Cognitive Work Analysis: Toward Safe, Productive, and Healthy Computer-Based Work

Black ( 1990). But to do this, software designers need to explicitly investigate the characteristics of the work they are designing for so that they can develop computer tools to support the end users of their products.

Hovde 's ( 1990) field study of information systems in hospitals, and Black ( 1990) study of desktop-publishing software both show the perils of ignoring work analysis. The lesson is that a work analysis must be conducted if there is to be a good fit between the support provided by the information system and the work demands. Only then can we achieve the situation depicted in Fig. 2.1b rather than that depicted in Fig. 2.1a.

Although work analysis is not appreciated or practiced by many information system designers, it is readily accepted in the behavioral design disciplines, such as human factors and HCI. Nevertheless, we show in this section that there is a lack of consensus on where the work analysis should begin. At the risk of greatly oversimplifying matters, we can divide the concept of work demands discussed in the previous section into two subsets, cognitive constraints and environment constraints.³Cognitive constraints are work demands that originate with the human cognitive system. For example, workers' subjective preferences and current mental models place cognitive constraints on work. In contrast, environment constraints are work demands that originate with the context in which workers are situated. For example, the physical and social reality that serve as the context for workers' behaviors are environmental constraints because they exist independently of what any one worker might think.⁴

The concept of environment constraints may be less familiar, so we give several examples. For instance, engineers working on a collaborative design project must take into account the intentions and actions of other engineers, otherwise their efforts will not be coordinated and the project goals will be compromised. Similarly, airline pilots must take into account the positions of other aircraft and the terrain if they are to achieve their goals. Also, the decisions made by a financial analyst must take

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