1. Introduction
Financial and prosocial biases in favor of physically attractive adults have been a phenomenon of considerable interest to economists, social psychologists, and evolutionary psychologists (throughout this article, all evolutionary behavioral scientists are referred to as evolutionary psychologists). Several different explanations have been proposed for this phenomenon. One influential model developed by economists (the “taste-based” discrimination model) assumes that these biases are the result of individual preferences or prejudices, without explaining why these preferences or prejudices occur (e.g., Gneezy & List Reference Gneezy and List2013; Hamermesh Reference Hamermesh2011). Other explanations proposed by economists and social psychologists assume that people are financially or prosocially biased toward attractive individuals because attractiveness is a reliable marker of psychological or behavioral characteristics (e.g., personality, intelligence, trustworthiness, professional competence, or productivity) (e.g., Hamermesh Reference Hamermesh2011; Hosoda et al. Reference Hosoda, Stone-Romero and Coats2003; Jackson et al. Reference Jackson, Hunter and Hodge1995; Langlois et al. Reference Langlois, Kalakanis, Rubenstein, Larson, Hallam and Smoot2000). Finally, many evolutionary psychologists have argued that financial or prosocial biases toward attractive adults occur because these individuals are preferred sexual partners (e.g., Farrelly et al. Reference Farrelly, Lazarus and Roberts2007; Iredale et al. Reference Iredale, Van Vugt and Dunbar2008; Kenrick et al. Reference Kenrick, Montello, Gutierres and Trost1993; Maner et al. Reference Maner, Kenrick, Becker, Delton, Hofer, Wilbur and Neuberg2003; Van Vugt & Iredale Reference Van Vugt and Iredale2013); different evolutionary explanations have been used with regard to positive biases toward attractive infants and children (see sect. 6). This view implies that in order to understand financial and prosocial decision making, one also has to take into account sexual motives.
One common feature shared by the explanations advanced by economists, social psychologists, and evolutionary psychologists is that they assume that attractiveness-related biases in human social transactions originate from biases in behavior and decision making at the individual level. An alternative viewpoint adopted by some sociologists and cultural anthropologists is that such biases reflect common or recurring sociocultural or historical factors such as conflict between classes, male domination and oppression of women, or intrinsic characteristics of capitalistic socioeconomic systems (e.g., Berry Reference Berry2007; Reference Berry2012; Wolf Reference Wolf1992).
In this article, we aim to (1) describe financial and prosocial biases in favor of attractive individuals in the labor market, in social transactions in everyday life, and in studies involving experimental economic games; (2) examine the explanations for this phenomenon provided by economists, social psychologists, and evolutionary psychologists; (3) review and evaluate the empirical evidence in favor of or against these explanations; (4) discuss some possible psychological and physiological mechanisms underlying the expression of positive biases in favor of attractive individuals; and (5) discuss the development of attractiveness-related positive biases early in life. Although there is a large body of research on attractiveness-related biases in social and developmental psychology, in this article we concentrate primarily on labor market studies and laboratory studies involving experimental economic games because we believe that these studies can provide the most direct documentation of financial and prosocial biases in favor of attractive individuals and the most useful evidence to understand their determinants. Labor market studies generally have large sample sizes and investigate attractiveness-related biases that have important real-life consequences: hiring decisions, career advancements, and wages. Laboratory studies involving experimental economic games provide the setting in which both independent variables (attractiveness) and dependent variables (decision making) are experimentally manipulated with a high degree of precision, and interactions between individuals take place according to highly standardized procedures. To our knowledge, there have been no systematic studies of the effects of attractiveness on decision making from a purely sociological or anthropological perspective; therefore, these perspectives are not addressed in this article. We do acknowledge, however, that financial and prosocial biases in favor of attractive people probably have multiple determinants and that sociocultural factors are likely to contribute to them.
2. Biases in favor of attractive individuals in the labor market and in social transactions in everyday life
The existence of a beauty premium in labor markets across industries, contexts, and cultures is well known and well documented (see Hamermesh Reference Hamermesh2011). Physically attractive individuals are more likely to be interviewed for jobs and hired, they are more likely to advance rapidly in their careers through frequent promotions, and they earn higher wages than unattractive individuals (see references listed subsequently).
A particularly effective research approach for documenting the advantage of attractive people in the job application and interview process involves sending curricula vitae (CVs) with photos of attractive and unattractive men and women to firms that have advertised job openings (e.g., Busetta et al. Reference Busetta, Fiorillo and Visalli2013; Lopez Boo et al. Reference Lopez Boo, Rossi and Urzua2013; Ruffle & Shtudiner Reference Ruffle and Shtudiner2015). In one recent study using this approach, Busetta et al. (Reference Busetta, Fiorillo and Visalli2013) sent 11,008 CVs to 1,542 job openings in Italy. They sent the same CV eight times to each job opening: In four cases, they included a photograph of the alleged applicant (as an attractive man, an unattractive man, an attractive woman, or an unattractive woman), whereas in the other four cases no photo was included. Callback rates were significantly higher for attractive women and men when compared with unattractive women and men (attractive women, 54%; unattractive women, 7%; attractive men, 47%; unattractive men, 26%) and with applicants without photos (39%). Overall, callback rates did not differ significantly for female and male applicants, indicating the absence of sex discrimination in the hiring process. However, there was a robust main effect of attractiveness, as well as a significant interaction between attractiveness and sex, because attractiveness mattered more for female applicants (54% vs. 7%) than for males (47% vs. 26%) (see Penninck [2014] for lack of effects of male attractiveness on callback rates).
Beyond its effect on initial hiring opportunities (see also Bardack & McAndrew Reference Bardack and McAndrew1985; Cann et al. Reference Cann, Siegfried and Pearce1981; Dipboye et al. Reference Dipboye, Fromkin and Wiback1975; Reference Dipboye, Arvey and Terpstra1977; Gilmore et al. Reference Gilmore, Beehr and Love1986; Hosoda et al. Reference Hosoda, Stone-Romero and Coats2003; Quereshi & Kay Reference Quereshi and Kay1986; Raza & Carpenter Reference Raza and Carpenter1987), physical attractiveness is also known to be a significant predictor of career advancement and promotions (Chung & Leung Reference Chung and Leung1988; Hosoda et al. Reference Hosoda, Stone-Romero and Coats2003; Jackson Reference Jackson1983; Marlowe et al. Reference Marlowe, Schneider and Nelson1996; Morrow et al. Reference Morrow, McElroy, Stamper and Wilson1990; Ross & Ferris Reference Ross and Ferris1981). Finally, a growing number of studies have reported that attractive individuals earn higher wages than unattractive individuals (Biddle & Hamermesh Reference Biddle and Hamermesh1998; Fletcher Reference Fletcher2009; Frieze et al. Reference Frieze, Olson and Russell1991; Hamermesh & Biddle Reference Hamermesh and Biddle1994; Hamermesh et al. Reference Hamermesh, Meng and Zhang2002; Harper Reference Harper2000; Johnston Reference Johnston2010; Roszell et al. Reference Roszell, Kennedy and Grabb1989); in some cases, the difference is found for women, but not for men (French Reference French2002; Sachsida et al. Reference Sachsida, Dornelles and Mesquita2003; see also Udry & Eckland Reference Udry and Eckland1984). The beauty premium in the labor market has been quantified: Workers of above-average beauty earn approximately 10% to 15% more than workers of below-average beauty (Hamermesh Reference Hamermesh2011). The size of this beauty premium is economically significant and comparable to the race and gender gaps in earnings in the U.S. labor market (Hamermesh Reference Hamermesh2011).
Physical attractiveness is also associated with greater financial rewards, success, and recognition outside of the labor market. For example, using a door-to-door fund-raising approach, Landry et al. (Reference Landry, Lange, List, Price and Rupp2006; see also Gneezy & List Reference Gneezy and List2013) reported that men's charity donations were positively correlated with female solicitor attractiveness (blonde solicitors were particularly successful) (Price Reference Price2008). Similarly, online donations to marathon runners were more numerous and of larger amounts for attractive than for unattractive runners (Raihani & Smith Reference Raihani and Smith2015). The effect occurred regardless of sex; however, men increased the size of their donation to an attractive female runner after another man had made a large donation to this runner, whereas the same effect was not found for women who made donations to attractive male runners. Several studies have also reported that attractive restaurant waitresses receive larger tips from men, regardless of the quality of the service they provide (Guéguen Reference Guéguen2012; Lynn Reference Lynn2009; Lynn & Simons Reference Lynn and Simons2000). Landy and Sigall (Reference Landy and Sigall1974) had male undergraduate students read an essay, which they were led to believe had been written by female college freshmen whose photos of faces (prerated for attractiveness) were attached to the essay. Male students had more positive evaluations for the essay and the essay writer if the writer was attractive than if she was unattractive. Several experimental studies of helping behavior have reported that men are more likely to help attractive than unattractive women (Benson et al. Reference Benson, Karabenick and Lerner1976; West & Brown Reference West and Brown1975; Wilson Reference Wilson1978), and experimental research on mock juror judgments has shown that it is advantageous for defendants to be physically attractive, female, and of high socioeconomic status, although these advantages are stronger for some crimes than for others (see Mazzella and Feingold [Reference Mazzella and Feingold1994] for a meta-analysis of this research). Hamermesh and Parker (Reference Hamermesh and Parker2005) showed that attractive professors at the University of Texas at Austin received better teaching evaluations from undergraduate students than less attractive professors. Finally, Hamermesh (Reference Hamermesh2006) showed that more attractive economists were more likely to be elected officers in the annual elections of the American Economic Association between 1996 and 2004 (see also Berggren et al. [Reference Berggren, Jordahl and Poutvaara2010] for further effects of attractiveness on electoral success).
2.1. Explanations for attractiveness-related positive biases
2.1.1. Explanations by economists
It is often argued by economists that the beauty premium in the labor market is a form of “taste-based” or “animus-based” discrimination (Becker Reference Becker1957). In this view, individuals have a preference for attractive people or a prejudice against unattractive people, regardless of their productivity (Hamermesh Reference Hamermesh2011). This is similar to positive or negative biases in favor of or against members of particular groups (e.g., in relation to their sex, ethnicity, race, or religion). The taste-based discrimination model provides no explanation as to why a preference for attractive people or a prejudice against unattractive people exists; in fact, this model is descriptive rather than explanatory.
