# Investigation of Interactive Strategies Used in Undertaking Collaborative Tasks
## 1 Introduction
Accordingly, we designed a CVE for the investigation where two users must work collaboratively to complete a task. One user was an expert corresponding to the role of the human operator; another was a novice playing the role of the robot. The CVE and the task to be undertaken were proven solutions used in our previous study which demonstrated ventral/dorsal streams possessing complementary function at making collaborative venture effectively [15]. Both expert and novice collaboratively undertook the task by deploying the following three interactive strategies, which on one hand allow the task to not be beyond the scope of cooperation, while on the other hand permitting the novice various degrees of autonomy from scratch, to less, to more:  
* Tele-Operation, under which the novice had no autonomy and executed all step-by-step operations decided by the expert for completing the task. * Tele-Assistance3, under which the novice received each sub-goal of the task from the expert and possessed a degree of autonomy to devise an operation plan of achieving the sub-goal and to execute the plan. The expert could overrule the operations if necessary. * Tele-Assistance7, under which the novice had more degree of autonomy than under Tele-Assistance3 to decide and act upon operations for completing a sub-goal, because the expert would not interfere with the operations of the novice. Three experiments were performed to observe the effect of interaction strategies on the task performance of an expert user and a participant working on a collaborative task. Each experiment consisted of the expert user interacting with the participant using two different interaction strategies. To keep the expert's level of expertise consistent, we always employed the developer of the CVE as the expert to pair with each novice (a human participant). Thus, we evaluated the performance of the novice under each interactive strategy by recording and analyzing four parameters: the completion time of the task, the error in performing the task, the number of operation steps, and the overall workload. The experiment results revealed that different interaction strategies help to facilitate the performance of a collaborative task in different ways. In particular, Tele-Operation is a suitable interaction strategy in situations where there are no communication delays between people, and where the expert user clearly knows what should be done at every step of the task. Tele-Operationallows the task to be completed in less time and error, as well as less workload for the novice. Tele-Assistance7 shows the power of tele-assistance. Although more time and larger error are obtained, Tele-Assistance7 shows that people actually used lesser amount of moves to perform the task compared to Tele-Operation. Tele-Assistance3 shows the advantages of both Tele-Operation and Tele-Assistance7 to complete the task efficiently. Giving the expert user the power to veto the participant's actions allows the task to be completed in a shorter time and a decrease in the overall workload perceived by the participant, as compared to Tele-Assistance7. The outcome of this investigation could aid in choosing an optimal interactive strategy for performing a collaborative task between an expert and a novice. There are many practical collaborative tasks involving these users, such as in remote maintenance tasks requiring a remote expert and a field worker who is not familiar to the task, and in surgical training tasks involving a skilled surgeon and a trainee, etc. The observations demonstrate that different interaction strategies affect the task performance in different ways. One should identify key performance parameters of a collaborative task when considering an interaction strategy for facilitating the task. Then, it is essential to assess the influence of the interaction strategy on these parameters.