Effects of electrodermal lability and introversion on vigilance decrement

Previous research has suggested that an autonomic nervous system measure, electrodermal lability, and a personality measure, introversion-extraversion, both predict vigilance decrement; mixed results have been obtained in research seeking to correlate these two variables. Two vigilance tasks requiring an easy and a difficult sensory discrimination produced an overall decline in performance over time, but electrodermally labile subjects (those with high frequencies of spontaneous fluctuations of skin conductance and slow habituation to a series of tones) did not show a decline on the difficult task. Signal detection measures of sensitivity and response bias suggest that the observed differences reflected changes in sensitivity over time and not just differences in criterion for responding. While not correlated with electrodermal lability, introversion was related to a higher initial level of performance on the difficult task. Vigilance tasks requiring rapid but cognitively simple discriminations appear to be more effective in eliciting overall declines in performance. The presence of such a decline may be necessary for observing differential declines in performance between electrodermal labiles and stabiles.