# Distraction Potential of Vehicle-Based On-Road Projection
## 3 Study Results
### Part II  
As described in Section 2.1, the test persons are informed about each overtaking maneuver in the second part of this study. From the 38 test persons, two data sets are not available. Another test person changes the sitting position so much during the overtaking maneuvers that an evaluation of the gaze data is also not possible. Therefore, 35 data sets are evaluated.  
While the definition of the starting point of an overtaking maneuver remains unchanged compared to the first part of this study, the end is individually adapted to the gaze behavior of the subject due to the more extended fixation of the projection compared to Part 1. An overtaking maneuver is considered complete when the driver no longer looks in front of the projection vehicle. According to this definition, an average overtaking maneuver takes about 8 s in this part. A total of 140 overtaking maneuvers with 70 static and 70 dynamic projections each are evaluated.  
In the first part, the red AOI (see Figure 5) is subdivided into glances at the projection vehicle and glances at the on-road projection since the dominant portion of the glances is directed at the projection vehicle. In this second part, it is the other way around, so this subdivision of the red AOI is not necessary.  
The gaze behavior changes significantly when an overtaking maneuver is indicated compared to the first part, as shown in Figure 8. The number of glances at the projection is now comparable to the number of glances at the own lane.  
An average gaze of a subject at the projection lasts 1083 ms. The longest uninterrupted look at the projection is measured with 6.85 s. Some subjects compensate the distraction by reducing their speed, especially during long gaze periods. After each passing maneuver, the questions of the questionnaire regarding the noticeability of the projection are asked again. The dynamic projection is evaluated by the subjects as better noticeable than the static one (see Figure 9 left, where 7 stands for a high noticeability).  
Furthermore, it can be stated that no significant information transfer takes place through the projection. Only two test persons were able to identify the excavator symbol correctly, and four test persons were at least able to recognize a vehicle. Seven test persons interpreted the projection as numbers or letters. In Figure 9 right, half a person has been added to the categories vehicle and letter/number, since one person do not decide whether the recognized projection should be a letter or a vehicle. The remaining 25 test persons were unable to identify the excavator symbol, even approximately (see Figure 9 right).  
With this information, the following question about the second part of the experiment (compare Section 2) can now be answered:  
_How well is the projected symbol perceived by the test persons?_  
All test persons stated that they can perceive the projection. However, only two test persons were able to identify it as an excavator. Four to five other test persons still recognized a vehicle (compare Figure 9 right).  
Figure 8: Relative number of glances during overtaking maneuvers.  
Figure 9: (Left) Boxplot of the noticeability of the projections evaluated by the subjects. (Right) Number of subjects who assigned the projection to an object category.  
On average, the dynamic projections are rated one scale level better than the static projections on a score of one to seven. From the second part, it can be concluded that the projected light is visible to other road users, but information transfer to them is practically non-existent due to a lack of recognition of the correct symbol. The study shows that dynamic projections are slightly more noticeable than static ones. In further research, it is useful to consider if there is a difference in identifying the symbol whether the projection is static or dynamic.