Experimental Evidence for Sex Differences in Sexual Variety Preferences: Support for the Coolidge Effect in Humans

Ejaculate Adjustment in Response to Sperm Competition Risk in Humans

Previous research suggests that human males, like males of many mammalian and avian species, adjust their ejaculate quality in accordance with sperm competition risk. Men who spend less time with their regular female partner since the couple's last copulation produce ejaculates with more sperm at the couple's next copulation (Baker & Bellis, 1993). We conducted a conceptual replication of this research to investigate whether sperm competition risk predicts ejaculate adjustment in human males using additional measures of sperm competition risk (e.g., perceptions of partner infidelity, presence of potential sexual rivals) and updated laser-optic semen analysis technology. We collected data from 34 heterosexual couples (age range 18-32 years) from a university population who completed self-report surveys on their relationship dynamics and provided six ejaculate samples (three copulatory and three masturbatory) across a 45-day period. Time spent together since the couple's last copulation was not significantly associated with ejaculate quality. However, sperm concentration for copulatory ejaculates was higher for men who perceived more potential sexual rivals. Discussion situates the current results within the literature on human sperm competition and suggests several directions for future research.

Gender differences in receptivity to sexual invitations: two naturalistic replication studies

In a seminal study, Clark and Hatfield (1989) found that men were more willing than women to accept casual sexual invitations, whereas no significant gender differences were observed in responses to propositions for non-committal social activities. The present research comprises two preregistered naturalistic replication studies (total N = 240). Study 1 serves as a direct replication, while Study 2 additionally tests whether differences in sociosexuality account for why men are more willing than women to accept casual sexual offers. In both studies, men more readily than women accepted a sexual invitation from a stranger of the opposite gender. In contrast to the original study, the gender difference was independent of the type of proposition. Individual differences in sociosexuality did not account for the observed gender differences. In summary, gender differences in the willingness to accept casual sexual invitations persist to this day, over 40 years after the initial Clark and Hatfield study.

Motivations for Endogamous Relationship Preferences

People tend to select romantic partners who belong to the same social group as themselves (i.e., endogamy). However, there is limited research on the proximal psychological motivations for choosing endogamous relationship partners. The purpose of this research was to develop a measure of motivations for endogamous relationship preferences and to assess whether such motivations were associated with actual dating experiences and attitudes toward endogamy across four common social categories: race and/or ethnicity, religion, social class, and education. Data from an online sample of participants (Study 1, n = 341) were used to generate items assessing motivations for endogamous relationship preferences. This initial set of items was administered to a new sample of participants (Study 2, n = 193) to establish the component structure of the measure and to examine whether the motivational components were associated with participants' past exogamous dating experiences as well as the perceived importance of dating within one's own racial and/or ethnic, religious, socioeconomic, and educational group. Endogamy motivations characterized by intergroup prejudice were the strongest and most consistent correlates of endogamous relationships and the perceived importance of endogamy. Study 3 (n = 332) replicated the component structure of the measure and the general pattern of associations documented in Study 2, and provided evidence for the measure's construct validity. The overall findings suggest that intergroup prejudice partially explains preferences for endogamous relationships.

A motivation model of sex addiction - Relevance to the controversy over the concept

An integrative model of sexual addiction is presented, involving a combination of models based upon (i) incentive motivation theory and (ii) the dual organisation of the control of behavior. The model is related to ongoing arguments about the validity of the notion of addiction when applied to sexual behavior. It is suggested that the evidence strongly favors the viability of an addiction model of sex. Strong similarities to the classical addiction to hard drugs are observed and features can be better understood with the help of the model. These include tolerance, escalation and withdrawal symptoms. It is argued that other candidates for accounting for the phenomena, such as obsessive-compulsive behavior, faulty impulse control, high drive and hypersexuality do not fit the evidence. The role of dopamine is central to the model. The model's relevance to stress, abuse, development, psychopathy, fantasy, sex differences, evolutionary psychology and the interaction with drug-taking is shown.

