## 6 Results and Discussion  
### Results  
The performance of the user is measured in terms of time spent and mistakes occurring while executing the task, for each of the proposed interfaces. Additionally, the questionnaire score results enabled a qualitative evaluation. **Task performance related measures:**  
Figure 7 depicts the mean task-time performance and standard deviation for the key block sequence touches while using the traditional interface and the immersive interface, Task 1 setup. Key_Seq. 1 corresponds to touching the first four blocks, Key_Seq. 2 to touching the second four  
Figure 6: (a) “HMD indirect vision (mono biocular)”: a video see-through HMD; (b,c) user performing a pick and place task using the setup “HMD indirect vision (mono biocular) + gripper”; (d) user performing a pick and place task using the setup “fixed monitor vision (mono biocular) + gripper”. blocks, and Keyb_Seq. 1+2 the time spent to correctly touch the eight blocks. The second trial Keyb_Seq. 2 is faster due to the learning process. These task performance measures are also available in Table 3, where for Task 1, \(\mu\) stands for mean task-time performance in seconds and \(\sigma\) is the standard deviation, and the respective subscript \(t\) stands for traditional and \(i\) for immersive. According to the one-way repeated measures ANOVA (analysis of variance) tests, the round comparisons of Task 1 are not statistically significant: \begin{tabular}{l l} Keyb_Seq. 1 & \(F_{1,8}=0.212\), \(p=0.657\); \\ Keyb_Seq. 2 & \(F_{1,8}=0.343\), \(p=0.574\); \\ KeybSeq. 1+2 & \(F_{1,8}=0.281\), \(p=0.609\); \\ \end{tabular}  where \(F\) stands for the \(F\)-statistic, \(p\) the \(p\)-value and should be \(<\)0.05 for significant comparisons. Basically, in Task 1, the immersive interface has a poor performance when compared with the fixed camera setup, although it is not a significant difference. Even in trials where participants had some manipulation training first with the \(Fix_{Display}+Fix_{Cam}\) setup, there were no changes. An explanation of this fact is that the tested workspace is small, fits all in the field of view of the user, and he/she does not feel the need to move his/her head to get better views. Figure 8 depicts the mean performance times (seconds) and standard deviation for the Task 2 setup. It shows that users perform the pick-and-place task faster while using the immersive interface than when using the traditional interface. The values are also presented in Table 3, and the comparison involving 20 participants is statistically significant. It was assessed using the one-way repeated measures (within subjects) ANOVA analysis: \(F_{1,19}=7.95\), \(p=0.0109^{*}\) (the asterisk indicates a significant comparison, \(p<0.05\)). Task 3's mean time performance measurements are presented in Figure 9a and in Table 3. The mean time performance using the traditional interface is similar to the immersive interface,  
Figure 8: Task 2: mean task-time performance for picking and placing blocks in the box’s holes. Figure 7: Task 1: mean task-time performance of participants while pressing on a sequence of key blocks determined by the computer: Keyb_Seq. 1 (first round), Keyb_Seq. 2 (second round), and Keyb_Seq. 1+2 (sum of both sequences). with \(F_{1,14}=0.037\) and \(p=0.85\). Nevertheless, for this task, a lower number of hits indicates better performances, and it occurs while using the immersive interface in opposition to the traditional interface; see Figure 9b. It has a statistically significant difference: \(F_{1,16}=4.747\), \(p=0.044^{*}\). **Control task:**  
Comparisons between individual disturbance factors introduced by each mediation technology (e.g., visual, haptic) while in a pick-and-place box task (Figure 6) are presented in Figure 10 regarding the mean task-time performance. The one-way ANOVA test for the five factors shows a statistically significant comparison: \(F_{4,32}=24.05\), \(p<0.001^{*}\).