## 4 Discussion
### The Role of VRT in the Design Process  
The use of VR resulted in improved in-design reviews between project partners. Similar to [PERSON] et al. [24], we found that VR can improve skills in identifying mistakes. During quick and dirty prototyping, it was also hard to communicate the design to the relevant stakeholders. Also, for this reason, it would be appropriate in large projects where the impact of the VR is meaningful, especially when it is used for communicating about the doubts faced during the project. VR could help in reducing the fuzziness involved in the design process. It is remarkable how clearly people could understand the prototype with little VR development effort. This visualization made the buzzwords used in the project tangible since many partners only had the description of the project as a reference, which was too abstract. The VR test made the project visual and explicit. This aligns with previous research by [PERSON] et al. [31], which emphasizes VR's potential to enhance communication and collaboration in design processes. The visual and interactive nature of VR prototypes helps to overcome the abstract nature of traditional design representations, enabling a more concrete and shared understanding of the design among stakeholders. Contrary to this, testing the low-fidelity concept in its correct context without the correct physical materialization caused some problems regarding external validity. For example, renders caused confusion in respect to the scale of the box. In line with this, testing in an open tent lacked proper cues like depth, sound and the visual look and feel of the interfaces. As a critical note, it was reported by a researcher that paper prototypes during the testing in the field did not add much value. From the researchers applying the test's view, the VR prototype could have been deployed in this part of the NPD cycle. Since VR also has the potential to be used within testing in the field, (mobile) VR could become a practical tool for testing outside of a lab environment. For instance, combining VR with full colour passthrough, AR or lidar environment scanning could enhance the contextual realism of the testing environment. This multi-modal approach could offer a more comprehensive evaluation of the product's usability and user experience, leading to more successful design outcomes. The ease of use of VRT also helped a lot with inducing enthusiasm and fun while testing. This, in turn, helped in onboarding people onto the project. VR can be a powerful tool for eliciting enthusiasm, which can help to maintain involvement. Later, a physical setup could be built resulting from the feedback of the VR test in the field. The level of fidelity as opposed to the freedom to change the design was also discussed with the expert on project management, debating how far the imagination of the participant can be pushed; the developer in the loop (flexible model) vs. a final fixed build arose (rigid model) was also discussed. This demonstrates that there are still opportunities to explore. It implies that VR can be applied in more creative ways than envisioned at the start of the development. The higher the level of realism, the more that useful assumptions and conclusions can be drawn from the VRT (e.g., when using foot tracking by placing Vive trackers on foot). Iterative VR tests could be used to look for solutions when problems occur during testing. Also, using VR instead of a real test setup during COVID was a clever idea. It made the barrier for testing lower, since the headset could be delivered to the participants' workplaces. All in all, while VR was useful, it remains difficult to assess beforehand which aspects will be realistic to evaluate in VR and which will not. A difficult question to assess as well, is the duration of the development of VR tests in advance. It is partly determined by the complexity of the assignment and expertise level of the developer. This is an issue that might be hard to address using the current tools.