Perceptual thresholds for display lag in a real visual environment are not affected by field of view or psychophysical technique

IntroductionLag between head movement and the time to render the visual consequences of the movement during head mounted display (HMD) applications presents challenges in the appearance of a stable image. This appearance of an image to “lag” behind or “swim” about may cause detriments in user performance, lack of user acceptance, and simulator sickness. These known potential consequences of HMD use motivated the current work to explore the human capability to detect display lag. The aim in this study was to gain a better understanding of the threshold for display lag detection and what variables affect this threshold.MethodsTwenty four subjects completed a repeated-measures three field of view (FOV; 10°, 38°, and full monocular) X two psychophysical technique (forced-choice and simple) experimental design. Passive sinusoidal head movements about the yaw axis were generated by an oscillating chair. A visual scene consisting of vertical bars was projected by an optokinetic drum moving in a sinusoidal fashion with the subjects. Subjects reported whether the scene lagged behind head movement.ResultsThe grand threshold mean for lag detection was 147.64 ms (SD = 84.91). The median was 130 ms and the 25th and 75th percentiles were 84.17 ms and 206.25 ms, respectively. Lag thresholds were not systematically influenced by either FOV or psychophysical technique.DiscussionNaïve subjects in the current study were less sensitive to lag as compared to thresholds reported in previous HMD studies, which provided lag detection strategies and practice [e.g., 77 ms; Ellis, Mania, Adelstein, & Hill, 2004]. Future examinations using the current paradigm should provide detection strategies and more practice.