Electrophysiological correlates of attention, inhibition, sensitivity and bias in a continuous performance task

Objective: The aim was to verify the occurrence of proposed electrophysiological correlates of attention, inhibition, sensitivity and bias in a continuous performance task and to support their functional interpretation by using a manipulation intended to enhance subjects' response bias. Methods: Electroencephalographic activity was recorded during administration of a transformed version of the AX continuous performance task in which cues signaled response alternatives. Results: The previously reported parietal P3, NoGo-N2, NoGo-P3 and contingent negative variation were replicated. Besides, the frontal selection positivity and the lateralized readiness potential were demonstrated. With increasing Go-probability, the parietal P3 to the cue increased without changes in other cue-related correlates. In addition, reaction times decreased, non-parametric measures of sensitivity and bias decreased, the NoGo-N2 increased, and the parietal Go-P3 decreased. Conclusions: The proposed electrophysiological correlates were identified. Sub-threshold LRPs suggested a central inhibition mechanism. Cue-related correlates revealed that anticipation of a high-probability Go-stimulus involves attention rather than bias. This implies that the increased NoGo-N2 reflected an increase in conflict rather than an increase in inhibition. Significance: Electrophysiological measures can greatly enhance our understanding of normal and abnormal information processing during continuous performance and related tasks. (C) 2004 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.