimulus arrays were designated targets and the remaining stimulus arrays were designated nontargets. In Experiments 1 and 2, both target and nontarget pop-out stimuli elicited an enhanced anterior N2 wave and a contralaterally larger posterior P1 wave, but Experiments 3 and 4 demonstrated that these components do not reflect fully automatic pop-out detection processes. In all four experiments, target pop-outs elicited enlarged anterior P2, posterior N2, occipital P3, and parietal P3 waves. The target-elicited posterior N2 wave contained a contralateral subcomponent (N2pc) that exhibited a focus over occipital cortex in maps of current source density. The overall pattern of results was consistent with guided search models in which preattentive stimulus information is used to guide attention to task-relevant stimuli.

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