Habituation of Sexual Responses in Men and Women: A Test of the Preparation Hypothesis of Women's Genital Responses

Romantic Love and Sexual Frequency: Challenging Beliefs

Common conceptions of romantic love suggest that romantic love is associated with increased sexual activity with more frequent sex in the earlier stages of a romantic relationship. To our knowledge, no studies have investigated individual-level factors and sexual frequency using a validated measure of romantic love. This study tested a number of hypotheses about the factors associated with sexual frequency among 720 sexually active young adults experiencing romantic love from the Romantic Love Survey 2022. We hypothesized that relationship duration, the intensity of romantic love and obsessive thinking about a loved one, commitment, and hypomanic-like features would be associated with sexual frequency. Using hierarchical linear regression, controlling for known covariates, we found no significant associations between any of our variables of interest and the frequency of sexual frequency and our entire model of 14 well-reasoned predictors explained only 4.06% of the variation in sexual frequency. The findings are surprising and highlight how little is currently known about sexual activity and sexual desire among individuals experiencing romantic love.

Been There, Done That: The Impact of the Novelty of Penile Vaginal Intercourse (PVI) and Participants' Sex on Delay and Probability Discounting of PVI

Delay and probability discounting tasks are useful for understanding aspects of decision making. The current study, which employed a mixed-model design to assess discounting of penile-vaginal intercourse (PVI), was conducted online with male and female participants recruited from Prolific (N = 300; mean age = 34.1 years). Results of the novel delay and probability discounting tasks indicated that as the delay to PVI increased, or as PVI became less certain to occur, participants were instead more likely to choose to receive oral sex, the reward initially indicated as less desirable. Having previously engaged in PVI, however, enhanced this reversal of preferences on both tasks, which suggests PVI loses some of its value when no longer novel. Males and females similarly discounted PVI on the delay discounting task, which suggests biological sex may not impact the propensity to wait for a preferred sexual behavior. On the probability discounting task, however, males were more averse to a reduced probability of PVI occurring and instead opted for receiving oral sex. The sexual behavior discounting tasks developed in the current study, and ones like it, may prove useful for identifying preferences in sexual behaviors, and ultimately enhance sexual and relationship satisfaction.

Rose Colored Glasses: An Exploration of the Relationship between Sexual Nostalgia and Sexual Satisfaction

Sexual satisfaction contributes significantly to one's quality of life and offers a variety of mental and physical health benefits. Consequently, numerous studies have examined ways to improve sexual satisfaction. However, no research has investigated how sexual nostalgia (i.e., "the sentimental longing for or wistful reflection on past sexual memories," p. 1539) with one's current partner impacts sexual satisfaction. Thus, this program of research was designed to develop the Sexual Nostalgia Inventory, assess the relationship between sexual nostalgia and sexual satisfaction, and to examine the moderating role of romantic attachment. The results of Study One (N = 227) indicated that the content of sexual memories can be conceptualized into one factor. The results from Study Two (N = 619) revealed that sexual nostalgia was positively related to sexual satisfaction and that romantic attachment moderated these relationships. In particular, the positive association between sexual nostalgia and satisfaction was greatest for those insecurely attached (i.e., those high in anxious and avoidant attachment). These findings have important implications for researchers looking to establish the causal link between nostalgia and satisfaction and clinicians working with couples experiencing low sexual desire and/or unmet sexual needs.

Does Sexual Desire Fluctuate More Among Women than Men?

There is a lay assumption that women's sexual desire varies substantially over time, whereas men's is stable. This assumption is mirrored in prominent theories of desire, which posit that women are more variable than men in the extent to which they desire sex, and that women's sexual desire is more contextually sensitive than men's. We tested this assumption across three longitudinal studies. Study 1 assessed desire at 3 time points spanning 13 years (N_observations = 5562), and Studies 2 and 3 (N_observations = 11,282) assessed desire moment-to-moment over 7 days. When desire was measured over years, women were more variable in their sexual desire than men (Study 1). However, we found a different pattern of results when desire was measured over the short term. In Studies 2 and 3, we found no significant differences in women's and men's desire variability. The extent to which desire varied as a function of affective states (e.g., happiness) and relationship-oriented states (e.g., partner closeness) was similar for women and men, with some exceptions; women's desire was more negatively associated with tiredness and anger in Study 2. These data qualify existing assumptions about sex differences in sexual desire variability.

