Electroencephalographic Correlates of Visual Search Task Solution in Humans

Abstract

The authors have undertaken a study of alpha EEG dynamics associated with a task involving visual search of a relevant stimulus among several irrelevant stimuli. The control condition involved simple examination of several identical stimuli. Video-oculography was used to verify gaze direction associated with relevant stimulus search. The alpha EEG dynamics (desynchronisation) was considered as a correlate of attentional processes, and was shown to increase upon discovery of a relevant stimulus, compared to the levels recorded under control condition. The increase in desynchronisation during visual search is apparently associated with processes of stimulus relevance estimation (when voluntary modality-specific attention is involved). Even larger desynchronisation occurring in the frontal lobes supposedly reflects the significance of carrying out an adequate motor programme (when prefrontal attention mechanisms are involved).