Evaluation of the effects of frame time variation on VR task performance

We present a first study of the effects of frame time variations, in both deviation around mean frame times and period of fluctuation, on task performance in a virtual environment (VE). Chosen are open and closed loop tasks that are typical for current applications or likely to be prominent in future ones. The results show that at frame times in the range deemed acceptable for many applications, fairly large deviations in amplitude over a fairly wide range of periods do not significantly affect task performance. However, at a frame time often considered a minimum for immersive VR, frame time variations do produce significant effects on closed loop task performance. The results will be of use to designers of VEs and immersive applications, who often must control frame time variations due to large fluctuations of complexity (graphical and otherwise) in the VE.