An alternative explanation taken into consideration by economists is that the differential treatment of attractive and unattractive employees in the labor market is a form of economic discrimination; namely, it reflects differences in productivity between them, which, according to human capital theory, may result from differences in education or training (e.g., Biddle & Hamermesh Reference Biddle and Hamermesh1998; Cipriani & Zago Reference Cipriani and Zago2011; Pfann et al. Reference Pfann, Biddle, Hamermesh and Bosman2000). In this view, attractive people are preferred and rewarded more in the labor market because they are more profitable employees to the organizations that hire them. Finally, it has also been proposed that the beauty premium in the labor market may be the result of attractive workers' greater self-confidence and their greater ability to negotiate higher wages with their employers (e.g., Mobius & Rosenblat Reference Mobius and Rosenblat2006).
Although attractiveness-related differences in workers' productivity or self-confidence could explain why attractive workers are more likely to be hired after being interviewed, advance in their careers more rapidly, and earn higher wages, neither differences in productivity nor differences in self-confidence can explain why attractive job applicants are more likely to be interviewed in the first place. To explain this bias, which entails the assumption that there are different expectations about attractive and unattractive individuals, economists generally refer to the stereotype-based theories advanced by social psychologists.
2.1.2. Explanations by social psychologists
The study of perceptual and behavioral biases toward attractive individuals has been a very active area of research in social psychology, with hundreds of studies on this topic being conducted in the period 1950–2000 (see Langlois et al. [2000] for a review and meta-analysis of this research). Social psychologists have shown or suggested that attractive people are often perceived as friendlier, healthier, and more intelligent, competent, generous, and trustworthy (the “beautiful is good” stereotype), whereas unattractive people are perceived as dull, introverted, and less generous or trustworthy (e.g., Adams Reference Adams1977; Dion et al. Reference Dion, Berscheid and Walster1972; Eagly et al. Reference Eagly, Ashmore, Makhijani and Longo1991; Feingold Reference Feingold1992a; Gillen Reference Gillen1981; Hosoda et al. Reference Hosoda, Stone-Romero and Coats2003; Jackson et al. Reference Jackson, Hunter and Hodge1995; Langlois et al. Reference Langlois, Kalakanis, Rubenstein, Larson, Hallam and Smoot2000; Lewis & Bierly Reference Lewis and Bierly1990; Webster & Driskell Reference Webster and Driskell1983; but see Dermer and Thiel [Reference Dermer and Thiel1975] as an example of opposite findings). According to stereotype-based theories (e.g., “social expectancy theory,” “implicit personality theory,” and “lack of fit model”) (see Hosoda et al. Reference Hosoda, Stone-Romero and Coats2003; Langlois et al. Reference Langlois, Kalakanis, Rubenstein, Larson, Hallam and Smoot2000), when someone is exposed to an attractive or an unattractive individual, a stereotype is activated about what psychological traits and behavior can be expected from that person. In this view, activation of positive stereotypes relative to the personality or expected behavior of attractive people explains why these people are treated more favorably than unattractive people.
Stereotype-based explanations of the effects of attractiveness are sometimes linked to research showing that people often make attributions of personality traits, trustworthiness, and professional competence from individuals' faces (e.g., Rule & Ambady Reference Rule and Ambadi2008; Reference Rule and Ambadi2009; Stirrat & Perrett Reference Stirrat and Perrett2010; Reference Stirrat and Perrett2012; Todorov et al. Reference Todorov, Mandisodza, Goren and Hall2005). However, the association between such attributions and physical attractiveness is complex, for example, because positive or negative attributions depend on the age, sex, and familiarity/resemblance of the face, as well as on particular facial characteristics (e.g., width, babyfacedness), which may or may not be associated with attractiveness. For example, in one study of attractiveness and corporate success, attractive male managers were judged to be more competent, whereas attractive female managers were judged to be less competent (Heilman & Stopeck Reference Heilman and Stopeck1985; see also Heilman & Saruwatari Reference Heilman and Saruwatari1979; Morrow Reference Morrow1990; Verhulst et al. Reference Verhulst, Lodge and Lavine2010; Zebrowitz & Rhodes Reference Zebrowitz and Rhodes2004). Moreover, faces that resemble the self generate positive attributions and elicit greater prosocial behavior, but such faces are rated low in attractiveness for short-term mating (DeBruine et al. Reference DeBruine, Jones, Little and Perrett2008).
Stereotype-based theories rarely address the functional significance of attractiveness-related stereotypes: In other words, they rarely attempt to explain why attractiveness-related stereotypes exist and why they are the way they are (e.g., why they involve the attribution of particular positive attributes to attractive individuals) (see Langlois et al. Reference Langlois, Kalakanis, Rubenstein, Larson, Hallam and Smoot2000). One notable exception is provided by Lemay et al. (Reference Lemay, Clark and Greenberg2010), who argued that people have positive stereotypes about the psychological and behavioral characteristics of attractive individuals because they desire to form social bonds with them. In their view, exposure to attractive individuals induces a motivational state described as “attractiveness-based affiliation.” Lemay and colleagues, however, did not address why people desire to form social bonds with attractive individuals and what is the precise nature of these bonds.
A more direct and comprehensive functional perspective is adopted by evolutionary explanations of attractiveness-related biases, most of which assume that attractive individuals receive financial and prosocial rewards because attractiveness is intrinsically valuable in the mating domain.
2.1.3. Evolutionary explanations
Across all human cultures, both men and women have a sexual preference for physically attractive as opposed to unattractive individuals. Research on marriage markets, responses to personal ads, online dating services, speed dating, and the like has confirmed that the preference for attractive individuals as romantic and/or sexual partners is ubiquitous and universal (e.g., Buss Reference Buss1989; Reference Buss2003; Buss & Schmitt Reference Buss and Schmitt1993). The universal preference for physically attractive individuals as sexual partners is also documented by research on prostitution, which clearly shows that customers are willing to pay larger amounts of money to more attractive prostitutes (Hamermesh Reference Hamermesh2011).
Although what an individual finds attractive in a potential sexual partner may vary in relation to the sex, age, sexual orientation, and culture of the two individuals, beautiful individuals are universally recognized as such, and reliably discriminated from unattractive individuals, regardless of sex, age, sexual orientation, and culture (e.g., Langlois et al. Reference Langlois, Kalakanis, Rubenstein, Larson, Hallam and Smoot2000; Little et al. Reference Little, Jones and DeBruine2011; Rhodes Reference Rhodes2006; Rhodes & Zebrowitz Reference Rhodes and Zebrowitz2002; Rhodes et al. Reference Rhodes, Yoshikawa, Clark, Lee, McKay and Akamatsu2001a). Whether men or women are attracted to same-sex or opposite-sex individuals, individuals much younger or older than themselves, or individuals who conform to particular cultural ideals, there is always a preference for more beautiful versus less beautiful individuals within that particular category of potential sexual partners. A preference for attractive individuals as potential sexual partners may not in itself increase an individual's biological fitness (e.g., if it involves same-sex individuals); however, it is likely that over the course of our evolutionary history this preference was selected for because it increased the probability of reproducing with individuals who were healthier, stronger, more fertile, or better able to invest in offspring. In fact, human facial attractiveness is likely to be an indicator of overall quality, including greater genetic quality, lower exposure to stress during early development, greater resistance to diseases and parasites, and greater fertility (see Barber Reference Barber1995; Buss Reference Buss2003; Fink & Penton-Voak Reference Fink and Penton-Voak2002; Gangestad & Scheyd Reference Gangestad and Scheyd2005; Hume & Montgomerie Reference Hume and Montgomerie2001; Little et al. Reference Little, Jones and DeBruine2011; Rhodes Reference Rhodes2006; Thornhill & Gangestad Reference Thornhill and Gangestad1993). Hence, faces that have particular attributes such as averageness, symmetry, masculinity/femininity, and youthfulness or babyfacedness are judged as beautiful and presumably signal greater quality, whereas faces that lack these attributes (e.g., highly anomalous or asymmetrical faces) are judged to be ugly and presumably signal low quality. Although the common view is that there is a linear relationship between high/low facial attractiveness and quality, it has also been argued that only the link between facial ugliness and low quality is real, and that preferences for beautiful faces are a perceptual by-product of aversion to and avoidance of ugly faces (for this “anomalous face overgeneralization hypothesis,” see Zebrowitz and Montepare [Reference Zebrowitz and Montepare2008]). Although men place more weight than women do on the physical attractiveness of a potential mate than on high status or possession of resources, both men and women value the physical attractiveness of a potential mate very highly, particularly in the context of short-term mating (e.g., Buss Reference Buss2003; Gangestad & Scheyd Reference Gangestad and Scheyd2005).
There are three different evolutionary explanations for financial and prosocial biases in favor of attractive people: One is that the predisposition to exhibit prosocial behavior toward attractive mating partners is so engrained in the human mind that it generalizes also to social situations that have no bearing on mating. For example, it has been suggested that a “switch” for turning off such a response in all but sexual encounters would have involved more fitness costs than gains and therefore would not have evolved (Mulford et al. Reference Mulford, Orbell, Shatto and Stockard1998). In this “evolutionary by-product” explanation, the beauty premium in the labor market is a nonfunctional by-product of a bias that is functional in another context, the context of mating and mate selection.
A different evolutionary explanation (the “functional evolutionary explanation”) is that the bias in favor of attractive people reflects sexual attraction, but that this bias is actually functional: Its function would be to maintain proximity to attractive people so as to increase the chances of having sexual interactions with them. In this view, decisions made by employers that benefit attractive individuals may be consciously or unconsciously made to increase the probability of gaining sexual access to these individuals. Given that it is not unusual for people to date or marry individuals whom they have met at work and for attractive female employees to experience male sexual harassment, it would be mistaken to assume that social interactions in the workplace, including financial transactions, have no bearing on mating.
A third evolutionary explanation – the “sexual signaling hypothesis” – is that by rewarding attractive individuals with lucrative job offers, promotions, and salary raises, employers are engaging in direct courtship behavior (as opposed to simply maintaining proximity) and attempting to make themselves appealing as potential sexual partners (see Miller Reference Miller2000; Roberts Reference Roberts1998; Tessman Reference Tessman1995). Because traits related to willingness to share resources (e.g., kindness, generosity, altruism, and helpfulness) make a person more attractive as a mating partner (Barclay Reference Barclay2010; Brase Reference Brase2006; Farrelly Reference Farrelly2011; Moore et al. Reference Moore, Wigby, English, Wong, Szekely and Harrison2013; Oda et al. Reference Oda, Shibata, Kiyonari, Takeda and Matsumoto-Oda2013), behaving prosocially toward attractive individuals who are potential mates can also be interpreted as courtship behavior aimed at increasing the probability of mating with these individuals.
