Evaluating Alternate Visualization Techniques for Overview Displays in Process Control

OCCUPATIONAL APPLICATIONS Three alternate visualization displays, currently being used in industry to represent similar high-level process conditions, were evaluated here regarding their relative effectiveness in terms of operator performance and situation awareness in an industrial control room environment. A “surface chart” visualization outperformed the other two displays (“heat map” and “visual thesaurus”) in detection and response time performance measures, though there were no significant differences in situation awareness. The surface chart visualization presents display designers with a potential improvement over more traditional visualizations that use features that are similar to heat map and visual thesaurus. TECHNICAL ABSTRACT Background: Different types of visualizations are currently being used in refinery control rooms across the globe. In these multi-task environments, operators must properly interact with technology to acquire situation awareness so that they can prevent and respond effectively to abnormal situations. Purpose: The purpose of this research was to identify which visualization of three alternate overview displays (surface chart, heat map, and visual thesaurus) better promotes operator performance and situation awareness in a dual-task environment. Methods: A total of 48 operators participated in a human-in-the-loop test bed simulating a crude oil process monitoring task. Dependent measures included situation awareness, click accuracy, response time, perceived workload (NASA task load index), and secondary task performance (multi-attribute task battery). The experiment used a 3 (display type) × 2 (complexity level) × 2 (trial) mixed-factorial design. Results: The surface chart display was superior in response time and accuracy in detection of gauge state changes. The surface chart also outperformed the heat map display on a portion of the secondary task. No differences were observed for perceived workload and situation awareness between displays. Conclusions: The single graphical object used within the surface chart display may have attributed to the higher detected performance measures. Additionally, it is also suggested that the surface chart may require less effort to detect state deviations due to the noted benefits within the literature on integrating information and using moving lines instead of changes in color. The implications of these findings are that there may exist two levels of a “high-level overview display” for the process industry, one that efficiently shows how a process is running via a single integrated object and another that shows a breakdown of a process through multiple graphical objects.