The Use of Subjective Workload Assessment Technique in a Complex Flight Task

Abstract : With the increasing tendency towards all-digital airborne and groundbased workspaces, the search for satisfactory mental workload measurement methods has become one of the most active human factors research areas. Designers and engineers have asked for the better methods to assess mental workload at all stages of system development-but especially in the high-fidelity simulator and in actual in-flight tests. Techniques for measuring mental workload (hereafter referred to merely as workload ) can be divided into three basic categories: physiological, behavioural, and subjective. The present paper deals with one particular technique belonging to the third group of methods, which always use some form of operator self-report (eg rating scales or questionnaires). The subjective methods seem at first glance to be almost too simple and unscientific . However, as Johannsen has noted, if an operator feels his workload level is high then is high, regardless of what other measures show. Some of the criteria normally applied in evaluating the various workload techniques are: non-intrusiveness, ease of implementation, operator acceptance, and sensitivity to variations in task demand. Although the subjective techniques tend to satisfy these requirements, probably better than behavioural and physiological methods, they have exhibited a couple of undesirable characteristics.