Effects of Partially Automated Vehicle Reliability on Vigilance Performance, Trust, and Workload

Partially automated vehicles control vehicle speed and roadway position but require drivers to monitor roadway and automation events that may go undetected by the automation. Although drivers must remain vigilant, their ability to detect and respond to roadway hazards declines over time. Higher automation reliability can lead to high trust resulting in overreliance and poorer monitoring. The study assessed drivers’ ability to remain vigilant when detecting hazardous automation events and how different automation reliability affects trust and vigilance. Participants completed a 40-minute simulated driving task under one reliability condition. Participants responded slower over time, suggesting a decline in vigilance toward hazardous automation behaviors. Moderate reliability supported better performance and user state. These findings suggest that while designers may aim to maximize reliability, consideration must be given to how reliability affects user performance and state.