## 6 Discussion  
At around 17 min as shown in Table 3, the total participation time of the subject was quite long. Common marketing questionnaires can be completed within several minutes. An efficient time range of 10-20 min for scientific surveys could be identified out of the literature [38], which shows that our survey duration is within the higher recommendation time. On the one hand, since the complete survey was globally published with free access, a longer time can be used as a kind of protection against not meaningful or just-for-fun answers. On the other hand, if the number of questions is too high, the subjects might start to lose interest or become annoyed, which leads finally to a cancellation without finishing the survey. Within our analysis, we only considered fully completed answers. Definitely, the comments out of the quantitative results can be interpreted as meaning full and topic-based participation which points to the fact that we reached a valuable target group, compare Figure 10.  
After the collection of the personal information, the first lighting question asked about color preferences realized as a line-shape at the door position. Within all four participating groups, Chinese male and female, European male and female, three categories could be identified named as polarization, attraction and merging as shown in Figure 2. Color preferences between genders and origins are already scientifically established. In one investigation, a comparison between people from China and the United Kingdom, the resulting preference tendency followed synchronized within all gender distributions with a small variation for the UK male group for several hue angles [39]. The average highest preference level within females was for the reddish-pink and for the male the bluish-green area, which partially match our results where the blue-cyan area was the highest preferred level, too. Since in our study the pink hue is missing, there is no comparison. In addition, there might be a physiological-evolutional-gender-based explanation which is connected with the opponent color theory by [PERSON], on chromosome or on testosterone levels, as mentioned in some theories [40; 41]. A more reasonable explanation might be on the context-based level: a color-preference is grounded based on growing-up, learning, education, social experiences and background as already shown by a color rating of daily used objects [42]. Supporting studies found that the preference rating for the color red clearly depended on the context in which it was rated [43]. The gender and origin merging effect of the multichromatic one can also be explained more besides the opponent color theory, because sunlight preferences might be available within all people. In addition, for warm-white and cold-white ones a recently performed study confirmed a higher satisfaction level within their 29 Korean students as subjects within a vehicle context [23]. The second part of the survey showed connections between joy, fatigue, attention and relaxation within the 10 proposed hues. For joy and fatigue there was no color identified which has a significant positive impact to one of these emotions. In comparison to attention and relax, where clear colors could be identified either for support or contradiction within genders and origins. Other studies found more lighter colors like yellow, orange or red are connected to joy and in addition with blue and green color for relaxation [44]. The missing clear color connection between joy and fatigue in our survey might be connected with the way how the colors are presented: we used a black dark-mode theme with small line lights positioned at the door for a major signaling purpose. The ratio of the color compared to the background might be too low to achieve a high-level feeling like joy or fatigue. On the other hand, to achieve an impulse of attention or relaxing, these settings might be useful as we could achieve there more significant differences within genders and origins.