ABSTRACT

To deal with the effects that virtual environment (VE) technologies might have on users, the categorization of direct versus indirect effects is used herein. Indirect effects affect the user at a high functional level. These include psychological effects, such as modi˜cation of phobias and enhancement or repression of emotions, as well as neurological effects on the visual system (eyestrain, modi˜cation of stereoscopic vision, and visual acuity). VEs can also affect the motion detection system (i.e., vestibular system) and may result in imbalance, nausea, and motion sickness. Research and recommendations into the indirect effects of VEs including eyestrain and motion sickness are reported in Chapters 23 through 26 and 32 through 33. Direct effects of VEs are less complex to study and control but are potentially as great a hazard to users as indirect effects. The direct effects of a VE system are those that act at a direct tissue level, as opposed to the body systems level of the indirect effects. Direct effects are the inªuence of energy on body tissues from the technology and the risk of trauma because of encumbrances (e.g., weight of a helmet-mounted display [HMD]). The incorporation of motion platforms and other heavy equipment in the home, vehicle simulators, and industry applications of VR increases physical trauma risks. Trauma is a particularly important issue, because the essential features of VEs are interactivity and immersion, where the user interacts in three dimensions with computer graphics. Irrational exuberance by users totally absorbed in the virtual experience might occur in some situations and result in injuries. Fortunately, dealing with direct effects of VEs is mostly a matter of common sense and awareness. Well-established standards based on extensive research provide clear guidance on how to implement safety programs.