Changes in scores on the Mental Rotations Test during the menstrual cycle.

The purpose of the study was to examine changes in performance on Vandenberg's Mental Rotations Test during the menstrual cycles of college women. Participants were 12 male and 34 female students recruited from undergraduate educational psychology and nursing classes at a large southeastern university. Each woman was tested once during the menstrual phase and once during the luteal phase of her menstrual cycle. Phases in which the testings occurred were counterbalanced. Men were also tested twice. For all participants, the two testing sessions were held exactly 14 days apart. Women who were contraceptive pill users did not perform significantly differently during either phase from women who were nonusers, and there was no interaction for pill use by phase. Therefore, users and nonusers were combined for a paired-sample t test which indicated that women scored significantly higher during the menstrual phase (Days 2-7) than during the luteal phase (Days 16-22 for 31 women and Days 24-26 for three women with longer cycles). The 12 men scored significantly higher than the 34 women during the initial testing; but not significantly higher than the 17 women who were in the menstrual phase during the first testing. Therefore, that the effect of the phase of menstrual cycle influences the sex difference in performance on the Mental Rotations Test was supported.