Assessing the impact of computer workload on operator stress: the role of system controllability

This paper considers the impact of working with computer-based systems in terms of mental workload and the well-being of operators. In particular, the paper focuses on issues of controllability in human-computer systems as they relate to operator stress. Through the adoption of a state control model of stress regulation, it becomes apparent that while general usability criteria are necessary for the design of controllable systems, they may not be sufficient to guarantee controllability. The implications for research and system design are discussed, with reference to the assessment of operator workload, controllability and stress. A methodology for assessing computer stress is described, based on the analysis of stressful computer-related episodes and their accompanying affective and cognitive states. This technique allows the relationship between workload and controllability to be studied in particular computer work environments, in relation to individual work goals and coping strategies.