Effects of End-to-end Latency on User Experience and Performance in Immersive Virtual Reality Applications

Immersive virtual reality (IVR) offers an opportunity to immerse oneself into a virtual world and experience an exciting adventure. However, latency between a user's movement and visual feedback has a big impact on user experience and performance. In this paper, we explore the effect of increased end-to-end latency in IVR applications by conducting a user study. Firstly, in the searching task, we analyze cybersickness level based on simulator sickness questionnaire. Secondly, in the reaching task, we measure the user performance by tracking the time they need to reach a target and the error they make during the execution. Lastly, in the embodiment task, we measure the sense of body ownership, agency, presence, and latency perception when only one body side is impaired by latency. We apply the Friedman test with Conover's test of multiple comparisons as a post-hoc test on all dependent variables to find significant results. Results show that the end-to-end latency above 63 ms induces significant cybersickness symptoms. In addition, user performance decreases with increasing delay and with end-to-end latency above 69ms, the users need significantly longer to complete the task. Results also show that end-to-end latency affects body ownership significant later, namely, not until 101 ms.