Matters of State: Examining the effectiveness of lane departure warnings as a function of driver distraction

•This study examined the effectiveness of lane departure warnings as a function of driver distraction.•Lane departure warnings were more effective for lane departures that occurred when drivers were distracted.•The paper discusses the implications for adaptive automation using driver state monitoring systems. Lane departure warnings (LDW) have the potential to mitigate a significant number of lane departure crashes. Such safety benefits have yet been realized, in part due to drivers deactivating LDW systems. Perceived false alarms—where drivers receive a warning but feel the warning was unnecessary or incorrect—could lead to system disuse. In part, this could be a failure of LDW systems to account for the state of the driver. The current study investigated whether LDWs were more effective for drivers when they were distracted compared to when they were undistracted, using a high-fidelity driving simulator. During distracted lane departures, drivers with LDW responded faster and had less severe lane departures than drivers without LDW. During undistracted lane departures, there was no evidence of a benefit of LDW over no warning. These results suggest that lane departure warnings are most effective when drivers are distracted. This study suggests a need for driver state monitoring systems to enable adaptive automation.