The electrodermal indices of the subjective perception of performance errors during drowsy changes in consciousness

The study was aimed at searching for objective criteria of subject's perception of errors in performance due to drowsiness and estimating the time between the onset of errors and the moment of their awareness. Healthy subjects (n = 64) with the pronounced EEG alpha were examined under conditions without sleep deprivation. Experiments (n = 280) lasted for 40 min. During the experiments, the EEG, EOG, EDR, EKG, and button pressings were recorded and subject's reports were registered. The subjects were waken up after the onset of errors or 20 min after the beginning of the performance independently of errors. The error onset was shown to be preceded by the EEG "drowsy pattern" and decrease in the rate of spontaneous EDR. The performance reappearance after the error was accomplished by alpha-rhythm independently from error awareness. The interrogation of subjects after the error and activity revival demonstrated a correlation between the error subjective perception and appearance of the EDR. The interval between the error and the first following EDR (mean 10.1 s) was significantly (p < 0.001, t-test for dependent samples) shorter than the interval between the error and the last preceding EDR (mean 69.8 s). It is suggested that the subjective perception of an error is a significant endogenous stimulus, which evokes the orienting response and accompanying sympathetic activation.