There is currently much research activity involving virtual environments (VEs) and spatial behavior (spatial perception, cognition, and performance). After some initial remarks describing and categorizing the different types of research being conducted on VEs and spatial behavior, discussion in this Forum paper focuses on one specific type, namely, research concerned with the use of VE technology for training spatial behavior in the real world. We initially present an overview of issues and problems relevant to conducting research in this area, and then, in the latter portion of the paper, present an overview of the research that we believe needs to be done in this area. We have written this paper for the forum section of Presence because, despite its length, it is essentially an opinion piece. Our aim here is not to report the results of research in our own laboratory nor to review the literature, as other available papers already serve these goals. Rather, the primary purpose of this paper is to stimulate open discussion about needed future research. In general, we believe that such a discussion can serve the research establishment as much as reports of completed work.

Experiments were conducted to determine how the ability to detect and discriminate head-motion parallax depth cues is degraded by time delays between head movement and image update. The stimuli consisted of random-dot patterns that were programmed to appear as one cycle of a sinusoi dal grating when the subject's head moved. The results show that time delay between head movement and image update has essentially no effect on the ability to discrimi nate between two such gratings with different depth char acteristics when the delay is less than or equal to roughly 265 ms.

This Forum article discusses the relationships among people, their avatars, and their virtual environment workstations in a shared virtual environment. It introduces the notion of togetherness, the sense of people being together in a shared space, which is the counterpart for shared VEs to the presence of an individual in a VE. The role of tactual communication is emphasized as being fundamental to togetherness.