Examining Visual Attention Patterns among Asexual and Heterosexual Individuals.

Asexuality has garnered much attention, and empirical data support its classification as a sexual orientation. Asexuality is defined as a lack of sexual attraction to others, with approximately 1% of the population falling in this category. As theoretical models situate attention as a central component of sexual response, the current study examined attentional processing of erotic stimuli in asexuals and heterosexuals. We hypothesized that heterosexual participants would have initial and controlled visual attention patterns favoring erotic images over non-erotic images. We predicted that asexual participants would have significantly smaller or non-existent differences in attention to erotic versus non-erotic images. Ninety-five adults completed an eye-tracking task viewing erotic and non-erotic images. Eye-tracking data showed no group differences in initial attention to erotic images. For controlled attention, there was a large effect size in the hypothesized direction. Heterosexual participants exhibited more and longer fixations on erotic images, whereas asexuals exhibited a more even distribution of attention across image types. Exploratory analysis of group differences in the association between visual attention and ratings of sexual attractiveness revealed a complex pattern of differences, with some indication of a stronger association between total fixation and sexual attraction for heterosexual participants. These findings suggest that differences in attention to sexual stimuli may represent key underlying differences between asexual and allosexual orientation. Findings also contribute to the larger literature on visual attention and attraction.

Patterns of Genital and Subjective Sexual Arousal in Cisgender Asexual Men.

Human asexuality has been defined as a lack of sexual attraction to others, although its nature is not well understood. Asexual men's genital and subjective sexual arousal patterns were compared to sexual men's to better understand asexual men's sexual response patterns. Using a penile plethysmograph to measure genital arousal, 20 asexual, 27 heterosexual, and 22 gay cisgender men (M age = 28.28, SD = 9.41) viewed erotic films depicting sexual activity or masturbation, and a subsample engaged in sexual fantasy of their choosing. Questionnaires assessing sexual function and behavior were also completed. Asexual men scored lower on sexual desire and orgasmic function, higher on sexual aversion, and did not differ on overall sexual satisfaction. Compared with gay and heterosexual men, asexual men demonstrated lower genital and subjective sexual arousal to the erotic films but displayed similar sexual arousal when engaging in sexual fantasy. Asexual men's lower levels of sexual excitation rather than their higher levels of sexual inhibition were associated with lower responses to the erotic films. These findings suggest asexual men have preferred sexual stimuli that differ from sexual men and have a similar capacity for sexual arousal as sexual men. Collectively these findings add to a growing literature aiming to understand the nature of asexuality.

A short review of biological research on the development of sexual orientation.

We review research supporting biological mechanisms in the development of sexual orientation. This research includes studies on neural correlates, prenatal hormones and related physical/behavioral correlates, genetics, and the fraternal birth order effect (FBOE). These studies, taken together, have provided substantial support for biological influences underlying the development of sexual orientation, but questions remain unanswered, including how biological mechanisms may differ in contributing to men's and women's sexual orientation development.

Fraternal Birth Order, Only-Child Status, and Sibling Sex Ratio Related to Sexual Orientation in the Add Health Data: A Re-analysis and Extended Findings.

The fraternal birth order (FBO) effect related to men's sexual orientation refers to the finding that the number of older brothers that a man has increases his chance of being androphilic. The FBO effect has generally been well replicated in diverse samples; one instance of non-replication was by Francis (2008) using Waves I and III of the Add Health data. We attempted to replicate the FBO effect in the Add Health data taking into account family size and other limitations of Francis' (2008) analyses. Also, we examined other sibling characteristics related to the FBO effect: sibling sex ratio and only-child status. We used two subsamples from Waves I (n = 20,745) and IV (n = 15,701) of the Add Health data, consisting of adolescents who were followed longitudinally from 1994 to 1995 until 2008. Wave I data were used to compute numbers of younger and older brothers and sisters from household roster information. Wave IV information about sexual orientation identity was used. Analyses were conducted within men and within women. We found modest support for the FBO effect in men, but not in women, using the older brother odds ratio, logistic regression analyses, and sibling sex ratio, which provided the strongest support for FBO. We found that gynephilic/biphilic women, but not androphilic/biphilic men, were more likely to be only-children compared to androphilic women and gynephilic men, respectively. We discuss limitations of the Add Health data and purported mechanisms for the FBO effect in men and the only-child effect in women.

Male homosexuality and maternal immune responsivity to the Y-linked protein NLGN4Y.

