User’s information needs when driving in automated vehicles

Background: With the development of progressively automated vehicles (AV), i.e., high and full automation, the role of a nowadays car driver executing the driving task or at least monitoring the automation and simultaneously the driving environment is turning into the future role of a mere user of the automated system. This raises the question of the amount of information conveyed by the on-board or internal Human-Machine Interface (iHMI) about the highly automated vehicle’s driving intentions the ‘driver’ or to-be user needs for user acceptance. This question might be even pronounced in highly automated driving situations with high uncertainty of interactions with other traffic participants, which is focused on in this study. Method: We used four urban traffic scenarios with high uncertainty of traffic participants’ interactions, i.e., a left-turn scenario through oncoming traffic (cars, cyclists, pedestrians), a right-turn scenario interacting with cyclists, and two bottleneck scenarios interacting with other cars or cyclists. In an explorative approach, we conducted two focus groups (n = 5 each) on the information about the driving situation conveyed via an AV’s iHMI needed for user acceptance. Focus groups differed in age (M = 22 yrs vs. M = 54 yrs) to cover a big variety of users. Both focus groups were introduced to highly automated driving and to the scenarios. They discussed the kind of information provided by the iHMI and the importance respectively for user acceptance. Results: The study results show that both focus groups differed with respect to kind and importance of information requested from the iHMI crucial for user acceptance: in general, the younger focus group requested especially information about the proper functioning auf the automation (e.g., mode awareness) whereas the older focus group requested rather information on the safe interaction with other traffic participants (e.g., position of cyclists). Conclusions: Results indicate that for highly automated driving situations with high uncertainty an iHMI interaction design adapted to the different user needs in contrast to a design for all is required for user acceptance. Results will be additionally discussed in the light of trust in automation