References:

1. Actual Time Real-Real Real-Virtual Experiment 2 Order Effects with Different Scenes Question Do improvements across environments in time-to-walk estimates depend on making judgments about the same scene? Participants Twenty-four undergraduates participated for course credit. Environments The RE-1 was the same scene used in the previous experiments. The RE-2 was a different grassy lawn between two university buildings. The VE-2 was a scene depicting RE-2. Design and Procedure Baseline walking. Same as Experiment 1. Time-to-walk estimates. Participants made two sets of time-to-walk estimates in one of the following conditions: 1) RE-1 first, VE-2 second; or 2) RE-1 first, RE-2 second. Real environment Virtual Environment Results Q: Do improvements across environments in time-to-walk estimations depend on making judgments about the same scene? Second time-to-walk estimates did not differ significantly between RE-2 and VE-2 (see Figure 2). Summary of Experiment 2 Again, time-to-walk estimates made second in the real and virtual environments were nearly identical, suggesting that transfer from real to virtual environments does not depend on making judgments about identical scenes 30 25 20 15 Time-to-Walk Estimate (s) 10 5 0 20 ft 40 ft 60 ft 80 ft 100 ft 120 ft Figure 2. Mean time-to-walk estimates made second Conclusions Together, the results of these experiments again confirm the presence of subtle, yet persistent order effects in judging distances in virtual environments. Participants who made judgments in the real environment first made more accurate subsequent judgments in the virtual environment. This transfer between environments did not depend on making judgments about identical scenes. One possible explanation for these results might be a practice effect. After judging distances in the real environment, participants may have used this experience as a guide for making judgments in the virtual environment. Although participants did not receive feedback during either the first or second set of estimates, perhaps a sense of timing in the real environment helped ground subsequent distance estimates in the virtual environment. Our results again show that although time-to-walk estimates made first were smaller in the virtual than in the real environment, they did not differ significantly. Nonetheless, the presence of order effects suggests that some caution in assessing performance in real and virtual environments using within-subjects designs. References: LOOMIS, J. M., BLASCOVICH, J. J., and BEALL, A. C. 1999. Immersive virtual environment technology as a basic research tool in psychology. Behavior Research Methods, Instruments, & Computers, 31, 557-564. LOOMIS, J. M. and KNAPP, J. M. 2003. Visual perception of egocentric distance in real and virtual environments. In Virtual and Adaptive Environments, Lawrence Erlbaum Associates, Mahwah, NJ. L. J. Hettinger and M. W. Haas, Eds., 21-46. PLUMERT, J. M., KEARNEY, J. K., and CREMER, J. F. 2004. Children’s perception of gap affordances: Bicycling across traffic-filled intersections in an immersive virtual environment. Child Development, 75, 1243-1253. PLUMERT, J. M., KEARNEY, J. K., CREMER, J. F., & RECKER, K. (2005). Distance perception in real and virtual environments. ACM Transactions in Applied Perception, 2, 216-233. THOMPSON, W. B., WILLEMSEN, P., GOOCH, A. A., CREEM-REGEHR, S. H., LOOMIS, J. M., and BEALL, A. C. In press. Does the quality of computer graphics matter when judging distance in visually immersive environments? Presence: Teleoperators and Virtual Environments . WHITMER, B. G. and SADOWSKI, W. J. J. 1998. Nonvisually guided locomotion to a previously viewed target in real and virtual environments. Human Factors, 40, 478-488. WILLEMSEN, P. and GOOCH, A. A. 2002. Perceived egocentric distances in real, image-based and traditional virtual environments. Proceedings of IEEE Virtual Reality Conference. 89-90. Acknowledgements This work was supported by NSF grants IIS 00-02535 and EIA 0130864.