To examine the effect of stereo vision on performance, presence and oculomotor disturbances within a virtual environment (VE), two groups of 23 participants (good stereo acuity/low stereo acuity) were evaluated. Groups were matched in terms of gender, age and VE design factors (the latter were accounted for to ensure a similar VE experience between groups). Participants were immersed in a VE maze for up to I It during which time they interacted with the environment while performing a number of stationary and movement-based tasks. Individuals with low stereo acuity traveled further to complete two tasks in the VE, yet performance time on these tasks was comparable to participants with good stereo acuity. Although participants with impaired stereo vision likely did not fully benefit from a stereoscopic view of the scene, they may have received sufficient depth information from movement-based cues to efficiently accomplish these tasks in a comparable amount of time. Overall performance, based on both the number of tasks completed and the total translational distance moved (based on input device movement) within the VE was not hindered for those with low stereo acuity. In addition, the expected increase in oculomotor disturbances for this group was not evident in this study, and both groups reported comparable amounts of presence from VE exposure. These results suggest that when head tracking is included as part of the VE experience (i.e., motion parallax cues exist), participants with low stereo acuity can be expected to perform comparable to normal sighted individuals, experience a comparable sense of presence, and report no increase in adverse effects when viewing scenes via stereoscopic displays. Thus, motion parallax cues may adequately provide a sense of depth within a VE, and alleviate theorized performance decrements for individuals with low stereo acuity. The results of this study have implications for those designing entertainment simulations or other such applications open to the general public, where people with low stereo acuity may routinely participate. (c) 2005 Elsevier Ltd. All rights reserved.
