نسبت دور کمر به باسن و جذابیت فیزیکی زنان: نقش تعدیل انگیزه قدرت و زمینه جفت یابی

The purpose of the present investigation was to extend the validity of Singh’s (1993) hypothesis of the effect of waist-to-hip ratio (WHR) on judgments of female attractiveness, using a motivational perspective which builds on motives and incentives. It is argued that the well-documented preference for normal weight females with a WHR of .7 is moderated by the power motive and by short-term vs. long-term mating contexts. A total of 133 participants (58 male, 75 female) were recruited to rate 12 line drawings varying in weight and WHR. Participants had to rate females’ attractiveness judged from the perspective of a person who is looking for a partner in a short-term, long-term, and work-partner relationship. Furthermore, individual differences in power motivation were examined. On the basis of evolutionary psychological considerations, it was expected and found that the preference for the .7 WHR and normal-weight category was moderated by individual differences as well as by situational contexts; with a stronger preference profile for individuals high in power motivation and for individuals who are looking for a partner in a short-term relationship. Results are interpreted in an evolutionary context which describes variable mating strategies as conditional on dispositional (motive) and situational (incentive) factors.

Evolutionary theories of human mate selection hold that strategies for selecting mating partners follow biological rules which enable men and women to enhance their reproductive success. Biological conditions and differential constraints in men and women, however, required differentiated gender-specific reproductive strategies, which are the result of different selection pressures operating on our ancestors. Historically, men have been constrained in their reproductive success primarily by the number of fertile women they can inseminate (Buss & Schmitt, 1993). Mens’ problems in order to ensure reproductive success are twofold: to identify women who are sexually accessible and who are able to bear healthy children (Buss, 1999, Buss and Schmitt, 1993, Gangestad and Simpson, 2000, Kenrick et al., 2003 and Li et al., 2002). But how can a man “figure out” which woman can help to ensure his reproductive success? The capacity of a woman to bear healthy children is not written on her forehead. That is why ancestral humans used various – often indirect – cues that provide information concerning a woman’s reproductive potential. With reference to bodily features of females, Singh, 1993 and Singh, 1994 has described an attribute that is both a marker of a female’s reproductive potential and is regarded as attractive at the same time. He has argued that female body shape, especially the waist-to-hip ratio (WHR) is a reliable indicator of a female’s reproductive status, reproductive capability, and health status. There are typical patterns of fat distribution in men and women which are under the control of sex hormones. Gynoid (female) and android (male) fat distributions engender a typical sex difference in WHR. For women it is considerably lower (.67–.80) than for men (.85–.95). The critical ratio of WHR = .7 is judged as highly attractive because it is a marker of fat distribution in the female body that is inherently related to the ability to bear healthy children. If this conception is valid, men should be able to “interpret” these female features and to use this information in assessing a female’s attractiveness and in making a decision on whom to mate with. A number of recent studies have corroborated this contention and have shown that variations in female WHR (in combination with weight) are important determinants of perceived attractiveness, reproductive potential, and health status (Forestell et al., 2004, Furnham et al., 2002, Furnham et al., 2004, Henss, 1995, Henss, 2000, Singh, 1993 and Tassinary and Hansen, 1998). These studies varied experimentally the weight and WHR of pictured females (line drawings and color photographs) and found (with some exceptions, however (e.g., Furnham et al., 2002)) that both men and women of different social classes, age groups, and different countries find a figure with moderate weight and with a WHR of approximately .7 to be the most attractive. While most WHR research focused exclusively on bodily characteristics of the female stimulus figures the present investigation incorporates the WHR concept into a broader motivational framework in which motives and situational contexts (incentives) play an important role. Motives and incentives are key ingredients in most modern theories of motivation (Atkinson, 1964, Eccles and Wigfield, 2002, Feather, 1982, Heckhausen, 1991, McClelland, 1985 and Schneider and Schmalt, 2000). A motive is regarded as a personal predisposition (capacity) to strive for certain valued goals and an incentive refers to situational factors that signal the opportunity to accomplish those valued goals. It is hypothesized that individual differences in a motive disposition to appreciate reproductive success together with various situational opportunities to maximize one’s reproductive success (incentives) should act as moderators on the WHR-attractiveness relationship. Turning to motives first, the power motive seems to be in a prominent position when sexual relationships are concerned. Winter (1973) found that high power-motivated individuals report “exploitive” sex experiences, which means that they prefer short-term sexual relationships with a strong tendency to leave after gaining sexual access to a woman (the “Don Juan Myth”, Winter, 1973). Similarly, in the eyes of females, highly dominant males are judged to be physically and sexually attractive mating partners (Sadalla, Kenrick, & Vershure, 1987). Even research on non-human primates reports a positive correlation between status position in the dominance hierarchy and reproductive success. Dominant males gain privileged access to fertile female members of the group (Harcourt, 1989 and Kuester and Paul, 1989). Gangestad and Thornhill (1997) reported that social dominance in men is correlated with their genetic fitness. A strong motive to strive for status and power brings a double adaptive advantage for men: they are motivated to gain privileged access to fertile women and females are more likely to use male status and power as a cue for mate selection (Kenrick et al., 2003, Li et al., 2002 and Simpson and Oriña, 2003). Consequently individuals high in power motivation who are looking for mating opportunities should scrutinize information that determines their own reproductive success. It is hypothesized that individuals high in power motivation are especially discriminative concerning WHR information which is related to a woman’s fertility and hence their own reproductive success. Accordingly their attractiveness ratings should co-vary markedly with WHR information as compared with low power motivated individuals. In their “Sexual Strategies Theory”, Buss and Schmitt (1993) have pointed out the fact that mating strategies are context-dependent and highly sensitive to the temporal duration of the aspired relationship. They make a theoretically important distinction between long-term mating, like marriage, which is usually regarded as a reproductive alliance, and short-term mating such as a one-night stand. Buss and Schmitt (1993) have argued that men and women engage in both long-term and short-term mating and prefer different types of partners. Men can enhance their reproductive success primarily by increasing their number of sexual partners in short-term relationships and not so much by increasing the number of children per partner in a long-term relationship. Imagine a man raising two children with his wife: he can increase his reproductive success by 50% if he successfully impregnates an extramarital partner in a short-term liaison; at the same time immensely reducing costs and investments. In the light of these considerations, Buss and Schmitt (1993, p. 206) conclude that a man’s problem of identifying fertile women is even greater when pursuing a short-term mating strategy rather than a long-term mating strategy. Thus, it is hypothesized that individuals in search of a partner for a short-term relationship are especially discriminative concerning WHR information because a short-term mating strategy improves his potential reproductive success exponentially when compared with a long-term relationship. To summarize, the aim of the present investigation was threefold: It was expected (1) to replicate previous findings that a WHR of about .7 is rated as most attractive. Furthermore it was expected that the power motive (2) and the mating context (3) operate as moderators. High power motivation and a short-term mating context should foster the tendency to scrutinize WHR information when evaluating the fertility of a potential partner.