Dynamic Changes of Latency Perception Threshold in Virtual Reality: Behavioral and EEG Evidence

Virtual Reality (VR) technologies in fields such as telehealth, teleconferencing, and virtual education are significantly affected by end-to-end latency, which notably impacts users' interactive experience and performance. Previous research suggests that a perceptual threshold may exist-once latency is reduced below a certain level, users no longer perceive it, and their interactive performance remains largely unaffected. However, there is no consensus on the exact value of this absolute latency perception threshold. In this study, we employed an experimental design based on Fitts' law to investigate whether interaction strategies and task difficulty can alter the latency perception threshold (LPT), and how variations in this threshold influence users' interactive performance. The results show that the LPT is approximately 130-170 ms, and that when interaction strategies prioritize speed or when tasks become more challenging, users exhibit heightened sensitivity to latency. Due to the presence of the LPT, the effect of latency on interactive performance follows a nonlinear pattern, and building on this finding, we refined a Fitts' law model to incorporate the influence of latency. Notably, electroencephalogram (EEG) signals can still capture users' perception of latency when they are unaware of minor latency, demonstrating a level of sensitivity that exceeds conscious awareness. Our findings provide insights into latency effects on performance and perception, guiding the design of more responsive VR interaction systems.