The Sexual Psychophysiology Laboratory

Below are summaries of some of our recent and ongoing studies. Visit our Study Participation Information page for details on becoming a participant in our research. Thank you for your interest!

Background: Historically, the reasons people have sex have been assumed to be few in number and simple in nature–to reproduce, to experience pleasure, or to relieve sexual tension. Several theoretical perspectives suggest that motives for engaging in sexual intercourse may be larger in number and psychologically complex in nature.

Objective: The purpose of this study is to gather detailed information about the reasons why people engage in sexual activities with others in order to understand the complexity of what motivates individuals to have sex.

Method: Information from 3000 individuals across North America will be collected. More information about this study as well as instructions on how to participate in this study via an online secure testing site may be found here.

Background: It has beceome apparent from previous research that motivations for engaging in sexual intercourse are wide ranging and psychologically complex. What has not been investigated are the reasons why individuals choose not to have sex. Asking this question will likely reveal a wide range of reasons that will give further insight into the psychology of sexual interactions.

Method: Information from 500 individuals across North America will be collected. More information about this study as well as instructions on how to participate in this study via an online secure testing site may be found here.

Evidence that long-term cigarette smoking is an independent risk factor for vasculogenic impotence is robust. Cigarette smoking also causes a variety of acute changes such as impairment in endothelium dependent venodilation; however, few studies have investigated these acute changes with respect to sexual arousal in humans, and none have looked at the effects of nicotine on physiological sexual arousal in women. Recently, we (Harte & Meston, 2008a; Harte & Meston, 2008b) conducted two studies that examined the effects of 6 mg of nicotine gum versus placebo on sexual arousal in men and women nonsmokers. Male genital arousal was assessed via penile circumferential change using a mercury-in-rubber strain gauge while female genital arousal was measured using vaginal photoplethysmography. Nicotine significantly reduced physiological sexual responses in both men and women. These data are in line with other research delineating nicotine’s vasoconstrictive properties and may support the hypothesis that nicotine deleteriously affects nitric oxide synthesis mechanisms that are integral to the sexual response in both men and women.

A growing literature has linked low sexual desire to low androgen levels in women. In recent years, exogenous testosterone, or the adrenal hormone dehydroepiandrosterone (DHEA) which serves as a precursor for testosterone, has been prescribed for women with low sexual desire . These treatments have been effective in some women with abnormally low testosterone levels, but not among women with normal testosterone (e.g., Meston & Heiman, 2002), and there are often unwanted side effects of testosterone administration (e.g., facial hair, acne). A few studies on women's endocrine response to sexual activity have shown that testosterone increases after sexual activity. We (Hamilton & Meston) are currently conducting the first empirical examination to see whether testosterone levels are influenced by either sexual activity or the anticipation of sexual activity in women. Women in long distance relationships who see their male sexual partners once per month or less each provide 5 saliva samples: one week before seeing their partner (and at least 2 weeks since their last sexual contact), the day before seeing their partner, when they are with their partner but prior to engaging in sexual activity, the day after their first sexual activity, and three days after their last sexual activity. Salivary measures of testosterone are analyzed using enzyme immunoassay. These findings could have clinical implications for developing a natural, non-invasive way of increasing androgens endogenously.

More information about this study as well as information on how to participate in this study may be found here.

A ubiquitous model for monogamy and promiscuity is the vole model that compares the closely related montane voles, which do not form pair bonds and mate freely with many partners, and prairie voles which are innately monogamous. Research comparing the montane and prairie voles has identified both oxytocin (OT) and vasopressin (AVP) as playing a key role in these behaviors with prairie voles having more OT and AVP as well as increased receptor density for these hormones (Insel & Shapiro, 1992). Vasopressin seems to play more of a role for male pair-bonding, while oxytocin is critical for female pair bonding (Carter et al., 1995). Specific brain areas, such as the ventral pallidum, nucleus accumbens, medial amygdala, medial preoptic area (MPOA) and the bed nucleus of the stria terminalis (BNST) have been identified as critical areas that are differentiated between montane and prairie voles. The most robust difference is seen in the larger number of V1aR receptors in the ventral pallidum in prairie voles, compared to montane voles. More recently, researchers have also found that prairie voles have a much higher density of D2 dopamine receptors in the nucleus accumbens and other areas in the dopamine reward pathway (Edwards & Self, 2006). Many of the areas identified as key dopamine receptor areas involved in bonding are also key areas for vasopressin receptor areas involved in bonding. Thus, in male prairie voles, there seems to be great overlap between reward and bonding.

We (Hamilton & Meston) are currently examining whether it is possible that the neural substrates that underlie monogamy and non-monogamy in men are similar to those in voles. In order to examine this relationship we are conducting an fMRI study in which monogamous and nonmonogamous participants are shown alternating blocks of erotic photos, bonding/romantic photos, and neutral photos. Each stimulus block (erotic, bonding/romantic, and neutral) includes 4 photos presented for 3 seconds each separated by a 15-second rest period. Our hypothesis is that monogamous men will show similar brain activation, as measured by BOLD signal, for both the erotic and romantic stimuli, and that nonmonogamous men will show more activation in reward and emotion-related areas of the brain for erotic stimuli, as opposed to romantic stimuli.

