Uncertainty on Display: The Effects of Communicating Confidence Cues in Autonomous Vehicle-Pedestrian Interactions

Uncertainty is inherent in the decision-making of autonomous vehicles (AVs), yet it is rarely communicated to pedestrians, hindering transparency. This study explored approaches and outcomes of communicating AV uncertainty to pedestrians. Two communication approaches (explicit and implicit) were developed to convey different confidence levels (high and low) of AVs. Through a within-subject virtual reality experiment (n=26), we evaluated these approaches in a crossing scenario, examining their impact on participants’ perceptions of safety, trust, and user experience. Our results show that explicit communication is more effective and preferred for conveying uncertainty, fostering safer, more trusting, and positive interactions. Conversely, implicit communication introduces ambiguity, especially when AV confidence levels are low. This research advances the understanding of how uncertainty communication influences pedestrians and provides valuable guidance for designing future eHMIs to effectively communicate uncertainty.