Abstract
Non-stereoscopic optic flow can evoke vection of an inaccurate magnitude (Jenkin, Redlick, Harris, ARVO 2000). Stereoscopic information can affect vection, shortening its latency and increasing its duration (Palmisano, Percept. Psych. 1996 58: 1168). Does stereoscopic information influence the magnitude of vection? Methods: Subjects wore alternating shutter glasses (96Hz) to view either a non-stereoscopic or a binocular, 3-dimensional virtual corridor projected onto a large display surface comprised of two orthogonal walls with their corner straight ahead at a distance of 3.5m. Subjects viewed a virtual target at between 4-32m which was extinguished before forward self-motion at either constant velocity (0.4m/s–6.4m/s) or acceleration (0.025m/s/s–1.0m/s/s) was simulated. Subjects reported when they perceived they had reached the previously presented target position. Results: When subjects viewed the large, non-stereoscopic display, we reproduced our previous results obtained in a non-stereoscopic HMD. Subjects overestimated their motion at slower accelerations (constant velocity and 0.025–0.4m/s/s), and were accurate at higher accelerations (0.4–1.0 m/s/s). When subjects viewed the display with stereoscopic cues, they overestimated their motion at both slower (0.025–0.4m/s/s) and higher accelerations (0.4m/s/s – 1m/s/s). Conclusion: Adding stereopsis, far from improving the accuracy of distance judgments, surprisingly was associated with overestimation even of high acceleration movements (which were judged accurately in non- stereoscopic displays).
Supported by Natural Science and Engineering Research.