ABSTRACT
A task can be viewed as a sequence of actions performed to accomplish one or more desired objectives. Task analysis and decomposition involve breaking down a task into identifiable elements or steps and analyzing them to determine the resources (human, equipment, and environmental) necessary for the accomplishment of the task. As indicated in earlier chapters, all human tasks require the interaction of mental and physical resources, but it is often convenient, for analytical purposes, to make a distinction between tasks that require predominantly physical resources of the person performing the tasks and tasks that require predominantly mental resources. These different types of tasks are often analyzed separately. Usually, in physical tasks, the mental requirements are described but are not analyzed as meticulously as the physical requirements. For example, a heavy-lifting task in industry requires musculoskeletal strength and endurance, decision making, and other resources, but the successful completion of such a task is
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limited by musculoskeletal strength. Decision-making and cognitive resources may be lightly tapped, and so the heavy-lifting task analysis will tend to focus only on those factors that modify the expression of musculoskeletal strength while keeping the other kinds of requirements at a descriptive level. The descriptions and analyses of manual materials handling tasks in Chaffin and Andersson [1991] and Ayoub and Mital [1991] exemplify this kind of focus. The degree with which a resource may be stressed depends on a number of factors, among which are the resource availabilities (capacities) of the person performing the task compared with the task demands.
