Facial features and expressions influence perceptions of attractiveness, personality, behavioral tendencies, and relationship preferences. We manipulated eyelid openness in facial images of two men. Consistent with our predictions, open eyelid images were associated more so with behaviors consistent with long-term mating strategies and lowered eyelid images were associated more so with behaviors consistent with short-term mating strategies. Participants generally rated the men depicted in the open eyelid images as more attractive; however, the difference between images decreased as the prospective relationship length decreased. Participants' preferences matched their expectations for the people in the images, for example, mate-guarding concerns were stronger for the lowered eyelid images. Our results suggest that eyelid openness serves as a heuristic in evaluating an individual's mating intentions. Understandably, we did not find effects seen for manipulations of structural characteristics such as facial masculinity and symmetry, which are thought to be indicators of genetic quality.
Kruger, D. J. & Hughes, S. M. (2011). Tendencies to fall asleep first after sex are associated with greater partner desires for bonding and affection. Journal of Social, Evolutionary, and Cultural Psychology, 5, 239-247.
Despite the large literature on human reproductive strategies, research on psychology and behavior following acts of sex is scarce. The Post-Coital Time Interval (PCTI) may be particularly important for pair bonding and establishing relationship commitment. This study examined how desires for long-term partner expressions of affection and emotional bonding relate to self-reports of sleep onset patterns between couples. We also examined whether sex differences existed in self-reports of sleep onset following sexual intercourse versus when falling asleep together after not engaging in sex. Participants (N = 456) completed an online inventory assessing bonding, affection, communication, focus of attention, satisfaction, and responsiveness during the PCTI and reported their perceptions of relative sleep onset after having sex and when not having sex. Participants' desires for partner expressions of emotional bonding, physical affection, and communication were higher when their partners' had greater tendencies to fall asleep first after sex. In contrast, responses to comparison items (e.g., humor) did not exhibit this effect. Men reported that their partners were more likely to fall asleep first when going to bed without having sex, but there was no sex difference in reports of relative sleep onset after having sexual intercourse.
Kruger, D.J., & Fitzgerald, C.J. (2011). Reproductive strategies and relationship preferences associated with prestigious and dominant men. Personality and Individual Differences, 50, 365-369.
Women prefer dominant men as short-term mates and prestigious men as long-term mates. People associate short-term mating with masculine male facial features and long-term mating with feminine male facial features. The present study found that people associate dominant men with masculine facial features and short-term mating strategies, and prestigious men with feminine facial features and long-term mating strategies. Both men and women prefer high-prestige men for social relationships. Women prefer high-prestige men for long-term romantic relationships, yet prefer high-dominance men for brief sexual affairs. Although men were generally accurate in predicting women's partner preferences, men overestimated the degree to which women would find the high-dominance man more attractive for all types of relationships.
Tifferet, S., & Kruger, D.J. (2010). The terminal investment hypothesis and age-related differences in female preference for dads vs.cads. Letters on Evolutionary Behavioral Science, 1 (2), 27-30.
Williams' (1966) terminal investment hypothesis states that in species showing an agerelated decline in reproductive value, reproductive effort should increase with age. Nonhuman primate studies have supported this hypothesis, though research in humans is lacking, likely due to the restricted age range of participants in typical studies in evolutionary psychology. We hypothesize that older women will decrease mating effort in order to allocate additional resources to parental effort, and that this shift will be manifested in women's mate selection preferences. Because older women are hypothesized to shift resources from mating to parenting, they may show greater preferences for partners with high potential for paternal investment compared to partners with features signaling high potential for genetic investment. We use character sketches of 'dad' and 'cad' male reproductive strategies to demonstrate the age-related shift in relationship preferences. We found that older women prefer mating strategies that are related with higher paternal investment. In addition, we found that a woman's self description changes with age, mediating the age related changes in mate preferences. We suggest that these changes serve the changing needs of an older woman and the transition from investing in future offspring to investment in the current offspring.
Kruger, D. J. & Hughes, S. M. (2010). Variation in reproductive strategies influences post-coital experiences with partners. Journal of Social, Evolutionary and Cultural Psychology, 4, 254-264.
The Post-Coital Time Interval (PCTI) may be particularly important for pair-bonding and establishing relationship commitment. Women have greater incentives for establishing relationship commitment than men because of their greater necessary investment in offspring and the benefits of long-term paternal investment. Thus, sex differences in PCTI experiences may emerge based on sex differences in reproductive strategies. We generated 16 items to assess PCTI experiences and extracted three factors related to: 1) satisfaction and bonding, 2) a desire for more signals of bonding and commitment from one's partner, and 3) romantic partners having a greater interest in talking about relationship issues. Consistent with our predictions, women's satisfaction with PCTI experiences was inversely related to the extent to which they desired greater bonding and commitment signals from their partner, whereas men's satisfaction with PCTI experiences was inversely related to the extent to which their partners had greater interests in talking about relationship issues. These dimensions were also related to other indicators of reproductive strategies, including attachment style.
