Effects of In-vehicle Auditory Interactions on Takeover Performance in SAE L2 Semi-automated Vehicles

Abstract

Commercially available automated vehicles require drivers to maintain focus on their driving environment and be prepared to fully control their vehicles (i.e., perform a takeover) when critical incidents occur (e.g., sudden automation failures). Therefore, drivers are discouraged from engaging in non-driving tasks that cause visual or manual distractions. Auditory interactions, despite being considered a safe alternative, can consume the attentional resources of drivers, causing them to respond poorly to critical situations. This study investigates (1) how varying levels of auditory interactions affect takeover performance and (2) what physiological contexts are related to the takeover performance in SAE Level 2 automated driving. For the investigation, 50 drivers wore wearable devices that collected various physiological signals and performed six different auditory tasks during L2 automated driving in a simulator-based experiment. The results showed that auditory interactions could degrade the takeover performance and that the task demand for auditory interactions nonlinearly affected the takeover performance, possibly owing to behavior changes intended to prevent the task difficulty from becoming excessively high. Additionally, physiological contexts such as pupil diameter, dispersion of eye movements, and inter-beat interval, were found to be related to the takeover performance. Subsequently, we discussed drivers’ behavior changes, practical deployment of in-situ physiological measures, and design implications for mitigating the degradation of takeover performance due to auditory tasks.