Effects of variation in system responsiveness on user performance in virtual environments

System responsiveness (SR) is defined as the elapsed time until a system re sponds to user control. SR fluctuates over time, so it must be described st atistically with mean (MSR) and standard deviation (SDSR). In this paper, w e examine SR in virtual environments (VEs), outlining its components and me thods of experimental measurement and manipulation Three studies of MSR and SDSR effects on performance of grasp and placement tasks are then presente d. The studies used within-subjects designs with 11, 12, and 10 participant s, respectively. Results showed that SDSR affected performance only if it w as above 82 ms. Placement required more frequent visual feedback and was mo re sensitive to SR. We infer that VE designers need not tightly control SDS R and may wish to vary SR control based on required visual feedback frequen cy. These results may be used to improve the human-computer interface in a wide range of interactive graphical applications, including scientific visu alization, training, mental health, and entertainment.