## 7 Limitations and Future Work  
This research has several limitations, which could also serve as directions for future work. One notable limitation was that during the experiment, we did not consider whether participants' relative body positions in the real world should be synchronized with their avatar positions. For our case, this may not have a significant impact as the distance between participants was short. However, for a more rigorous experimental design, they will be coincident in the next main study. On the other hand, when the distance among users is large, the direction of sound could have an effect on the user experience (e.g., if users are facing different directions). In future studies, this element may need to be considered when dealing with colocated collaborations. Regarding the position arrangements, we did not include a face-to-face possibility as one of the major forms for collaborating in real-world scenarios. We did this because of the relatively large size of the user interfaces and 3D visualizations, which may block the view of participants from seeing each other. In addition, instead of strictly controlling the time in each position arrangement, we gave the participants the freedom to choose their preferred position(s) because we wanted to find out participants' preferences for each arrangement. Given that we now know their preferences, in the near future we plan to run a more controlled study on both interaction and position and try to distill further insights that can guide the design of collaborative VR environments.  
We did not use a high-fidelity avatar because we did not want the physical features and facial expressions to become a confounding variable in our study. Instead, we chose a simple avatar representation in which users of a pilot study indicated that their features were not culturally orientated and were sufficient to give them a good awareness of the other user's actual physical movements. Similarly, we did not explore the suitability of the interaction techniques provided in the VR environment. As prior research shows that the types of interactions provided in an interactive environment can affect exploration and sense-making [60; 71], it is important to explore what types of interactions are suitable in VR collaborative environments. A user-elicitation approach with multiple users is one way to explore the design of simple interaction techniques [72; 73] or more complicated ones, for example those that include haptics feedback [74] and involve other body parts in addition to users' hands [75].  
Finally, as a pilot study, our sample size was small and lacked statistical power to do more robust analyses. Given the number of participants we had per group, we also acknowledge that the results and interpretations of this pilot study are only predictive and may have been underpowered to detect significant differences in certain aspects. On the other hand, the number of participants is within the normal for this kind of experiment (e.g., see [76]), and the results still led us to several useful findings and observations that have some practical implications. However, further experimentations will be needed to more precisely understand how collaborative modes and position arrangements can influence task performance and immersive experiences of users. In a future study, we will use a larger and possibly more representative sample pool when the situation for large-scale studies is possible.