Kruger, D.J. & Fisher, M. (2008). Women's life history attributes are associated with preferences in mating relationships. Evolutionary Psychology, 6, 245-258.
Life History Theory (LHT) is a powerful framework for examining relationship choices and other behavioral strategies which integrates evolutionary, ecological, and socio-developmental perspectives. We examine the relationship between psychological and behavioral indicators of women's life history attributes and hypothetical relationship choices with characters representing short-term and long-term male sexual strategies. We demonstrate that psychological indicators of women's life history strategies are related to predicted and actual behaviors in mating relationships. Women with insecure attachment styles, especially those with negative evaluations of both themselves and others (fearful attachment), were more likely to consider men with attributes indicating short-term mating strategies for short-term and long-term relationships than women with a secure attachment style. Women with relatively unrestricted sociosexuality were more likely to predict they would have sexual affairs with men in general, with the tendency being generally stronger when considering men with attributes indicating short-term mating strategies. Those who scored high on self-monitoring were also more likely to predict having sexual affairs and short-term relationships with these men. These and other findings demonstrate the usefulness of a life history approach for understanding women's relationship choices.
Kruger, D.J. (2006). Male facial masculinity influences attributions of personality and reproductive strategy. Personal Relationships, 13, 451-463.
Facial masculinity may be used as a cue in female mate choice, as it reflects the success of the male genotype in its developmental environment. Women may maximize reproductive success by using a conditional strategy favoring highly masculine facial features for short-term relationships and feminized facial features in men for long-term relationships. Three studies examine reactions to masculinized and feminized male facial composites. Properties of the original composite image affect ratings of critical attributes and the magnitude of the differences in ratings between versions undergoing identical process of geometric manipulation (Study 1). Both men and women attribute personality, behavior, and mating strategies consistent with predictions derived from the good genes and mating trade-off hypotheses (Study 2). Participants accurately grouped behavioral tendencies related to high mating effort/risky strategies and high parenting effort/risk adverse strategies and associated mating effort more so with masculinized faces and parenting effort more so with feminized faces (Study 3). These results indicate that male facial masculinity serves as a visual cue for inferring personality and reproductive strategy.
Kruger, D.J., & Fisher, M. (2005). Alternative Male Mating Strategies are Intuitive to Women. Current Research in Social Psychology, 11, 39-50.
In this investigation, female college students (291) read brief sketches of characters from 19th Century novels exemplifying alternative male mating strategies. The proper hero dad advertises high potential for paternal investment by being compassionate, romantic, and industrious, whereas the dark hero cad advertises high genetic quality by being competitive, dominant, and brave. Women preferred the dad for long-term relationships, but were more likely to choose the cad for brief sexual relationships. These preferences were expected, as they benefit the women's reproductive success. Participants also inferred critical attributes and behaviors from the character descriptions that omitted this information.
Kruger, D.J., & Fisher, M. (2005). Males identify and respond adaptively to the mating strategies of other men. Sexualities, Evolution, and Gender, 7, 233-244.
We recently demonstrated that college-aged women who were given a brief character sketch of personality features consistent with each strategy readily comprehended alternative male mating strategies. In the current study, we confirmed that collegeaged males are also able to identify traits and tendencies associated with long-term dad and short-term cad mating strategies. Participants were aware of the cads' greater tendency for mating effort and success with women and the dads' greater suitability for long-term relationships and potential for paternal investment in offspring. There was some preference for dads rather than cads in social alliances. Participants also predicted responses to these characters in ways that would benefit their own reproductive success. Participants' personality attributes, hypothetical behaviors, and actual behaviors generally corresponded with their judgments of their similarity to the character descriptions.
Kruger, D.J., Fisher, M., & Jobling, I. (2003). Proper and dark heroes as dads and cads: Alternative mating strategies in British Romantic literature. Human Nature, 14, 305-317.
Empirical tests described in this article support hypotheses derived from evolutionary theory on the perceptions of literary characters. The proper and dark heroes in British Romantic literature of the late eighteenth and early nineteenth centuries respectively represent long-term and short-term mating strategies. Recent studies indicate that for long-term relationships,women seek partners with the ability and willingness to sustain paternal investment in extended relationships. For short-term relationships, women choose partners whose features indicate high genetic quality. In hypothetical scenarios, females preferred proper heroes for long-term relationships. The shorter the relationship under consideration, the more likely women were to choose dark heroes as partners.
See also: Economic and consumer behavior
See also: Evolutionary Demography