The impact of drowsiness on in-vehicle human-machine interaction with head-up and head-down displays

Abstract

Various studies show that drowsiness reduces driver alertness and can significantly affect driver performance. In this paper, we investigate the effect of drowsiness on the interaction with the in-vehicle infotainment system (IVIS) while driving. The motivation was to investigate whether a specific type of user interface can provide better performance and lower distraction when the driver is drowsy. The users were asked to navigate a vehicle in a driving simulator and simultaneously perform a set of tasks of varying complexity first when they were rested and alert and then when they were drowsy, after 7 h without sleep. A hierarchical, list-based menu was presented using a stereoscopic head-up display (HUD) and a head-down display (HDD). Based on the results, no general and statistically significant connection was found between drowsiness and driving performance. Surprisingly, the secondary task performance was even better when participants were drowsy, which was evident from the faster task completion times. This could be attributed to extra efforts invested in executing tasks as a result of the participants being aware of their drowsiness. However, when comparing the participants’ performance using HUD and HDD displays, the results showed that using HUD introduces less mental fatigue than using HDD but only in rested and alert condition. No significant difference between the displays was found in the drowsy state.