The evolutionary by-product explanation is quite broad and can apply to virtually any interactions with attractive people, including same-sex interactions and temporally isolated interactions that are not conducive to long-term professional relationships. The other evolutionary explanations apply well to opposite-sex interactions, and particularly to all situations in which older and powerful male employers make hiring, career, or salary decisions about younger and attractive female employees. Although they may also apply to female employers and male employees, they are less likely to apply to same-sex interactions, unless same-sex sexual attraction is involved. In fact, the mating-related evolutionary explanations predict that heterosexual people will have negative biases against attractive same-sex individuals because these are perceived as potential sexual competitors (e.g., Agthe et al. Reference Agthe, Spöerrle and Maner2010; Reference Agthe, Spöerrle and Maner2011; Reference Agthe, Spörrle, Frey and Maner2014; Kenrick et al. Reference Kenrick, Montello, Gutierres and Trost1993; Maner et al. Reference Maner, Kenrick, Becker, Delton, Hofer, Wilbur and Neuberg2003; Reference Maner, Gailliot, Rouby and Miller2007b; Reference Maner, Miller, Rouby and Gailliot2009b). The sexual signaling hypothesis predicts that financial generosity or prosocial behavior can be used as courtship display toward attractive potential mates not only when these individuals are the beneficiaries of these actions, but also when they witness, as bystanders, these actions being directed toward other individuals.
3. Studies addressing the possible determinants of financial and prosocial biases in favor of attractive individuals
3.1. Field studies
The hypothesis that the beauty premium in the labor market is because of differences in productivity between attractive and unattractive workers was addressed in a study of Dutch advertising firms, in which firm revenues were analyzed in relation to the physical attractiveness of company executives (Pfann et al. Reference Pfann, Biddle, Hamermesh and Bosman2000). The authors of this study reported that the physical attractiveness of board members was associated with higher revenues in large firms, but with lower revenues in small firms. The mechanism underlying the correlations between attractiveness and company revenues remained unclear. In an unpublished study of an online lending market in which photographs of borrowers were available as part of an application process, Ravina (Reference Ravinaunder review) reported that physically attractive borrowers received better terms from lenders. Contrary to the economic discrimination hypothesis, the author also found that attractive borrowers were more likely to become delinquent on loans; therefore, they were less reliable and less profitable customers. The economic discrimination explanation was also addressed in an unpublished British study of a Dutch television game (cited by Hamermesh Reference Hamermesh2011). In this game, five players had to answer questions posed by the moderator in multiple consecutive rounds; right answers would bring monetary winnings to the players' group. At each round, the players had an opportunity to exclude from the game one of their fellow contestants. The British researchers examined whether decisions to eliminate players were accounted for by their physical attractiveness or by their ability to answer previous questions and, therefore, their ability to earn money for the group. At each round, the physical attractiveness of the player being eliminated was always lower than the average attractiveness of the remaining players. Therefore, attractiveness in itself was rewarded, whereas the productivity of the players did not matter (and there was no association between attractiveness and ability to answer questions and earn money). Finally, the hypothesis that the beauty premium results from employee productivity was specifically tested in a study by Mobius and Rosenblat (Reference Mobius and Rosenblat2006). The authors of this study created an experimental labor market made up of college students, in which “employers” determined wages of “workers” who performed a maze-solving task. This task required a true skill that was unaffected by physical attractiveness. Employers were tested in different conditions: baseline, in which they only reviewed workers' resumes without any information on their characteristics; visual, in which the employers saw the resume and a photo of the worker; oral, in which the employers saw the resume and had a 5-minute phone interview with the worker; visual+oral, in which the employers saw the resume and the photo and had a 5-minute phone interview with the worker; and face-to-face, in which the employers saw the resume and the photo and had a 5-minute face-to-face interview with the worker. There was no beauty premium in the baseline condition, but attractive workers were offered higher wages in all of the other conditions, the highest (17%) being in the face-to-face condition.
Mobius and Rosenblat (Reference Mobius and Rosenblat2006) proposed that the beauty premium in their experimental labor market may have been the result of the attractive workers' greater self-confidence and greater ability to negotiate higher wages with employers when they interacted face-to-face with them. However, the study showed that even when self-confidence was controlled for, attractive employees received higher wages. In a Canadian study of the labor market (cited by Hamermesh Reference Hamermesh2011), physical attractiveness and self-confidence were positively correlated, but the correlation was weak. Again, even when their self-confidence was controlled for, attractive individuals earned higher wages. Finally, Leigh and Borland (Reference Leigh and Borland2007) analyzed the relationship between attractiveness and labor market outcomes using an Australian database known as the 1984 National Social Science Survey. This database contains information on earnings, attractiveness of respondents rated by interviewers, and self-rated attractiveness by respondents. Regressions were run in which the dependent variable was a labor market outcome (employment or hourly wages) and independent variables were the respondent's interviewer-rated beauty and self-perception of beauty. Objectively assessed beauty was associated with higher wages, but self-perceived beauty was not. The authors concluded that the beauty premium was because of others' responses to physical appearance, whereas self-perceived attractiveness (and presumably also self-confidence) did not matter.
3.2. Studies involving experimental economic games
3.2.1. Experimental economic games
Controlled laboratory experiments to investigate biases in behavior and decision making are used by many behavioral scientists who believe that the behavior observed in these settings is representative of human behavior in general and related to economic processes at the societal level. To this end, experimental paradigms have been designed – referred to as experimental economic games – that are informed by theoretical models of behavior and are highly standardized in terms of procedures and data collection and interpretation. The experimental economic games that have been most commonly used in behavioral research include the prisoner's dilemma, the trust game, the ultimatum game, the dictator game, and the public goods game (see Camerer Reference Camerer2003). Each of these games sheds light on different aspects of decision making in the context of social transactions between two or more individuals. When economists study decision making in experimental economic games, they often conceal information about the players' identities and their characteristics, so as to minimize the influence of these “confounding” variables. One can take the opposite approach, however, and use economic games to investigate precisely how players' identities and characteristics, as well as the circumstances of their interactions, influence decision making and behavior in the real world (e.g., Andreoni & Petrie Reference Andreoni and Petrie2008; Eckel Reference Eckel2007; Hancock & DeBruine Reference Hancock and DeBruine2003). For example, behavioral economists such as Andreoni and Petrie (Reference Andreoni and Petrie2008) have argued that studying the effects of sex and attractiveness on decision making in economic games can elucidate why these factors play an important role in the labor market.
3.2.2. Effects of physical attractiveness on behavior in economic games
Evidence for effects of physical attractiveness on decision making in a laboratory setting has been provided by numerous studies involving the prisoner's dilemma, the dictator game, the ultimatum game, the trust game, and the public goods game. These effects are all in the same direction (i.e., attractive individuals are treated more favorably) and are generally consistent regardless of how attractiveness is assessed, for example, through subjective self-ratings, third-party ratings, or using physical characteristics that are generally associated with physical attractiveness such as facial symmetry, waist-to-hip ratio (WHR) for women, facial femininity for women and masculinity for men, and body mass index (BMI). Although many studies report a main effect of attractiveness such that attractive men and women receive more favorable treatments, interactions between the sex and attractiveness of the two players have also been reported. In addition to investigating the occurrence and magnitude of the effects of attractiveness on decision making, many studies involving economic games have also made attempts to understand the mechanisms underlying these effects.
In one of the earliest studies examining the effects of sex and attractiveness on decision making in economic games, Kahn et al. (Reference Kahn, Hottes and Davis1971) had male and female participants play a yoked prisoner's dilemma game with opposite-sex partners. Participants were randomly assigned to one of two different conditions, one in which the optimal response was to cooperate and the other in which it was to compete with the other player. Participants were more likely to cooperate with attractive than with unattractive partners, although the effect of partner attractiveness was partially modulated by the player's sex, the player's own attractiveness, and the experimental condition (i.e., whether it was optimal to cooperate or to compete). In particular, men always cooperated more with attractive female players, regardless of their own attractiveness and whether cooperation or competition was optimal. Women cooperated more with attractive men when cooperation was optimal but not when it was not optimal, and the effect of partner's attractiveness was stronger for unattractive than for attractive women. This study thus provided early evidence that both men and women are biased in favor of attractive opposite-sex partners and that these biases are expressed more consistently by men than by women.
In a more recent study with similar experimental procedures, participants could choose with whom they wanted to play a prisoner's dilemma game (Mulford et al. Reference Mulford, Orbell, Shatto and Stockard1998). After playing the game, participants assessed both their own and their partner's physical attractiveness (attractiveness was also independently rated by observers). Participants also provided an assessment of their expectation that players would cooperate in the game. The authors found that participants were both more likely to enter a game and more likely to cooperate with others they found more physically attractive. As in the study of Kahn et al. (Reference Kahn, Hottes and Davis1971), tendencies to cooperate with attractive versus unattractive players were modulated by sex and one's own attractiveness (e.g., attractive women were generally less likely than unattractive women to cooperate with both sexes, whereas the opposite was true for attractive men; furthermore, the preference for attractive players was greater for attractive than for unattractive men and women). The results obtained with choices to enter the game and to cooperate versus defect were similar. Therefore, attractive players were given more opportunities to engage in social exchange, and they received more cooperation. Although participants expected more cooperation from players whom they rated as highly attractive, the tendency to prefer attractive players was independent of this expectation of behavior. Hence, although this study confirmed the existence of a stereotype about the cooperative tendencies of attractive people, it also showed that the tendency to prefer attractive players was independent of this stereotype.
Further evidence for biases in favor of attractive individuals has been provided by studies using the ultimatum and the dictator game. Solnick and Schweitzer (Reference Solnick and Schweitzer1999) conducted a study in which participants played an ultimatum game, then they were photographed, and these photos were rated for attractiveness by a panel of judges. The most and the least attractive photos were then used in another ultimatum game in which subjects viewed these photos and made ultimatum game decisions that were resolved by pairing their decisions with those of the photographed subjects. Attractive and unattractive men and women in the photos made similar offers and demands (i.e., specified similar minimum acceptable levels). However, attractive people were offered more money, regardless of their sex. They did not demand more; they were offered more because they were attractive. No explanations for this effect were provided, and possible differences between same-sex and opposite-sex interactions were not investigated. Rosenblat (Reference Rosenblat2008) conducted a study with a dictator game, in which allocators listened to a speech recorded by recipients and were also shown their photos before making their decision. Allocators (females more than males) gave more to physically attractive male and female recipients (there was no significant difference in relation to sex of the recipient). In a similar study conducted by Zaatari et al. (Reference Zaatari, Palestis and Trivers2009), male and female participants made offers in an ultimatum game to symmetrical and asymmetrical faces of opposite-sex individuals. Subjects made higher offers to photos they rated as attractive, and more symmetrical faces were rated as more attractive than less symmetrical faces.
