Highlighting Bicyclist Biological Motion Enhances Their Conspicuity in Daylight.

For safety purposes, it is critical that bicyclists be conspicuous to drivers. We report two experiments that investigated the benefits of bicycle taillights and fluorescent clothing for enhancing the bicyclist's rear conspicuity in daylight. In Experiment 1, 24 participants sat in a car parked on a closed road at each of three distances and rated the conspicuity of four bicyclists displaying taillights that varied in their placement, intensity, and mode. The results confirmed that bicycle taillights can significantly enhance conspicuity in daylight. Varying the placement of the taillights revealed that having an "always on" taillight mounted to each of the rider's ankles was the most conspicuous location to mount taillights, and this effect was particularly strong at greater viewing distances. For seat post-mounted taillights, flashing taillights were rated as more conspicuous. In Experiment 2, 186 participants were passengers on a short drive during which they pressed a button each time they recognized that a bicyclist was present. Each participant passed a test bicyclist wearing one of four clothing configurations. When the cyclist wore a fluorescent yellow jersey paired with fluorescent yellow leg covers, participants responded from a distance that was 3.3 times greater than when the cyclist wore the same jersey without the yellow leg covers. Both of these experiments demonstrate that highlighting bicyclists' pedaling motion enhances their conspicuity when viewed from behind. These results further emphasize the conspicuity benefits of biological motion and provide bicyclists with techniques to enhance their own conspicuity in daylight.