Comparative Study on Differences in User Reaction by Visual and Auditory Signals for Multimodal eHMI Design

External human–machine interfaces: Gimmick or necessity?

“…Most of the eHMI research thus far has been conducted online or in virtual-reality environments, with little opportunity for visual or cognitive distraction. There is a limited but growing number of eHMI studies conducted with real vehicles, but typically in simple settings such as parking lots (Ahn et al, 2021;Chen et al, 2020;Hensch et al, 2020;Liu et al, 2021), indoor environments (Burns et al, 2019;Reschke et al, 2018), test tracks (Faas et al, 2021;Fuest et al, 2020;Horn et al, 2021), or roads with otherwise restricted access (Barendse, 2019;Dey et al, 2021a;Habibovic et al, 2018;Joisten et al, 2019;Morales Alvarez et al, 2019;Mührmann, 2019;Papakostopoulos et al, 2021;Zadeh Darrehshourian, 2021). Research in real traffic is still relatively rare (Cefkin et al, 2019;Forke et al, 2021;Merat et al, 2018;Mirnig et al, 2021;Monzel et al, 2021), and some evidence concurs that eHMIs will have to compete with other visual cues in the environment.…”