Temporal aspects of interaction in shared virtual worlds

In this paper we examine the problems of usability and related temporal issues in shared virtual environments. Shared virtual environments involve physically distributed users interacting with each other and with distributed objects via complex highly graphical user interfaces. These factors can result in interaction which suffers from serious and unpredictable delays in system response times. Careful interaction design can alleviate the problems resulting from such delays. We look at several areas of shared virtual world design, including object interaction, avatars and scene rendering, investigating ways of dealing with communicating information, preserving world coherence and providing users with effective real-time interaction. Our medium of analysis is the Extended User Action Notation (XUAN), a variant of the User Action Notation that enables us to express explicitly and clearly the temporal features of our examples. Finally, we discuss the implications of our temporal analysis for further research and development of shared virtual worlds, and the implications for the further development and use of XUAN.