The Influence of Initial Overtrust on Pedestrian Behaviour in Response to Incongruent Behaviour of Connected and Automated Vehicles

Abstract

This study examined how pedestrians interact with connected and automated vehicles (CAVs) of various sizes, whilst using external human-machine interfaces (eHMIs) to improve pedestrian safety. Previous research demonstrated that congruent implicit and explicit CAV communications increased pedestrians' willingness to cross, but has not yet addressed the effect of initial overtrust during incongruent implicit and explicit CAV communication. Using an online video survey, we tested the generalizability of Lau et al.'s (2022) findings in right (Netherlands) and left (UK) driving countries. Additionally, we compared pedestrians’ willingness to cross between participants with initial overtrust and no initial overtrust in the respective countries. Therefore, participants observed rendered videos of a mixed-traffic environment with various-sized CAVs, displaying congruent and incongruent implicit and explicit CAV communication. The results validated Lau et al.'s findings for both countries. However, vehicle size didn't significantly influence crossing behaviour as opposed to Lau et al.'s work. Initial overtrust consistently boosted willingness to cross, irrespective of vehicle size, country, or communication congruency. Countryspecific responses to eHMI status and congruency emphasized the complexity of formulating universal CAV traffic rules. Acknowledging limitations, such as unverified overtrust cut-offs, future work should design more realistic settings for understanding size differences and optimizing CAV interactions and explore the reliability and validity to test initial trust.