ABSTRACT
Vigilance is about sustaining attention for the occurrence of some rare critical event, as in tasks like radar and sonar monitoring where an operator has to look or listen over lengthy periods of time for an infrequent signal or target. The complex, demanding, monitoring tasks may produce a genuine loss of vigilance, a decrement in the ability to sustain attention to the task. In vigilance research, detections and detection latencies are used to index the level of vigilance. And although the persistence of the decrement in conditions of complex monitoring signifies that problems of maintaining vigilance may be just as great in the complex as in the simple case, it is not evident that the problems become more, or less, acute when the monitoring load is increased. The truly complex monitoring task involves different kinds of signals occurring at different sources or locations.
