The Effects of Automated Vehicle Behavior Explanations on Drivers’ Physiological Responses in High-Risk Situations

Automated vehicles (AVs) have the potential to improve road safety, but unexpected behaviors in safety-critical situations can increase driver discomfort, stress, and distrust. While prior work suggests that AV explanations may improve trust, anxiety, and user experience, their physiological effects remain underexplored. This pilot study examined whether speech-based explanations influence driver stress after safety-critical driving events. Fourteen participants viewed five 2-min driver-perspective driving videos that varied by risk level and explanation condition. Heart rate and galvanic skin response were analyzed during the 40 s following each explanation. Results showed that explanations were associated with significantly higher LF/HF ratios in both low risk and high risk conditions, higher GSR mean amplitude in low-risk conditions, and higher SDNN in high-risk conditions. Explanations increased physiological arousal, potentially indicating greater engagement and attention. Findings may inform intelligent AV explanation systems that support safer real-time driver feedback.