Electrophysiological Evidence of Enhanced Processing of Novel Pornographic Images in Individuals With Tendencies Toward Problematic Internet Pornography Use

Novelty seeking is regarded as a core feature in substance use disorders. However, few studies thus far have investigated this feature in problematic Internet pornography use (PIPU). The main aim of the present study was to examine group differences in electrophysiological activity associated with novelty processing in participants with high tendencies toward PIPU vs. low tendencies using event-related potentials (ERPs). Twenty-seven participants with high tendencies toward PIPU and 25 with low tendencies toward PIPU completed a modified three-stimulus oddball task while electroencephalogram (EEG) was recorded. Participants were instructed to detect neutral target stimuli from distracting stimuli. The distracting stimuli contained a familiar sexual stimulus and a set of novel sexual stimuli. The novel-familiar difference waves were calculated to identify specific group difference in novelty effect. While both groups demonstrated a sustained novelty effect in the late positive potential (LPP) within the 500–800 ms time windows, the novelty effect was greater in the high tendencies toward PIPU group than in the low tendencies toward PIPU group. This result suggests that individuals with high tendencies toward PIPU allocate more attentional resources for novelty processing. Enhanced brain responding to novel sexual stimuli may facilitate pornographic consumption and play an essential role in the development and maintenance of PIPU.

Mechanisms, development, and comparative perspectives on experience-dependent plasticity in social behavior

Revealing the mechanisms underlying experience-dependent plasticity is a hallmark of behavioral neuroscience. While the study of social behavior has focused primarily on the neuroendocrine and neural control of social behaviors, the plasticity of these innate behaviors has received relatively less attention. Here, we review studies on mating-dependent changes to social behavior and neural circuitry across mammals, birds, and reptiles. We provide an overview of species similarities and differences in the effects of mating experiences on motivational and performative aspects of sexual behaviors, on sensory processing and preferences, and on the experience-dependent consolidation of sexual behavior. We also discuss recent insights into the neural mechanisms of and developmental influences on mating-dependent changes and outline promising approaches to investigate evolutionary parallels and divergences in experience-dependent plasticity.

Exploring Variations in North American Adults' Attitudes, Interest, Experience, and Outcomes Related to Mixed-Gender Threesomes: A Replication and Extension

Mixed-gender threesomes (MGTs) are a type of consensually nonmonogamous sexual encounter involving three people of more than one gender. Little research has been conducted on MGTs, and what little work does exist is limited to college students, who may actually be less experienced with MGTs than older adults. The present study investigated attitudes toward, interest in, experiences with, and outcomes of MGTs in two samples (college N = 231; online N = 1342), comprised of 907 heterosexual and 666 sexual minority participants in total. Results indicated that participants reported neutral-to-positive attitudes toward and moderate-to-high levels of interest in MGTs (81% indicated some degree of interest). MGTs involving familiar others were preferred to those involving strangers. Men, sexual minority individuals, and participants from the online sample reported more favorable attitudes toward and greater interest in MGTs as compared to women, heterosexual individuals, and participants from the student sample. In addition, 30% of participants indicated having experience with a MGT. Sexual minority individuals reported more experience with MGTs and more positive outcomes than did heterosexual individuals. In addition, on average, participants reported that their MGT experiences "met expectations." Overall, these results indicate that MGTs are a common sexual behavior that often results in positive outcomes, especially among sexual minority individuals. Additional research on this understudied topic is needed, particularly as it relates to outcomes and the role of MGTs in consensually nonmonogamous relationships.

COVID-19 Pandemic on Fire: Evolved Propensities for Nocturnal Activities as a Liability Against Epidemiological Control