The hypothesis that decision making in economic games may be influenced by attractiveness-related mating motives was explicitly addressed by a study conducted by Farrelly et al. (Reference Farrelly, Lazarus and Roberts2007), in which they tested the following predictions. First, heterosexual participants should be more cooperative with individuals of the opposite sex. Second, participants should be more cooperative when opposite-sex partners are more attractive. Third, males should show a stronger cooperative bias than females when paired with attractive players of the opposite sex. Fourth, more cooperative partners should be judged to be more attractive. Subjects played four games (a mutualism game, a prisoner's dilemma, a standard dictator game, and a charity dictator game) with four virtual players (four attractive or unattractive males and females). They were told that they were interacting with real people via the Internet (in reality, their opponents were virtual players) and that they would be able to meet the players in person in the future. Participants were randomly allocated to one of two conditions: cooperative or uncooperative partners (the responses of the virtual players were pre-programmed). The first prediction, that participants should be more cooperative with opposite sex partners, received mixed support. The prediction that participants should be more cooperative toward more attractive members of the opposite sex received support in both sexes in all games. Cooperation was not influenced by the attractiveness of same-sex partners in any game. The prediction that males, more than females, would favor more attractive members of the opposite sex was not supported. Finally, more generous partners were rated as more attractive in every case.
Some of the findings by Farrelly et al. (Reference Farrelly, Lazarus and Roberts2007) were replicated and extended by a study by Lucas and Koff (Reference Lucas and Koff2013), who had female participants play ultimatum and dictator games using photographs of other male and female players that had been rated for attractiveness. The authors of this study found a significant sex of partner × attractiveness interaction predicting the amounts offered in both the ultimatum game and the dictator game. In the ultimatum game, female participants offered higher amounts to attractive men but not to attractive women. In the dictator game, both attractive men and attractive women received higher offers, but the effect of attractiveness was stronger for men than for women. This study also showed that women were more favorably biased toward attractive men when they were fertile than when they were not fertile.
Effects of attractiveness have also been reported in trust games and in public goods games. In a study by Wilson and Eckel (Reference Wilson and Eckel2006), male and female subjects had their photos rated for attractiveness by independent judges and then played trust games, in which they sent varying amounts of money to other players, after viewing their photographs, under the expectation that this money would be later reciprocated. Attractive partners were trusted more (i.e., they received more money) than unattractive ones. Trustees were also asked to guess how much money was going to be sent. They expected higher amounts of money from attractive trusters. If these expectations were not met, attractive trusters were punished by imposing a penalty. Data were not analyzed in relation to the sex of truster and trustee. The authors argued that their results were consistent with stereotype-based explanations but provided no evidence that expectations about the behavior of attractive individuals were causally related to greater trust in these individuals. Stirrat and Perrett (Reference Stirrat and Perrett2010) found that facial attractiveness in photos positively correlated with perceived trustworthiness, but attractiveness and trustworthiness had separate and independent effects on decision making in a trust game (see also Van't Wout and Sanfey [Reference van't Wout and Sanfey2008] for similar results).
Andreoni and Petrie (Reference Andreoni and Petrie2008) conducted a study with public goods games in which they showed each player digital photos of all other members of their group. In one condition, total group contributions were known but individual contributions were kept anonymous, whereas in the other condition each player's contribution was revealed. The results showed that in the condition in which individual contributions were anonymous, participants who were rated as highly attractive made approximately 12% more than participants who were rated as unattractive. The attractiveness effect was stronger for women than for men. In the second condition, however, the difference was reversed so that unattractive people made approximately 8% more than attractive people. The explanation for the results obtained in the second condition, when contributions were not anonymous, was straightforward and related to differences in behavior between attractive and unattractive people. In this condition, attractive players made fewer contributions to the public good and therefore were punished by unattractive people, who reduced their cooperation. In the anonymous condition, however, there were no differences in contributions to the public good between attractive and unattractive people. Instead, attractive people spontaneously engendered more cooperation from other players, suggesting that in the absence of any information about contributions, there is a clear bias in favor of attractive people, particularly women.
In a study by Li and Zhou (Reference Li and Zhou2014), participants observed a dictator game in which proposers made offers to anonymous recipients. The participants, acting as the interest-free third party, evaluated the reasonableness of the offers and made decisions as to whether to punish the proposers. The design of the study included conditions in which male and female participants observed attractive or unattractive proposers of the same or the opposite sex. There was a main effect of offer fairness (unfair offers were punished more than fair ones) and a main effect of proposer attractiveness (attractive proposers were punished less than unattractive ones), as well as interactions between participant's sex, proposer's sex, and proposer's attractiveness. The beauty premium, in terms of reduced probability of being punished, was strongest for opposite-sex individuals: Attractive opposite-sex proposers were punished less by participants than attractive same-sex proposers; moreover, male participants were particularly lenient of attractive female proposers.
3.2.3. The effects of attractive bystanders on behavior in economic games
The association between attractiveness and positive financial and prosocial biases has been reported not only in studies in which attractive individuals are active participants in experimental economic games, but also in studies in which they act as bystanders – in other words, when a game between two players is observed by an attractive third-party individual who does not participate. In one of these studies, conducted by Iredale et al. (Reference Iredale, Van Vugt and Dunbar2008), male and female participants played social dilemma games and made charity donations under three different audience conditions. One group of participants made decisions under anonymity conditions, a second group made decisions with a physically attractive same-sex observer, and a third group made decisions with a physically attractive opposite-sex observer. Results showed that male charity donations were significantly higher in the mixed-sex observer condition compared with the same-sex observer condition and the anonymity condition. However, female charity donations did not vary across conditions. Van Vugt and Iredale (Reference Van Vugt and Iredale2013) further explored the effects of attractive third-party observers on decisions made in a one-shot public goods game. In this study, a confederate sat near the computer and watched as participants made contributions to the public good. Men being observed by an attractive woman made larger contributions to the public pool, as compared with men with an attractive male observer and men with no observer. In a second experiment, Van Vugt and Iredale (Reference Van Vugt and Iredale2013) also found that men with an attractive female observer made larger contributions to the public pool in a repeated public goods game and that they volunteered to spend more hours doing charitable work in their spare time, as compared with men with an attractive male observer and men with no observer. Finally, Jensen (Reference Jensen2013) extended the design of Van Vugt and Iredale (Reference Van Vugt and Iredale2013) by manipulating the attractiveness of the observer, such that both attractive and unattractive observers of the opposite sex were included in the study. Specifically, men played the dictator game, the trust game, and the public goods game in two conditions: while being observed by an attractive woman and while being observed by an unattractive woman (in contrast, the men in the studies by Van Vugt and Iredale were being observed by attractive women or attractive men). There was a significant effect of women's attractiveness on men's behavior, as predicted, but it was moderated by men's assertiveness (i.e., dominance). The effect was strong in nondominant men but weak in dominant men.
4. Evaluating the evidence
4.1. Evidence in favor or against different explanations
The taste-based discrimination model acknowledges the existence of preferences for attractive individuals but does not address the origin or functional significance of such preferences. The study of earnings in Dutch firms by Pfann et al. (Reference Pfann, Biddle, Hamermesh and Bosman2000) provided partial support for the hypothesis that attractive workers are more productive. However, the hypothesis that the beauty premium in the labor market is accounted for by the greater productivity of attractive workers was contradicted by the study of online lenders and borrowers by Ravina (Reference Ravinaunder review), by the British study of the Dutch television show (cited by Hamermesh Reference Hamermesh2011), and more importantly by the study by Mobius and Rosenblat (Reference Mobius and Rosenblat2006) in which workers' skills and productivity were clearly unrelated to their attractiveness.
Mobius and Rosenblat's suggestion that the beauty premium may be accounted for by attractive employees' self-confidence was contradicted by their own results (the beauty premium persisted after workers' self-confidence was controlled for), by a Canadian study of the labor market (cited by Hamermesh Reference Hamermesh2011) showing that attractive individuals earned higher wages even when their self-confidence was controlled for, and by the study by Leigh and Borland (Reference Leigh and Borland2007) in which the beauty premium was unrelated to self-perceived beauty. Taken together, the findings of these studies provide little evidence for a correlation between workers' attractiveness and their productivity or self-confidence (see also the meta-analysis of attractiveness research in social psychology conducted by Langlois et al. [2000], which showed that differences in self-perceptions and competence between attractive and unattractive individuals are small). Moreover, there is little or no evidence that differences in productivity or self-confidence between attractive and unattractive workers are causally related to positive biases in favor of attractive workers (see also Hamermesh Reference Hamermesh2011; and Langlois et al. [2000], who reached a similar conclusion for attractiveness biases outside of the workplace).
Because empirical support for economists' explanations for the effects of attractiveness is weak, economists have sometimes avoided any explanations for this phenomenon altogether (e.g., Gneezy & List Reference Gneezy and List2013) or have invoked the explanations proposed by social psychologists, according to whom favorable biases toward attractive people are the result of expectations about the personality traits and the interpersonal behavior of attractive and unattractive people (e.g., Andreoni & Petrie Reference Andreoni and Petrie2008). Although stereotype-based explanations are plausible, the association between perceived positive traits and attractiveness is not as robust as the beauty premium effect in the labor market (e.g., Segal-Caspi et al. Reference Segal-Caspi, Roccas and Sagiv2012). Furthermore, studies of the labor market that had information about personality traits found that attractive employees earned higher wages even after controlling for personality traits (e.g., Fletcher Reference Fletcher2009; Harper Reference Harper2000; see also Baert & Decuypere Reference Baert and Decuypere2014), leading Hamermesh (Reference Hamermesh2011) to conclude that the impact of beauty on earnings appears to be independent of any association between beauty and personality. Evidence from experimental studies is equally weak. For example, in the study by Mobius and Rosenblat (Reference Mobius and Rosenblat2006), physically attractive workers were expected to perform better by employers, despite the fact that differences in skills among workers were unrelated to their attractiveness. The authors interpreted this finding as being consistent with stereotype-based theories. Their study, however, provided no evidence that the employers' expectation about the performance of attractive workers played a causal role in their willingness to pay them higher wages. A meta-analysis of the effects of attractiveness on hiring decisions reported that biases in favor of attractive people are independent of the amount of job-relevant information employers have about their potential employees (Hosoda et al. Reference Hosoda, Stone-Romero and Coats2003). This argues against stereotype-based hypotheses, which predict that the effects of attractiveness on hiring decisions should be stronger when little information is available about potential employees and weaker when more information is available (Hosoda et al. Reference Hosoda, Stone-Romero and Coats2003). Similarly, in their meta-analysis of attractiveness research in social psychology, Langlois et al. (Reference Langlois, Kalakanis, Rubenstein, Larson, Hallam and Smoot2000) showed that the association between attractiveness and preferential treatment is independent of familiarity: The effects of attractiveness are as strong when agents and targets know each other as when they do not (e.g., in ongoing romantic relationships, people report more passionate love, intimacy, and commitment when their partners are physically attractive; Sangrador & Yela Reference Sangrador and Yela2000).
