Appetitive responses to sexual stimuli are attenuated in individuals with low levels of sexual desire

Sex Differences in Sexual Motivation in Humans and Other Mammals: The Role of Conscious and Unconscious Processes

In self-report questionnaires, men report higher scores than women on variables such as desire for sex, frequency of sexual thoughts, number of sex partners, etc. Based on this, men are considered to have a higher level of sexual motivation than women. However, retrospective self-reports may be unsuitable for estimations of the inherent level of sexual motivation. We review data on automatic (unconsciously controlled) responses and measures of implicit motivation during exposure to sexual stimuli. These responses and measures are inaccessible to willful manipulations and make it possible to determine whether the sex difference in answers to questionnaires is replicated when volitional response manipulations are unlikely. We complement the human data with observations from some rodent and non-human primate species. The attentional resources allotted to stimuli with sexual relevance as well as genital responses to such stimuli are similar in men and women. Measures of implicit motivation also fail to detect any sex difference. Finally, the frequency of masturbation is superior in female infants before the age at which social expectations begin to determine behavior. Neither in rodents nor in non-human primates is there any clear-cut evidence for sex differences in motivation. It seems that males and females are similar with regard to the intensity of sexual motivation. The responses to questionnaires may be affected by social learning of sexual scripts and/or the inferior quality of sexual experiences in women, among other things.

No Sex Difference Found: Cues of Sexual Stimuli Activate the Reward System in both Sexes

Sexually explicit material (SEM) is increasingly used in western societies. One reason for this high usage might be the rewarding property of SEM demonstrated in many brain imaging studies showing an activation of the reward system during the presentation of SEM. It is not yet well understood why women use SEM to a remarkably lesser extent than men. Maybe men react stronger to stimuli - so called SEM cues -, which signal the presentation of SEM and are therefore more vulnerable to use SEM than women. Therefore, the present study aimed at investigating the sex specific neural correlates towards SEM and SEM cues. We were further interested in whether person characteristics as trait sexual motivation, extent of SEM use in the last month, and age at onset of goal-oriented SEM use affect the neural responses to SEM and SEM cues. The trials of the fMRI experiment consisted of an expectation phase with SEM or neutral cues and a presentation phase with SEM or neutral stimuli, respectively. Analyses showed that the reward circuitry was activated by SEM, but also by SEM cues. There were some sex differences in hemodynamic responses to SEM during the presentation phase, but not during the expectation phase to SEM cues in any of the regions of interest. The influence of the investigated person characteristics was only small if existent. The results suggest that sex specific cue processing cannot explain sex differences in the use of SEM.

Sexual Desire Inventory: Two or Three Dimensions?

The Sexual Desire Inventory (SDI), developed by Spector, Carey, and Steinberg in 1996, has been widely used to assess sexual desire in men and women throughout the world. This questionnaire categorizes sexual desire in two dimensions: dyadic sexual desire and solitary sexual desire. Our study addressed the factorial structure of the SDI, an aspect that until now has been largely neglected. We recruited two samples of Spanish men and women involved in stable heterosexual relationships. The first sample consisted of 3,417 subjects (1,600 males and 1,817 females), ages 18 to 84; the second sample consisted of 677 subjects (285 males and 392 females), ages 18 to 50. The results of an exploratory factor analysis (EFA) showed that instead of two dimensions the SDI should have three: (1) partner-focused dyadic sexual desire, (2) general dyadic sexual desire for an attractive person, and (3) solitary sexual desire. A confirmatory factor analysis (CFA) supported the robustness of this new three-factor structure. No gender differences were revealed, except for dyadic sexual desire for an attractive person, for which men reported higher scores. Good validity and reliability values were obtained. Moreover, standard scores for men and women by different age groups were developed.

