Electrophysiological correlates of visual search asymmetry in humans.
Visual evoked potentials (VEPs) were recorded during a visual search task to evaluate parallel and serial models of visual processing. A target stimulus elicited a discrete posterior negative wave in the 150-300 ms latency range. Furthermore, there was a close correlation between the search performance and the activity of the negative wave. When the target had a unique feature, neither the search time nor the characteristics of the negative wave was affected by the number of items in display. However, when the target lacked a unique feature, both the search time and the latency of the negative wave increased with the number of items. These results were consistent with a claim that an object with a unique feature is detected preattentively.
Sugita
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Y
Laboratory for Neural Systems, Toyohashi University of Technology, Japan.
D000328:Adult; D004594:Electrophysiology; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology*; D013997:Time Factors; D014795:Visual Pathways / Q000502:physiology*