ABSTRACT
Vigilance is one of the forms of sustained focussed attention and it denotes an observer’s state of readiness to respond to weak, unpredictable, and rare events over a prolonged period of time. It is characteristic of vigilance tasks that an alert observer will easily detect these critical events, but an inattentive observer will miss them. The overall ability to detect these critical events is referred to as the “vigilance level.” It has been known since the early experiments of Mackworth in the 1950s that observers were unable to maintain their initial detection rates over prolonged periods of time on these repetitive monitoring tasks. The trademark of the vigilance task, therefore, is the deterioration in the overall vigilance level over time and this is referred to as the “vigilance decrement.”
