Romantic kissing is theorized to promote positive psychological outcomes in close relationships, potentially serving as a mate assessment tool and a mechanism for relationship maintenance. However, to date no empirical evidence supports the hypothesis that romantic kissing acts as a catalyst for sexual intercourse (the arousal hypothesis). However, lack of support for this hypothesis may be due to a focus on the sensation of a kiss when it was conceptualised. As such, past tests of this hypothesis have underplayed the role of mental states that are a prerequisite for sexual arousal. Addressing this gap, this study investigated whether intimate fantasies predict the perceived importance of arousal when defining the qualities of a "good kiss." As predicted, daytime fantasy proneness was correlated with the importance of arousal in a good kiss, independent of general creative thinking and sexual desire. By linking cognition to expressions of emotional intimacy, these findings advance our understanding of romantic rituals and highlight pathways for refining couples' therapy interventions.

Mate choice, and sex differences in romantic behaviours, represented one of the first major applications of evolutionary biology to human behaviour. This paper reviews Darwinian approaches to heterosexual mate assessment based on physical characteristics, placing the literature in its historical context (1871-1979), before turning (predominantly) to psychological research on attractiveness judgements based on physical characteristics. Attractiveness is consistently inferred across multiple modalities, with biological theories explaining why we differentiate certain individuals, on average, from others. Simultaneously, it is a judgement that varies systematically in light of our own traits, environment, and experiences. Over 30 years of research has generated robust effects alongside reasons to be humble in our lack of understanding of the precise physiological mechanisms involved in mate assessment. This review concludes with three questions to focus attention in further research, and proposes that our romantic preferences still provide a critical window into the evolution of human sexuality.

This study is the first systematic examination of trainee interviewer and actor behaviour during Joint Investigative Interviewing Training (JIIT) simulations across two training sites in Scotland. As expected, interviewers were poor at adhering to best practice interview guidelines in the pre-substantive and closure phases of the interviews. Although invitations were used within the range of best practice, they were not used more often and did not elicit more allegation-related details than directive questions. Critically, actors’ responses to invitations were less informative than their responses to all other question types. Furthermore, large differences were observed between the two training sites in the number of questions asked and amount of information elicited by interviewers. Our results show that (1) trainee interviewers are not utilising simulations to practice all required interviewing skills, (2) adult actors are not reinforcing interviewers’ use of invitations as intended, and (3) trainee interviewers are not being afforded the same opportunities to practice their skills due to variation in resources across Scotland. We recommend improvements to the JIIT programme to address these concerns.

Pornography has become widely accessible in recent years due to its integration with the Internet, generating social scientific and moralistic debate on potential "media effects," given correlations between consumption and various sexual traits and behaviors. One popular public debate (Wilson, 2012) claimed that exposure to Internet pornography has addictive qualities that could impact men's sexual relationships, underpinned by the "Coolidge effect," where males are sexually motivated by the presence of novel mates. As claims about Internet and sexual addictions are scientifically controversial, we provide a direct experimental test of his proposal. Adapting a paradigm used to examine "Coolidge-like" effects in men, we examined the extent to which exposure to images of pornographic actresses altered men's attractiveness ratings of (1) familiar faces/bodies on second viewing and (2) familiar versus novel women's faces/bodies. Independent of slideshow content (pornographic versus clothed versions of same actress), heterosexual men were less attracted to familiar bodies, and homosexual men were less attracted to familiar women (faces and bodies), suggesting that mere visual exposure to attractive women moderated men's preferences. However, consistent with one of our preregistered predictions, heterosexual but not homosexual men's preferences for familiar versus novel women were moderated by slideshow content such that familiar women were less salient on the attractiveness dimension compared to novel women when sexual arousal was greater (pornographic versus clothed slideshows). In sum, our findings demonstrate that visual exposure/sexual arousal moderates attractiveness perceptions, albeit that much greater nuance is required considering earlier claims.

Feeling and expressing love is at the core of romantic relationships, but individuals differ in their proclivity to worry about their relationships and/or avoid intimacy. Saying "I love you" signals a commitment to a future with our romantic partner. Contrary to gender stereotypes, research in the United States demonstrates that men are more likely to confess love first. We aimed to replicate this sex difference in an online cross-national sample (seven countries, three continents), while testing for variation according to attachment style and environment (the national sex ratio). Men were more likely to confess love first in a relationship, with preliminary evidence that this was more likely when men had more choice (more female-biased sex ratio). Independent of biological sex, highly avoidant respondents were less happy to hear "I love you" than less avoidant respondents, and highly anxious respondents were happier to hear "I love you" than less anxious respondents. Our findings suggest that prior observations generalize beyond an ethnically homogenous sample and incorporate attachment theory into the study of love confessions. Our research suggests a dissociation between initial declarations of love (moderated by biological sex) and emotional responses to love confessions, moderated by attachment style but not by biological sex.

