Active and Passive Fatigue States

This chapter outlines a new model of fatigue that makes a critical distinction between two forms of fatigue state: and fatigue. In the experimental record on fatigue and common task performance, most studies have examined perceptual-motor capability involved for prolonged periods. Active fatigue is then derived from continuous and prolonged, task-related perceptual-motor adjustment. In contrast is a second form of fatigue, passive fatigue, which requires system monitoring with either rare or even no overt perceptual-motor response requirements. Closely allied with vigilance, this form of fatigue develops over a number of hours of doing what appears to be nothing at all. In the present work, the authors consider the commonalities and differences between these fatigue states. In particular, their concern is a very practical one. Research on fatigue has often been applied to vehicle control. Loss of control, associated with fatigue, is an immediate precursor to accidents in all realms of transportation. In ground transportation in particular, active fatigue is a frequent occurrence. For motorcycles, cars, vans, trucks, and the like, the rider or driver must make adjustments on a momentary basis. As a result, active fatigue is the state experienced by and is familiar to drivers. However, in the light of current transportation developments such as those proposed by intelligent transportation system (ITS) developers, it appears possible and even probable that many aspects of vehicle operation become subject to either full or semi-automated control. The authors' contention is that under such forms of control, the fatigue experienced by drivers changes radically from active to passive fatigue. In reviewing evidence associated with these two fatigue states, the authors endeavor to show how such a transition affects transportation operations, errors, and crashes associated with these respective forms of performance stress. For the covering abstract see ITRD E108674.