The effect of update rate on the sense of presence within virtual environments

The current study was done to investigate the effect of varying the update rate of a computer-generated simulation (5, 10, 15, 20, 25 Hz) on the sense of presence within stereoscopic virtual environments. Thirteen subjects navigated a virtual representation of Stonehenge and were asked to search for a rune, inscribed upon the wall of one of Stonehenge's edifices. After performing the search task, subjects completed a questionnaire designed to assess their level of presence within the virtual environment. The results indicated that the subjective report of presence within the virtual environment was significantly less using an update rate of 5 and 10 Hz when compared to update rates of 20 and 25 Hz. Furthermore, the reported level of presence using a 15 Hz update rate was similar to the reported level of presence using update rates of 20 and 25 Hz thus indicating that computational resources could be saved using a slower update rate while maintaining a given level of presence. In addition, a factor analysis procedure indicated that the 13 questions designed to assess the subjects sense of presence within virtual Stonehenge could be grouped into three factors: (1) virtual presence, (2) navigation within the virtual environment, and (3) knowledge of real world surroundings while in the virtual world. Finally, comments on a descriptive model of presence within virtual environments are presented.