Sex differences in tolerance to visually-induced motion sickness.

Background: Women report a history of motion sickness (MS) about twice as frequently as men, but the results of experimental studies are equivocal. In the present investigation, we sought to replicate previous findings that women report a greater history of MS than men when interrogated with MS history questionnaires. We examined the hypothesis that those reporting that they are prone to MS are less likely to volunteer for MS provocative experiments than those who are MS resistant. Finally, using a subset of these participants, we exposed men and women, during two separate sessions, to visually elicited apparent motion, with and without voluntary head motion (pseudo-Coriolis stimulation), to examine any differences in MS elicited between these two groups on exposure to such motion stimulation. Method: Experiment 1 used a MS History Questionnaire, which included an opportunity for male and female participants to volunteer for "psychology experiments" in the coming semester. This instrument was used to determine effects of sex and volunteer status on motion sickness susceptibility (MSS). Experiment 2 involved exposing a subset of these participants to rotation of a vertically striped rotating drum under static and head movement conditions. Measures of vection and MS were recorded. Results: We found higher MSS scores in women vs. men, particularly when looking at participants who elected to volunteer. Women in the second experiment reported significantly more MS, but they exhibited less tolerance with head movement. No significant differences in vection were observed. Conclusions: The results indicate that laboratory manipulations that are more provocative of MS reveal reliable sex differences.