Whether face appears more masculine or feminine appears to be more important in judging its attractiveness than other factors, according to research published March in the journal Human Nature.

In the study, researchers had 508 heterosexual adults rate the attractiveness of male and female facial photographs as either long-term or short-term partners. The study found that the masculinity or femininity of a face appeared to be more important than the symmetry of facial features or healthy/unhealthy skin coloration, particularly for male faces.

The study also found that more masculine faces were preferred more for a short-term relationship than for a long-term relationship, for both men and women.

PsyPost interviewed the study’s corresponding author, Justin K. Mogilski of Oakland University. Read his explanation of the research below:

PsyPost: Why were you interested in this topic?

Mogilski: So, there are two aspects of this research which are worth distinguishing: 1) using conjoint analysis (CA) more broadly to research human mate preferences and 2) using CA to specifically examine preference for morphological facial features (which is what we did in this particular study). CA is a popular multivariate statistical analysis in marketing research that is used to assess how individuals make trade-offs among multiple attributes when evaluating “whole” units that comprise those attributes. Compared to traditional methods (e.g., self-report Likert scales) which measure how much an attribute is independently preferred compared to other attributes, a conjoint design permits conclusions about which attributes are prioritized during holistic evaluation of a collection of attributes.

When I first stumbled upon CA, I thought it had incredible practical and theoretical utility for studying romantic decision-making. It not only addresses several recurrent design limitations within the scientific study of human mating, but it can also be used to test currently unresolved questions within facial attractiveness and person perception research more generally.

To that end, we designed this study to demonstrate CA’s utility as well as examine the relative salience of three well-studied facial cues of attractiveness (i.e., sexually dimorphic shape cues, bilateral symmetry, and color cues to health) during holistic perception of potential romantic partners’ desirability as long-term and short-term (i.e., purely sexual) mates. The importance of these traits in signaling aspects of partner quality (e.g., health and sexual maturity) is well established, but before this study nobody had previously forced people to make trade-offs among these traits (i.e., prioritize one at the cost of losing the others).

What should the average person take away from your study?

Overall, we found that sexually dimorphic shape cues (i.e., how masculine or feminine a face appears) were relatively more important than symmetry and color cues to health. In other words, when evaluating faces that varied concurrently by each of these three traits, variation in masculinity and femininity seemed to be relatively more consequential to how people evaluated each face. We argue that people may preferentially attend to these cues insofar the sex-typicality of a person’s face reliably communicates personality variation (e.g., cooperativeness, sexual attitudes, aggression) that otherwise cannot be discerned from the other two traits. It’s also possible that shape cues are prioritized inasmuch as they aid during initial sex classification of a romantic partner.

Are there any major caveats? What questions still need to be addressed?

Like with any new technique, there are a few design limitations which we are working to address with future studies. This includes, perhaps most importantly, standardizing the digital manipulations that we applied to each face by establishing the Just Noticeable Difference for each facial attribute. Nevertheless, we’ve already replicated our results in two separate, not-yet-published samples. We’re expanding our work to examine the relative importance of each of these traits to perceptions of social dominance and same-sex rivalry. We’re also exploring whether CA can be used to examine which specific sexually dimorphic facial features (e.g., jawbone + cheekbone prominence, eye size) are relatively more salient during social evaluation and person perception.

Is there anything else you would like to add?

I think systematically examining how people prioritize certain qualities over others during partner evaluation has the potential to reveal evolved architectural design features of the human brain. There is a fairly robust scientific literature documenting how selection pressures have shaped the neurocomputational features of person perception. CA is a fairly simple yet elegant tool for examining how humans process complex informational arrays and prioritize certain qualities of a decision over competing alternatives. I recommend that anyone who is interested in these types of research questions should check out this article and our previous publication, which are available for download from my ResearchGate account and from the Welling Research Lab website.

The study, “The Relative Importance of Sexual Dimorphism, Fluctuating Asymmetry, and Color Cues to Health during Evaluation of Potential Partners’ Facial Photographs“, was also co-authored by Lisa L. M. Welling.