Oman York Conference(2001 in press)11/2/01 Page 15 (Figure 13)and viewed a sequence of virtual spacecraft interior scenes(Figure 14), presented at random angles with respect to their body axis. Subjects indicated the sv using a joystick controlled pointer. Responses were categorized as to whether they were aligned within 5 degrees of one of the scene visual axes, the body axis or in between. We defined a metric which gave us a measure of average visual vS. idiotropic dominance across all angles of scene tilt. We tested the subjects preflight and postflight in both a gravitationally upright and supine position Inflight, we tested them on the third or fourth day of the mission both free floating and while standing in spring harness that pulled them down to the deck with an 70 pound force. As we expected, we usually saw "in between"responses only in the IG conditions. Inflight, responses aligned with either the body axis or one of the scene axes. Based on results of previous and concurrent O-G linear- and circular-vection experiments(Young, et al, 1996: Oman et al, 2000) which showed increased sensitivity to moving visual scenes, we expected that our observer might also be more reliant on the orientation of frame in polarity cues in motionless visual scenes. One observer who was moderately visually independent on the ground became more visually dependent in flight, and then recovered postflight, after a short period of carry over. He responded to the scene polarity manipulation inflight. But the other three observers-two of whom were strongly"idiotropic"and one of whom was strongly"visual"showed little overall change during or after the flight. The down cues from the spring harness did reduce the visual category responses of the two visual observers. None of these observers showed any signs of inversion illusion" during these flight day 4 tests, although one reported a brief inversion illusion in darkness while a subject in another experiment. Obviously these results are only preliminary. Ultimately we cannot be sure that subjects respond exactly the same way to our virtual environments as they would if we could use real ones. But our results do confirm the notion-suggested by Young et al (1986)and Reschke, et al (1994)based on astronaut debriefs Figure 14. Stereogram of polarized visual scene used in Neurolab visual orientation experiments that crewmembers differ markedly in terms of whether they adopt a"visual or"idiotropic reference frame in making subjective vertical judgements. We expect to have the opportunity to test more observers over a longer flight duration on International Space Station missions starting in about two yearsOman York Conference (2001 in press) 11/2/01 Page 15 (Figure 13) and viewed a sequence of virtual spacecraft interior scenes (Figure 14), presented at random angles with respect to their body axis. Subjects indicated the SV using a joystick controlled pointer. Responses were categorized as to whether they were aligned within 5 degrees of one of the scene visual axes, the body axis or in between. We defined a metric which gave us a measure of average visual vs. idiotropic dominance across all angles of scene tilt. We tested the subjects preflight and postflight in both a gravitationally upright and supine position. Inflight, we tested them on the third or fourth day of the mission both free floating and while “standing” in spring harness that pulled them down to the deck with an 70 pound force. As we expected, we usually saw “in between” responses only in the 1G conditions. Inflight, responses aligned with either the body axis or one of the scene axes. Based on results of previous and concurrent 0-G linear- and circular-vection experiments (Young, et al, 1996; Oman et al, 2000), which showed increased sensitivity to moving visual scenes, we expected that our observers might also be more reliant on the orientation of frame in polarity cues in motionless visual scenes. One observer who was moderately visually independent on the ground became more visually dependent in flight, and then recovered postflight, after a short period of carry over. He responded to the scene polarity manipulation inflight. But the other three observers – two of whom were strongly “idiotropic” and one of whom was strongly “visual” showed little overall change during or after the flight. The “down” cues from the spring harness did reduce the visual category responses of the two visual observers. None of these observers showed any signs of “inversion illusion” during these flight day 4 tests, although one reported a brief inversion illusion in darkness while a subject in another experiment. Obviously these results are only preliminary. Ultimately we cannot be sure that subjects respond exactly the same way to our virtual environments as they would if we could use real ones. But our results do confirm the notion - suggested by Young et al (1986) and Reschke, et al (1994) based on astronaut debriefs - Figure 14. Stereogram of polarized visual scene used in Neurolab visual orientation experiments. that crewmembers differ markedly in terms of whether they adopt a “visual” or “idiotropic” reference frame in making subjective vertical judgements. We expect to have the opportunity to test more observers over a longer flight duration on International Space Station missions starting in about two years