Intolerance of uncertainty and startle potentiation in relation to different threat reinforcement rates

Fear conditioning research on threat predictability has primarily examined the impact of temporal (i.e., timing) predictability on the startle reflex. However, there are other key features of threat that can vary in predictability. For example, the reinforcement rate (i.e., frequency) of threat is a crucial factor underlying fear learning. The present study examined the impact of threat reinforcement rate on the startle reflex and self-reported anxiety during a fear conditioning paradigm. Forty-five participants completed a fear learning task in which the conditioned stimulus was reinforced with an electric shock to the forearm on 50% of trials in one block and 75% of trials in a second block, in counter-balanced order. The present study also examined whether intolerance of uncertainty (IU), the tendency to perceive or experience uncertainty as stressful or unpleasant, was associated with the startle reflex during conditions of low (50%) vs. high (75%) reinforcement. Results indicated that, across all participants, startle was greater during the 75% relative to the 50% reinforcement condition. IU was positively correlated with startle potentiation (i.e., increased startle response to the CS+ relative to the CS-) during the 50%, but not the 75%, reinforcement condition. Thus, despite receiving fewer electric shocks during the 50% reinforcement condition, individuals with high IU uniquely demonstrated greater defense system activation when impending threat was more uncertain. The association between IU and startle was independent of state anxiety. The present study adds to a growing literature on threat predictability and aversive responding, and suggests IU is associated with abnormal responding in the context of uncertain threat.

Viewing Sexual Stimuli Associated with Greater Sexual Responsiveness, Not Erectile Dysfunction

Introduction

Time spent viewing visual sexual stimuli (VSS) has the potential to habituate the sexual response and generalize to the partner context.

Aim

The aim of this study was to examine whether the time spent viewing VSS is related to sexual responsiveness felt in the laboratory or with a sexual partner.

Methods

Nontreatment-seeking men (N = 280) reported their weekly average VSS viewing in hours. VSS hours were examined in relation to the sexual arousal experienced while viewing a standardized sexual film in the laboratory and erectile problems experienced with a sexual partner.

Main Outcome Measures

Self-reported sexual arousal in response to sexual films and erectile problems on the International Index of Erectile Function were the main outcome measures.

Results

More hours viewing VSS was related to stronger experienced sexual responses to VSS in the laboratory, was unrelated to erectile functioning with a partner, and was related to stronger desire for sex with a partner.

Conclusions

VSS use within the range of hours tested is unlikely to negatively impact sexual functioning, given that responses actually were stronger in those who viewed more VSS.

Modulation of late positive potentials by sexual images in problem users and controls inconsistent with "porn addiction"

"Excessive" viewing of visual sexual stimuli (VSS) is the most commonly reported hypersexual behavior problem and is especially amenable to laboratory study. A pattern of enhanced sexual cue responsiveness is expected in this sample if hypersexuality shares features of other addiction models. Participants (N=122) who either reported or denied problematic VSS use were presented with emotional, including explicit sexual, images while their evoked response potentials were recorded. An interaction of hypersexual problem group and the level of desire for sex with a partner predicted LPP amplitude. Specifically, those reporting problems regulating their VSS use who also reported higher sexual desire had lower LPP in response to VSS. This pattern appears different from substance addiction models. These are the first functional physiological data of persons reporting VSS regulation problems.

Sex differences in addictive disorders

Gender-dependent differences in the rate of initiation and frequency of misuse of addicting drugs have been widely described. Yet, men and women also differ in their propensity to become addicted to other rewarding stimuli (e.g., sex, food) or activities (e.g., gambling, exercising). The goal of the present review is to summarize current evidence for gender differences not only in drug addiction, but also in other forms of addictive behaviours. Thus, we first reviewed studies showing gender-dependent differences in drug addiction, food addiction, compulsive sexual activity, pathological gambling, Internet addiction and physical exercise addiction. Potential risk factors and underlying brain mechanisms are also examined, with particular emphasis given to the role of sex hormones in modulating addictive behaviours. Investigations on factors allowing the pursuit of non-drug rewards to become pathological in men and women are crucial for designing gender-appropriate treatments of both substance and non-substance addictions.

Biases for affective versus sexual content in multidimensional scaling analysis: an individual difference perspective

Visual sexual stimuli can motivate sexual behaviors that can risk or enhance health. How one allocates attention to a sexually motivating stimulus may be important for predicting its effect on sexual feelings, sexual risk behaviors, and sexual problems. A large sample (N = 157) of men and women rated the similarity of all possible pairs of photographs of women, which had been pretested to vary in their sexual and affective content. Multidimensional scaling was used to extract two dimensions of sex and affect, including the extent to which each person relied on each dimension in making their similarity judgments. These individual weights were then used to predict sexual variables of interest. Participants who relied more on the affect information judging photograph similarity were more likely to be female, viewed erotica less frequently, reported fewer sexual partners, reported less sexual desire, and more sexual problems. Those who relied more on the erotic content in making their similarity judgments were more likely to be male, viewed more erotica weekly, experienced higher sexual desire, and were more likely to have taken an HIV test. The "double edge sword" of attention weight to affect in sexual cues is discussed for its potential to both enhance and harm sexual health.