Although online dating allows us to access a wider pool of romantic partners, choice could induce an 'assessment mindset', orienting us toward 'optimal' or alternative partners and undermining our willingness to commit or remain committed to someone. Contextual changes in judgements of facial attractiveness can shed light on this issue. We directly test this proposal by activating a context where participants imagine choosing between items in picture slideshows (dates or equally attractive desserts), observing its effects on attraction to i) faces on second viewing and ii) novel versus familiar identities. Single women, relative to single men, were less attracted to the same face on second viewing (Experiments 2 and 4), with this sex difference only observed after imagining not 'matching' with any romantic dates in our slideshow (i.e., low choice, Experiment 4). No equivalent sex differences were observed in the absence of experimental choice slideshows (Experiment 3), and these effects (Experiment 2) were not moderated by slideshow content (romantic dates or desserts) or choice set size (five versus fifteen items). Following slideshows, novel faces were more attractive than familiar faces (Experiment 1), with this effect stronger in men than in women (Experiment 2), and stronger across both sexes after imagining 'matching' with desired romantic dates (i.e., high choice, Experiment 4). Our findings suggest that familiarity does not necessarily 'breed liking' when we have the autonomy to choose, revealing lower-order socio-cognitive mechanisms that could underpin online interactions, such as when browsing profiles and deciding how to allocate effort to different users.

While first impressions of dominance and competence can influence leadership preference, social transmission of leadership preference has received little attention. The capacity to transmit, store and compute information has increased greatly over recent history, and the new media environment may encourage partisanship (i.e., "echo chambers"), misinformation and rumor spreading to support political and social causes and be conducive both to emotive writing and emotional contagion, which may shape voting behavior. In our pre-registered experiment, we examined whether implicit associations between facial cues to dominance and competence (intelligence) and leadership ability are strengthened by partisan media and knowledge that leaders support or oppose us on a socio-political issue of personal importance. Social information, in general, reduced well-established implicit associations between facial cues and leadership ability. However, as predicted, social knowledge of group membership reduced preferences for facial cues to high dominance and intelligence in out-group leaders. In the opposite-direction to our original prediction, this "in-group bias" was greater under less partisan versus partisan media, with partisan writing eliciting greater state anxiety across the sample. Partisanship also altered the salience of women's facial appearance (i.e., cues to high dominance and intelligence) in out-group versus in-group leaders. Independent of the media environment, men and women displayed an in-group bias toward facial cues of dominance in same-sex leaders. Our findings reveal effects of minimal social information (facial appearance, group membership, media reporting) on leadership judgments, which may have implications for patterns of voting or socio-political behavior at the local or national level.

Assessing dominance is important for effective social interactions, and prior research suggests that testosterone is associated with men's dominance perceptions. The present study tested for a causal effect of exogenous testosterone on men's sensitivity to vocal cues of other men's dominance, an important parameter in male-male competition across species. One hundred and thirty-nine Chinese men received a single dose (150 mg) of testosterone or placebo gel in a double-blind, placebo-controlled, between-participant design. Participants reported their own dominance and judged other men's dominance from voices. Men's dominance sensitivity was significantly weaker in the testosterone group compared to those in the placebo group. Moreover, men's dominance sensitivity was negatively associated with their self-reported dominance in our Chinese sample, consistent with findings from Western populations. These results indicate that exogenous testosterone has a causal effect in decreasing men's dominance sensitivity, consistent with the Challenge Hypothesis, suggesting that the fluctuation of testosterone concentration mediates individuals' behaviors. Additionally, the present study could motivate further work on vocal assessment in the context of competition in humans and other species.

High heels are symbols of female sexuality and are "costly signals" if the risks of wearing them are offset by improving women's attractiveness to men. From a functionalist perspective, the costs versus benefits of wearing heels may vary according to personal and contextual factors, such as her effectiveness at competing for mates, or at times when such motives are stronger. Here, we examined potential differences between women (self-rated attractiveness, dyadic versus solitary sexual desire, women's age, competitive attitudes toward other women) and contextual variation (priming mating and competitive motives) in their responses to high heels. Study 1 (N = 79) and Study 2 (N = 273) revealed that self-rated attractiveness was positively related to orientation toward heeled shoes. When examining responses to two very attractive shoes (one higher heel, one lower heel) in Study 2, dyadic sexual desire, but not solitary sexual desire or intrasexual competitiveness, predicted their inclination to buy the higher-heeled shoe. In Study 3 (N = 142), young women chose high heels when primed with free choice of a designer shoe (95% CI [53.02 mm, 67.37 mm]) and preferred a heel 22 mm (0.87") higher than older women (Study 4, N = 247). Contrary to predictions, priming mating or competitive motives did not alter women's preference toward a higher heel (Studies 3 and 4). Our studies suggest that attractive women augment their physical appeal via heels. High heels may be a subtle indicator of dyadic sexual desire, and preferences for heels are stronger at times in the lifespan when mating competition is relatively intense.

