Affiliation: College of Arts and Sciences, Department of Computer Science
Historically, research into subjective user experience in virtual environments has focused on presence, the feeling of "being there" in the virtual environment. Recently, Professor Mel Slater proposed that in addition to this feeling of being in the virtual space, researchers also need to consider the subjective feeling that the events depicted in the virtual environment appear real. He coined the terms Place Illusion (PI) and Plausibility Illusion (Psi), respectively, to refer to these subjective feelings. There exists a substantial amount of previous research applicable to PI, but very little regarding Psi. This dissertation fleshes out the concept of Plausibility Illusion by introducing new terminology, and reports on several experiments investigating the factors and effects of Psi. I demonstrate that Psi can be detected using existing presence measures, including questionnaires and physiological metrics. Of particular interest in these results is that factors contributing to Plausibility Illusion affected heart rate, with inconsistent behavior of the virtual environment leading to increased heart rate. I also demonstrate that study participants' individual differences affected how they interacted with a virtual environment, leading to different levels of Plausibility Illusion and, therefore, presence. I further demonstrate that, among the factors tested, the virtual body is the most important factor contributing to users' feelings of Plausibility Illusion, and that the coherence of the virtual scenario is the second most important factor. This shows it is feasible to determine a rank ordering of factors that affect users' sense of Plausibility Illusion in virtual environments, offering guidance to creators and developers.