# Distraction Potential of Vehicle-Based On-Road Projection
## 3 Study Results
### Part I  
A total of 39 subjects participated in the study. For one subject, the gaze data cannot be used due to a faulty calibration of the eye-tracking system. Only the overtaking maneuvers are examined according to the following definition: While the test person is being overtaken by the projection car, the projection car's headlamps are visible to the test person in the left exterior mirror (blue box in Figure 5). As the distance between both vehicles decreases, one headlamp disappears in the mirror. This moment is taken as the starting point for the evaluation period. The overtaking maneuver is considered to be completed as soon as the rear of the projection vehicle has passed the left A-pillar of the test vehicle from the driver's point of view. Typically, when maintaining the differential speed of 15 km/h, this takes 6 s.  
Some overtaking maneuvers cannot be carried out due to the traffic situation or technical difficulties, so in total, 221 overtaking maneuvers are carried out, of which 76 are with dynamic projection, 74 with static projection and 71 without projection. Figure 6 shows the relative number of glances to the individual areas of interest (AOI). The glances at the red AOI \"projection area\" (see Figure 5) are divided into glances at the projection vehicle itself and glances in front of it when a projection is switched on. In the second case, looking at this area offers the possibility to see the on-road projection. Figure 5: Eye tracking recording from the subject vehicle with six areas of interest (AOI) and glowing QR-code similar squares for eye-tracking calibration. Figure 6: Relative number of glances during overtaking maneuvers. With dynamic projection, 430 glances from 38 test persons are recorded during the overtaking maneuvers. The highest proportion of glances is clearly on the own lane. Six test persons look in front of the projection vehicle and potentially see the projected pattern (in total seven glances). The gaze duration of these seven glances ranges from 125 ms to 867 ms with an average of 323 ms (see Figure 7), and, with the exception of the most extended gaze, between 125 ms and 340 ms.  
Figure 7: Boxplots of the glance time while overtaking maneuvers on the (**a**) own lane (bars are cut off), (**b**) projection vehicle, (**c**) on-road projection, (**d**) right roadside, (**e**) interior, (**f**) left exterior mirror and (**g**) rear mirror. While static projection, four out of 395 glances in front of the vehicle are recorded from three persons (glance durations between 272 ms and 886 ms, average 492 ms). The distraction potential can be classified as non-critical overall. On the one hand, the gaze times are significantly shorter than even the more critical literature value of 1.6 s on distraction defined in Section 1. On the other hand, no conspicuous feature (e.g., steering behavior, acceleration and leaving the lane) in the driving behavior of the test persons is visible. The first part of the experiment ends with a questionnaire (see Figures 15 and 16 in the Appendix A) in which 37 out of 38 subjects state that they did not notice any light projection. Only one subject stated that he noticed two overtaking maneuvers with static projection. During the first overtaking maneuver with static projection, this subject looked at the projection for 886 ms and 272 ms during the second overtaking maneuver. The projection vehicle, on the other hand, is noticed by some subjects, mainly because of the license plate from a remote location in Germany and the luxury vehicle class. With this information, the questions about the first part of the experiment (compare Section 2) can now be answered:  
_How long do test persons look at the projections?_  
Based on the eye-tracking data, 11 glances of 8 different test persons are directed at the projection on the street. This is a percentage of 1.33% out of a total of 825 glances.