Head Tracking Latency in Virtual Environments: Psychophysics and a Model

Abstract

Quantification of perceptual sensitivity to latency in virtual environments (VEs) and elucidation of the mechanism by which latency is perceived is essential for development of countermeasures by VE designers. We test the hypothesis that observers use “image slip” (i.e., motion of the VE scene caused by system time lags) to detect the consequences of latency rather than explicitly detecting time delay. Our presumption is that forcing observers to change from constant rate to randomly paced head motion will disrupt their ability to discriminate latency based on perceived image slip. This study indicates that the disruption in motion pattern causes a shift in latency detection criteria and a minor degradation in discrimination ability. It is likely therefore that observers make at least some use of image slip in discriminating VE latency. It can also be inferred that when observers learn to discriminate latency, their Just Noticeable Difference (JND) remains below 17 ms.