Many interfaces exist for locomotion in virtual reality, although they are rarely considered fully natural. Past research has found that using such interfaces places cognitive demands on the user, with unnatural actions and concurrent tasks competing for finite cognitive resources. Notably, using semi-natural interfaces leads to poor performance on concurrent tasks requiring spatial working memory. This paper presents an adaptive system designed to track a user's concurrent cognitive task load and adjust interface parameters accordingly, varying the extent to which movement is fully natural. A fuzzy inference system is described and the results of an initial validation study are presented. Users of this adaptive interface demonstrated better performance than users of a baseline interface on several movement metrics, indicating that the adaptive interface helped users manage the demands of concurrent spatial tasks in a virtual environment. However, participants experienced some unexpected difficulties when faced with a concurrent verbal task.

There is currently no fully natural, general-purpose locomotion interface. Instead, interfaces such as gamepads or treadmills are required to explore large virtual environments (VEs). Furthermore, sensory feedback that would normally be used in real-world movement is often restricted in VR due to constraints such as reduced field of view (FOV). Accommodating these limitations with locomotion interfaces afforded by most virtual reality (VR) systems may induce cognitive demands on the user that are unrelated to the primary task to be performed in the VE. Users of VR systems often have many competing task demands, and additional cognitive demands during locomotion must compete for finite resources. Two studies were previously reported investigating the working memory demands imposed by semi-natural locomotion interfaces (Study 1) and reduced sensory feedback (Study 2). This paper expands on the previously reported results and adds discussion linking the two studies. The results indicated that locomotion with a less natural interface increases spatial working memory demands, and that locomotion with a lower FOV increases general attentional demands. These findings are discussed in terms of their practical implications for selection of locomotion interfaces when designing VEs.

When people have visual access to the same space, judgments of this shared visual space (shared vista) can facilitate communication and collaboration. This study establishes baseline performance on a shared vista task in real environments and draws comparisons with performance in visually immersive virtual environments. Participants indicated which parts of the scene were visible to an assistant or avatar (simulated person used in virtual environments) and which parts were occluded by a nearby building. Errors increased with increasing distance between the participant and the assistant out to 15 m, and error patterns were similar between real and virtual environments. This similarity is especially interesting given recent reports that environmental geometry is perceived differently in virtual environments than in real environments.