Romantic mouth-to-mouth kissing is culturally widespread, although not a human universal, and may play a functional role in assessing partner health and maintaining long-term pair bonds. Use and appreciation of kissing may therefore vary according to whether the environment places a premium on good health and partner investment. Here, we test for cultural variation (13 countries from six continents) in these behaviours/attitudes according to national health (historical pathogen prevalence) and both absolute (GDP) and relative wealth (GINI). Our data reveal that kissing is valued more in established relationships than it is valued during courtship. Also, consistent with the pair bonding hypothesis of the function of romantic kissing, relative poverty (income inequality) predicts frequency of kissing across romantic relationships. When aggregated, the predicted relationship between income inequality and kissing frequency (r = 0.67, BCa 95% CI[0.32,0.89]) was over five times the size of the null correlations between income inequality and frequency of hugging/cuddling and sex. As social complexity requires monitoring resource competition among large groups and predicts kissing prevalence in remote societies, this gesture may be important in the maintenance of long-term pair bonds in specific environments.

Cosmetics alter social perceptions, and prior work suggests that cosmetic use may aid female intrasexual competition, making women appear more dominant to other women but more prestigious to other men. It is unclear whether these findings reflect general improvements in perceptions of traits related to women’s dominance or if they are specific to mating contexts only. Here, across two ethnicities, we examined effects of cosmetics used for a social night out on perceptions of women’s leadership ability, a trait that denotes competence/high status outside of mating contexts. Participants of African and Caucasian ethnicity judged faces for leadership ability where half of the trials differed in ethnicity (own- vs. other-ethnicity face pairs) and the subtlety of the color manipulation (50% vs. 100%). Regardless of the participant’s sex or ethnicity, makeup used for a social night out had a negative effect on perceptions of women’s leadership ability. Our findings suggest that, in prior work, women are afforded traits related to dominance, as makeup enhances perceptions of traits that are important for successful female mating competition but not other components of social dominance such as leadership.

Although creativity is attractive in a potential mate, it is unclear (i) whether the effects of creativity on attractiveness generalize to other social contexts and (ii) whether creativity has equivalent effects on men's and women's attractiveness. As social knowledge of creativity may either enhance or 'offset' the appeal of social partners who differ in physical attractiveness, three repeated measures experiments were conducted to directly address these issues. Here, participants rated a series of face-text pairs for attractiveness on trials that differed in one of four combinations of facial attractiveness (attractive and less attractive) and creativity (creative and less creative), rating story-tellers in two experiments (short interpretations of an identical painting) and creative ideas in a further experiment (alternative uses for an everyday object). Regardless of the sex of the judge, creativity and facial attractiveness had independent effects on men's overall attractiveness (initial experiment) and, in further experiments, more substantial effects on the attractiveness of men with less attractive faces than men with attractive faces (when using a different measure of creativity) and specific effects on the attractiveness of individuals with less attractive faces (when using different face stimuli). Collectively, across three experiments, these findings suggest that creativity may compensate for putative cues to lower biological 'quality' and that the benefits of creativity to social groups more generally enhance attraction to creative men (in two experiments) and creative men and women (one experiment). More broadly, the data suggest that species can integrate knowledge of cognitive intelligence with visual cues to biological 'quality' to facilitate mate and/or ally choice.

While facial cues to body size are a valid guide to health and attractiveness, it is unclear whether the observer's own condition predicts the salience of (low) size as a cue to female attractiveness. The current study examines whether measures related to women's own attractiveness/appearance predict the extent to which they use facial cues to size to differentiate other women on the attractiveness dimension. Women completed a body mass index (BMI) preference task, where they indicated their preference for high- versus low-BMI versions of the same woman, provided data to calculate their BMI and completed various psychometric measures (self-rated attractiveness/health, dissatisfaction with physical appearance). Here, attractive women and women who were dissatisfied with their own appearance were more likely to associate facial cues to low body size with high attractiveness. These data suggest that psychological factors related to women's appearance shape their evaluations of other women based on cues to size. Such variation in attractiveness judgements may function to reduce the costs of female competition for resources, for example, by identifying "quality" rivals or excluding others based on cues to size.