Are individual differences in appetitive and defensive motivation related? A psychophysiological examination in two samples

Appetitive and defensive motivation account for a good deal of variance in personality and mental health, but whether individual differences in these systems are correlated or orthogonal has not been conclusively established. Previous investigations have generally relied on self-report and have yielded conflicting results. We therefore assessed the relation between psychophysiological indices of appetitive and defensive motivation during elicitation of these motivational states: specifically, frontal electroencephalogram asymmetry during reward anticipation and startle response during anticipation of predictable or unpredictable threat of shock. Results in a sample of psychopathology-free community members (n=63), an independent sample of undergraduates with a range of internalising symptoms (n=64), and the combination of these samples (n=127) revealed that differences in responding to the two tasks were not significantly correlated. Average coefficients approached zero in all three samples (community: .04, undergraduate: -.01, combined: .06). Implications of these findings for research on normal and abnormal personality are discussed.

Male rats that differ in novelty exploration demonstrate distinct patterns of sexual behavior

High- versus low-novelty exploration predicts a variety of behavioral differences. For example, rats selectively bred for high-novelty exploration (bred-high responders, bHR) exhibit exaggerated aggression, impulsivity, and proclivity to addictive behaviors compared with low-novelty reactive rats (bred-low responders, bLRs), which are characterized by a high anxiety/depressive-like phenotype. Since bHR/bLR rats exhibit differences in dopaminergic circuitry and differential response to rewarding stimuli (i.e., psychostimulants, food), the present study examined whether they also differ in another key hedonic behavior-sex. Thus, adult bHR/bLR males were given five 30-min opportunities to engage in sexual activity with a receptive female. Sexual behavior and motivation were examined and compared between the groups. The bHR/bLR phenotype affected both sexual motivation and behavior, with bLR males demonstrating reduced motivation for sex compared with bHR males (i.e., fewer animals copulated, longer latency to engage in sex). The bHR males required more intromissions at a faster pace per ejaculation than did bLR males. Thus, neurobiological differences that affect motivation for drugs of abuse, aggression, and impulsivity in rats also affect sexual motivation and performance.

Sexual desire, not hypersexuality, is related to neurophysiological responses elicited by sexual images

BACKGROUND

Modulation of sexual desires is, in some cases, necessary to avoid inappropriate or illegal sexual behavior (downregulation of sexual desire) or to engage with a romantic partner (upregulation of sexual desire). Some have suggested that those who have difficulty downregulating their sexual desires be diagnosed as having a sexual 'addiction'. This diagnosis is thought to be associated with sexual urges that feel out of control, high-frequency sexual behavior, consequences due to those behaviors, and poor ability to reduce those behaviors. However, such symptoms also may be better understood as a non-pathological variation of high sexual desire. Hypersexuals are thought to be relatively sexual reward sensitized, but also to have high exposure to visual sexual stimuli. Thus, the direction of neural responsivity to sexual stimuli expected was unclear. If these individuals exhibit habituation, their P300 amplitude to sexual stimuli should be diminished; if they merely have high sexual desire, their P300 amplitude to sexual stimuli should be increased. Neural responsivity to sexual stimuli in a sample of hypersexuals could differentiate these two competing explanations of symptoms.

METHODS

Fifty-two (13 female) individuals who self-identified as having problems regulating their viewing of visual sexual stimuli viewed emotional (pleasant sexual, pleasant-non-sexual, neutral, and unpleasant) photographs while electroencephalography was collected.

RESULTS

Larger P300 amplitude differences to pleasant sexual stimuli, relative to neutral stimuli, was negatively related to measures of sexual desire, but not related to measures of hypersexuality.

CONCLUSION

Implications for understanding hypersexuality as high desire, rather than disordered, are discussed.

