The classification of vigilance tasks in the real world

The ability to generalise vigilance research to operational environments has been questioned, largely due to differences between laboratory research and real-world settings. The taxonomy of vigilance tasks proposed by Parasuraman and Davies (1977) represents an attempt to classify vigilance tasks so that tasks with similar information-processing demands can be compared and the ability to generalise results enhanced. Although the taxonomy originally included complexity, the term specifically referred to multiple sources of information. Complexity has been overlooked in much of the traditional vigilance literature, although it is included in more recent studies of jobs such as air traffic control. In this paper, the taxonomy is evaluated in relation to two vigilance intensive jobs - closed circuit television surveillance operators and air traffic controllers. In its present form, the existing taxonomy of experimental settings has limited applicability to these operational settings. Therefore, recommendations for expanding the taxonomy to include more aspects of complexity are made. It is argued that the revised taxonomy be used in conjunction with situation awareness, which makes provision for the cognitive processes involved in these jobs.