Sexual attraction to visual sexual stimuli in association with steroid hormones across menstrual cycles and fertility treatment

BACKGROUND

Steroid hormones (i.e., estradiol, progesterone, and testosterone) are considered to play a crucial role in the regulation of women's sexual desire and sexual attraction to sexual stimuli throughout the menstrual cycle. However, the literature is inconsistent, and methodologically sound studies on the relationship between steroid hormones and women's sexual attraction are rare.

METHODS

This prospective longitudinal multisite study examined estradiol, progesterone, and testosterone serum levels in association with sexual attraction to visual sexual stimuli in naturally cycling women and in women undergoing fertility treatment (in vitro fertilization, IVF). Across ovarian stimulation of fertility treatment, estradiol reaches supraphysiological levels, while other ovarian hormones remain nearly stable. Ovarian stimulation hence offers a unique quasi-experimental model to study concentration-dependent effects of estradiol. Hormonal parameters and sexual attraction to visual sexual stimuli assessed with computerized visual analogue scales were collected at four time points per cycle, i.e., during the menstrual, preovulatory, mid-luteal, and premenstrual phases, across two consecutive menstrual cycles (n = 88 and n = 68 for the first and second cycle, respectively). Women undergoing fertility treatment (n = 44) were assessed twice, at the beginning and at the end of ovarian stimulation. Sexually explicit photographs served as visual sexual stimuli.

RESULTS

In naturally cycling women, sexual attraction to visual sexual stimuli did not vary consistently across two consecutive menstrual cycles. While in the first menstrual cycle sexual attraction to male bodies, couples kissing, and at intercourse varied significantly with a peak in the preovulatory phase, (all p ≤ 0.001), there was no significant variability across the second cycle. Univariable and multivariable models evaluating repeated cross-sectional relationships and intraindividual change scores revealed no consistent associations between estradiol, progesterone, and testosterone and sexual attraction to visual sexual stimuli throughout both menstrual cycles. Also, no significant association with any hormone was found when the data from both menstrual cycles were combined. In women undergoing ovarian stimulation of IVF, sexual attraction to visual sexual stimuli did not vary over time and was not associated with estradiol levels despite intraindividual changes in estradiol levels from 122.0 to 11,746.0 pmol/l with a mean (SD) of 3553.9 (2472.4) pmol/l.

CONCLUSIONS

These results imply that neither physiological levels of estradiol, progesterone, and testosterone in naturally cycling women nor supraphysiological levels of estradiol due to ovarian stimulation exert any relevant effect on women's sexual attraction to visual sexual stimuli.

Validation of laser Doppler flowmetry for the continuous measurement of women's genital response

Laser Doppler imaging is a valid method of assessing genital response, detecting increases in genital blood flow to sexual, but not nonsexual stimuli. Although laser Doppler imaging provides a direct measure of genital blood flow, its discrete perfusion images provide a discontinuous assessment of genital response, limiting some study designs. The aims of this study were to investigate the measurement properties of laser Doppler flowmetry, a direct and continuous measure of blood flow, as well as examine the time course of genital response using flowmetry. A sample of 45 cisgender women attended two experimental sessions wherein they viewed sexual and nonsexual stimuli (e.g., neutral, anxiety, humor) while their genital responses were assessed using laser Doppler flowmetry. As expected, laser Doppler flowmetry was a valid measure of genital response-detecting increases in genital blood flow elicited by the sexual stimuli only-and was sensitive to varying degrees of genital response elicited by low, moderate, and high-intensity sexual stimuli. The measure also exhibited convergent validity with genital response assessed via laser Doppler imaging, test-retest reliability across testing sessions, and internal consistency as well as high sexual concordance with self-reported sexual arousal. Descriptive analyses showed that genital blood flow assessed using laser Doppler flowmetry was highly responsive, with initial, peak, and return to baseline responses occurring within timeframes appropriate for repeated measurement within a single session. Laser Doppler flowmetry is a valid, reliable, and sensitive measure of women's genital response that can be usefully applied in sexual psychophysiology research.

