Sexual Selection, Agonistic Signaling: Presence of beard increased the speed & accuracy with which participants recognized displays of anger but not happiness; & increased the rated prosociality of happy faces

Sexual Selection, Agonistic Signaling, and the Effect of Beards on Recognition of Men’s Anger Displays. Belinda M. Craig, Nicole L. Nelson, Barnaby J. W. Dixson. Psychological Science, March 25, 2019. https://doi.org/10.1177/0956797619834876

Abstract: The beard is arguably one of the most obvious signals of masculinity in humans. Almost 150 years ago, Darwin suggested that beards evolved to communicate formidability to other males, but no studies have investigated whether beards enhance recognition of threatening expressions, such as anger. We found that the presence of a beard increased the speed and accuracy with which participants recognized displays of anger but not happiness (Experiment 1, N = 219). This effect was not due to negative evaluations shared by beardedness and anger or to negative stereotypes associated with beardedness, as beards did not facilitate recognition of another negative expression, sadness (Experiment 2, N = 90), and beards increased the rated prosociality of happy faces in addition to the rated masculinity and aggressiveness of angry faces (Experiment 3, N = 445). A computer-based emotion classifier reproduced the influence of beards on emotion recognition (Experiment 4). The results suggest that beards may alter perceived facial structure, facilitating rapid judgments of anger in ways that conform to evolutionary theory.

Keywords: facial hair, emotion recognition, face processing, intrasexual selection, open data

---
Is this perceived intuitively by soldiers? Many more soldiers than civilians wear a beard in countries like the US, where for decades the overwhelming majority of men didn't sport one.

---
Excerpts: Agonistic interactions between males during competition over resources, status, and mating opportunities occur across the mammalian class and have shaped the evolution of weaponry and threat displays (Darwin, 1871; Emlen, 2008; Kokko, Jennions, & Brooks, 2006). In humans, these displays are manifest in a variety of bodily and facial dimorphisms, of which beardedness is one of the most visually salient (B. J. Dixson & Vasey, 2012; B. J. W. Dixson, Lee, Sherlock, & Talamas, 2017). Beards provide an accurate indication of male sexual maturity, and bearded faces are rated as more masculine, dominant, and aggressive than clean-shaven faces (B. J. Dixson & Brooks, 2013; Muscarella & Cunningham, 1996; Neave & Shields, 2008). These effects stem from the fact that beards grow around the jaw and mouth, and thus emphasize jaw size and masculine facial structure (B. J. W. Dixson et al., 2017; B. J. W. Dixson, Sulikowski, Gouda-Vossos, Rantala, & Brooks, 2016; Sherlock, Tegg, Sulikowski, & Dixson, 2017). Beardedness has a greater influence on ratings of masculinity and dominance than does craniofacial shape or jaw size (B. J. W. Dixson et al., 2017; Sherlock et al., 2017).The enhancing effects of facial hair on judgments of men’s facial masculinity, dominance, and aggressiveness by framing components of masculine facial shape have been measured using stimuli depicting neutral facial expressions. However, faces carry multiple sources of social information, including emotional facial expres-sions that can convey internal states and intentions. Facial expressions such as displays of anger can be enacted in agonistic interactions to signal interpersonal threat (Blair, 2003; Schmidt & Cohn, 2001; Sell, Cosmides, & Tooby, 2014; Tay, 2015). It has been hypothesized that beardedness facilitates recognition of threatening displays, including displays of anger, by enhancing masculine facial features related to dominance (particu-larly jaw size; Blanchard, 2009; Goodhart, 1960; Guthrie, 1970), but to date, there have been no behavioral studies detailing whether beards influence recognition of angry expressions.Although the influence of facial hair on recognition of expressions of anger has not been directly tested, previous findings suggest that it is plausible that beards facilitate the recognition of anger. Previous research has demonstrated that people are faster to recognize anger when it is displayed on male faces than when it is displayed on female faces (Becker, Kenrick, Neuberg, Blackwell, & Smith, 2007). This influence of masculinity on recognition of anger has been partly attributed to overlap between structural cues of anger and masculinity. It has been suggested that angry facial expressions emphasize masculine facial structures, such as the prom-inence of the jaw (Becker et al., 2007; Hess, Adams, Grammer, & Kleck, 2009; Sacco & Hugenberg, 2009). Facial hair grows around the areas involved in express-ing a range of emotions, including anger, and also enhances masculine craniofacial structure and the prominence of the jaw (B. J. W. Dixson et al., 2017; Sherlock et al., 2017). These observations suggest that the pres-ence of a beard may facilitate recognition of angry expressions.To test whether beards amplify displays of anger, we presented participants with photographs of standard-ized expressions of anger and happiness posed by the same men when bearded and clean-shaven. Participants categorized the emotion displayed in each face, and we examined how facial hair affected their speed and accuracy. If participants were faster to recognize anger but not happiness on bearded than on clean-shaven faces, this would indicate that beardedness facilitates recognition of a threatening emotional expression spe-cifically and not emotional expressions more generally. After we found such a specific effect, we explored pos-sible underlying mechanisms in two behavioral experi-ments and a final experiment with a computer-based emotion classifier.