Motion sickness is more common among women than among men. In vehicles, motion sickness is more common among passengers than among drivers. We asked whether these two effects might interact. In a yoked-control design using a head-mounted display, one member of each pair drove a virtual automobile, while the other member watched a recording of the driver’s performance. Overall reports of motion sickness were representative of previous research. We found no evidence that the incidence of motion sickness, or the severity of motion sickness symptoms differed between the sexes, or between drivers and passengers. However, among participants who discontinued early, the exposure time for female drivers was significantly less than for male drivers. The results confirm that motion sickness is a common effect of HMD use, and suggest that in virtual environments sex differences in motion sickness may vary with specific tasks.

We investigated the perception of affordances for walking along a narrow path. We asked whether participants could perceive changes in affordances brought about by manipulation of properties of the body, or of the environment, without direct practice of the to-be-perceived affordance, and without external feedback about the accuracy of perception. In Experiment 1, participants made a series of 8 judgments of how far they could walk along a narrow path either, 1) without added weight, 2) while wearing a weighted vest, or 3) while wearing weights on their ankles. Before walking, mean judgments were lower when wearing weights than in the no-weight condition. In addition, in both weight conditions judgments changed across the series of 8 judgments, in the direction of greater accuracy. Control of the body in walking also can be influenced by motion of the ground surface, as commonly happens in vehicles. In Experiment 2, on a ship at sea, we evaluated the effects of walking with or without weight added to the body at the ankles. We again asked participants (experienced maritime crewmembers) to judge how far they could walk along a narrow path, with versus without ankle weights. As in Experiment 1, judgments made before walking mirrored the observed differences in walking performance. In addition, we again found evidence that judgment improved (without walking practice, or feedback) over the series of judgments. We conclude that participants were sensitive to (and spontaneously learned about) how affordances for walking were influenced by changes in the dynamics of body and the environment.