# A Multi-Object Grasp Technique for Placement of Objects in Virtual Reality
## 5 Results
### Subjective Results  
Subjective results are shown by condition and scenarios: NASA-TLX in Figure 6, and SUS in Figure 7. Qualitative questionnaires for Desktop and Shelf scenarios were answered at the end of the first session, questionnaires from the Room scenario were gathered in session 2. _NASA-TLX questionnaire:_ The users felt more comfortable in terms of difficulty and system complexity in the real condition. The required mental effort to complete the tasks under this condition was quantified as the lowest, and so was the physical one. The users also indicated that the real-life condition made the activities more dynamic and they felt successful in finishing the task without putting too much effort into them. They did not experience frustration during the real-world scenarios. Under the VR conditions, users were more comfortable with the single-object technique in terms of the needed effort to successfully complete the tasks with a lower mental effort than when using the multi-object grasp technique. Nevertheless, the users also reported that the physical effort was larger when using the single-object technique. They also felt they had to make more of an effort when using the single-object grasp to finish the activities. In regard to the physical effort, the multi-object grasp technique was reported to be less tiring than the single-object grasp technique. The results also show that the users found the dynamics of the activity faster when they were able to use the multi-object grasp technique. Overall, the users felt capable of completing the activities successfully in all the scenarios. Even though the real-world scenario felt the easiest and the VR with multi-object the hardest, the differences were not significant. The users felt a higher frustration when they were using the single-object grasp technique than the multi-object grasp one. In addition, they felt that the general effort to complete the activities was higher when using the single-object rather than the multi-object technique. Figure 6: NASA TLX: (**a**) Desktop and Shelf scenarios; (**b**) Room scenario. Error bars indicate standard error. Figure 7: SUS results: (**a**) Desktop and Shelf scenarios; (**b**) Room scenario. Error bars indicate standard error. SUS questionnaire:Users had a preference towards the real environment condition. They preferred the real world system, followed by the VR with multi-object grasp technique. They also found the real environment condition less complex than the two VR conditions and they did not think they would need technical help to complete the tasks in that situation. The real-life system was the least cumbersome and the one in which they felt more confident, with no need to learn instructions before the execution of the tasks. Focusing on the VR conditions, the users would prefer to use the multi-object grasp technique frequently, even though they found this technique to be the most complex one. The users did not find any of the conditions exceedingly complex, although the multi-object grasp technique was perceived as the most difficult one. The users felt that they would need more support to use the multi-object grasp technique. The users found that the functions were well integrated in all the conditions with multi-object obtaining the lowest score. Users did not encounter many inconsistencies, but they found more in the multi-object grasp technique than in the single-object grasp technique. Users reported that the single-object technique is faster to learn than the multi-object one. Users did not find any of the conditions cumbersome to use, although the multi-object technique was found to be the most cumbersome. They also felt less confidence when using the multi-object grasp technique than when using the single-object one. In conclusion, although users find the multi-object grasp technique more difficult in some aspects and with a steeper learning curve, the physical effort to finish the tasks was lower.