## 3 Experimental Results  
Figure 4 shows the cumulative working times of three of the experimenters with the HMD device while performing the 69 unit operations using the four user interface devices in the VR environment. The working times for each user interface device differed slightly for each experimenter. Experimenter No. 1 was able to finish operations the fastest when using the Kinect sensors and the bend-sensing data glove, and spent the longest time when using the 2D & 3D mice. On the other hand, Experimenters No. 2 and No. 3 spent the shortest time when using the 2D mouse. Apart from the VR controller, no significant difference was observed in the working time spent by experimenter No. 2 when using the other three user interface devices. However, for experimenters No. 1 and No. 3, there was a difference in the working time spent on using all four user interface devices. The difference in the number of device-clicks with fingers while performing operations was relatively small for each experimenter (Figure 5). All experimenters (Nos. 1-3) recorded the fewest clicks when using the Kinect sensor and the bend-sensing data glove, followed by the 2D mouse, 2D &  
Figure 3: Images of experimenters controlling the KmodStudio software in a virtual reality (VR) environment using different user interface devices. (**a**) Two-dimensional (2D) mouse; (**b**) 2D and three-dimensional (3D) mice; (**c**) VR controller; and (**d**) bend-sensing data glove with a Kinect sensor. 3D mice, and the VR controller. The reason why the number of clicks was generally higher when using the VR controller is considered to be because the VR controller is difficult to control precisely. Figure 6 shows the mean and box plots of the experimental results for the 10 experimenters. The box plots include minimum, median and maximum values, along with the interquartile range (IQR), composed of the first quartile (Q1) and third quartile (Q3). The mean value for the 10 experimenters is denoted by the X symbol. The 2D mouse recorded the shortest total working time with an average of 99.3 s, followed in order by the Kinect sensor and the bend-sensing data glove and the 2D & 3D mice. The VR controller recorded the longest time, taking 30 s longer than the 2D mouse. The Kinect sensor and the bend-sensing data glove took longer than the 2D mouse; however, the difference was only 3.6 s.  
The number of device-clicks while performing the operations was the fewest (31.4 clicks) when using the Kinect sensor and the bend-sensing data glove. This is because we used the shortcut command functions according to the finger motions when controlling KmodStudio processes, as shown in Table 1. This was followed in order by the 2D mouse, the 2D & 3D mice, and the VR controller, which recorded the greatest number of clicks. The reason behind the difference in the number of clicks between user interface devices is that the number of incorrect clicks while performing the operations is also included in the total number of clicks. A greater number of clicks to perform the same operations translates into more incorrect clicks. Figure 4: Cumulative working time for controlling KmodStudio in a virtual reality (VR) environment, using different user interface devices. Experimenter No. (**a**) 1, (**b**) 2, and (**c**) 3. Figure 5: The cumulative number of clicks for controlling KmodStudio in a virtual reality (VR) environment using different user interface devices. Experimenter No. (**a**) 1, (**b**) 2, and (**c**) 3. The click accuracy refers to the ratio of the number of correct clicks to the total number of clicks. Using the 2D mouse resulted in a 6% higher click accuracy than using the 2D & 3D mice together, and a 5% higher click accuracy than using the Kinect sensor and the bend-sensing data glove. That is, the click accuracies of these three devices were similar. On the other hand, there was a significant difference (of 14%) between the 2D mouse and the VR controller.