Causal Discovery from Psychological States to Walking Behaviors for Pedestrians Interacting an APMV Equipped with eHMIs

This study aims to investigate the causal relationships from pedestrians’ psychological states to their walking behavior during interactions with an autonomous personal mobility vehicle (APMV) featuring automation capabilities ranging from SAE levels 3 to 5. A subjective experiment was conducted, where various external human-machine interfaces (eHMIs) were designed to induce participants to experience different levels of subjective feelings and generate corresponding walking behaviors. By employing a structural equation model named DirectLiNGAM to analyze the collected data for causal discovery, the results of causal discovery align with the hypothesized model of the pedestrian’s cognition-decision-behavior process. Furthermore, the experimental results have enriched the detailed causal relationships within the hypothesized model, i. e., the outcomes of situation awareness lead to a sense of danger, trust in APMV and a sense of relief; the outcomes of situation awareness, the sense of danger and trust in APMV lead to hesitation in decision-making; and the outcomes of situation awareness, the sense of danger and hesitation lead to walking behaviors.