Similar to the study by Mobius and Rosenblat (Reference Mobius and Rosenblat2006), in some experimental studies with economic games in which participants were asked to estimate the future cooperation of attractive players, the existence of a positive stereotype was confirmed (e.g., Mulford et al. Reference Mulford, Orbell, Shatto and Stockard1998; Wilson & Eckel Reference Wilson and Eckel2006; but see Muñoz-Reyes et al. [2014], in which participants had a right expectation about the uncooperative behavior of attractive players). No study, however, has provided evidence that the attractiveness stereotype is causally related to the preferential treatment of attractive people (see also Langlois et al. [2000], who concluded that stereotype-based theories are largely unproven explanations of the attractiveness effects). In fact, in some studies, the effects of attractiveness were found after controlling for stereotypes and, therefore, independent from them (e.g., Mulford et al. Reference Mulford, Orbell, Shatto and Stockard1998).
Direct experimental evidence that positive stereotypes do not cause prosocial biases toward attractive individuals was provided by the study by Lemay et al. (Reference Lemay, Clark and Greenberg2010). Lemay and colleagues hypothesized that perception of attractiveness leads to enhanced motivation to affiliate with the attractive target, and this in turn leads to the attribution of positive characteristics to the attractive target. In other words, as a result of their motivation to form close bonds with attractive individuals, people construct images of attractive individuals as interpersonally receptive and responsive in return. Lemay et al. showed that people attributed more desirable interpersonal traits (e.g., extraverted, generous, kind, and warm) to physically attractive strangers portrayed in photos relative to unattractive strangers. This effect was explained by the subjects' desire to establish relationships with the attractive strangers (data were not analyzed in relation to the sex of the perceiver and of the target). The alternative mediation model (derived from traditional stereotype theories), according to which perception of attractiveness leads to attribution of positive traits, which in turn leads to affiliative motivation, was not supported by the data. These results were replicated in two additional experimental studies involving, instead of strangers, attractive and unattractive romantic partners or friends. Lemay et al. concluded that the beautiful-is-good effect is explained by a combination of attractiveness-based motivation to bond and projection of that motivation to attractive individuals. Therefore, the motivation to behave prosocially toward attractive individuals pre-exists the attribution of positive characteristics to them and is not caused by them, as assumed by stereotype-based theories. The most striking finding of the study by Lemay et al. was that once the subjects' motivation to affiliate with the attractive targets was controlled for, the attractive targets were perceived in more negative, but perhaps more realistic, terms.
Similar results had been provided by an earlier study by Snyder et al. (Reference Snyder, Tanke and Berscheid1977), in which male college students were shown photos of attractive and unattractive female students and told that they would be able to talk with them on the phone later. Men who anticipated talking with physically attractive partners expected to interact with sociable, poised, humorous, and socially adept women; whereas men anticipating unattractive partners fashioned images of unsociable, awkward, serious, and socially inept women. However, as in the study by Lemay et al. (Reference Lemay, Clark and Greenberg2010), men's attribution of positive characteristics to the attractive females was likely an inconsequential by-product of their motivation to sexually flirt with them, which they did during the course of later “getting to know each other” phone conversations (although the women in these conversations were not those shown in the photos). The study provided no evidence for a causal role of stereotypes in the positive biases toward attractive opposite-sex individuals, whereas the men's sexual flirting behavior suggested that mating motivation was important.
Studies with experimental economic games have reported that the positive stereotypes about the prosocial behavior of attractive individuals (e.g., their friendliness or generosity) simply do not correspond to reality (see also Feingold [1992] and Langlois et al. [2000] for lack of an association between attractiveness and intelligence; Jackson et al. [1995] for lack of an association between attractiveness and competence; and Segal-Caspi et al. [2012] for lack of an association between attractiveness and positive personality traits in women). Although a few studies found no significant differences in behavior between attractive and unattractive people in experimental economic games (for the ultimatum game: men or women, see Solnick & Schweitzer [1999]; for the ultimatum game: women, Takahashi et al. [2006]), there is little evidence that attractive people are more cooperative/generous/trustworthy (only one study reported this and only in men: Mulford et al. [1998]), whereas the overwhelming majority of studies have reported that attractive people, both men and women, are less cooperative, less generous, less trusting, and less trustworthy (men: Andreoni & Petrie Reference Andreoni and Petrie2008; Eckel Reference Eckel2007; Sanchez-Pages & Turiegano Reference Sanchez-Pages and Turiegano2010; Shinada & Yamagishi Reference Shinada and Yamagishi2014; Takahashi et al. Reference Takahashi, Yamagishi, Tanida, Kiyonari and Kanazawa2006; Zaatari & Trivers Reference Zaatari and Trivers2007; women: Andreoni & Petrie Reference Andreoni and Petrie2008; Eckel Reference Eckel2007; Mulford et al. Reference Mulford, Orbell, Shatto and Stockard1998; Muñoz-Reyes et al. Reference Muñoz-Reyes, Pita, Arjona, Sanchez-Pages and Turiegano2014; Zaatari & Trivers Reference Zaatari and Trivers2007).
The most likely explanation for these findings is that attractive people expect favorable treatment from others because of their physical appearance (for evidence of this, see Smith et al. [Reference Smith, DeBruine, Jones, Krupp, Welling and Conway2009]) and therefore are less inclined to cooperate and more likely to exploit others. This explanation is generally consistent with the evolutionary explanations for the effects of attractiveness on decision making: In these explanations, attractiveness has intrinsic value (because attractive individuals have high mate value) rather than simply being a marker of personality or behavior. Given that attractiveness has intrinsic value, people's willingness to invest prosocially and financially in attractive individuals can be explained by the possibility that such investment may be reciprocated in a different currency. Transactions in which physical attractiveness is traded for financial and other resources are well known in human mating and marriage markets, in which young and physically attractive women are often paired with wealthy and powerful men (e.g., Buss Reference Buss2003). Further evidence in favor of evolutionary explanations comes from the finding that financial and prosocial biases in favor of attractive individuals are moderated by sex.
4.2. Effects of sex on financial and prosocial biases in favor of attractive individuals
In their meta-analysis of attractiveness research in social psychology, Langlois et al. (Reference Langlois, Kalakanis, Rubenstein, Larson, Hallam and Smoot2000) did not find significant sex differences in the importance of attractiveness. This meta-analysis, however, did not include labor market analyses or laboratory studies with experimental economic games. Moreover, Langlois et al. (Reference Langlois, Kalakanis, Rubenstein, Larson, Hallam and Smoot2000) acknowledged that much research included in their meta-analysis examined only a single sex as target or did not distinguish between males and females (as actors) in the data analysis. If the effects of opposite-sex attraction and same-sex competition are not analyzed separately, these effects can potentially cancel each other out, resulting in no sex differences in attractiveness biases.
Table 1 presents a summary of studies in which financial and prosocial biases in favor of attractive individuals were analyzed in relation to the sex of the target (i.e., the individual receiving favorable treatment) and the relative sex of the two individuals in the interaction (i.e., interactions in which attractive individuals received favorable treatments, and such treatments were provided either by an individual of the same sex or by one of the opposite sex). Also included are two bystander studies, one of which examined participants' charity donations in the presence of an attractive bystander of the same sex, of the opposite sex, or without an audience (Iredale et al. Reference Iredale, Van Vugt and Dunbar2008). Among studies that analyzed the effects of target sex (n = 14), attractiveness-related biases were reported more often (or were stronger) for female targets (n = 9) than for male targets (n = 1; this is a study in which effects were significant for both sexes but stronger for men; no study has reported significant effects for men but not for women; four studies reported no significant effects of target sex). Among studies that examined financial and prosocial biases in same-sex versus opposite-sex interactions (n = 8, including a study with two different experiments), such biases were reported most often (or found to be stronger) in opposite-sex interactions (n = 7). One study reported no significant differences between same-sex versus opposite-sex interactions. In no cases were significant financial or prosocial biases toward attractive people only found (or found to be stronger) in same-sex interactions.
Table 1. (Maestripieri et al.). Summary of studies reporting whether the financial or prosocial biases in favor of attractive individuals were reported only for men (OM), stronger for men (SM), stronger for women (SW), only for women (OW), or not different in relation to sex (ND); and whether these biases were reported only in opposite-sex (OOS) interactions, stronger in opposite-sex (SOS) interactions, stronger in same-sex (SSS) interactions, only in same-sex (OSS) interactions, or not different in relation to the relative sex of the interacting individuals (ND).
* Bystanders.
** The study involved two different games.
The information summarized in Table 1 is relevant for assessing the different models or explanations advanced to describe or account for financial and prosocial biases in favor of attractive people.
The information presented in Table 1 suggests that the taste-based discrimination model, which assumes that people have a generic preference for beauty, does not provide an accurate description of attractiveness-related biases in financial and prosocial decision making. People express a taste for beauty only in some circumstances, in relation to their own sex and the sex of the individual with whom they are interacting.
The effects of sex reported in Table 1 are not predicted by any hypotheses that assume that physical attractiveness is a marker of psychological traits or behavior. They are predicted, however, by evolutionary theories of attractiveness biases, according to which attractive individuals of the opposite sex are viewed as desirable potential mates, whereas attractive individuals of the same sex are viewed as sexual competitors (e.g., Maner et al. 2007; 2009). The biases in favor of attractive, lower-level female employees in the labor market are presumably linked to the overrepresentation of men in positions of power, including positions in which hiring, promotion, and salary decisions are made (e.g., Cash & Kilcullen Reference Cash and Kilcullen1985; French Reference French2002). In fact, studies have shown that when employers are women, attractive female job candidates are less likely to be hired than unattractive ones, a phenomenon that is usually explained in terms of jealousy and envy related to same-sex competition (Agthe et al. Reference Agthe, Spöerrle and Maner2010; Reference Agthe, Spöerrle and Maner2011; Reference Agthe, Spörrle, Frey and Maner2014; Luxen & Van de Vijver Reference Luxen and van de Vijver2006; Ruffle & Shtudiner Reference Ruffle and Shtudiner2015); some evidence for this also exists for men, as reported by Agthe et al. (Reference Agthe, Spöerrle and Maner2010; Reference Agthe, Spöerrle and Maner2011). This is consistent with the results of a study involving ultimatum and dictator games, which showed that women in the fertile phase of their menstrual cycle were less generous toward attractive women when compared with unattractive women (Lucas & Koff Reference Lucas and Koff2013).