We conducted a direct test of an immunological explanation of the finding that gay men have a greater number of older brothers than do heterosexual men. This explanation posits that some mothers develop antibodies against a Y-linked protein important in male brain development, and that this effect becomes increasingly likely with each male gestation, altering brain structures underlying sexual orientation in their later-born sons. Immune assays targeting two Y-linked proteins important in brain development-protocadherin 11 Y-linked (PCDH11Y) and neuroligin 4 Y-linked (NLGN4Y; isoforms 1 and 2)-were developed. Plasma from mothers of sons, about half of whom had a gay son, along with additional controls (women with no sons, men) was analyzed for male protein-specific antibodies. Results indicated women had significantly higher anti-NLGN4Y levels than men. In addition, after statistically controlling for number of pregnancies, mothers of gay sons, particularly those with older brothers, had significantly higher anti-NLGN4Y levels than did the control samples of women, including mothers of heterosexual sons. The results suggest an association between a maternal immune response to NLGN4Y and subsequent sexual orientation in male offspring.

Personality and Sexual Orientation: Extension to Asexuality and the HEXACO Model.

Previous research has examined self-identified sexual orientation in relation to self-reports on the Big Five personality factors. Here we extend this research by including asexuality as a fourth sexual orientation and by assessing the HEXACO personality factors, using self-report data from a large anonymous online sample (N ≈ 100,000). A large overlap was observed among all sexual orientation groups on all six HEXACO dimensions, but notable group differences also emerged. All nonheterosexual groups, particularly bisexual people, averaged higher in openness to experience than did heterosexuals. Heterosexual men averaged much lower in emotionality than heterosexual women, but only a small difference was observed between gay men and lesbians on this dimension. Asexual men and women averaged lower in extraversion and in some facets of emotionality (specifically, dependence and sentimentality) than did the other sexual orientation groups of the same sex. Results are discussed in relation to the different social realities that each sexual orientation group often experiences, along with the (gender-related) developmental influences hypothesized to underlie in part the origins of sexual orientation.

Sexual Orientation, Objective Height, and Self-Reported Height.

Studies that have used mostly self-reported height have found that androphilic men and women are shorter than gynephilic men and women, respectively. This study examined whether an objective height difference exists or whether a psychosocial account (e.g., distortion of self-reports) may explain these putative height differences. A total of 863 participants, recruited at a Canadian university, the surrounding region, and through lesbian, gay, bisexual, and transgender (LGBT) events across Canada, self-reported their height and had their height measured. Androphilic men were shorter, on average, than gynephilic men. There was no objective height difference between gynephilic, ambiphilic, and androphilic women. Self-reported height, statistically controlling for objective height, was not related to sexual orientation. These findings are the first to show an objective height difference between androphilic and gynephilic men. Also, the findings suggest that previous studies using self-reported height found part of a true objective height difference between androphilic and gynephilic men. These findings have implications for existing biological theories of men's sexual orientation development.

Handedness, sexual orientation, and somatic markers for prenatal androgens: Are southpaws really that gay?

BACKGROUND: Some evidence suggests that prenatal androgens influence both handedness and sexual orientation. This study sought to clarify how androgens, handedness, and sexual orientation are interrelated. METHODS: Data were obtained from large samples of students enrolled at universities in Malaysia and the US, including self-reported information on handedness, sexual orientation, and five somatic markers of prenatal androgen exposure (2D:4D, height, strength, muscularity, and athletic ability). Factor analysis of these somatic markers yielded two factors: a muscular coordination and a bone growth factor. RESULTS: In women, but not in men, ambidextrousness was more prevalent among those with homosexual tendencies. Modest and often complex associations were found between the androgen factors and handedness. Clear links between the androgen factors and sexual orientation were found, especially for muscular coordination. For males and females, intermediate sex-typical androgen exposure was associated with heterosexual preferences. CONCLUSIONS: Ambidextrousness appears to be somewhat more common among females with homosexual tendencies, but left-handedness is nearly as strongly associated with heterosexual preferences, particularly in males, as is right-handedness. Factors indicative of prenatal androgen exposure are associated with sexual orientation in theoretically predictable ways, especially for muscular coordination, but associations between prenatal androgens and handedness are complex.

Gay Male Only-Children: Evidence for Low Birth Weight and High Maternal Miscarriage Rates.

