Women’s Probability of Conception Is Associated with their Preference for Flirtatious but not Masculine Facial Movements (Morrison et al, 2009) Michelle, Kyle P, Ellen

Introduction Depending on the stage of a women’s menstrual cycle, preferences in women’s behaviors change o Height (Pawlowski & Jasienska, 2005) o Voice pitch (Feinberg et al., 2006) o Odor (Gangstad & Thornhill, 1998) o Facial symmetry During the fertile window, women prefer more masculine faces (Johnston et al., 2001)

Introduction Traits related to testosterone thought to signal immunocompetence (Folstad & Karter, 1992) and developmental health o Height, voice pitch, facial structure Good genes may indicate a good quality mate, it could also indicate negative personality attributes (Perrett et al., 1998) o Coldness, dishonesty, less parental investment o High quality but high risk mate o Ovulatory shifts in preference leads to trading off traits depending on chance of conception

Introduction Flirting can also signal reward for invested mating effort (Mishra, Clark, & Daly, 2007) o Signals interest to a women, who can be time-strained by fertility windows o Limited by whether or not using static stimuli or dynamic video Because flirtatious displays are dynamic in nature, attractiveness ratings do not necessarily correlate (Lander, 2008)

Introduction Hypothesis (1): female preferences for masculine movement should be higher in the follicular phases of the menstrual cycle Hypothesis (2): female preferences for flirtatious facial movement should be more important when chance of conception is highest o Signals reward for mating effort

Methods Five 1 minute clips of men talking to interviewer Divided up into 10 second clips (30 clips total) 30 points on the face analyzed for movement Transferred to Androgynous animation face Calculate mean distance travelled from center points

Methods (cont.) Thirty 10 second clips Analyzed for masculinity Flirtatiousness ratings (1-7) Short Term attractiveness ratings (1-7)

Methods (cont.) Probability of Conception calculated Flirtatiousness mostly agreed upon Divide clips into most flirtatious and most masculine Give each woman a score based on preference for flirtatiousness and one for masculinity Run Hierarchical linear modeling

Results- Conception Probabilities Estimated mean probability of pregnancy of following a single act of unprotected intercourse Of all participants was 2.7% Late follicular phase (days 7-15) was 4.8% Menses and luteal phase (days 1-6 and 16-29) was 1.3%

Results

Results

Results

Weaknesses Use of forward counting method instead of reverse counting 5 young Christian men talking about Christmas for male facial data Only identified male faces correctly 60% of the time

Possible Evolutionary Benefits Direct o Increased probability of reward for mating efforts Indirect o Good genes o Handicap Principle

Discussion Not just movement, must be seen as flirtatious Concealed ovulation No testosterone-facial movement link found Flirtatiousness and masculinity negatively correlated Can we really determine gender based on facial animations?

Recommend research Improvements in animation What is flirtatiousness/masculinity? How do static and dynamic masculinity differ?