An Absence of Vigilance Decrement in a Complex Dynamic Task

Abstract

Although it is sometimes stated that there is a danger of a loss of vigilance in supervisory tasks where the main task is monitoring, there appears to be no experimental research on the vigilance decrement in complex realistic tasks. In this paper we report an experiment on the detection of dynamic faults in a rather complex microworld, PASTEURISER. An overall decrement in target detection was found, but no vigilance decrement as a function of time during the first 30 minutes or 1 hour. Even when the system was made increasingly simple no vigilance decrement curves were found, although it was possible to replicate Mackworth's original experiment with a simulated clock. We conclude that at least for some kinds of dynamic signals there is no progressive loss of vigilance during the fiurst half hour to an hour of watchkeeping tasks.