Recent findings suggest that there may be a maternal immune response underpinning the etiology of sexual orientation of gay male only-children. This maternal immune response appears to be distinct from that which is purported to explain the classic fraternal birth order effect found in studies of male sexual orientation. We tested two predictions related to the hypothesized maternal immune response in mothers of gay male only-children: (1) elevated fetal loss among mothers who have had gay male only-children and (2) lower birth weight in gay male only-children. Mothers of at least one gay son (n = 54) and mothers of heterosexual son(s) (n = 72) self-reported their pregnancy histories, including the birth weights of newborns and number of fetal losses (e.g., miscarriages). Mothers of gay male only-children (n = 8) reported significantly greater fetal loss compared with mothers of males with four other sibship compositions (gay with no older brothers, gay with older brothers, heterosexual only-children, heterosexual with siblings) (n = 118). Also, firstborn gay male only-children (n = 4) had a significantly lower birth weight than firstborn children in the four other sibship compositions (n = 59). Duration of pregnancy was not significantly different among the groups of firstborn children in the birth weight analyses. Thus, this study found further support for a distinct pattern of maternal immune response implicated in the etiology of male sexual orientation. Mechanisms that may underlie this potential second type of maternal immune response are discussed.

Pubertal Stress and Nutrition and their Association with Sexual Orientation and Height in the Add Health Data.

A number of studies have indicated that gay men tend to be shorter, on average, than heterosexual men. Less evidence exists that lesbian women are taller, on average, than heterosexual women. The most popular explanation of the association between sexual orientation and height involves prenatal factors, such that, for example, gay men may have been exposed to lower than typical androgens during fetal development, which impacts their height and sexual orientation as adults. An alternative explanation involves stress, given that stress has been associated with sexual minority identification and with lower height. Another alternative explanation involves nutrition, although its relationship is less clear with sexual minority identification. Using the Add Health data, which is a large, nationally representative and longitudinal sample of American adolescents (n = 14,786), we tested a mediation model, such that sexual orientation → pubertal stress/nutrition → height. Within men, we found that gay men (n = 126) were shorter, on average, than heterosexual men (n = 6412). None of the 24 pubertal stress-related and 15 pubertal nutrition-related variables assessed in the Add Health data mediated the relationship between sexual orientation and height in men. Within women, lesbians (n = 75) did not differ significantly in stature compared to heterosexual women (n = 6267). Thus, prenatal mechanisms (e.g., hormones, maternal immune response) are likely better candidates for explaining the height difference between gay men and heterosexual men.

Asexuality: what it is and why it matters.

In this review article, human asexuality, a relatively understudied phenomenon, is discussed. Specifically, definitions and conceptualizations of asexuality (e.g., is it a unique category of sexual orientation?), biological and historical contexts, identity issues, discrimination against asexual people relative to other minorities, origins, and variations, including gender differences, are reviewed. Whether asexuality should be construed as a disorder is also discussed. The study of asexuality allows for a better understanding of an underrecognized sexual minority but also affords a unique opportunity to examine and better understand human sexuality.

Gender Differences in Object of Desire Self-Consciousness Sexual Fantasies.

In a recent review article, Bogaert and Brotto (2014) discussed "object of desire self-consciousness," a perception that one is romantically and sexually desirable in another's eyes. They argued that this perception is more relevant to women's sociosexual functioning than it is to men's. In the present study, we attempted to find direct evidence that object of desire themes are linked more to women's sexual desire and arousal than they are to men's by examining the differences in content between men's and women's sexual fantasies. A total of 198 men and women reported on arousing themes in sexual fantasies using three methodologies: endorsement of items on a sexual fantasy questionnaire, sentence completion of sexually-charged scenarios, and open-ended sexual fantasies. The men and women also rated their attractiveness and were rated for attractiveness by two female experimenters. On all three fantasy composites, women endorsed more object of desire themes than did men, and these effects occurred independent of the subjective and observer-rated attractiveness measures. The results were discussed in relation to theorizing that object of desire self-consciousness can function as part of many women's self-schemata or scripts related to romance and sexuality.

Facial Structure Predicts Sexual Orientation in Both Men and Women.