The Empirical Status of the Preparation Hypothesis: Explicating Women's Genital Responses to Sexual Stimuli in the Laboratory

Research conducted in our laboratory and in other laboratories has revealed that (1) women's genital responses to visual and auditory stimuli are strongly affected by the presence of sexual cues, but that (2) specific sexual cues (e.g., gender of actors, the presence of sexual violence) often have little impact on the magnitude of the responses-that is, similar genital responses are observed to very different sexual stimuli. In addition, (3) women's genital responses do not strongly correspond with self-reported sexual partner and activity preferences, or (4) with self-reported sexual arousal during the presentation of sexual stimuli. Taken together, these facts represent a puzzle, especially considering that men's genital responses are highly affected by specific sexual cues and strongly correspond to stated preferences and self-reported sexual arousal. One hypothesis to explain female low cue-specificity and low concordance (relative to men) is the preparation hypothesis: Women's indiscriminate genital responses serve a protective function. That is, they do not indicate or necessarily promote sexual interest and motivation, but rather prepare the vaginal lumen for possible sexual activity and therefore prevent injuries that may occur as a result of penetration. We review evidence for and against this hypothesis. We conclude that the evidence is favorable but not entirely convincing, and more work is required to reach a firm conclusion. We offer directions for future research.

Sex Drive as a Possible Mediator of the Gender Difference in the Prevalence of Paraphilic Interests in a Nonclinical Sample

There is a general gender difference in paraphilic interests, such that men report more interest (and greater engagement) in a variety of paraphilic behaviors. Using a nonclinical sample, Dawson et al. (Sexual Abuse, 28(1):20-45, 2016, https://doi.org/10.1177/1079063214525645 ) found that the gender difference in paraphilic interests was eliminated when scores on measures of sex drive were used as mediators. However, their measures of sex drive were about more than just sex drive and included a measure of hypersexuality (i.e., distress, perceived lack of control, and problematic consequences of one's sexuality). This study had two aims: to replicate Dawson et al.'s mediation results (using the same measures and scoring methods), and to discern the effect of sex drive itself (by replacing their measure of hypersexuality with a measure of sex drive). A nonclinical sample of 517 men and 615 women completed an online questionnaire. As expected, men reported less repulsion than women for most paraphilic themes. The gender difference in paraphilic interests was reduced (but not eliminated) both when reproducing Dawson et al.'s analysis and when examining a mediation model focused on sex drive specifically. The same results were obtained when examining the paraphilic interest with the largest gender difference (i.e., voyeurism). A full mediation effect was obtained in an unplanned supplementary analysis using a factor score (derived from eight measures) putatively assessing sex drive. While the main findings are consistent with Dawson et al.'s conclusions that sex drive is a possible mediator, they also suggest that other factors need to be considered to help explain the gender difference in the prevalence of paraphilic interests.

