The influence of the modality of tele-cooperation on performance and workload

Current industrial processes often involve the collaboration of people at distant and remote locations. The technological media for such a tele-cooperation reach from simple email or text-based chatting systems to highly-sophisticated systems for an interactive video-conferencing. But with limited bandwidth the communication between persons at distant locations is often restricted to single modalities. Although this may still be suitable for some tasks, it may result into serious shortcomings and decreased performance with complex tasks like cooperative assembly or maintenance. This is because restricted communication reduces the availability of a common ground, i.e. sharing a common understanding of knowledge, opinions, and goals. The study presented in this paper examines the effect of different communication media on performance of a collaborative assembly task. The results show that tele-cooperation leads to additional verbal communication (AM(direct)=71.1s; AM(video)=145.6s; AM(audio)=204.7s) and, thus, longer times to complete the task (AM (direct)=45.95 min; AM (video)=50.2 min; am AM(audio)=56.16 min). The percentage of relative speech duration also increases significantly. Workload measurement with NASA-TLX did not show any significant differences between cooperation modes. The results allow estimating the effect of reduced communication modalities on time to complete an assembly task. This facilitates a quantification of temporal requirements in time-critical maintenance and repair tasks.