Biological models have typically framed sexual orientation in terms of effects of variation in fetal androgen signaling on sexual differentiation, although other biological models exist. Despite marked sex differences in facial structure, the relationship between sexual orientation and facial structure is understudied. A total of 52 lesbian women, 134 heterosexual women, 77 gay men, and 127 heterosexual men were recruited at a Canadian campus and various Canadian Pride and sexuality events. We found that facial structure differed depending on sexual orientation; substantial variation in sexual orientation was predicted using facial metrics computed by a facial modelling program from photographs of White faces. At the univariate level, lesbian and heterosexual women differed in 17 facial features (out of 63) and four were unique multivariate predictors in logistic regression. Gay and heterosexual men differed in 11 facial features at the univariate level, of which three were unique multivariate predictors. Some, but not all, of the facial metrics differed between the sexes. Lesbian women had noses that were more turned up (also more turned up in heterosexual men), mouths that were more puckered, smaller foreheads, and marginally more masculine face shapes (also in heterosexual men) than heterosexual women. Gay men had more convex cheeks, shorter noses (also in heterosexual women), and foreheads that were more tilted back relative to heterosexual men. Principal components analysis and discriminant functions analysis generally corroborated these results. The mechanisms underlying variation in craniofacial structure--both related and unrelated to sexual differentiation--may thus be important in understanding the development of sexual orientation.

Psychopathic Sexuality: The Thin Line Between Fantasy and Reality.

In two studies, we explored the relations between psychopathic traits and sexual fantasy content. In Study 1, we rated content themes in the fantasy narratives of 195 men and women recruited at a Canadian university. In Study 2, we administered a sexual fantasy questionnaire to a sample of 355 Canadian undergraduate students. In Study 1, we found that psychopathic traits predicted themes of anonymous, uncommitted, and nonromantic sexual activity after controlling for participant sex. In Study 2, we found that psychopathy added to the prediction of self-reported engagement in unrestricted, dominant, submissive, deviant, and adventurous sexual activity, even after controlling for participant sex and level of fantasizing about that activity. Furthermore, an interaction between psychopathy and level of fantasizing was observed for unrestricted and deviant sexual behavior, such that participants who reported high levels of fantasizing about these sexual themes were more likely to engage in that behavior if they also reported high levels of psychopathic traits. These findings suggest that psychopathy is related not only to interest in particular sexual behaviors, but also to whether individuals will translate these fantasized behaviors into reality.

Consensual Nonmonogamy: Psychological Well-Being and Relationship Quality Correlates.

Consensually nonmonogamous relationships are those in which all partners explicitly agree that each partner may have romantic or sexual relationships with others (Conley, Ziegler, Moors, Matsick, & Valentine, 2013 ). In this article, research examining the associations between consensual nonmonogamy, psychological well-being, and relationship quality is reviewed. Specifically, three types of consensual nonmonogamy are examined: swinging, open relationships (including sexually open marriage and gay open relationships), and polyamory. Swinging refers to when a couple practices extradyadic sex with members of another couple; open relationships are relationships in which partners agree that they can have extradyadic sex; and polyamory is the practice of, belief in, or willingness to engage in consensual nonmonogamy, typically in long-term and/or loving relationships. General trends in the research reviewed suggest that consensual nonmonogamists have similar psychological well-being and relationship quality as monogamists. Methodological challenges in research on consensual nonmonogamy and directions for future research are discussed.

Object of desire self-consciousness theory.

In this article, the authors discuss the construct of object of desire self-consciousness, the perception that one is romantically and sexually desirable in another's eyes. The authors discuss the nature of the construct, variations in its expression, and how it may function as part of a self-schemata or script related to romance and sexuality. The authors suggest that object of desire self-consciousness may be an adaptive, evolved psychological mechanism allowing sexual and romantic tactics suitable to one's mate value. The authors also suggest that it can act as a signal that one has high mate value in the sexual marketplace. The authors then review literature (e.g., on fantasies, on sexual activity preferences, on sexual dysfunctions, on language) suggesting that object of desire self-consciousness plays a particularly important role in heterosexual women's sexual/romantic functioning and desires.

Physical size and sexual orientation: Analysis of the Chinese health and family life survey.

In the present study, the relationship between physical size and sexual orientation was examined. Participants were men and women comprising the Chinese Health and Family Life Survey (N > 3,500), which employed a national probability sample from China. This survey is important because no research has examined these issues in a representative, non-Western sample. Participants completed self-report measures of height, weight, and sexual orientation. Some evidence was found that men with same-sex inclinations were significantly shorter than heterosexual men. The evidence that women with same-sex inclinations were significantly taller and heavier than heterosexual women was equivocal. The results add modest support to some prior research suggesting that men with same-sex inclinations have a different pattern of growth and development relative to heterosexual comparisons.