This paper reports the results of three studies, each of which investigated the sense oi presence within virtual environments as a function of visual display parameters. These factors included the presence or absence of head tracking, the presence or absence of stereoscopic cues, and the geometric field of view used to create the visual image projected on the visual display. In each study, subjects navigated a virtual environment and completed a questionnaire designed to ascertain the level of presence experienced by the participant within the virtual world. Specifically two aspects of presence were evaluated: (1) the sense of ''being there'' and (2) the fidelity of the interaction between the virtual environment participant and the virtual world. Not surprisingly, the results of the first and second study indicated that the reported level of presence was significantly higher when head tracking and stereoscopic cues were provided. The results from the third study showed that the geometric field of view used to design the visual display highly influenced the reported level of presence, with more presence associated with a 50 and 90 degrees geometric field of view when compared to a narrower 10 degrees geometric field of view. The results also indicated a significant positive correlation between the reported level of presence and the fidelity of the interaction between the virtual environment participant and the virtual world. Finally, it was shown that the survey questions evaluating several aspects of presence produced reliable responses across questions and studies, indicating that the questionnaire is a useful tool when evaluating presence in virtual environments.
