# Investigation of Interactive Strategies Used in Undertaking Collaborative Tasks
## 1 Introduction  
Collaborative virtual environments (CVEs) are computer simulated settings that allow multiple people (the users) from disparate locations to work collaboratively on a task. Such a collaborative task requires each user to share information and delegate activities in order to achieve a common goal. The applications of CVEs have been increased drastically due to the improved performance of personal computers and networks that they operate on. Research efforts of CVEs have mainly focused on investigating whether factors such as communication, awareness, and presence enhance user experience. These factors let the users feel the sense of being immersed in an environment and enable them to interact socially with each other [1, 2]. For the factor of communication, the tools and methods were designed to transmit information through various networked media in order to facilitate collaborative tasks [3, 4]. In contrast, the factor of awareness relies heavily on the users' mental perception of their surroundings and their exercise of this perception to aid their communication [5, 6]. Furthermore, the factor of presence allows the users to have a sense of working at the same location [7]. The users are more inclined to interact with collocated users at a high degree of presence, rather than with remote users at a low degree of presence [8]. As for interactive strategy design, research studies have concentrated on the feasibility and efficiency of task accomplishment, such as allowing multiple users to implement simultaneous manipulation in efficient and usable manner rather than single-user manipulation [9]. Nevertheless, these research activities did not take into account the users' level of expertise. When the users have shared a common ground of knowledge and have been at the same level of expertise, each of them has worked autonomously as their interactive strategy to perform a collaborative task [10]. In the casethat the users have had different levels of expertise, their interactive strategy has commonly been for an expert to guide a novice using different tools [11]. Most research efforts of CVEs need to deploy one interactive strategy among the users. The efforts rarely consider the effect of interactive strategies on performing a collaborative task, especially when the users have different levels of expertise. Thus, we have investigated three interactive strategies for undertaking a collaborative task between two users with different levels of expertise. The investigation is the first step towards discovering general rules of applying these strategies to facilitate collaborative tasks in different scenarios. For instance, learning tasks, surgical training, and maintenance tasks may require different interactive strategies, respectively, in order to achieve desired performance outcomes. The strategies under investigation were inspired from human/robot interactions, especially from [PERSON]'s work [12]. To perform a collaborative task, interactive strategies between two users with different levels of expertise could be similar to those in human/robot systems. In a human/robot system, the human operator possesses a high level of expertise and is a supervisor and/or controller of movements, whereas the robot has a low level of expertise and is the executor of the movements. Many studies exist on human/robot interactions [13; 14], especially for optimizing the operator's intervention to the robot's movements and the division of tasks between the operator and robot, etc. In general, human/robot interactions fall into a spectrum encased by two extreme types [12]. One type is tele-operation, in which the human operator directs every movement of the robot; another type is autonomous, in which the robot runs pre-defined routines without any intervention from the operator. Within the spectrum is the flexible type of tele-assistance, in which the operator may intervene at certain degrees with particular movements of the robot.