If stereotype-based theories were right, and if the attractiveness of potential employees simply signaled their friendliness, trustworthiness, competence, or productivity, why would male employers be more sensitive to women who have these qualities than to men, other things being equal? In fact, there is no evidence that attractive women are more competent or more productive employees than attractive men. Moreover, meta-analyses of studies of attractiveness-related stereotypes found that these stereotypes are not affected by the sex of target or sex of judge (Eagly et al. Reference Eagly, Ashmore, Makhijani and Longo1991; Feingold Reference Feingold1992a; Langlois et al. Reference Langlois, Kalakanis, Rubenstein, Larson, Hallam and Smoot2000; see also Webster & Driskell Reference Webster and Driskell1983). Another recent meta-analysis of sex differences in cooperation in social dilemmas concluded that men and women do not differ in their overall amounts of cooperation (Balliet et al. Reference Balliet, Li, Macfarlan and Van Vugt2011; see also Croson & Gneezy Reference Croson and Gneezy2009), although there is some conflicting evidence for sex differences in cooperation with same-sex versus opposite-sex partners (Balliet et al. Reference Balliet, Li, Macfarlan and Van Vugt2011; Saad & Gill Reference Saad and Gill2001).
The finding that the effects of attractiveness on financial and prosocial decision making are moderated by the sex of the target and the relative sex of the interacting individuals is predicted by the functional evolutionary and sexual signaling hypotheses. Both hypotheses predict that financial and prosocial biases in favor of attractive individuals should be limited to or be stronger in opposite-sex versus same-sex interactions (for heterosexuals; the opposite should be true for homosexuals). Although both men and women are expected to manifest positive biases toward attractive potential mating partners, men probably have more opportunities to express these biases, and men's biases are less likely to be constrained by sociocultural factors than women's biases.
The finding reported by some studies (e.g., Mulford et al. Reference Mulford, Orbell, Shatto and Stockard1998) that attractive heterosexual individuals express a stronger bias in favor of attractive individuals of the opposite sex (but see Kahn et al. [1971], who reported a stronger effect for unattractive than for attractive women and no difference for men) is predicted by the evolutionary explanations considered in this article but not by any of the other models we have discussed. Attractive individuals have high mate value and therefore are more likely to select potential mating partners of equally high value than unattractive individuals (Buss Reference Buss2003). The effect of one's own attractiveness on the tendency to express financial and prosocial biases toward attractive individuals, however, has been taken into consideration only in a few studies, and no firm conclusions concerning this variable can be drawn (but see the effects of one's own attractiveness on biases about others in Agthe et al. [2010] and Lee et al. [Reference Lee, Loewenstein, Ariely, Hong and Young2008]). The finding that women are more biased in favor of attractive men during fertile than during nonfertile phases of their menstrual cycle (Lucas & Koff Reference Lucas and Koff2013) is also consistent with the evolutionary explanations and not predicted by any of the other models, but this finding needs to be replicated by other studies before any conclusions about female fertility can be made.
Further evidence consistent with evolutionary explanations comes from studies involving experimental economic games in which attractive individuals are bystanders. Stereotype-based theories predict that the attractiveness of a third-party observer should not matter because this individual is not involved in the game, and therefore, expectations of his/her future behavior based on attribution of personality traits or behavioral tendencies are simply irrelevant. In contrast, the sexual signaling hypothesis predicts that individuals should be more cooperative not only when playing with an attractive player, but also when a dyadic game is observed by an attractive third-party individual. Accordingly, studies have reported that men express greater prosocial behavior in economic games played in the presence of an attractive female bystander. Consistent with these results, other studies have shown that when being observed by a woman, men engage in more helping of strangers in need (Latané Reference Latané1970), are more generous toward panhandlers (Latané Reference Latané1970; but see Goldberg [Reference Goldberg1995], who found that men accompanied by their partner are less likely to donate to female panhandlers), and are more motivated to make physical sacrifices for the group (McAndrew & Perilloux Reference McAndrew and Perilloux2012) or more willing to donate money to others (Tognetti et al. Reference Tognetti, Berticat, Raymond and Faurie2012).
Overall, the results of studies with experimental economic games, in which decision making is examined under controlled laboratory conditions and in which financial and prosocial biases in favor of attractive individuals are objectively quantified, provide the strongest support for evolutionary explanations. Studies investigating the psychological and physiological mechanisms by which mating motives in human social interactions affect behavior and decision making provide a more comprehensive understanding of the evolutionary bases of financial and prosocial biases in favor of attractive people.
5. Psychological and physiological mechanisms underlying positive biases toward attractive individuals
5.1. Emotional and neural responses to visual exposure to attractive faces
It has long been known or suspected that exposure to physically attractive individuals is rewarding and generates positive emotions (e.g., Byrne et al. Reference Byrne, London and Reeves1968). A more recent study showed that subliminal presentations of attractive faces prime positive emotion concepts (Olson & Marshuetz Reference Olson and Marshuetz2005), suggesting that positive affective reactions to attractive faces may be automatic. However, although exposure to an attractive opposite-sex individual leads to positive affect, exposure to an attractive same-sex individual may lead to negative affect (e.g., lower mood; Kenrick et al. Reference Kenrick, Montello, Gutierres and Trost1993). In a study by Hazlett and Hoehn-Saric (Reference Hazlett and Hoehn-Saric2000), women viewed slides of adult male and female faces that varied in attractiveness. When women viewed male faces, ratings of felt pleasure, arousal, and to a lesser extent zygomatic muscle activity (measured with facial electromyography, or EMG) were greater in response to the attractive males than to the unattractive males. When women viewed female faces, the highly attractive targets evoked greater mean corrugator muscle (brow lowering muscle) EMG and greater reported arousal, whereas reported pleasure was not affected by target attractiveness. The authors' interpretation of these results was that women viewed attractive men as potential mating partners and attractive women as potential sexual competitors.
Studies in which neural activation was measured in response to exposure to same-sex and opposite-sex attractive and unattractive faces have provided further evidence consistent with the evolutionary explanations of the effects of attractiveness in terms of mating motivation. In a study by Aharon et al. (Reference Aharon, Etcoff, Ariely, Chabris, O'Connor and Breiter2001), young heterosexual males rated pictures of beautiful males and females as attractive but exerted effort via a key-press procedure only to view pictures of attractive females. Therefore, although ratings of beauty for same-sex and opposite-sex faces reflected aesthetic judgments (i.e., “liking”), key-press behavior reflected the reward value of attractive female faces (i.e., “wanting”). Functional brain imaging (fMRI) procedures showed that passive viewing of beautiful female faces activated brain reward circuitry, in particular the nucleus accumbens in the ventral striatum. An extended set of subcortical and paralimbic reward regions also appeared to follow aspects of the key press rather than the rating procedures, suggesting that reward circuitry function presumably associated with enhanced mating motivation was activated by attractive opposite-sex individuals but not by attractive same-sex individuals (see Senior [Reference Senior2003] for a further discussion of these results).
Subsequent fMRI studies have provided further evidence that exposure to attractive faces stimulates activity in brain regions known to be involved in processing rewarding stimuli. O'Doherty et al. (Reference O'Doherty, Winston, Critchley, Perrett, Burt and Dolan2003) showed that activation of the medial orbitofrontal cortex occurred when subjects were not explicitly assessing faces for attractiveness, suggesting that the response is automatic. Although the effects of attractive faces on activation of the medial orbitofrontal cortex were similar in males and females and for both same-sex and opposite-sex faces, there was significantly greater activation in the ventromedial prefrontal cortex (a brain region implicated in affective-decision making and in responsiveness to sexual stimuli) in response to opposite-sex attractive faces in males than in females (O'Doherty et al. Reference O'Doherty, Winston, Critchley, Perrett, Burt and Dolan2003; see also Winston et al. Reference Winston, O'Doherty, Kilner, Perrett and Dolan2007). In a recent study, Tsukiura and Cabeza (Reference Tsukiura and Cabeza2011b) showed that activity in the medial orbitofrontal cortex increased as a function of both attractiveness and goodness ratings, whereas activity in the insular cortex decreased with both attractiveness and goodness ratings. The authors argued that their study provided evidence for a neural basis for the “beautiful is good” stereotype. Furthermore, in a related study, the same authors provided evidence that attractive faces not only capture more attention and interest, but also are easier to remember. Specifically, Tsukiura and Cabeza (Reference Tsukiura and Cabeza2011a) reported that better memory for attractive faces reflects greater interaction between a region associated with reward, the orbitofrontal cortex, and a region associated with successful memory encoding, the hippocampus.
Taken together, the findings of several recent brain imaging studies have provided converging evidence that viewing faces of attractive opposite-sex individuals activates areas of the brain that are involved with reward. Further evidence for an association between exposure to attractive opposite-sex individuals and activation of mating motivation is provided by studies of mating motives in human social transactions and their underlying psychological and physiological mechanisms.
5.2. Mating motives in human social transactions and their psychological and physiological mechanisms
The evolutionary explanations of the effects of attractiveness on decision making in the labor market, in social transactions in everyday life, and in experimental economic games assume that when individuals engage in decision making in social transactions, multiple motivations may simultaneously be at play; some of these are related to obtaining resources (e.g., financial), whereas others may be social (e.g., status) or sexual. Just as financial considerations can drive decisions about partner selection for romantic and mating purposes, it should not be surprising that mating motives can influence economic decision making (e.g., Griskevicius et al. Reference Griskevicius, Tybur, Sundie, Cialdini, Miller and Kenrick2007). Given that sex can be a valuable commodity, mating and financial motives and goals are often closely intertwined in human social affairs.
5.2.1. Men
The notion that mating motives can influence economic decision making in men is supported by experimental evidence. For example, Wilson and Daly (Reference Wilson and Daly2004) reported that exposure to photos of faces of attractive women induces men to prefer immediate smaller rewards over delayed larger rewards (see also Van den Bergh et al. Reference Van den Bergh, Dewitte and Warlop2008). Similarly, Van den Bergh and Dewitte (Reference Van den Bergh and Dewitte2006) reported that men who are primed with sexual stimuli are more willing to accept low offers in an ultimatum game, especially if these men have lower 2D:4D finger ratios (a marker of prenatal exposure to testosterone). These results suggest that exposure to attractive women activates men's mating motivation and that such motivation enhances the desire for immediate rewards.
