# A Study on Ergonomic Layout of Automotive Electronic Shift Buttons
## 4 Discussion
In contrast, 2 of the 11 respondents in the novice driver group stated that it would be desirable to swap the positions of the D and R buttons (i.e., to change the order to P-D-N-R by applying the compatibility principle instead of the consistency principle) to improve L9. The aforementioned results indicate that the ergonomic principle that was considered important when designing shift button layouts can vary depending on the level of driving experience. For the novice driver group, in _Research activity 2-2_, L12 showed higher mean scores than L11; L3 showed higher mean scores than L9; and L8 showed higher mean scores than L7 (Table 8). These findings suggest that the compatibility, functional similarity, and stereotype principles should be considered when designing shift button layouts for novice drivers. In particular, the importance of the compatibility principle for the novice driver group confirmed in _Research activity 2-2_ is consistent with the result of _Research activity 2-1_, wherein the compatibility principle was more significant than the consistency principle for novice drivers. In general, it is known that the user learning speed and satisfaction are improved, and the reaction time and error rate are reduced in a system to which the compatibility principle is applied [18]. Given that novice drivers are inexperienced drivers who generally have inadequate driving skills and difficulties perceiving traffic conditions [30], it is important to apply the compatibility principle when designing shift button layouts for them. In the experienced driver group, L1 had higher mean scores than L2; L3 had higher mean scores than L4; and L9 had higher mean scores than L10 (Table 9). Here, L1, L3, and L9, which received high marks, were the layouts in which the consistency principle was applied. These results are in accordance with the existing literature, which states that it is easier for users to learn and process information in systems designed to be similar or identical to existing systems [19]. According to a previous study [31], unlike a new driver, an experienced driver may have even more difficulty adjusting to a vehicle because the previously acquired habits may interfere with the new skills required, which becomes particularly critical in emergency situations in which quick and accurate responses are needed. Thus, it is apparently important to apply the consistency principle when designing shift button layouts for experienced drivers. The aforementioned results suggest that for novice drivers, among the four layouts (L1, L2, L3, and L4) that received high marks in _Research activity 2-1_, L4--to which the compatibility, functional similarity, and stereotype principles that were found to be important in _Research activity 2-2_ were applied altogether--can be recommended as the most ergonomic layout. For experienced drivers, L1, L3, and L9 can be recommended as the most ergonomic layouts. These layouts not only received high marks in _Research activity 2-1_, but also incorporated the consistency principle that was found to be important in _Research activity 2-2_. In summary, as an answer to **Research question 1** (What constitutes an ergonomic electronic shift button layout? ), it can be concluded that L3 is the best layout in terms of ergonomics, regardless of driving experience. Given the finding that the layout evaluations varied depending on the level of driving experience, it would be more desirable to consider the level of driving experience when designing layouts. Regarding **Research question 2** (How does the ergonomic performance of electronic shift button layouts vary depending on driving experience? ), L4 can be recommended as the most ergonomic layout for novice drivers, and L1, L3, and L9 can be recommended for experienced drivers. The current study has both practical and theoretical implications. First, it may help not only prevent driver confusion and erroneous operation, but also improve driving safety and convenience by providing ergonomic design guidelines for shift button layouts.