Self-reported sexual desire in homosexual men and women predicts preferences for sexually dimorphic facial cues

Recent studies investigating the relationship between self-reported sexual desire and attraction to same- and opposite-sex individuals have found that homosexual men's sexual desire is positively correlated with their self-reported attraction to own-sex individuals only, while homosexual women's sexual desire is positively correlated with their self-reported attraction to both men and women. These data have been interpreted as evidence that sexual desire strengthens men's pre-existing (i.e., dominant) sexual behaviors and strengthens women's sexual behaviors in general. Here we show that homosexual men's (n = 106) scores on the Sexual Desire Inventory-2 (SDI-2) were positively correlated with their preferences for exaggerated sex-typical shape cues in own-sex, but not opposite-sex, faces. Contrary to the hypothesis that sexual desire strengthens women's preferences for sexual dimorphism generally, homosexual women's (n = 83) SDI-2 scores were positively correlated with their preferences for exaggerated sex-typical shape cues in opposite-sex faces only. Together with previous research in heterosexual subjects, our findings support the proposal that sexual desire increases the incidence of existing sexual behaviors in homosexual and heterosexual men, and increases the incidence of sexual responses more generally in heterosexual women, although not necessarily in homosexual women.

Testosterone and libido in surgically and naturally menopausal women

The assessment and then treatment of a change in libido, or a change in the desire to partake in sexual activity, during the menopausal transition and beyond has been a challenging and elusive area of clinical research. This is partly due to the multidimensional nature of female sexuality, the difficulties of measuring testosterone in women in a reliable and accurate manner, and the complexity of the neurobiology and neurobehavior of female sexual desire. In addition, there is a lack of evidence for diagnostic specificity of low free testosterone levels for the symptom of low libido in women for whom there are no confounding interpersonal or psychological factors; although, in the symptomatic population of surgically or naturally menopausal women, a low level of free testosterone often accompanies a complaint of reduced desire/libido. The randomized clinical trial research on testosterone replacement for naturally and/or surgically menopausal women with sexual dysfunction has been criticized for a high placebo response rate, supraphysiological replacement levels of testosterone, the perception of modest clinical outcome when measuring objective data such as the frequency of sexual intercourse relative to placebo, and the unknown safety of long-term testosterone replacement in the estrogen-replete surgically or naturally menopausal woman. A careful review of current evidence from randomized, controlled trials lends support to the value of the replacement of testosterone in the estrogen-replete menopausal woman for whom libido and desire has declined. The issue of long-term safety remains to be answered.

Reported sexual desire predicts men's preferences for sexually dimorphic cues in women's faces

Recent studies investigating the relationship between sexual desire and sexual attraction have found that heterosexual women's reported sexual desire is positively correlated with their reported attraction to both own- and opposite-sex individuals, but that heterosexual men's reported sexual desire is positively correlated with their reported attraction to opposite-sex individuals only. These findings have led to the proposal that sexual desire is a generalized energizer of sexual attraction in heterosexual women (i.e., influences women's attraction to both men and women), but only energizes heterosexual men's sexual attraction to women. Here we show that heterosexual men's scores on the Sexual Desire Inventory-2 were positively correlated with their preferences for exaggerated sex-typical shape cues in opposite-sex, but not own-sex, faces. Together with previous research showing that heterosexual women's reported sexual desire is positively correlated with their preferences for exaggerated sex-typical shape cues in both own- and opposite-sex faces, our findings present novel converging evidence for sex-specific relationships between sexual desire and attractiveness judgments of own- and opposite-sex individuals.

Does intolerance of uncertainty predict anticipatory startle responses to uncertain threat?

Intolerance of uncertainty (IU) has been proposed to be an important maintaining factor in several anxiety disorders, including generalized anxiety disorder, obsessive-compulsive disorder, and social phobia. While IU has been shown to predict subjective ratings and decision-making during uncertain/ambiguous situations, few studies have examined whether IU also predicts emotional responding to uncertain threat. The present study examined whether IU predicted aversive responding (startle and subjective ratings) during the anticipation of temporally uncertain shocks. Sixty-nine participants completed three experimental conditions during which they received: no shocks, temporally certain/predictable shocks, and temporally uncertain shocks. Results indicated that IU was negatively associated with startle during the uncertain threat condition in that those with higher IU had a smaller startle response. IU was also only related to startle during the uncertain (and not the certain/predictable) threat condition, suggesting that it was not predictive of general aversive responding, but specific to responses to uncertain aversiveness. Perceived control over anxiety-related events mediated the relation between IU and startle to uncertain threat, such that high IU led to lowered perceived control, which in turn led to a smaller startle response. We discuss several potential explanations for these findings, including the inhibitory qualities of IU. Overall, our results suggest that IU is associated with attenuated aversive responding to uncertain threat.