Humans have been using fire for hundreds of millennia, creating an ancestral expansion toward the nocturnal niche. The new adaptive challenges faced at night were recurrent enough to amplify existing psychological variation in our species. Night-time is dangerous and mysterious, so it selects for individuals with higher tendencies for paranoia, risk-taking, and sociability (because of security in numbers). During night-time, individuals are generally tired and show decreased self-control and increased impulsive behaviors. The lower visibility during night-time favors the partial concealment of identity and opens more opportunities for disinhibition of self-interested behaviors. Indeed, individuals with an evening-oriented chronotype are more paranoid, risk-taking, extraverted, impulsive, promiscuous, and have higher antisocial personality traits. However, under some circumstances, such as respiratory pandemics, the psychobehavioral traits favored by the nocturnal niche might be counter-productive, increasing contagion rates of a disease that can evade the behavioral immune system because its disease cues are often nonexistent or mild. The eveningness epidemiological liability hypothesis presented here suggests that during the COVID-19 pandemic, the evening-oriented psychobehavioral profile can have collectively harmful consequences: there is a clash of core tendencies between the nocturnal chronotype and the recent viral transmission-mitigating safety guidelines and rules. The pandemic safety protocols disrupt much normal social activity, particularly at night when making new social contacts is desired. The SARS-CoV-2 virus is contagious even in presymptomatic and asymptomatic individuals, which enables it to mostly evade our evolved contagious disease avoidance mechanisms. A growing body of research has indirectly shown that individual traits interfering with social distancing and anti-contagion measures are related to those of the nocturnal chronotype. Indeed, some of the social contexts that have been identified as superspreading events occur at night, such as in restaurants, bars, and nightclubs. Furthermore, nocturnal environmental conditions favor the survival of the SARS-CoV-2 virus much longer than daytime conditions. We compare the eveningness epidemiological liability hypothesis with other factors related to non-compliance with pandemic safety protocols, namely sex, age, and life history. Although there is not yet a direct link between the nocturnal chronotype and non-compliance with pandemic safety protocols, security measures and future empirical research should take this crucial evolutionary mismatch and adaptive metaproblem into account, and focus on how to avoid nocturnal individuals becoming superspreaders, offering secure alternatives for nocturnal social activities.

Pandemic Leadership: Sex Differences and Their Evolutionary-Developmental Origins

The COVID-19 pandemic has caused a global societal, economic, and social upheaval unseen in living memory. There have been substantial cross-national differences in the kinds of policies implemented by political decision-makers to prevent the spread of the virus, to test the population, and to manage infected patients. Among other factors, these policies vary with politicians' sex: early findings indicate that, on average, female leaders seem more focused on minimizing direct human suffering caused by the SARS-CoV-2 virus, while male leaders implement riskier short-term decisions, possibly aiming to minimize economic disruptions. These sex differences are consistent with broader findings in psychology, reflecting women's stronger empathy, higher pathogen disgust, health concern, care-taking orientation, and dislike for the suffering of other people-as well as men's higher risk-taking, Machiavellianism, psychopathy, narcissism, and focus on financial indicators of success and status. This review article contextualizes sex differences in pandemic leadership in an evolutionary framework. Evolution by natural selection is the only known process in nature that organizes organisms into higher degrees of functional order, or counteracts the unavoidable disorder that would otherwise ensue, and is therefore essential for explaining the origins of human sex differences. Differential sexual selection and parental investment between males and females, together with the sexual differentiation of the mammalian brain, drive sex differences in cognition and behavioral dispositions, underlying men's and women's leadership styles and decision-making during a global pandemic. According to the sexually dimorphic leadership specialization hypothesis, general psychobehavioral sex differences have been exapted during human evolution to create sexually dimorphic leadership styles. They may be facultatively co-opted by societies and/or followers when facing different kinds of ecological and/or sociopolitical threats, such as disease outbreaks or intergroup aggression. Early evidence indicates that against the invisible viral foe that can bring nations to their knees, the strategic circumspection of empathic feminine health "worriers" may bring more effective and humanitarian outcomes than the devil-may-care incaution of masculine risk-taking "warriors".

Fantasies About Consensual Nonmonogamy Among Persons in Monogamous Romantic Relationships

The present research explored fantasies about consensual nonmonogamous relationships (CNMRs) and the factors that predict such fantasies in a large and diverse online sample (N = 822) of persons currently involved in monogamous relationships. Nearly one-third (32.6%) of participants reported that being in some type of sexually open relationship was part of their favorite sexual fantasy of all time, of whom most (80.0%) said that they want to act on this fantasy in the future. Those who had shared and/or acted on CNMR fantasies previously generally reported positive outcomes (i.e., meeting or exceeding their expectations and improving their relationships). In addition, a majority of participants reported having fantasized about being in a CNMR at least once before, with open relationships being the most popular variety. Those who identified as male or non-binary reported more CNMR fantasies than those who identified as female. CNMR fantasies were also more common among persons who identified as anything other than heterosexual and among older adults. Erotophilia and sociosexual orientation were uniquely and positively associated with CNMR fantasies of all types; however, other individual difference factors (e.g., Big Five personality traits, attachment style) had less consistent associations. Unique predictors of infidelity fantasies differed from CNMR fantasies, suggesting that they are propelled by different psychological factors. Overall, these results suggest that CNMRs are a popular fantasy and desire among persons in monogamous romantic relationships. Clinical implications and implications for sexual fantasy research more broadly are discussed.