Presence as the Defining Factor in a VR Application

The sense of presence that a user experiences in a virtual environment is perhaps the best known attribute of virtual reality. It is an appeal to this sense of presence that is used to distinguish virtual reality as something different from merely a multimedia system or an interactive computer graphics display. Our basic understanding of presence, however, is still primarily anecdotal in nature. We have yet to rigorously explore basic questions about the nature of presence. We describe an application of virtual reality, virtual reality graded exposure (VRGE), in which a sense of presence is the salient factor determining the success of the application. Sujective and objective data from a clinical study on the usefulness of VRGE for treating persons with acrophobia is analyzed as experimental evidence for formulating several assertions about the characteristics and nature of presence. We then discuss the implications of our assertions on several open questions concerning the definition, quantification and usefulness of presenc