Dysregulated sexuality and high sexual desire: distinct constructs?

The literature on dysregulated sexuality, whether theoretical, clinical or empirical, has failed to differentiate the construct from high sexual desire. In this study, we tested three hypotheses which addressed this issue. A sample of 6458 men and 7938 women, some of whom had sought treatment for sexual compulsivity, addiction or impulsivity, completed an online survey comprised of various sexuality measures. Men and women who reported having sought treatment scored significantly higher on measures of dysregulated sexuality and sexual desire. For men, women, and those who had sought treatment, dysregulated sexuality was associated with increased sexual desire. Confirmatory factor analysis supported a one-factor model, indicating that, in both male and female participants, dysregulated sexuality and sexual desire variables loaded onto a single underlying factor. The results of this study suggest that dysregulated sexuality, as currently conceptualized, labelled, and measured, may simply be a marker of high sexual desire and the distress associated with managing a high degree of sexual thoughts, feelings, and needs.

Attention and emotional responses to sexual stimuli and their relationship to sexual desire

Little is known about why individuals vary in their levels of sexual desire. Information processing models, like Barlow's (Journal of Consulting and Clinical Psychology 54:140-148, 1986) model of sexual functioning, suggest that individuals with higher sexual desire attend more and respond with more pleasant emotions to sexual cues than individuals with lower levels of sexual desire. In this study, 69 participants (36 women, 33 men) completed a dot detection task measuring attention capture by sexual stimuli and a startle eyeblink modulation task indexing the valence of emotional response to affective stimuli. Participants with high levels of sexual desire were slower to detect targets in the dot detection task that replaced sexual images but did not differ in startle eyeblink responses to sexual stimuli. The results suggest that the amount of attention captured by sexual stimuli is a stronger predictor of a person's sexual desire level than the valence of the emotional responses elicited by such stimuli.

Epidemiology and neurobiology of female sexual dysfunction

INTRODUCTION

Although several conceptual frameworks for female sexual dysfunction (FSD) have been advanced, there still is considerable disagreement over what constitutes a normal vs. abnormal response. Sexual dysfunction is a disturbance in sexual functioning involving one or multiple phases of the sexual response cycle or pain associated with sexual activity, while a sexual disorder includes both dysfunction and marked distress.

AIM

Review the literature regarding the epidemiology and neurobiology of FSD.

METHODS

Review of the literature.

RESULTS

While a wide range of epidemiologic studies has been published, it is still difficult to determine the scope of FSD and sexual disorders in the general population. It is becoming clear that good sexual health is associated with good physical and mental health as well as compatible relationships with one's sexual partner. Central nervous system (CNS) control of the sexual response is a relatively new area of scientific exploration.

CONCLUSIONS

We are improving our understanding of the contributions of the CNS neuroendocrine and neurotransmitter systems that modulate sexual behavior.

Asexuality: classification and characterization

The term "asexual" has been defined in many different ways and asexuality has received very little research attention. In a small qualitative study (N = 4), individuals who self-identified as asexual were interviewed to help formulate hypotheses for a larger study. The second larger study was an online survey drawn from a convenience sample designed to better characterize asexuality and to test predictors of asexual identity. A convenience sample of 1,146 individuals (N = 41 self-identified asexual) completed online questionnaires assessing sexual history, sexual inhibition and excitation, sexual desire, and an open-response questionnaire concerning asexual identity. Asexuals reported significantly less desire for sex with a partner, lower sexual arousability, and lower sexual excitation but did not differ consistently from non-asexuals in their sexual inhibition scores or their desire to masturbate. Content analyses supported the idea that low sexual desire is the primary feature predicting asexual identity.