Evidence also exists about the potential psychological and physiological changes that occur in men following exposure to potential mates: These mechanisms can influence the evaluation of the potential benefits and costs of an ongoing or future interaction (therefore affecting decision making about this interaction), facilitate the expression of courtship behavior, and ultimately lead to favorable behavioral biases toward attractive individuals.
In a pioneering study, Roney (Reference Roney2003) reported that in men, exposure to women either in person or through photos can prime large changes in attitudes, mood, and self-perceived personality traits. These changes are such that men show greater conformity to female mate preferences (e.g., preferences for men with resources who are willing to invest in their partners, through acts of generosity). Men exposed to women report higher valuations of material wealth, greater momentary feelings of ambition, higher valuations of indicators of high social status, and greater extraversion and generosity. These changes occur unconsciously. Roney (Reference Roney2003) argued that cues from potential mates prime psychological representations that facilitate the behavioral expression of courtship tactics. In subsequent studies, Roney et al. (Reference Roney, Mahler and Maestripieri2003; Reference Roney, Lukaszewski and Simmons2007) also showed that in men, a brief casual conversation with a moderately attractive woman produces an increase in salivary concentrations of testosterone (see also Van der Meij et al. Reference Van der Meij, Buunk, van de Sande and Salvador2008). Recently, Zilioli et al. (Reference Zilioli, Caldbick and Watson2014) reported that the mere exposure to faces of women (but not of men) increases men's testosterone, regardless of the emotional expressions of these faces. Increased testosterone in men may enhance their behavioral courtship displays toward women, including humorous flirting, representing themselves in a favorable light, or displaying wealth, high social status, or generosity. As an example of this, it has been reported that male skateboarders who are being observed by an attractive woman experience an increase in testosterone and become more willing to display risky skateboard performances in front of the woman (Ronay & von Hippel Reference Ronay and von Hippel2010). Increased risk taking and other testosterone-associated attitudes in turn can influence financial decision making (e.g., Burnham Reference Burnham2007; Zak et al. Reference Zak, Kurzban, Ahmadi, Swerdloff, Park, Efremidze, Redwine, Morgan and Matzner2009), and the decisions themselves can become courtship displays.
Further experimental evidence indicating the activation of men's mating motives upon exposure to women comes from studies focusing on cognition and cortisol. Karremans et al. (Reference Karremans, Verwijmeren, Pronk and Reitsma2009) showed that interacting with women (but not with men) leads to a decline in men's cognitive performance, as assessed with a working memory task. The more attractive the women, the stronger is the effect on cognition. Moreover, there was a negative correlation between performance management and cognitive performance, such that the more men invested effort in trying to make a good impression during the conversation, the worse was their subsequent performance on the cognitive task. The effect was interpreted as evidence of the cognitive costs of trying to make a good impression during the interaction. There were no effects of mixed-sex encounters on cognitive performance in women. In a follow-up study, it was shown that men's cognitive performance (but not women's) declined if they were led to believe that they interacted with a woman via a computer or even if they merely anticipated an interaction with a woman, suggesting that the effect can occur in the absence of a physical interaction with a woman and in the absence of any information about the woman's attractiveness (Nauts et al. Reference Nauts, Metzmacher, Verwijmeren, Rommeswinkel and Karremans2012). Again, these effects were interpreted as being the result of impression management efforts by the subjects. However, arousal-related mechanisms are also possible. When men have a brief casual interaction with a woman, there is an increase not only in their salivary testosterone, but also in their cortisol (Roney et al. Reference Roney, Simmons and Lukaszewski2010; Van der Meij et al. Reference Van der Meij, Buunk and Salvador2010). Cortisol concentrations are generally elevated in situations of high arousal, including sexual arousal (e.g., Goldey & van Anders Reference Goldey and van Anders2012). Given that cortisol and other glucocorticoid hormones are known to influence cognitive function including spatial cognition, learning and memory, and working memory (e.g., de Kloet et al. Reference de Kloet, Oitzl and Joels1999), cortisol may be a mechanism mediating the association between exposure to women and changes in cognitive function in men. Consistent with this hypothesis, an unpublished study by Zilioli and Watson (Reference Zilioli and Watson2014) demonstrated that men experience a cortisol increase after viewing photos of happy female faces; that they subsequently show a decrease in performance on a mental rotation task; and that the greater the increase in cortisol, the worse is the cognitive performance.
The effects of exposure to potential mates on physiology, self-perception, cognition, and decision making can potentially account for the tendency to show increased financial generosity or prosocial behavior toward attractive members of the opposite sex, even when such exposure is casual and very brief, when exposure occurs through photos of faces, and even in the absence of expectations of future interactions with the attractive individual. When a male employer has the opportunity to hire an attractive female employee, and therefore gain proximity to and familiarity with this individual for extended periods in the future, it is likely that the man's mating motivation is activated, consciously or unconsciously, regardless of his moral principles or intentions, and regardless of whether he will ever act on it. When a man is exposed to a photo of an attractive woman, it is likely that his mating motivation is activated regardless of whether the woman in the photo really exists and whether he will meet her in the future. The changes in physiology, self-perception, mood, and cognition that accompany the activation of sexual motivation by a potential mate occur regardless of conscious representations of goals or utilities, or knowledge of the probability of future interactions with the potential mate.
The human mind is equipped with mechanisms that are designed to trigger responses to specific cues, regardless of any conscious representations of goals or probabilities (e.g., Bargh & Chartrand Reference Bargh and Chartrand1999). For example, heterosexual males experience sexual arousal to pornographic images of women they will never meet and with whom they will never mate. Seeing a potential mate briefly in person or being shown his or her photo is likely to be sufficient to trigger the cognitive and physiological mechanisms regulating mating motivation and courtship behavior. These mechanisms may have a low activation threshold, especially in men, because of error management issues (Haselton & Nettle Reference Haselton and Nettle2006), namely, the cost of missing a mating opportunity being greater than the cost of activating the mechanism when no mating opportunity is present. Moreover, these evolved mechanisms may treat novel stimuli, such as realistic visual images of attractive adults (or pornography), as veridical because the mechanisms are not prepared to make the distinction between real social stimuli and visual reproductions of these stimuli made with technology that has become available only recently. Furthermore, exposure to potential mates or their images is likely to activate the cognitive and physiological mechanisms regulating sexual interest and courtship behavior regardless of whether one is told that no further interaction with this person will ever occur. This is because during much of our evolutionary history, when humans mostly interacted with individuals that lived in the same geographic area and photos and computer screens had not yet been invented, any direct social interaction with a potential mate (or even a simple visual interaction) was likely to be followed by further interactions with this individual, especially if the initial response to the potential mate was conducive to further interactions.
5.2.2. Women
Similar to men, women are biased toward attractive individuals as potential sexual partners, and this is especially the case in the initial stages of courtship and relationship formation (for evidence from speed-dating studies, see Kurzban and Wedeen [Reference Kurzban and Weeden2005]). Similar to men, there is evidence that when women are primed with intersexual courtship they show an increased willingness to engage in risky behavior (e.g., Hill & Durante Reference Hill and Durante2011). There is also evidence that watching a video showing an attractive man courting a young woman can increase women's testosterone and cortisol (Lopez et al. Reference Lopez, Hay and Conklin2009). Although in men, simply interacting with women or viewing photos of their faces may release testosterone and cortisol, no study to date has shown that any interaction with men can trigger women's hormones. Such triggering, however, is not to be expected because the range of stimuli and situations that can activate mating motivation is more restricted in women than in men. A large body of research on men's and women's mating strategies has shown that women are more selective than men in their choice of mating partners and of the circumstances in which sexual interactions can take place (e.g., Buss Reference Buss2003). In particular, although both men's and women's short-term mating strategies include pursuing casual sex with attractive partners, women are much more discriminating about the circumstances in which casual sex may take place than are men. For example, in a study in which campus students were approached by an attractive person of the opposite sex and asked a question – “Hi, I've been noticing you around town lately, and I find you very attractive. Would you have sex with me?” – 75% of men answered yes, whereas 0% of the women gave a positive answer (Clarke & Hatfield Reference Clarke and Hatfield1989).
When women's mating motivation is activated, however, it is likely that such activation is accompanied by physiological, psychological, and behavioral changes that promote female sexual courtship and render women more receptive to male courtship behavior. Some of these changes may be similar to those occurring in men, whereas others are likely to be different. For example, there is evidence that sexual thoughts, in the absence of any external sexual stimuli, can increase testosterone in women (Goldey & van Anders Reference Goldey and van Anders2011). Increased testosterone in women, in turn, can influence risk taking and decision making (e.g., Bos et al. Reference Bos, Panksepp, Bluthe and van Honk2012). There is also evidence that women's increased sexual motivation driven by rising concentrations of estradiol during the peri-ovulatory phase of their menstrual cycle is accompanied by changes in self-perception; self-presentation; sociability; and interest in more attractive (e.g., more symmetrical) and more masculine features of men's faces, voices, and scents (Roney & Simmons Reference Roney and Simmons2013; Roney et al. Reference Roney, Simmons and Gray2011; Thornhill & Gangestad Reference Thornhill and Gangestad2008). In general, although men's mating motivation is more dependent on external stimuli to be activated, women's mating motivation is more dependent on their reproductive condition and hormonal status (e.g., whether cycling or on contraceptives; pregnant; breastfeeding; and in the follicular, peri-ovulatory, or luteal phase of the menstrual cycle). In so far as women find physically attractive men appealing as potential mating partners and their mating motivation is active, one can expect positive behavioral biases toward attractive men similar to those displayed by men toward attractive women. These positive behavioral biases may also include employment or career advancement decisions, or allocation of financial resources in the labor market and in experimental economic games. Important sex differences in mating motivation and mating strategies, however, may result in the effects of attractiveness on decision making being more consistent, and perhaps also stronger, in men than in women. Sociocultural factors are likely to contribute to this sex difference as well.
6. Development of attractiveness-related biases
Preferences for attractive faces begin very early in life, as 2- or 3-month-old infants look longer at attractive than unattractive faces of adults (Langlois et al. Reference Langlois, Roggman, Casey, Ritter, Rieser-Danner and Jenkins1987). In their meta-analysis of the attractiveness bias literature, Langlois et al. (Reference Langlois, Kalakanis, Rubenstein, Larson, Hallam and Smoot2000) examined possible age effects on the reliability of attractiveness ratings and in the judgment and treatment of attractive individuals by children aged 6 years and older. They found no significant effects of age and concluded that attractiveness is as important for children as for adults (e.g., see Dion Reference Dion1977). Agthe et al. (Reference Agthe, Spörrle, Frey, Walper and Maner2013), however, showed that at the time of puberty there is a sharp increase in the extent to which adolescents display a positive bias toward attractive opposite-sex targets (who are potential mates) and a negative bias toward attractive same-sex targets (who are potential sexual rivals), indicating that important changes in attractiveness-related biases occur when mating motivation is strongly activated by pubertal hormonal changes.
