Numerical versus graphical aids for decision-making in a multi-cue signal identification task

Decision aids are commonly used in tactical decision-making environments to help humans integrate base-rate and multi-cue information. However, it is important that users appropriately trust and rely on aids. Decision aids can be presented in many ways, but the literature lacks clarity over the conditions surrounding their effectiveness. This research aims to determine whether a numerical or graphical aid more effectively supports human performance, and explores the relationships between aid presentation, trust, and workload. Participants (N = 30) completed a signal-identification task that required integration of readings from a set of three dynamic gauges. Participants experienced three conditions: unaided, using a numerical aid, and using a graphical aid. The aids combined gauge and base-rate information in a statistically-optimal fashion. Participants also indicated how much they trusted the system and how hard they worked during the task. Analyses explored the impact of aid condition on sensitivity, response bias, response time, trust, and workload. Both the numerical and graphical aids produced significant increases in sensitivity and trust, and significant decreases in workload in comparison to the unaided condition. The difference in response time between the graphical and unaided conditions approached significance, with participants responding faster using the graphical aid without decrements in sensitivity. Significant interactions between aid and signal type indicated that both aided conditions promoted faster responding to non-hostile signals, with larger mean differences in the graphical aid condition. Practically, graphical aids in which suggestions are more salient to users may promote faster responding in tactical environments, with negligible cost of accuracy.