From virtual to actual mobility: Assessing the benefits of active locomotion through an immersive virtual environment using a motorized wheelchair

As we move around, in a real or virtual environment, the process of keeping track of where we are, in relation to the portions of the environment that are out of view, is referred to as spatial updating. Studies have shown that in the real world, when we use real walking to get around, this process is both effortless and automatic, but that in virtual environments, when purely virtual methods of locomotion are used, the accuracy and ease of spatial updating is significantly diminished. In this paper, we present the results of an experiment intended to assess the impact, on spatial updating performance, of enabling people to physically move about in an immersive virtual environment using a motorized wheelchair. This study is motivated by an interest in probing the potential of re-directed driving as an alternative method for enabling people to effectively explore a relatively larger virtual space while physically moving about in a smaller actual space. A total of 24 participants in our within-subjects experiment traveled through a 24' wide circularly symmetric virtual room, searching the contents of 16 randomly positioned and oriented boxes to locate 8 hidden targets, using each of the following four locomotion methods: real walking (R), virtual translation with real rotation by standing and using a body-worn joystick (S), real driving in a motorized wheelchair (W), and virtual translation with real rotation by sitting in a swivel chair and using a joystick mounted on one of its arms (J). We computed four measures of search efficiency: total distance traveled, total number of targets revisited, proportion of perfect trials, and total search time. Overall, we found that performance was significantly better with real walking than with either of the virtual travel methods, consistent with most previous findings, and that performance with the wheelchair was intermediate. These results suggest some advantage in enabling actual, as opposed to purely virtual, translational movement in a locomotion interface, and lend support to the potential viability of a re-directed driving implementation.