Date of Award


Degree Type


Degree Name


Degree Program




Major Professor

May, James

Second Advisor

Daniel, Jill

Third Advisor

Dobie, Thomas

Fourth Advisor

King, Bruce

Fifth Advisor

Warren, Barbara

Sixth Advisor

Williams-Brewer, Mary


It is well established that exposure to virtual motion environments (VME) can elicit postural instability (PI) in addition to motion sickness (MS). While research has found sex differences in motion sickness, the results of experimental studies are equivocal regarding these differences, and previous studies utilizing VME have failed to address the factor of sex differences in terms of hormonal fluctuations, which may also be instrumental in behavioral responses to VME, such as PI. The intent of this investigation was to determine whether exposure to VME, during various phases of the menstrual cycle (premenstrual, permenstrual, ovulation) would reveal sex differences in MS and PI during some phases, but not others. The first experiment involved men and women completing Daily Living Logs for a period of 40 days to provide a baseline for any sex differences (and for women, menstrual phase differences) in motion related activity and symptomatology. The second experiment involved 24 participants (6 men) viewing a rotating Archimedes spiral for a period of twenty minutes. Exposures were timed to place each woman in three phases of her menstrual cycle; men were exposed by yoking their exposure time to a female counterpart. Multiple measures of PI and MS were recorded before, after and during exposure. Results of the first experiment found no significant effects of sex or phase upon symptomatology, revealing no support for the theory of a reporting bias as influencing sex differences in MS or PI elicited in the laboratory. The second experiment found no significant effect of sex of phase upon any of the PI measures, but found significant interaction effects of sequence and phase, as well as sequence and sex, upon reported magnitude ratings of illusory self-motion perception. There were also significant effects of sex found upon measures of MS, with women reporting more discomfort to exposure to motion stimulation, as compared to men. There were no significant effects of phase upon any of the MS measures. While these findings show no support for a reporting bias influencing the sex differences found experimentally induced MS, it yields no evidence to support a hormonal influence on these differences.


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