Integrating Task Analysis in Software Usability Evaluation: A Case Study

This paper describes a task analysis approach to usability engineering a digital Emergency Medical Services system. In a hierarchical task analysis, we decomposed user's workflow into major tasks and examined the compatibility between software functionality and user's work process. In a cognitive task analysis, we built an expanded GOMS model to account for user interaction at the procedural level. The analyses revealed that the system's physical setup made it difficult to be integrated into user's primary patient care tasks and that the interface design put high demand on users' information processing resources at both the cognitive and perceptual-motor levels. These results complemented our previous work of heuristic evaluation of the same system but allowed us to examine software usability issues in a broader context as well as at a more fundamental level. The expanded GOMS analysis technique we introduced here is also useful in the revision of the software's user interface.