Measurement of Sexual Interests with Pupillary Responses: A Meta-Analysis

Objective measures of sexual interest are important for research on human sexuality. There has been a resurgence in research examining pupil dilation as a potential index of sexual orientation. We carried out a meta-analytic review of studies published between 1965 and 2020 (Mdn year = 2016) measuring pupil responses to visual stimuli of adult men and women to assess sexual interest. Separate meta-analyses were performed for six sexual orientation categories. In the final analysis, 15 studies were included for heterosexual men (N = 550), 5 studies for gay men (N = 65), 4 studies for bisexual men (N = 124), 13 studies for heterosexual women (N = 403), and 3 studies for lesbian women (N = 132). Only heterosexual and gay men demonstrated discrimination in pupillary responses that was clearly in line with their sexual orientation, with greater pupil dilation to female and male stimuli, respectively. Bisexual men showed greater pupil dilation to male stimuli. Although heterosexual women exhibited larger pupils to male stimuli compared to female stimuli, the magnitude of the effect was small and non-significant. Finally, lesbian women displayed greater pupil dilation to male stimuli. Three methodological moderators were identified-the sexual explicitness of stimulus materials, the measurement technique of pupillary response, and inclusion of self-report measures of sexual interest. These meta-analyses are based on a limited number of studies and are therefore preliminary. However, the results suggest that pupillary measurement of sexual interest is promising for men and that standardization is essential to gain a better understanding of the validity of this measurement technique for sexual interest.

Hormones and the Coolidge effect

The Coolidge effect is the renewal of sexual behavior after the presentation of a novel sexual partner and possibly occurs as the result of habituation and dishabituation processes. This re-motivation to copulate is well studied in males and is commonly related to sexual satiety, which involves several neurobiological changes in steroid receptors and their mRNA expression in the CNS. On the other hand, there are few reports studying sexual novelty in females and have been limited to behavioral aspects. Here we report that the levels of rat proceptive behavior, a sign of sexual motivation, declines after 4 h of continuous mating, particularly in females that were unable to regulate the time of mating. Such reduction was not accompanied by changes in lordosis, suggesting that they were not due to the vanishing of the endocrine optimal milieu necessary for the expression of both components of sexual behavior in the female rat. These and previous data support important differences between sexual behavior in both sexes that would result in natural divergences in the Coolidge effect expression. We here also review some reports in humans showing peculiarities between the pattern of habituation and dishabituation in women and men. This is a growing research field that needs emphasis in female subjects.

Paraphilic Interests: An Examination of Sex Differences in a Nonclinical Sample

Little research has been conducted to examine paraphilic sexual interests in nonclinical samples. The little that exists suggests that atypical sexual interests are more common in men than in women, but the reasons for this difference are unknown. In this study, we explored the prevalence of paraphilic interests in a nonclinical sample of men and women. We expected that men would report greater arousal (or less repulsion) toward various paraphilic acts than women. We also examined putative correlates of paraphilias in an attempt to explain the sex difference. In all, 305 men and 710 women completed an online survey assessing sexual experiences, sexual interests, as well as indicators of neurodevelopmental stress, sex drive, mating effort, impulsivity, masculinity/femininity, and socially desirable responding. As expected, significant sex differences were found, with men reporting significantly less repulsion (or more arousal) to the majority of paraphilic acts than women. Using mediation analysis, sex drive was the only correlate to significantly and fully mediate the sex difference in paraphilic interests. In other words, sex drive fully accounted for the sex difference in paraphilic interests. The implications of these findings for understanding the etiology of atypical sexual interests are discussed.

When Does Familiarity Promote Versus Undermine Interpersonal Attraction? A Proposed Integrative Model From Erstwhile Adversaries

This article began as an adversarial collaboration between two groups of researchers with competing views on a longstanding question: Does familiarity promote or undermine interpersonal attraction? As we explored our respective positions, it became clear that the limitations of our conceptualizations of the familiarity–attraction link, as well as the limitations of prior research, were masking a set of higher order principles capable of integrating these diverse conceptualizations. This realization led us to adopt a broader perspective, which focuses on three distinct relationship stages—awareness, surface contact, and mutuality—and suggests that the influence of familiarity on attraction depends on both the nature and the stage of the relationship between perceivers and targets. This article introduces the framework that emerged from our discussions and suggests directions for research to investigate its validity.

