Automated vehicles are pictured as the future of transportation, and facilitating safer driving is only one of the many benefits. However, due to the constantly changing role of the human driver, users are easily confused and have little knowledge about their responsibilities. Being the bridge between automation and human, the human-machine interface (HMI) is of great importance to driving safety. This study was conducted in a static driving simulator. Three HMI designs were developed, among which significant differences in mental workload using NASA-TLX and the subjective transparency test were found. An electroencephalogram was applied throughout the study to determine if differences in the mental workload could also be found using EEG’s spectral power analysis. Results suggested that more studies are required to determine the effectiveness of the spectral power of EEG on mental workload, but the three interface designs developed in this study could serve as a solid basis for future research to evaluate the effectiveness of psychophysiological measures.

Until fully automated vehicles are widely spread, human drivers will remain indispensable. Until then, driving tasks exceeding the operational boundaries of the vehicle would be delegated to drivers by take-over requests, with the driver as a fallback operator. In cooperative approaches, an appropriate interface is essential for driving safety to prevent accidents. In this study, we propose not to rely on the commonly used touchscreen but on the natural habituated interface (NHI) in the form of the steering wheel, which is highly trained during manual driving. Using safety-critical driving scenarios, we compared the safety, usability, and criticality of both interaction approaches in a driving simulator experiment (N = 26). Our results indicate a significantly lower number of dangerous overtakes leading to accidents; and a higher usability score when using the NHI compared to the touchscreen interface.