Academic journal article Human Factors

Effects of Instruction Type and Boredom Proneness in Vigilance: Implications for Boredom and Workload

Academic journal article Human Factors

Effects of Instruction Type and Boredom Proneness in Vigilance: Implications for Boredom and Workload

Article excerpt


Vigilance refers to the ability of an observer to maintain attention over long, uninterrupted periods. In vigilance research subjects are typically asked to look for infrequent and often subtle critical signals in an unchanging environment, free from distractions. Since Mackworth's (1948) pioneering vigilance studies, researchers have generally found that one's ability to detect critical signals drops rapidly from the onset of a vigil and then stabilizes at a significantly lower level within 25 to 35 min (see Warm and Jerison, 1984, for a review). This decline in performance is so consistent among varying conditions that the phenomenon has been dubbed the vigilance decrement (Davies and Parasuraman, 1982).

In the more than 40 years since Mackworth's original work, thousands of research articles and several books have been written on the topic of vigilance. One might presume that this wealth of information had an enormous impact on vigilance problems in the real world, but the practical significance of vigilance research is still much debated. On one hand, Parasuraman, Warm, and Dember (1987) summarized numerous examples of the successful application of vigilance research to real-world problems. On the other hand, some members of the human factors community have been particularly outspoken in questioning the relevance of vigilance research (Alluisi, Coates, and Morgan, 1977; Chapanis, 1967; Mackie, 1984).

One source of fuel for this debate may lie with how the problem of vigilance has been attacked experimentally over the years. Mackie (1987) argued that, traditionally, experimental resources have been targeted at aspects of vigilance that may not be important to monitors in actual work settings. For instance, Mackie, Wylie, and Smith (1985) asked sonar operators to rank the importance of 19 sources of stress in vigilance and compared those ratings with the current state of knowledge in the literature. Mackie and his colleagues found that the effects of factors such as circadian rhythms, heat, noise, and illumination were well researched but of only moderate importance when ranked by the operators. The effects of boredom, fatigue, command pressure, and operator overload were rated as having the highest adverse impact on operators but were among those stressors receiving the least experimental attention. Thus it appears that much is known about environmental stressors but that very little is known about cognitive stressors such as boredom and command pressure. Hancock and Warm (1989) proposed a dynamic model of stress and sustained attention that emphasizes the potential interactions of multiple sources of stress. To date, however, the effects of cognitive stressors within this model have not been examined.

The importance of studying poorly understood sources of stress in vigilance is clear: There remains little hope for an adequate model of stress in vigilance until the role of these cognitive stressors is better understood. The main objective of the present study, therefore, was to begin to tip the balance in the other direction. Toward that end, we selected two aspects of vigilance for study that have escaped experimental scrutiny but that operators consider to be critical (Mackie et al., 1985). One concerns the explicit and implicit pressures placed on subjects by traditional vigilance instructions, and the other is a measure of individual differences in boredom proneness, or trait boredom.

Stress and Mental Workload in Vigilance

For many years it was believed that the information-processing demands or workload imposed by vigilance tasks were minimal (Bergum, 1966; Dember and Warm, 1979). However, the results of several recent studies have demonstrated that subjects find vigilance tasks to be both stressful (Fulop and Scerbo, 1991; see Hancock and Warm, 1989, for a review) and demanding (Deaton and Parasuraman, 1993; Galinsky, Dember, and Warm, 1989). For instance, Scerbo, Greenwald, and Sawin (1993) assessed workload in a vigilance task using the NASA Task Load Index (NASA-TLX) developed by Hart and Staveland (1988). …

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