Touch satiety: differential effects of stroking velocity on liking and wanting touch over repetitions

A slow, gentle caress of the skin is a salient hedonic stimulus. Low threshold, unmyelinated C-tactile afferents fire preferentially to this type of touch, where slow (<1 cm/s) and fast (>10 cm/s) stroking velocities produce lower firing frequencies and are rated as less pleasant. The current aim was to investigate how the experience of tactile pleasantness changes with repeated exposure (satiety to touch). A further aim was to determine whether tactile satiety varied with different stroking velocities. The experimental paradigm used a controlled brush stroke to the forearm that was delivered repeatedly for ∼50 minutes. In Experiment 1, brush strokes were administered at three different velocities (0.3 cm/s, 3 cm/s and 30 cm/s), which were presented in a pseudo-randomised order. In Experiment 2, brush strokes were applied using only one velocity (either 3 or 30 cm/s). After each stroke, the participants rated both subjective pleasantness (liking) and wanting (the wish to be further exposed to the same stimulus) for each tactile sensation. In Experiment 1, both pleasantness and wanting showed a small, but significant, decrease over repetitions during stroking at 3 cm/s only, where the mean values for pleasantness and wanting were similar. Conversely, slower (0.3 cm/s) and faster (30 cm/s) stroking showed no decrease in ratings over time, however pleasantness was rated higher than wanting. In Experiment 2, both pleasantness and wanting showed a significant decrease over repetitions for both applied velocities, with a larger decrease in ratings for stroking at 3 cm/s. In conclusion, satiety to touch occurred with a slow onset and progression, where pleasantness and wanting ratings to stroking at 3 cm/s were affected more than at the slower or faster velocities. Tactile satiety appears to differ compared to appetitive and olfactory satiety, because the hedonic and rewarding aspects of touch persist for some time.

Gender-Specificity of Women's and Men's Self-Reported Attention to Sexual Stimuli

Men's sexual arousal is largely dependent on the actor's gender in a sexual stimulus (gender-specific), whereas for women, particularly androphilic women, arousal is less dependent on gender (gender-nonspecific). According to information-processing models of sexual response, sexual arousal requires that attention be directed toward sexual cues. We evaluated whether men's and women's self-reported attention to sexual stimuli of men or women were consistent with genital responses and self-reported arousal. We presented gynephilic men (n = 21) and women (n = 22) and androphilic men (n = 16) and women (n = 33) with audiovisual stimuli depicting men or women engaged in sexual activities. Genital responses were continuously recorded and, following each stimulus, participants reported the amount of attention paid to the video and feelings of sexual arousal. Self-reported attention was gender-specific for men and gender-nonspecific for women, and generally mirrored genital responses and self-reported arousal. Gender-specificity of genital responses significantly predicted gender-specificity of self-reported arousal; however, for men only, this effect was significantly mediated by gender-specificity of self-reported attention. Gender differences in gender-specificity of sexual arousal may be partially accounted for by differences in gender-specificity of self-reported attention, although attention may play a greater role in men's sexual arousal than women's.

The role of conditioning, learning and dopamine in sexual behavior: a narrative review of animal and human studies

Many theories of human sexual behavior assume that sexual stimuli obtain arousing properties through associative learning processes. It is widely accepted that classical conditioning contributes to the etiology of both normal and maladaptive human behaviors. Despite the hypothesized importance of basic learning processes in sexual behavior, research on classical conditioning of the sexual response in humans is scarce. In the present paper, animal studies and studies in humans on the role of pavlovian conditioning on sexual responses are reviewed. Animal research shows robust, direct effects of conditioning processes on partner- and place preference. On the contrast, the empirical research with humans in this area is limited and earlier studies within this field are plagued by methodological confounds. Although recent experimental demonstrations of human sexual conditioning are neither numerous nor robust, sexual arousal showed to be conditionable in both men and women. The present paper serves to highlight the major empirical findings and to renew the insight in how stimuli can acquire sexually arousing value. Hereby also related neurobiological processes in reward learning are discussed. Finally, the connections between animal and human research on the conditionability of sexual responses are discussed, and suggestions for future directions in human research are given.