Exaggerated sex-typical (i.e., masculine) characteristics in men have been proposed as indicators of a strong immune system that would be inherited by offspring but also linked to reduced willingness to invest time and other resources in personal relationships (Gangestad, Simpson, Cousins, Garver-Apgar, & Christensen, 2004; Gildersleeve, Haselton, & Fales, 2014; Little, Jones, & DeBruine, 2011; Penton-Voak et al., 1999; Perrett et al., 1998). Given this proposed trade-off between the benefits and costs of choosing a masculine mate, researchers have hypothesized that women could maximize the benefits of their mate choices by mating with masculine men when fertile, while forming long-term relationships with relatively feminine men (Gangestad et al., 2004; Gildersleeve et al., 2014; Little et al., 2011; Penton-Voak et al., 1999).

Consistent with this hypothesis, some studies have reported that women show stronger preferences for masculine characteristics in men’s faces when in hormonal states associated with high fertility (e.g., during the ovulatory phase of the menstrual cycle or when not using hormonal contraceptives; Ditzen, Palm-Fischbacher, Gossweiler, Stucky, & Ehlert, 2017; Johnston, Hagel, Franklin, Fink, & Grammer, 2001; Little, Burriss, Petrie, Jones, & Roberts, 2013; Little & Jones, 2012; Little, Jones, Penton-Voak, Burt, & Perrett, 2002; Penton-Voak et al., 1999; Penton-Voak & Perrett, 2000; Roney & Simmons, 2008; Roney, Simmons, & Gray, 2011; Vaughn, Bradley, Byrd-Craven, & Kennison, 2010; Welling et al., 2007). These effects are widely cited as evidence that sexual selection has shaped women’s judgments of men’s facial attractiveness (Fink & Penton-Voak, 2002; Gangestad & Simpson, 2000; Grammer, Fink, Møller, & Thornhill, 2003; Thornhill & Gangestad, 1999).

The claim that women’s preferences for facial masculinity are related to their hormonal status has been influential. However, it is also highly controversial (see Gildersleeve et al., 2014, and Wood, Kressel, Joshi, & Louie, 2014, for meta-analyses drawing opposite conclusions about the robustness of hypothesized links between women’s masculinity preferences and hormonal status). In particular, recent work has highlighted four potentially serious methodological problems with research on the hormonal correlates of masculinity preferences.

First, sample sizes are usually small, meaning that studies are very underpowered (Gangestad et al., 2016). For example, the mean sample size of within-subjects studies reporting significant effects of hormonal status on facial-masculinity preferences is 40 women (Mdn = 34). Consequently, results from previous studies are difficult to interpret (Blake, Dixson, O’Dean, & Denson, 2016; Gangestad et al., 2016).

Second, hormonal status is typically assessed using self-reported menstrual cycle data (e.g., number of days since onset of last menses or number of days until expected date of next menses; Harris, 2013; Johnston et al., 2001; Little & Jones, 2012; Muñoz-Reyes et al., 2014; Penton-Voak & Perrett, 2000; Penton-Voak et al., 1999; Scott et al., 2014; Zietsch, Lee, Sherlock, & Jern, 2015). This method is imprecise and prone to bias (Blake et al., 2016; Gangestad et al., 2016; Harris, 2013).

Third, many studies use between-subjects designs. Use of between-subjects designs in this research is potentially problematic because, even with large samples, the substantial genetic contribution to individual differences in facial-masculinity preferences (Zietsch et al., 2015) could obscure subtle effects of hormonal status. Thus, although several recent studies testing for possible effects of hormonal status on facial-masculinity preferences have reported null results (Harris, 2013; Marcinkowska et al., 2016; Muñoz-Reyes et al., 2014; Scott et al., 2014; Zietsch et al., 2015), it is noteworthy that these studies all used between-subjects designs.

Fourth, studies using within-subjects designs typically test women on only two occasions (Johnston et al., 2001; Little et al., 2013; Little & Jones, 2012; Penton-Voak et al., 1999; Roney et al., 2011). This limited approach may not adequately capture complex changes in hormonal status (e.g., Roney & Simmons, 2013).

The current study directly addressed all of these potentially serious methodological problems by recruiting 584 heterosexual women for a longitudinal (i.e., within-subjects) study in which both women’s hormonal status and preferences for masculinity in men’s faces were repeatedly assessed (519 women completed at least 5 test sessions, 176 women completed at least 10 test sessions). Changes in women’s hormonal status were assessed by measuring steroid hormones from saliva samples and also by tracking within-subjects changes in hormonal contraceptive use.

Fig. 1. Examples of masculinized (a) and feminized (b) versions of men’s faces used to assess facial-masculinity preferences in our study.

Source: http://journals.sagepub.com/doi/10.1177/0956797618760197