Samenvatting
It is argued that effects of fatigue on performance should be progressive as time goes on. Initial decrements, often found in vigilance tasks, cannot be described to what is usually called fatigue, but rather reflect a change from a state of hypervigilance to normal vigilance occurring within the first half hour of the work period. Studies on very long-term performance have generally failed to show progressive effects. In an attempt to demonstrate progressive decrement an exploratory experiment was carried out where the effects of long-term work, declining diurnal rhythm and accumulating sleep loss converge. The test is described and the results are discussed.