# Investigation of Interactive Strategies Used in Undertaking Collaborative Tasks
## 4 Experiments
### Experiment I: Tele-Operation vs. Tele-Assistance7
In addition, the overall workload perceived by the participants was different between Tele-Operation and Tele-Assistance7. Specifically, the participants under the Tele-Operation perceived a lower workload (47.67 \(\pm\) 3.35) compared to under Tele-Assistance7 (65.02 \(\pm\) 2.30), as depicted in Figure 5d. The difference of these workloads was statistically significant (Z = \(-\)3.866; \(p\) < 0.05). Figure 5: Results of Experiment I: (**a**) Average completion time of the task; (**b**) Average error of performing the task; (**c**) Average number of operations executed by the participants; (**d**) Average workload perceived by the participants. (Error bars represent standard error.) Discussion: For executing the task, the mental computation of the novice could play an important role in the completion time of the task. Under Tele-Operation, the novice was in some extent required to interpret the expert's intention for every operation but had no need to plan the course of operations. That is, under this format the expert shoulders the whole burden of the planning. Fortunately, the expert (the developer of the CVE) was familiar with the task and undertook the planning before the experiment. Thus, the completion time of the task depended heavily upon the length of each novice's mental computation of the operations. Under Tele-Assistance7, however, the novice had to understand what needed to be done and to compute the shortest distance between the selected control point on the manipulator object and the reference point. This certainly elevated the demand of the novice's mental computation and, in turn, resulted in a longer time required for the computation. In other words, both expert and novice shared the burden of planning the course of operations. Therefore, the completion time of the task was shorter under Tele-Operation than under Tele-Assistance7, mirroring the lower workload of the novice under Tele-Operation than under Tele-Assistance7. Additionally, there existed a smaller error in performing the task under Tele-Operation than under Tele-Assistance7. This may result from the preciseness of the operations commanded by the expert under Tele-Operation. Despite resulting in more time and errors in the process of performing the task, Tele-Assistance7 had an advantage of facilitating the collaboration. The novice was able to complete the task with less number of operations under Tele-Assistance7 than under Tele-Operation. This implies that the break down of the sub-goals of the task, as explained in Section 3, permitted the novice to have certain autonomy in finding an efficient way in completing the task. This is because in Tele-Operation, the number of steps decomposed by the expert was not the least to accomplish the task, however, in Tele-Operation7, the set of sub-goal steps was the key operations to achieving the final goal. Under Tele-Assistance7, on one hand the expert gave his intention of operations through a series of sub-goals and communicated these sub-goals via a high-level symbolic language--using the widget indicator, the selected control point on the manipulator object, and the reference point; on the other hand, the novice used the haptic device as a 6 DOF input device and had the ability of performing fine movements in 3D space. Consequently, the novice could find relatively optimal sequences amongst many alternatives for each sub-goal.