The performance of females on two mental rotation tasks: A possible mediating role of female hormones

Differences and similarities between the sexes has long been an area of curiosity and inquiry. Historically, research into sex differences in cognition has found differences favouring women in verbal tasks and men in visuospatial tasks. The visuospatial task that has consistently produced the largest and most robust sex differences favouring men has been the Mental Rotation Task. One of the leading explanatory theories for this sex difference in visuospatial ability has been hormonal influences; particularly the influences' of testosterone and estrogen. Previous research has shown a strong positive testosterone and strong negative estrogen correlation to visuospatial performance, in particular mental rotation performance. Although Mental Rotation Task performance results typically favor males, the data are not altogether consistent across studies, with some failing to report this difference. One explanation for this inconsistency could be that many studies fail to report or investigate the possibility of performance differences between female oral contraceptive users and naturally cycling participants. Oral contraceptives inhibit monthly estrogen fluctuations that accompany the female menstrual cycle, thus hypothetically those participants on oral contraceptives should have enhanced performance on Mental Rotation Tasks in comparison to naturally cycling participants, a finding which could influence studies examining male-female differences. The current study examined performance differences between oral contraceptive users and naturally cycling participants on two Mental Rotation Tasks: the Shepard and Metzler (1971) and the Vandenberg and Kuse (1978). The results failed to reveal a significant performance difference between these two groups on either of the two mental rotation tasks. However, when collapsed across groups, the data revealed a significant difference (p <.01) in performance as measured by correct responses between the two tasks, with participants performing worse on the Vandenberg and Kuse assessment compared to the Shepard and Metzler assessment. Further examination revealed a strong significant relationship between participant's performances on both assessments while in the menstrual phase, but no relationship between assessments for participants in the luteal or follicular phase. Continued research with respect to hormonal influences, oral contraceptive influence, and their relationship to sex and cognitive performance is needed. In addition, a more standardized version of the Shepard and Metzler mental rotation task should be developed in an effort to control for variability among conditions in future studies.