## 3 Performance Verification and Results
### Results
#### 3.2.2 Experiment Two  
We tested the performance of the system using fourteen subjects (eight males and six females) for all different scenes (difficulty adjustment). The objective for the user is to direct the player to collect all the target objects in a short time using any chosen trajectory. Player positions and completion time are logged and reported here for comparison. Figure 9 shows the average time taken and the total trajectory length (total distance traveled in the \(x\)- and \(y\)-axis) for all scenes (levels). Scenes 3 and 10 are the most time-expensive in the experiment, although the trajectory length is longer in scene 10. This is attributed to the positioning of scene 3, i.e., before the user gets accustomed to controlling the interface. The trajectory of the two scenes (scenes 3 and 10) are shown in Figures 10 and 11. From this trajectory, it is clear that the EMG control is handled in a uni-dimensional manner by the user--indicated by straight vertical and horizontal lines--and further exacerbated by a setup that seems to enforce the regulation by using impenetrable horizontal and vertical collider walls. Figure 8: Game performance metrics showing scores and miss rate of control model for experiment 1 setup: (**a**) scores (total intercepted objects) for experiment one; and (**b**) average miss rate. Figure 9: Average performance of all subjects indicated by the completion time and trajectory length of the experiment scenes: (**a**) average completion time; and (**b**) average path length. Figure 11: The trajectory of the fastest subject (S2) and the slowest subject (S6) command input for scene 10 with corresponding completion time. Input Command  
In Figure 12, the red line central mark indicates the median, and the bottom and top edges of the box indicate the 25 th and 75 th percentiles, respectively. The whiskers extend to the most extreme data points not considered outliers, and the outliers are plotted individually using the '+' red symbol. The performance of the succeeding scenes is compared based on the commands given by all subjects. These commands are summed to provide a single index for each subject. From these results, the SCM EMG is an estimate of twice the Masseter EMG, partly due to the game design with the horizontal (left and right) dimensions being more large than vertical (up and down). Group Comparison  
The test subjects contained distinguishable gender groupings that we separated to find out if there were significant control differences. In division, six female subjects and fourteen male subjects' data were tested for statistical significance, as shown in Table 2. We performed a one-way ANOVA test on reaction time (the time taken before a viewable control input is displayed when the scene is loaded), completion time, and summed neck and bite EMG. As shown in Table 2, there was no significant difference between the two groups as indicated by the completion time (P(F > 0.43) = 0.519). Similarly, there was no statistical difference between the mean of the neck and bite EMG (\(p\) = 0.48 and \(p\) = 0.7595, respectively  
The overall performance is captured for all evaluated scenes. In Table 3, the scenes can be reorganized into 1, 5, 6, 4, 2, 8, 7, 3, 9, and 10, based on the completion time. This rating coincides with the vertical index (v-index) order adopted in the scene. This is further elaborated by the correlation test shown in Table 4.