Original Articles
Facial correlates of sociosexuality

https://doi.org/10.1016/j.evolhumbehav.2007.12.009Get rights and content

Abstract

Previous studies have documented variation in sexual behaviour between individuals leading to the notion of ‘restricted’ individuals (i.e., people who prefer long-term relationships) and ‘unrestricted’ individuals (i.e., people who are open to short-term relationships). This distinction is often referred to as sociosexual orientation. Observers have been previously found to distinguish sociosexuality from video footage of individuals, although the specific cues used have not been identified. Here we assessed the ability of observers to judge sexual strategy based specifically on cues in both facial composites and real faces. We also assessed how observers' perceptions of the masculinity/femininity and attractiveness of faces relate to the sociosexual orientation of the pictured individuals. Observers were generally able to identify restricted vs. unrestricted individuals from cues in both composites and real faces. Unrestricted sociosexuality was generally associated with greater attractiveness in female composites and real female faces and greater masculinity in male composites. Although male observers did not generally associate sociosexuality with male attractiveness, female observers generally preferred more restricted males' faces (i.e., those with relatively strong preferences for long-term relationships). Collectively, our results support previous findings that androgenisation in men is related to less restricted sexual behaviour and suggest that women are averse to unrestricted men.

Introduction

Across individuals, there is variation in the tendency to which each person engages, or is prepared to engage, in short-term sexual relationships. The most commonly used tool for assessing relative interest in short-term sexual relationships is the Sociosexual Orientation Inventory (SOI) developed by Simpson and Gangestad (1991). The SOI was developed to assess individual propensity to engage in short-term sexual relationships. A high score on the SOI indicates an ‘unrestricted’ sociosexuality (i.e., being more open to short-term sexual relationships) while a low score indicates a ‘restricted’ sociosexuality (i.e., being less willing to engage in short-term sexual relationships).

Using the SOI, Gangestad, Simpson, DiGeronimo, and Biek (1992) demonstrated that female observers could accurately assess the sociosexual orientation of men solely from visual cues such as their appearance and body language. In the Gangestad et al. study, observers rated the sociosexuality of men after viewing silent video-taped footage of them talking to a camera as if to a potential date. While this video technique produced high ecological validity, it cannot distinguish whether the observers were using cues related to the physical appearance or the body language of the video-taped males.

It may, however, be possible to assess sociosexuality based on physical appearance alone in the absence of movement cues. Less restricted sociosexuality (i.e., greater willingness to engage in short-term relationships) has been shown by Clark (2004) to be linked to greater masculinisation in female cognitive (better mental rotation ability) and physical (smaller second-fourth digit ratio) traits. Such masculinisation may also be visible in female faces, possibly leading to a more masculine appearance (see Schaefer, Fink, Mitteroecker, Neave, & Bookstein, 2005, for evidence regarding digit ratio and facial shape; although cf. Koehler, Simmons, & Rhodes, 2004). Clark also found evidence that less restricted females rated themselves as being more attractive. Contrastingly, Rhodes, Simmons, and Peters (2005) found that more feminine-looking females and more masculine-looking males reported having had more sexual partners (although more feminine-looking females also reported having had more long-term partners, suggesting that opportunity for relationships may mediate the association between femininity and number of sexual partners, rather than the sociosexual orientation of feminine women).

In males, less restricted sociosexuality has been linked to decreased fluctuating asymmetry in both the face and body (Thornhill and Gangestad, 1994, Simpson et al., 1999). Similarly, Rhodes et al. (2005) found that women with more symmetric-looking bodies reported having more sexual partners. Low levels of fluctuating asymmetry are considered to be attractive in potential partners' faces (Penton-Voak et al., 2001, Rhodes et al., 2001) and thus we hypothesise that less restricted (and ergo more symmetrical) individuals should be more attractive. Indeed, amongst males, possession of attractive traits such as low levels of fluctuating asymmetry should positively predict an interest by that male in short-term relationships, because their ‘valuable’ genes are in demand (Gangestad & Simpson, 2000). Therefore it may be that observers can use these cues (attractiveness, symmetry and masculinity) to distinguish between individuals with unrestricted (short-term) and restricted (long-term) relationship strategies purely on the basis of facial appearance in static images.

Although we know of no published studies linking the sociosexuality of individuals to their facial appearance in static photographs, several studies to date have found that observers can predict an individual's behaviour based solely on appearance in a photograph. For instance, Berry and Wero (1993) showed that observers could accurately determine which psychology students would be most likely to agree to deceive experimental participants. Similarly, Yamagishi, Tanida, Mashima, Shimoma, and Kanazawa (2003) found that observers could identify the individuals who were likely to cheat in prisoner's dilemma tasks. Most recently, Penton-Voak, Pound, Little, and Perrett (2006) found that observers could accurately ascribe certain aspects of five-factor personality scores to strangers' faces. Like deception and core personality, sexual behaviour is a domain of social behaviour which it may be advantageous for an observer to be able to predict in both potential partners (for instance, avoiding unsuitable long-/short-term mates before expending energy in pursuit) and also in potential rivals, selection for which would result in a generalised ability to judge the likely sociosexual orientation of others (see, e.g., Boothroyd, Jones, Burt, & Perrett, 2007, for evidence of males and females showing similar judgments of males' apparent fidelity).

The studies reported here assessed both the facial characteristics associated with sociosexuality and whether observers were sensitive to such facial cues. Study 1 used composite facial images, while Study 2 used photographs of real faces in a correlational method.

Section snippets

Study 1

Study 1 used facial composites of unrestricted (open to short-term relationships) and restricted (prefer long-term relationships) individuals. The principle of averaging images means that randomly varying traits across two groups will tend towards average in composites, while traits that are significantly different between groups will be more clear in composites (Perrett et al., 1994). Thus, this method is ideal for detecting subtle structural differences between groups (e.g., a larger, squarer

Study 2

Study 1 found evidence that observers are sensitive to cues to sociosexuality in composite facial images — either through explicit identification of unrestricted images (for which there is partial evidence) or, amongst women, through aversions to unrestricted males with whom long-term relationships would be unsuitable — and that unrestricted male faces appear more masculine. Study 2 built upon Study 1 in two key aspects. Firstly, despite the advantages of composites, as discussed in Study 1

Discussion

These studies first sought to determine whether observers were able to identify sociosexually restricted vs. unrestricted individuals by static facial cues alone. The results (summarised in Table 3) suggest that observers are indeed able to distinguish between individuals on the basis of sociosexuality, although in Sample 1a males had difficulty identifying unrestricted female composites, and in Sample 1b both sexes of observer had difficulty identifying unrestricted male composites. These

Acknowledgments

L Boothroyd was supported during Study 1 by an MRC studentship and an ESRC Postdoctoral Fellowship (PTA-026-27-0475). D Burt was support by a Unilever research grant. The authors wish to thank Charlotte Dunkley and Lucie Holmes for their assistance in Study 2.

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