1. INTRODUCTION HYPOTHESES MEASURES RESULTS Correspondence to: erin.krafka@gmail.comPresented at the 26 th Annual Association for Psychological Science, Washington D.C, May 2013 RESULTS Erin Krafka and Michael Knepp, PhD University of Mount Union 20 male undergraduates had their faces imaged as a stock photo and wore a shirt to bed for two consecutive nights, following a list of instructions for the odor preference portion of the study 51 female undergraduates rated the photos and shirts on attractiveness and had their blood pressure recorded during both phases of the menstrual cycle PARTICIPANTS CONCLUSIONS Birth Control Reverses Follicle and Luteal Phase Attraction Ratings to Male Body Odors in College Women Approximately ten million American adolescents and young adults use oral contraceptive pills (Jonk, 2008) Women on birth control experience different menstrual cycles than women not on birth control, as it prevents them from experiencing “duel sexuality” (Alvergne & Lummaa, 2009) Oral contraceptives may alter the attraction between members of the opposite sex in odor preference and attraction ratings (Alvergne & Lummaa, 2009; Jones et al., 2005; Roberts, Gosling, Cater, & Petrie, 2008) The consumption of oral contraceptives causes hypertension in some females (Chasan-Taber et al., 1996) H1: Odor preference and physical attractiveness ratings of pictures would change during different phases of the menstrual cycle in women not consuming birth control, however blood pressure would remain constant. H2: Odor preference and physical attractiveness ratings of pictures would not change during different phases of the menstrual cycle in women consuming birth control, however blood pressure would increase. A significant interaction was found, as females not on birth control increased their ratings for the shirts as they transferred from the luteal phase into the follicle phase, whereas females on birth control had the opposite effect F(1,42)=6.908, p<.02 A trend was found that females on birth control increased their ratings for the stock photos between the two phases of the menstrual cycle F(1,49)=3.361, p<.10 When comparing females on and off birth control, there were no differences in systolic blood pressure, diastolic blood pressure or weight P values >.10 Odor preference and physical attractiveness ratings were measured with six level Likert Scales Blood pressure was recorded with an automated blood pressure cuff Days of the menstrual cycle were recorded by the participants, as they determined which day they were on each time they participated in the study The phase of the menstrual cycle each woman was experiencing was determined based on this data Procedure for females during the follicle and luteal menstrual cycle phases: Baseline blood pressure was recorded Women were presented with 20 frozen shirts, one at a time, for approximately thirty second intervals They made their rating after each shirt was presented Women were presented with 20 photographs of males, one at a time, for approximately thirty second intervals They rated each photo after it was presented Women on birth control differ in attraction preference than women not on birth control The results from this study suggest that birth control reverses the phase in which odor preference ratings increase, making women less attracted to males when they are fertile Future research is necessary to determine attraction changes in different forms of birth control and in pills containing different levels of hormones Figure 1: Interaction of Birth Control and Menstrual Cycle Phase on Odor Preference Figure 2: Interaction of Birth Control and Menstrual Cycle Phase on Face Preference