In women, changes in preference during the menstrual cycle have been documented for attractiveness judgements of odour and various physical and behavioural male traits. Although many studies have demonstrated greater attraction to masculine traits, such as male faces, bodies, and voices, at high fertility, several recent studies present null results for these shifts in preferences. Moreover, evidence for stronger attraction to symmetric faces at high fertility is equivocal. Here we examined variation in preferences across the cycle for both facial masculinity and symmetry according to relationship context. Using both within-subject (Study 1) and between-subject (Study2) designs, we show that women prefer masculinity and symmetry in male faces at times when their fertility is likely to be highest (during the follicular phase of their cycle) when judging the faces for short-term relationship attractiveness. No effect of cycle was seen for long-term judgements. These results indicate that cyclic shifts in women are most apparent when judging for short-term relationships, which may explain the null results in studies where only general attractiveness was assessed. Cyclical preferences could influence women to select a partner who possesses traits that may enhance her offspring's quality at times when conception is most likely and/or serve to improve partner investment when investment is important.
Women differ in their face preferences and one biological explanation for within-individual variation lies with hormonal changes during the menstrual cycle. Many studies have demonstrated that women's preferences for certain male traits change during the menstrual cycle. Increased preferences for facial masculinity (Frost, 1994, Penton-Voak et al., 1999, Penton-Voak and Perrett, 2000 and Johnston et al., 2001), vocal masculinity (Puts, 2005 and Feinberg et al., 2006), dominant behaviour (Gangestad et al., 2004), the smell of dominant men (Havlicek et al., 2005) and for masculine body shapes (Little et al., 2007b) that coincide with the late follicular (i.e. fertile) menstrual cycle phase have been reported. Cyclic shifts are also seen for other mate choice relevant traits whereby fertile women are quicker to categorise men's faces as male (Macrae et al., 2002) and generally rate men as more attractive (Danel and Pawlowski, 2006). Shifts are also seen for face traits such as self-resemblance (DeBruine et al., 2005) and are also evident in increases in pupil diameter when viewing sexually partners during the fertile phase (Laeng and Falkenberg, 2007). Cyclic shifts are thought to reflect the underlying effects of female hormones on preferences for male traits. Several hormones change across the cycle and shifts have been linked to oestrogen (Roney and Simmons, 2008), progesterone (Jones et al., 2005 and Puts, 2005), and testosterone (Welling et al., 2007), although such shifts are potentially best explained by complex interactions among multiple hormones (Feinberg et al., 2006 and Welling et al., 2007).
