Changes in cognitive task performance across the menstrual cycle.

Menstrual-cycle-related changes in estrogen were expected to differentially affect various cognitive tests. Specifically, the estrogen peak occurring at midcycle in ovulatory women was expected to facilitate performance of highly practiced "automatized" tasks and to impair performance of "perceptual-restructuring" tasks, compared with performance of these tasks in the postovulatory phase of the cycle when progesterone is thought to counteract the action of estrogen. Perceptual-restructuring tasks are defined as tasks in which the initial percepts to obvious stimulus attributes are wrong and must be set aside in favor of percepts to less obvious stimulus attributes. Eight-seven regularly menstruating undergraduate women were studied. Odd-numbered subjects were tested first on or about Day 10 of their cycle and then again on Day 20; even-numbered subjects, in the reverse sequence. Daily basal body temperature records were obtained. These temperature records suggested that 21, or 24%, of the subjects did not ovulate in the cycle(s) studied. No main effect of Day 10 versus Day 20 occurred for any task in the 66 women who did appear to ovulate. However, the magnitude of predicted shifts in performance was significantly correlated with proximity of the "Day 10" testing day to the thermal nadir of the basal body temperature record, the presumed preovulatory estrogen peak; and to the "Day 20" proximity to the basal body temperature thermal peak, the presumed progesterone peak. Subjects tested 3 or fewer days before the thermal nadir and on or after the thermal peak had the predicted significant changes on three of the four administered tasks. No other temporally defined group produced significant changes. The results of the study support the experimental hypotheses and also indicate that precise timing is essential to demonstrate the phenomena.