Consistency in Subjective Judgments of Service Vehicle Type Based On Vehicle and Flashing Light Colors

The present study focused on the consistency in perceiving the intended function of a simulated service vehicle when its color, the color of its flashing lights, and its flashing light pattern varied. Tests were conducted during the day and at night. Participants driving along a test track were presented with a red or yellow vehicle equipped with either red or yellow flashing lights. Although driving speed differed only between ambient lighting conditions (daytime and nighttime), consistency in the participants’ perceptions of the simulated situation (emergency or nonemergency) was higher when the color of the vehicle was the same as the flashing lights. Ambient lighting conditions also significantly influenced participants’ judgments of each situation because the color of the vehicle was more apparent during the day than during the night with only headlight illumination on the vehicle. The flash pattern (faster or slower) had a negligible impact on participants’ perception of the simulated situation. These results reinforce previous findings that coordinating the colors of the flashing lights and the vehicle better informs drivers about the situations they encounter along the road, improving the safety of emergency responders and other service workers.