Abstract
Research has shown that people are able to judge distances accurately in full-cue, real-world environments using visually directed actions. However, in virtual environments viewed with head-mounted display (HMD) systems, there is evidence that people act as though the virtual space is smaller than intended. This has been a surprising result given how well people act in real environments. The behavior in the virtual setting may be linked to distortions in the available visual cues or to a person's ability to locomote without vision. Either could result from issues related to added mass, moments of inertia, and restricted field of view in HMDs. In previous studies, subjects showed a reliable effect of compression compared to unrestricted viewing while wearing a mock HMD in a real room. The mock HMD replicated the mass, moments of inertia, and field of view of our HMD. The current investigation dealt specifically with understanding how the additional mass and moments of inertia associated with the HMD might affect distance judgments. Subjects wore an inertial headband designed to replicate the moments of inertia and mass found with our HMD. The headband was constructed to not restrict the field of view of the observer or otherwise feel like wearing a helmet. Subjects performed either a direct walking task or a triangulated walking task without vision to previously seen targets on the ground in a real room while wearing the inertial headband. We compared their performance to the same tasks performed in a real room with no viewing or inertial restrictions, in a real room with the mock HMD, and in the virtual environment wearing the HMD. Indicated distances with the inertial headband were somewhat compressed relative to those with no restrictions, but this difference was not statistically significant. This is in contrast to the mock HMD combining mass, moments, and field of view restrictions, which does show a reliable difference from the no restriction condition.
This work was supported by NSF grants IIS-00-80999 and IIS-01-21084.