Assessing mental workload and situation awareness in the evaluation of real-time, critical user interfaces

Graduation date: 2010While there are many ways to evaluate a user interface design, the user's mental workload and situation awareness (SA) are particularly important considerations in the supervisory control of safety-critical systems. Typically, operators of these systems must monitor high-volume, time-sensitive status information. Interface design for this domain can be challenging and should consider both workload and SA, because presenting too much information can lead to cognitive overload. For highly automated systems, operator underload and poor SA are also potential issues. This study reviewed subjective and objective techniques for assessing workload and SA, and analyzed the suitability of each. In recommending a suite of measures, we sought general applicability to the real-time, critical application domain, but we focused particularly on next-generation multi-modular reactor control rooms. Based on a human factors experiment in which each participant\ud monitored and controlled multiple simulated reactors, we recommend the NASA-TLX instrument and a chest-band heart rate monitor for assessing mental workload. For the assessment of SA, we recommend using eye gaze data. In support of summarizing the results of user interface evaluation along multiple dimensions (e.g., workload, SA, user error), we propose that these inter-related constructs be presented in a single,\ud standardized, task-based format