Although there is no experimental research on this topic, it is likely that the neural and psychological mechanisms underlying positive biases toward attractive individuals are already present shortly after birth, even though these biases may have no immediate functional significance in the infants' social world. Selective attention to attractive faces early in life and social preferences for attractive individuals during later stages of development (e.g., Dion Reference Dion1973; Dion & Berscheid Reference Dion and Berscheid1974), however, may facilitate the expression of biases that are functional and adaptive later in life; for example, it is possible that greater selective attention to attractive faces in infancy is associated with greater positive biases toward attractive opposite-sex individuals after puberty.
The association between being attractive and receiving favorable treatment from others also begins very early in life. There is evidence that adults direct more attention and more positive behavioral responses to attractive (“cute”) young infants, both males and females (Hildebrandt & Fitzgerald Reference Hildebrandt and Fitzgerald1978; Karraker Reference Karraker1986; Ritter et al. Reference Ritter, Casey and Langlois1991). Mothers, too, appear to be more favorably biased toward their more attractive babies (Langlois et al. Reference Langlois, Ritter, Casey and Sawin1995; Rieser-Danner et al. Reference Rieser-Danner, Roggman and Langlois1987; see Leinbach and Fagot [Reference Leinbach and Fagot1991] for older children). Furthermore, it has been shown repeatedly that schoolteachers have more positive expectations about the academic performance of attractive male and female children and adolescents and treat them more favorably (Babad et al. Reference Babad, Inbar and Rosenthal1982; Barocas & Black Reference Barocas and Black1974; Berkowitz & Frodi Reference Berkowitz and Frodi1979; Clifford & Walster Reference Clifford and Walster1973; Dion Reference Dion1974; Felson Reference Felson1980; Kenealy et al. Reference Kenealy, Frude and Shaw1987; Lerner et al. Reference Lerner, Delaney, Hess, Jovanovic and von Eye1990; Mohr & Lund Reference Mohr and Lund1933; Murphy et al. Reference Murphy, Nelson and Cheap1981). Finally, more attractive children and adolescents are more popular with their peers (Dion & Berscheid Reference Dion and Berscheid1974; Dion & Stein Reference Dion and Stein1978; Felson & Bohmstedt Reference Felson and Bohmstedt1979; Kleck et al. Reference Kleck, Richardson and Ronald1974; Lippitt Reference Lippitt1941; Ritts et al. Reference Ritts, Patterson and Tubbs1992; Smith Reference Smith1985; Vaughn & Langlois Reference Vaughn and Langlois1983; Weisfeld et al. Reference Weisfeld, Bloch and Ivers1983; Reference Weisfeld, Weisfeld and Callaghan1984).
Preferential treatment of attractive infants and young children by their own parents can be explained, from an evolutionary perspective, with the differential parental solicitude model (Daly & Wilson Reference Daly, Wilson and Gazzaniga1995). According to this model, if attractiveness is an indicator of genetic or phenotypic quality, parents should invest more in attractive than in unattractive children (see also Langlois et al. Reference Langlois, Kalakanis, Rubenstein, Larson, Hallam and Smoot2000). Because adults can respond parentally toward children who are not their biological offspring, the differential parental solicitude model can also explain the favorable biases toward attractive infants and young children expressed by adults who are not their biological parents. In terms of mechanisms, a number of studies have shown that perceptual biases exist in human minds that make infant faces attractive to older individuals (in children older than 6 years, adolescents, and adults; for evidence that these biases are stronger in females than in males, see Maestripieri and Pelka [Reference Maestripieri and Pelka2002]), that visual and auditory responsiveness to infants is regulated by areas of the brains involved in reward (Glocker et al. Reference Glocker, Langleben, Ruparel, Loughead, Valdez, Griffin, Sachser and Gur2009), and that interest in infants is upregulated by estrogen in women and downregulated by testosterone in men (Law Smith et al. Reference Law Smith, Deady, Moore, Jones, Cornwell, Stirrat, Lawson, Feinberg and Perrett2012; Zilioli et al. Reference Zilioli, Ponzi, Henry, Kubicki, Nickels, Wilson and Maestripieri2016). Presumably, the same mechanisms responsible for positive biases toward infants in general are also responsible for greater biases toward attractive than unattractive infants.
As children grow older and become objects of romantic interest and, at around the time of puberty, also of sexual interest to other children, it is likely that attractive children who early on stimulated greater parental motivation and investment later elicit greater romantic and sexual interest. The transition from being the recipient of parental investment to being the target of sexual interest presumably occurs at earlier ages for girls than for boys, in relation to girls' earlier timing of puberty and to the notion that males value young age in potential mates more than do females (e.g., Buss Reference Buss2003). Because the regulation of mammalian parental and mating motivation has been quite conservative from an evolutionary perspective (e.g., in females, estrogen acts in the same brain region, the preoptic area of the hypothalamus, to regulate both parental and sexual motivation) (Saltzman & Maestripieri Reference Saltzman and Maestripieri2011), one may speculate that the same neural and neuroendocrine mechanisms that regulate perceptual and behavioral biases toward attractive children from a parental motivation perspective also regulate perceptual and behavioral biases toward attractive adolescents and adults from a mating motivation perspective. Positive biases toward attractive children and attractive adults may essentially be the same phenomenon, which acquires different functional significance in different contexts. Therefore, evolutionary explanations, coupled with our knowledge of the physiological regulation of motivation, can potentially account for favorable biases toward attractive individuals across the life span, from the earliest manifestations of these biases toward attractive infants to later manifestations of biases toward attractive middle-aged and elderly individuals (for sex differences in perceived attractiveness of middle-aged individuals, see Maestripieri et al. [Reference Maestripieri, Klimczuk, Traficonte and Wilson2014]).
7. Conclusions, limitations, and future directions
In the real world, decisions made in social transactions between two or more individuals, whether they involve money, are generally affected by the characteristics of the individuals and by the context in which the transactions occur. The same is true about decisions made in experimental economic games when the players' identities are known and regardless of whether these decisions involve donating or sharing money, or investing in others in hopes that they will reciprocate. In both the real world and in the laboratory, people are often biased in favor of attractive individuals. These effects of attractiveness on decision making have baffled economists for decades because they are not predicted by their rational models of human behavior. The effects of attractiveness on decision making have also attracted the interest of social psychologists and of evolutionary psychologists, who have attempted to explain these effects using the conceptual tools of their discipline.
Although many would agree that financial and prosocial biases in favor of attractive people probably have multiple determinants, economists and social psychologists attempting to explain these biases often ignore the role of mating motivation (but see Langlois et al. [2000] as an important exception). Whether physical attractiveness is correlated with particular personality traits, prosocial behavior, professional competence, or productivity remains an open question. Evolutionary psychologists, however, recognize that physical attractiveness has intrinsic value and it is not simply a marker of behavior. Therefore, there is an incentive to invest in attractive people because of their high mate value, regardless of their psychological or behavioral characteristics. Moreover, the human mind is probably predisposed to respond to cues of mating and activate courtship behaviors regardless of any conscious awareness of goals, incentives, or probabilities of future gains.
The effects of attractiveness on financial and prosocial biases are often moderated by the sex of the target (i.e., the attractive person who benefits from biased financial and prosocial behavior) and the sex of the actor (i.e., the person who expresses biased behavior in favor of the attractive individual). The importance of sex has been highlighted by laboratory studies involving experimental economic games and by field and laboratory studies of the labor market, whereas a previous meta-analysis of studies of attractiveness-related biases in social psychology did not report significant sex effects (Langlois et al. Reference Langlois, Kalakanis, Rubenstein, Larson, Hallam and Smoot2000). If future empirical studies or reviews of the literature fail to confirm that financial and prosocial biases toward attractive people are stronger in opposite-sex than in same-sex interactions, this would indicate that the evolutionary models of attractiveness-related biases are limited in their ability to account for this phenomenon in its entirety and that other explanatory models, not involving sexual attraction and mating motivation, should be taken into serious consideration. Similarly, future research on positive biases toward attractive children and adolescents may also highlight the limitations of evolutionary models in explaining all attractiveness-related biases if such research were to show that positive biases toward children and adults are regulated by different mechanisms (e.g., if the biases toward children are entirely driven by differences in behavior between attractive and unattractive children). It is unlikely, however, that future empirical studies or reviews of the literature would come to the conclusion that mating motivation plays a trivial role in the genesis of financial and prosocial biases toward attractive individuals and that this factor can be safely ignored by economists and social psychologists, the way they ignored it in the past. Future studies examining the hypothesis that attractiveness-related financial and prosocial biases are driven by mating motivation could test novel predictions of this hypothesis: For example, there should be a stronger bias if the attractive target is romantically available (e.g., single) or sexually receptive (e.g., he or she has an unrestricted sociosexual orientation). Cultural differences in the strength of biases could also be expected, depending on how common sexual promiscuity is within a culture.
Recognizing the important role of mating motivation in financial and prosocial decision making implies that knowledge of the factors that lead to variation in mating motivation among different individuals or among the same individuals over time or in relation to context is highly relevant to understanding interindividual and intra-individual variation in decision making. Because evolutionary psychologists have in the past few decades accumulated an impressive body of knowledge about human mating motivation, this body of knowledge should be increasingly connected with research on financial decision making (e.g., Wilson and Daly [2004] is an early example of this).
Evolutionary approaches to human behavior emphasize its functional significance (i.e., the notion that humans evolved psychological predispositions and behavioral preferences that maximize biological fitness). Recognition of the functional significance of behavior or preferences is often absent from models developed by economists and psychologists (see Burnham Reference Burnham2013). Evolutionary perspectives can therefore complement the theoretical perspectives adopted by other behavioral scientists who focus their attention on similar phenomena. This is especially the case when these phenomena include biases in behavior and decision making associated with evolutionarily meaningful human biological characteristics such as physical attractiveness.
ACKNOWLEDGMENTS
We thank Sian Beilock, Anna Dreber, Emir Kamenica, and James Roney for helpful discussions and comments on an earlier draft of this manuscript. We also thank Ariadne Souroutzidis for assistance with the literature review. Finally, we thank six anonymous reviewers for providing constructive criticism and helpful suggestions that greatly improved the manuscript.
Target article
Explaining financial and prosocial biases in favor of attractive people: Interdisciplinary perspectives from economics, social psychology, and evolutionary psychology
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Moving forward with interdisciplinary research on attractiveness-related biases