## 5 Discussion  
Based on the results of this study, a 3D microgesture set of 19 microgestures is proposed for 20 commands used in a VR or AR system, determined by popularity with adjustment. The microgestures proposed in this study were from a set of microgestures designed by ergonomists who have experience in designing gestures and tools for human-computer interaction that minimize discomfort and fatigue and optimize interaction efficiency. Users performed 3D microgestures with the forearm and hand on a table to reduce the loads to the neck and shoulder muscles [48]. Therefore, with these gestures, users should be able to perform the gestures repeatedly while interacting with VR/AR displays. Furthermore, the gesture-command combinations were selected by participants based on their prior experience and familiarity with gestures used for touch screens making the findings acceptable to others. Additionally, the assignment of microgestures to commands was completed by 40 participants with multinational backgrounds improving acceptability across cultures. There was a significant difference in comfort and privacy ratings on the proposed microgesture set between participants from China and those from the US and Europe (\(p<0.05\)) which demonstrates that nationality has some effect on user preference of microgestures. Therefore, the development and evaluation of universal gesture sets should include participants of different nationalities. The commands assigned to microgestures will vary from application to application. It is likely that a particular application will just use a subset of the proposed microgesture-command set. For example, microgestures used to watch an interactive movie with a VR HMD are likely to be needed for just a few commands, such as _volume up/down_ and _pause_. A larger set of command and microgestures are likely to be needed by CAD designers using VR/AR HMDs, who may perform gestures for a prolonged period while conceptualizing their ideas. More research may be needed to optimize the microgesture-command set for specific applications. However, the generalized microgesture-command set developed here can be a starting point for such research. For the proposed gesture-command set, the correlation between the characteristics of preference and match was high, indicating that assigning gestures to commands based on popularity is a reasonable approach. Interestingly, comfort had a very strong correlation with privacy (R = 0.75). This may be due to comfort including assessment of both physical and emotional comfort; gestures involving very small finger or hand motions are both less \begin{table}
\begin{tabular}{l c c c} \hline \hline  & **USA \& Europe (\(n\) = 18)** & **China (\(n\) = 22)** & \(p\)**-Value** \\ \hline Preference & 9.46 (1.02) & 9.52 (0.43) & 0.81 \\ Match & 9.23 (1.01) & 9.21 (0.46) & 0.93 \\ Comfort & 9.43 (0.81) & 10.27 (0.82) & 0.01 \\ Privacy & 8.85 (1.06) & 10.2 (0.73) & 0.00 \\ Popularity & 12.1 (3.16) & 12.5 (3.43) & 0.53 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Ratings 1 for the proposed microgestures for participants from the US and Europe and from China. \begin{table}
\begin{tabular}{l c c c c} \hline \hline  & **Preference** & **Match** & **Comfort** & **Privacy** & **Popularity** \\ \hline Correlation & 0.12 & \(-\)0.01 & \(-\)0.13 & \(-\)0.14 & 0.65 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Correlations (R) of ratings 2 for the proposed microgestures between participants from China and the US and Europe. physically demanding and are not easily noticed by others. The agreement score had a weak positive relationship with preference and comfort, which may have been influenced by the way the experiment was conducted. The agreement score calculated based on multiple gestures selected for a given command in this study was lower than observed in prior studies [37; 42; 43; 44]. recalculating the agreement score based on the most preferred microgesture for commands increased the score.