# Motion Sickness in Mixed-Reality Situational Awareness System
## 5 Results
### SSQ Change over Time  
Understanding the dynamics of motion sickness and its thresholds is critical for ensuring a comfortable and immersive virtual reality experience. In this section, we delve into the results of long-term tests, focusing on the change of the SSQ scores over time and the establishment of motion sickness thresholds. The outcomes of extensive long-term tests provide us with valuable insights into the trajectory of SSQ changes over extended durations and the convergence of these changes. By analyzing the baseline curve of SSQ change over time, we gain an overall perspective of how SSQ scores tend to increase over prolonged periods until they level off. This baseline curve, in conjunction with the level-off period and its corresponding value, serves as a means to assess the disparity between simulation and field tests. The adaptation of simulation test results onto field tests is facilitated through this comparative approach. Across the spectrum of tests, encompassing both field tests and simulated experiments, a notable motion sickness threshold emerges. Approximately at an SSQ score of 75-80, users exhibit signs of motion sickness-related effects. Beyond this threshold, impairing symptoms become prominent. The upper limit of SSQ scores that users can tolerate before discontinuation lies within the range of 100-120 SSQ score. The lower bounds of these lines have been visualized in Figure 7.  
Figure 7: Logarithmic, polynomial, exponential curvature and linear regression lines on the gathered SSQ data. The top plot contains the raw measurements, the bottom two are MSQ scaled with MSQ being set to 0 and 5.0, the median in the data set. The green dotted line denotes the first impairment line and the red dotted line denotes the approximate upper limit. The magenta dots are raw measurement samples. This figure and all following figures have time in minutes as the \(x\)-axis. Visualizing these thresholds, a plotted representation includes user data recorded for durations exceeding 15 min. Instances where users crossed the green dotted threshold line of 75 SSQ score reported symptoms causing impairment. Crossing the more critical red dotted line of 100 SSQ score led users to a point where they were unable to continue. The data encompasses general trends, though it should be noted that two anomalous edge cases were excluded due to their rapid and severe SSQ score increase. These cases were attributed to erroneous tests, showcasing SSQ scores surpassing 100, and resultant impairment. In both cases, the test setup experienced frame-rate drop unrelated to the experiment, causing a rapid increase in SSQ scores. When searching for the best fitting function for the given dataset, linear regression was first applied. This fit the dataset quite well while the experiments lasted up to 15 min. The root-mean-square deviation (RMSE) for linear regression on all of the data was 27.4, while for the MSQ-scaled results, RMSE was 24.5. Once longer tests were conducted, it became apparent the SSQ results tended to level off at around 30 to 40 min. The RMSE for a logarithmic curve on all of the data was 23.9 and for the MSQ-scaled results RMSE was 20.1. Both a polynomial as well as an exponential fit were also tested during this time. While the exponential fit had a slightly worse RMSE (24.1 and 20.2), the polynomial fit had a better RMSE (23.5 and 19.8) than the logarithmic function. Manually reviewing the fit, it was apparent the low overall scores of the longest tests greatly impacted the polynomial fit, causing it to slope downwards after the 45 min mark. As this sort of a reduction in MS was not observed on individual test subjects, only on the data as a whole, the fit was discarded as being caused by a lower number of \(>\)45 min tests. For fitting, 61 separate test results were used, which translated into 244 data points with a mean of 24.8 min and Standard Deviation of 18.3 min. Similar RMSE MSQ scaling patterns were found when only fitting for experiments where the tests lasted longer than 15 min.