From Warnings to Workload: The Impact of Driver Monitoring System Warnings on Drivers' Self-Reported Workload

Driver Monitoring Systems (DMS) are designed to assist drivers by issuing warnings when distraction is detected. However, evidence from other warning systems suggests that warnings may also increase the workload of the driver. This study therefore examined the impact of DMS warnings on drivers’ workload, measured by the NASA TLX. Participants performed typical in-vehicle infotainment tasks during driving. For half of the tasks, the DMS was active and triggered warnings, whereas for the other half, it was inactive and did not trigger warnings. The results indicate that warnings, issued by the active DMS, resulted in a significantly higher self-reported workload, particularly in terms of higher perceived temporal demand and lower perceived performance. Furthermore, there was a significant positive correlation between the self-reported workload and the number of warnings. These findings underscore the necessity of carefully designing DMS to balance the benefits of distraction mitigation and the potential impacts on workload.