Exploring False Warnings and Modalities for Emergency Vehicle Alerts and Their Impact on Driver Behavior

Weibull, Kajsa; Norell, Marius Brudvik; Thorslund, Birgitta; Lidestam, Björn · 2026 · Crossref

DOI: 10.1177/00187208261436744

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Summary

This study investigates the impact of warning modality and the sequence of false alarms on driver behavior when receiving Emergency Vehicle Approaching (EVA) alerts. The research addresses the need to optimize in-car warning systems to reduce delays for emergency vehicles while mitigating the negative effects of false warnings, which can erode driver trust and compliance. Specifically, the authors examine whether auditory or visual alerts yield faster move-over responses and how the order in which drivers experience true versus false alerts influences their subsequent reactions. The researchers conducted a driving simulator experiment with 80 participants using a 2 (Event) × 2 (Modality) × 2 (Warning Combination) split-plot factorial design. Participants drove for 30 minutes on a simulated highway and received three EVA alerts, one of which was false. Half of the participants received auditory warnings (a voice message), while the other half received visual warnings (dashboard text). The sequence of alerts was manipulated into two groups: True-False-True (TFT) or False-True-True (FTT). The primary dependent variable was the delay time imposed on the emergency vehicle, calculated by comparing the distance traveled at preferred speed versus actual speed when blocked by the participant’s vehicle. The results demonstrated that auditory warnings were more effective than visual ones, with drivers receiving auditory alerts moving over significantly faster (mean delay 3.37 seconds) compared to those receiving visual alerts (mean delay 5.41 seconds). Regarding false alarms, a significant order effect was observed: drivers who experienced a false warning before their first true warning (FTT group) exhibited longer delays during that first true event compared to the TFT group. However, this order effect disappeared in the second true interaction, where both groups showed similar delay times. This indicates that while an initial false alarm impairs immediate compliance, drivers adjust their behavior once they have experienced an equal number of true and false alerts. The findings imply that auditory modalities are preferable for EVA systems to minimize visual distraction and improve response times. Furthermore, the study highlights that while false alarms initially degrade performance, drivers are robust in adapting to system reliability over time, provided they have experienced true alerts. The authors conclude that warning design must account for modality and the potential for false alarms, suggesting that multimodal alerts might be beneficial in high-urgency scenarios, though auditory alerts remain superior for standard EVA warnings. These insights are critical for designing intelligent vehicle systems that maintain driver trust and ensure efficient emergency response.

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-09; verification: verified.

Topics

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• auditory warnings
• warning design
• feedback modes
• multimodal feedback
• haptic feedback
• auditory

Information type

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• Applied Guidance: design guidelines
• Empirical Findings: behavioral performance data
• Theoretical Contribution: theory or model