Depth of Presence in Virtual Environments
This paper "Depth of Presence in Virtual Environments" describes a study to assess the influence of a variety of factors on reported level of presence in immersive virtual environments.
It introduces the idea of “stacking depth,” that is, where a participant can simulate the process of entering the virtual environment while already in such an environment, which can be repeated to several levels of depth. Presence was assessed by the subjects as their sense of “being there”, the extent to which they experienced the virtual environments as more the presenting reality than the real world in which the experiment was taking place, and the extent to which the subject experienced the virtual environments as places visited rather than images seen.