Rapid advances in computer and display technologies have made it possible to present high quality virtual reality (VR)
environment. To use such virtual environments effectively, research should be performed into how users perceive and
react to virtual environment in view of particular human factors. We created a VR simulation of sea fish for science
education, and we conducted an experiment to examine how observers perceive the size and depth of an object within
their reach and evaluated their visual fatigue. We chose a multi-projection system for presenting the educational VR
simulation, because this system can provide actual-size objects and produce stereo images located close to the observer.
The results of the experiment show that estimation of size and depth was relatively accurate when subjects used physical
actions to assess them. Presenting images within the observer’s reach is suggested to be useful for education in VR
environment. Evaluation of visual fatigue shows that the level of symptoms from viewing stereo images with a large
disparity in VR environment was low in a short time.
The authors have developed a virtual reality exposure system that reflects the Japanese culture and environment.
Concretely, the system focuses on the subway environment, which is the environment most patients receiving treatment
for panic disorder at hospitals in Tokyo, Japan tend to avoid. The system is PC based and features realistic video images
and highly interactive functionality. In particular, the system enables instant transformation of the virtual space and
allows situations to be freely customized according to the condition and symptoms expressed by each patient. Positive
results achieved in therapy assessments aimed at patients with panic disorder accompanying agoraphobia indicate the
possibility of indoor treatment. Full utilization of the functionality available requires that the interactive functions be
easily operable. Accordingly, there appears to be a need for usability testing aimed at determining whether or not a
therapist can operate the system naturally while focusing fully on treatment. In this paper, the configuration of the virtual
reality exposure system focusing on the subway environment is outlined. Further, the results of usability tests aimed at
assessing how naturally it can be operated while focusing fully on treatment are described.
A common cause of asthenopia is viewing objects from a short distance, as is the case when working at a VDT (Visual Display Terminal). In general, recovery from asthenopia, especially accommodative asthenopia, is aided by looking into the distance. The authors have developed a stereoscopic 3-D display with dynamic optical correction that may reduce asthenopia. The display does this by reducing the discrepancy between accommodation and convergence, thereby presenting images as if they were actually in the distance. The results of visual acuity tests given before and after presenting stereoscopic 3-D images with this display show a tendency towards less asthenopia. In this study, the authors developed a refraction feedback function that makes the viewer's distance vision more effective when viewing stereoscopic 3-D images on the this display. Using this function, refraction is fed back during viewing and the viewer gradually acquires distance vision. The results of the study suggest that stereoscopic 3-D images are more effective than 2-D images for recovery from asthenopia.