Fast non-invasive measures of binocular visual processes relevant to virtual environments

Abstract

Precise coordination of many visual processes is required for clear and precise binocular viewing. However, few studies have measured these binocular processes across large samples to examine how they may differ. The two aims of the experiment were to develop new, fast and non-invasive tests for several binocular visual processes and to administer these tests to a large sample. The tests were designed to obtain thresholds of performance for vergence movement duration, latency, and range, fusion range, and static stereoacuity. Thresholds were obtained using a staircase procedure, with a two-alternative forced-choice paradigm in each staircase, which was chosen to minimise the number of trials required. The stimuli were presented stereoscopically in a mirror stereoscope, with subjective perceptions of nonius lines and static random dot stereograms as the measures of interest. The tests were administered to a sample of 108 participants and demonstrated marked variability in threshold performance within each test. These thresholds are compared to findings in previous research, and consequences for virtual reality design are explored.