# Impact of Latency on QoE, Performance, and Collaboration in Interactive Multi-User Virtual Reality
## 4 Results and Discussion
### Subjective Results
#### 4.4.3 Cybersickness  
Figure 17 shows the distribution of the cybersickness scores for each scenario, calculated as the difference with the pre-session baseline VRSQ. Figure 17a shows the VRSQ score, while Figure 17b,c show the sub-scales relating to oculomotor and disorientation symptoms, respectively. No significant differences were found between the four scenarios for VRSQ, oculomotor or disorientation ([PERSON]: \(p=0.219\), \(p=0.223\) and \(p=0.645\), respectively). For each of the three, however, scenario D (burst + latency) approaches significance regarding its difference from 0 ([PERSON] signed rank test, \(p=0.084\); \(p=0.081\) and \(p=0.061\), respectively). As such, this indicates a weakly significant increase in cybersickness symptoms with respect to the baseline questionnaire. As configuration B (burst) also shows a \(p\)-value of \(p=0.097\) ([PERSON] signed rank test) regarding oculomotor symptoms, burst effects inducing oculomotor symptoms seem to be the main representation of cybersickness in this experience. It is also interesting to note that scenarios A (no distortions) and B (burst) show a weakly significant higher occurrence of disorientation symptoms for User B compared to User A (Mann-Whitney U, \(p=0.090\) and \(p=0.116\) for A and B, respectively). A possible explanation is the fact that User B has to rotate more in the environment as they have to perform actions both at the table and the oven (which are oriented opposite to each other), therefore making this user role more susceptible to  
Figure 16: Overview of the subjective time estimation errors (= time estimation - actual time) for each of the four scenarios. The full orange line indicates the median, the green dotted line the mean. The bullets indicate outliers, which are defined as samples laying outside the interval \([Q1-1.5\cdot\text{IQR},Q3+1.5\cdot\text{IQR}]\), with IQR the Interquartile Range defined as \(\text{IQR}=Q3-Q1\). disorientation with regard to the real, physical world. However, as this difference is shown to be less pronounced for scenarios C (latency) and D (burst + latency), it seems that the presence of latency in the system is counteracting this phenomenon to some extent. As the feeling of presence inside a virtual environment is known to be correlated with the probability of cybersickness occurrence, one can assume that latency has a greater effect on the degradation of presence in multi-user VR than is the case for burst. Additional research is required, however, to confirm this assumption. Nevertheless, both burst and latency are shown to play a role with respect to cybersickness--on the one hand, burst is shown to be the main inducer of oculomotor effects, while on the other hand, latency is shown to counteract feelings of disorientation. In Figure 18, the results of the post-session question are shown in which users were asked to rank the four scenarios, without revealing the actual configuration, from most (1) to least (4) sickness-inducing (\"Please order the playthroughs from most (1) to least (4) sickness-inducing\"). Similar to Figure 13, a clear preference towards scenario A (no distortions) can be observed for User B, with five out of six subjects (four subjects did not fill in or incorrectly filled in the post-session questions) considering it as the least cybersickness-inducing scenario. For user role A, though, four out of eight participants (two subjects were excluded) considered scenario A (no distortions) to be the most or second to most cybersickness-inducing scenario.The same observation can be made for configuration D. Five out of six subjects with user role B considered configuration D (burst + latency) to be at least one of the two worst scenarios regarding cybersickness, and none of the subjects considered it to be the best. For user role A, though, three out of eight subjects assessed scenario D (burst + latency) to be the least or second to least cybersickness-inducing scenario.