Inspiring External Human-Machine Interface Designs for Autonomous Personal Mobility Vehicle: Causal Discovering the Influence of Passengers' Personality Traits on User Experience

Abstract

As autonomous personal mobility vehicles (APMVs) are increasingly integrated into shared spaces, short-distance interactions between pedestrians and APMVs will become more frequent. To facilitate communication in shared spaces, APMVs equipped with external human-machine interfaces (eHMIs). Although the eHMI is primarily designed to communicate with pedestrians, its communication also affects the APMV passenger due to the short-distance interaction. This paper focused on the effect of passengers’ personality traits on their user experience when the APMV exhibits different eHMIs. An experiment was conducted in the field with 24 participants as APMV passengers who experienced three distinct eHMI types: eHMI-T (text-based), eHMI-NV (neutral voice-based), and eHMI-AV (affective voice-based). Through causal discovery analysis, our findings revealed that when the APMV is equipped with eHMI-T, various personality traits of passengers collectively influenced their user experience. In contrast, the eHMI-NV design demonstrated that personality traits had no direct influence on user experience. The eHMI-AV design primarily showed that agreeableness and extraversion negatively influenced concerns about drawing attention, which subsequently affected other user experience. Based on the results, this paper recommends designing different eHMIs based on the APMV ownerships, such as private or public shared APMVs.