A Virtual Presence Counter

TLDR

This paper introduces a new unobtrusive measure of presence in immersive virtual environments based on data collected during the experience. The measure counts transitions between interpreting the environment as virtual or real, models them with a Markov chain, and estimates the equilibrium probability of presence; it was applied to an experiment where subjects reached for chess pieces versus clicking a mouse. In the active group, increased body movement was significantly associated with higher presence, supporting interaction paradigms that align sensory data with proprioception.

Abstract

This paper describes a new measure for presence in immersive virtual environments (VEs) that is based on data that can be unobtrusively obtained during the course of a VE experience. At different times during an experience, a participant will occasionally switch between interpreting the totality of sensory inputs as forming the VE or the real world. The number of transitions from virtual to real is counted, and, using some simplifying assumptions, a probabilistic Markov chain model can be constructed to model these transitions. This model can be used to estimate the equilibrium probability of being “present” in the VE. This technique was applied in the context of an experiment to assess the relationship between presence and body movement in an immersive VE. The movement was that required by subjects to reach out and touch successive pieces on a three-dimensional chess board. The experiment included twenty subjects, ten of whom had to reach out to touch the chess pieces (the active group) and ten of whom only had to click a handheld mouse button (the control group). The results revealed a significant positive association in the active group between body movement and presence. The results lend support to interaction paradigms that are based on maximizing the match between sensory data and proprioception.