COMPARISON OF QEEG AND RESPONSE ACCURACY IN GOOD VS POORER PERFORMERSDURING A VIGILANCE TASK

Subjects performed an auditory continuous performance test requiring t hem to detect targets in a series of letters presented at a rate of 2/ s. 2-min samples of EEG were obtained from eight bipolar sites during a resting condition and during early and late (7-10 min) test performa nce. EEG power spectra from 27 subjects whose performance accuracy dec reased between these latter periods (LoVig group) were compared with t hose from 27 subjects who maintained a constant level of performance ( HiVig group). In both groups EEG power changed significantly between r esting and test conditions for all frequency bands: beta power increas ed, especially in fronto-temporal and temporal left-hemisphere sites; alpha and posterior theta decreased; anterior theta and delta increase d. Significant changes also were found between early and late test per formance: anterior theta and delta power decreased in both groups; tem poral beta power decreased in the LoVig group only, and is thus consid ered the best indicator of performance changes. Other differences foun d between groups were across conditions. The HiVig group had more ante rior beta and less posterior alpha and theta than the LoVig group. EEG results are discussed in relation to an explanation of vigilance erro rs based on signal detection theory.