Heather Rupp, a research fellow at the Kinsey Institute for Research in Sex, Gender, and Reproduction at IU Bloomington, said the results of her study suggest that the female brain system may be more sensitive to rewards during the part of the menstrual cycle when conception may occur. She also believes that women may be more likely to engage in risky sexual behaviors, and drug or alcohol abuse, during their fertile periods.
Functional magnetic resonance imaging was utilized to observe the brain activity of the women who participated in the study. The scans were performed around the time of ovulation, as well as later in the menstrual cycle of the women. None of the women who participated used hormonal contraception or were in committed relationships. During the scans, women were shown 256 pictures of men’s faces that varied in masculinity and sexual risk. A computer-morphing program was used to change the masculinity of the men’s faces, and sexual behavior information was provided with each image. The women used a response paddle to indicate how likely she was to engage in sexual activity with each man.