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 changeo 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 healtho 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 investmento High quality but high risk mateo 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 windowso 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 highesto 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

• Directo 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-facialmovement 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?