The construct of self-focused attention has been discussed as relating to sexual function since Masters and Johnson’s (1970) introduction of the constructs “spectatoring” and “sensate focus.” Spectatoring refers to focusing on and evaluating oneself from a third person perspective during sexual activity. This focus of attention outward on sexual performance rather than inward on the sensory aspects of a sexual experience (i.e., sensate focus) is believed to have deleterious effects on sexual performance (see Trapnell & Meston, 1997). To begin empirically testing these constructs, I conducted a study (Meston, 2006) that examined state self-focused attention and trait self-consciousness on sexual arousal and function in sexually functional and dysfunctional women. Self-focused attention was induced using a 50% reflectant television screen in one of two counterbalanced sessions during which sexual responses were measured. In a second study (Seal & Meston, 2007), self-focused attention was induced by placing a full-length mirror in front of the participants throughout testing and instructing them to use the mirror to place ten electrodes evenly on each side of their bodies in preparation for a possible electrocardiogram. The findings from these two studies provided empirical evidence for a role of both state and trait self-focused attention in female sexual function.

Read the papers published in the Journal of Sexual Medicine (PDF 165 KB) and Behaviour Research and Therapy (PDF 236 KB).

Numerous laboratory studies have shown that men without sexual dysfunction respond to erotic cues with positive affect, positive expectancies, and perceived control of erectile response whereas men with a history of sexual dysfunction respond to erotic cues with negative affect, negative expectancies, and perceived lack of control of erectile response. These findings have been explained in terms of a feedback loop whereby expectancies are shaped by an individual’s recollections of past sexual experiences (Barlow, 1986). To begin examining the role of expectancies on women’s sexual response, we (McCall & Meston, 2007) investigated the impact of both false positive and false negative feedback (vaginal photoplethysmograph response print-out) on subsequent sexual responding in sexually healthy women and women with female sexual arousal disorder (FSAD). False positive feedback increased subjective arousal in both groups of women whereas false negative feedback decreased subjective levels of arousal in both groups of women. Sexually healthy women had overall higher expectancies for sexual arousal than women with FSAD. Unexpectedly, false positive feedback did not significantly impact physiological arousal in sexually healthy women but decreased physiological arousal in women with FSAD. False negative feedback had no significant effect on physiological sexual response in sexually healthy women or women with FSAD.

Read the paper published in Archives of Sexual Behavior: PDF (310 KB)

Gingko biloba extract (GBE), a naturally occurring substance from the ancient Chinese Gingko tree, facilitates blood flow, influences nitric oxide systems and has a relaxant effect on smooth muscle tissue. These processes are integral to the female sexual response and, hence, it is feasible that GBE may enhance women’s sexual response.

To examine this hypothesis, I was funded by the National Center for Complementary and Alternative Medicine to provide a comprehensive examination of the potential effectiveness of using GBE to treat sexual desire, arousal, and orgasm difficulties in women. In this 5 year investigation, the acute effects of GBE on subjective and physiological sexual arousal were examined in 99 women with DSM-IV-TR diagnosed sexual dysfunction using a double-blind protocol in which the women received either 300mg GBE or placebo 90 min prior to viewing neutral and erotic film stimuli. A single dose of GBE significantly increased physiological but not subjective levels of sexual arousal to erotic videos compared to placebo. The chronic effects of GBE on sexual function were assessed by randomly assigning participants to 8 weeks of either GBE, Placebo, Sex Therapy, or Sex Therapy plus GBE, and comparing sexual outcome measures at 4 weeks (Mid-Treatment), and 8 weeks (Post-Treatment). When combined with sex therapy, but not alone, 8 weeks daily treatment with 300mg GBE significantly increased validated measures of sexual desire and contentment beyond placebo. Sex therapy alone significantly enhanced orgasm function compared with placebo. Chronic GBE did not significantly enhance laboratory measures of arousal beyond placebo (Meston, Rellini, & Telch, 2007).

A Treatment-Outcome Study for Sexually Dysfunctional Women with a History of Childhood Sexual Abuse

Findings from numerous studies indicate that a history of childhood sexual abuse is associated with the tendency to engage in high-risk sexual behaviors and to experience a number of psychological disturbances known to adversely impact intimate relationships and sexual function. Despite these well-substantiated findings, little research has examined the mechanisms by which these detrimental effects occur and/or are maintained in adulthood. I am currently being funded by the National Institute of Child Health and Human Development to conduct a 5-year investigation that will help elucidate these processes. The study has two primary goals. The first goal is to explore the mediational role of schemas in the relation between childhood abuse and adverse relational and sexual consequences in adulthood. Women with (n = 150) and without (n = 150) a history of childhood sexual abuse write a neutral essay as a control for writing style and an essay that serves as a proxy for intimacy schemas. Information on schemas is derived from conducting human-aided content analyses and computer-aided language analyses of the essays. The degree to which psychological variables, abuse variables (e.g., age at abuse, time since abuse), and physiological reactivity (heart rate variability, cortisol) serve as risk factors in the relation between childhood sexual abuse and outcome measures is being examined.

The second goal of this investigation is to examine whether a writing intervention that focuses specifically on intimacy themes will impact relational and sexual adjustment among women with a history of childhood abuse. Pennebaker and associates have found that writing about emotionally relevant themes causes beneficial changes in numerous psychological, behavioral and physiological indices. To date, no studies have examined the impact of a writing intervention on relationship-relevant variables in women with a history of childhood abuse. To accomplish this goal, 160 women with a history of childhood abuse and sexual dysfunction are being randomly assigned to one of three conditions: (1) writing about time management (control); (2) writing about a past traumatic experience; and (3) writing about relational-relevant schemas. Assessments are being conducted at 1-month, 3- months, and 6-months following the writing intervention to examine the impact of the three writing interventions on relational and sexuality variables. The findings from this investigation will have implications for understanding the mechanisms that link childhood sexual abuse with detrimental intimacy/sexual factors in adulthood and may help develop effective and cost-efficient treatments for sexually dysfunctional women with a history of childhood sexual abuse.

More information about this study as well as information on how to participate in this study may be found here