Examining gender specificity of sexual response with concurrent thermography and plethysmography

Men's genital responses are significantly greater to sexual stimuli of their preferred gender compared to their nonpreferred gender (gender‐specific), whereas androphilic (i.e., sexually attracted to men) women's genital responses are similar to sexual stimuli depicting either women or men (gender‐nonspecific). This gendered pattern of genital response has only been demonstrated using vaginal photoplethysmography (VPP) in women and primarily penile plethysmography (PPG) in men. These measures assess different aspects of genital vasocongestion, thereby limiting comparisons between genders. Thermography is a newer sexual psychophysiology methodology that measures genital vasocongestion via temperature change and is better suited to assess sexual response between genders because the dependent measure, change in genital temperature, is similar for women and men. Further, previous studies have assessed gender specificity of sexual response across relatively short sexual stimuli, allowing only the examination of initial phases of sexual response. We examined gender specificity of sexual arousal by measuring women's and men's genital responses to lengthier stimuli with concurrent thermography and VPP/PPG. Gynephilic men (i.e., sexually attracted to women; n = 27) and androphilic women (n = 28) viewed 10‐min films depicting men masturbating, women masturbating, and a nonsexual film, and reported feelings of sexual arousal while genital responses were assessed. Across measures, men's sexual responses were gender‐specific and women's responses were gender‐nonspecific, indicating that the gender difference in gender specificity of arousal is robust to methodology and stimulus duration. These findings replicate previous research, extend knowledge of gendered sexual response, and highlight the utility of multimethod approaches in sexual psychophysiology.     

A sex difference in features that elicit genital response

Previous research suggests that women's genital arousal is an automatic response to sexual stimuli, whereas men's genital arousal is dependent upon stimulus features specific to their sexual interests. In this study, we tested the hypothesis that a nonhuman sexual stimulus would elicit a genital response in women but not in men. Eighteen heterosexual women and 18 heterosexual men viewed seven sexual film stimuli, six human films and one nonhuman primate film, while measurements of genital and subjective sexual arousal were recorded. Women showed small increases in genital arousal to the nonhuman stimulus and large increases in genital arousal to both human male and female stimuli. Men did not show any genital arousal to the nonhuman stimulus and demonstrated a category-specific pattern of arousal to the human stimuli that corresponded to their stated sexual orientation. These results suggest that stimulus features necessary to evoke genital arousal are much less specific in women than in men.     

Sex differences in concordance rates between auditory event‐related potentials and subjective sexual arousal

Much research indicates men show a greater concordance between subjective and genital sexual arousal than do women. We investigated the relationship between subjective sexual arousal and brain activation in men and women. Subjective sexual arousal and auditory N1 and P3b ERP amplitudes were measured while 38 participants viewed erotic and non‐erotic films. Most notably, there was a significant correlation between N1 amplitude and sexual arousal in men; for women, there was a significant correlation between the P3b amplitude and sexual arousal. ERP amplitudes were inversely associated with reported arousal, suggesting that sexual arousal interferes with early tone processing for men, and with later tone processing for women. Lastly, for women, pornography/erotica consumption was negatively correlated with P3b amplitudes, suggesting that women who consume more pornography/erotica may also show greater attention to erotic films.     

Determinants of subjective experience of sexual arousal in women: Feedback from genital arousal and erotic stimulus content

Sixty-two women participated in a study designed to explore the association between gential and subjective sexual arousal. Four stimulus conditions were created, designed to evoke differential patterns of genital arousal over time. Subjects were instructed to report sensations in their genitalia while being exposed to the same erotic stimulus on repeated trials or to a series of varying erotic stimuli. Detection of genital arousal was facilitated by the occurrence of changes in genital arousal over trials. That is, genital and subjective sexual arousal were linearly related in conditions that resulted in large differences in genital arousal over trails, whereas such a relation was absent in conditions in which genital arousal levels remained relatively constant. In women, peripheral feedback from consciously detected genital arousal seems to be a relatively unimportant determinant of subjective sexual arousal.     

Effects of fragrance on female sexual arousal and mood across the menstrual cycle

The effects of fragrance on sexual response in women were investigated using subjective and physiological measures of sexual arousal and of mood. Responses were obtained from female participants in three different fragrance conditions (female fragrance, male fragrance, and a "blank" or neutral substance), as they viewed erotic and sexually neutral films, and fantasized about sexual situations. Each woman was tested twice: during the midfollicular and periovulatory phases of her menstrual cycle. Menstrual cycle phase effects were apparent; self-report data indicated greater sexual arousal and more positive mood during the periovulatory than during the follicular phase. Results demonstrated a positive effect of the male fragrance on genital arousal during erotic fantasy, but this finding was apparent only during the follicular phase testing session. This effect did not appear to be mediated by any effects of fragrance on mood.     

The Relationship Between Sexual Arousal Experience and Genital Response

In studies of sexuality, there has been a wide divergence in findings concerning the correlation between the subjective and genital measurements of sexual arousal. The present study is aimed at helping clarify this situation by examining the role of certain factors involved in determining the subjective-genital correlation. Thus, the following study was designed to (1) employ a methodology aimed at improving the correlation between the subjective and genital measurements of arousal in women, and (2) determine the effect of attending to bodily cues upon the subjective-genital relationship. To accomplish this end, 36 female subjects were separated into two experimental groups and one control group. The experimental groups were given instructions suggesting that they attend to either genital or non-genital body signals of sexual arousal while viewing a series of 10 erotic slides. Subjects in the control group were given no attention instructions. Subjective levels of arousal to the erotic slides were scaled by having subjects set the intensity of sound and light to match their intensity of arousal (cross-modality matching) and by using a rating scale. Genital measures of sexual arousal consisted of measurement of vaginal pulse amplitude. Analyses revealed that group computed correlations were very high and that individually computed subjective-genital correlations were highest in the attention groups. Paying attention to bodily cues has a significant and positive effect on the subjective-genital relationship. Possible explanations for these results are given along with a discussion of the role of methodological variables in influencing the genital-subjective correlation. The finding of high levels of correlation raises doubts on the heretofore made assumption of low subjective-genital correlations for women.     

Physiological Assessment of Sexual Arousal in Women

The purpose of this investigation was to validate the use of vaginal photoplethysmography along with six other physiological measures for the assessment of sexual arousal in women. Six women in counterbalanced order were presented control, dysphoric, and sexually arousing videotapes. Subjective ratings revealed that subjects experienced moderate levels of sexual and anxiety arousal during the videotapes, and comprehension quizzing at the end of the experiment showed that subjects attended to the content. Heart rate, heart rate variability, and skin conductance response failed to discriminate between any of the videotapes. In order from highest to lowest sensitivity, vaginal blood volume, skin conductance, systolic and diastolic blood pressure, and forehead temperature showed significant increases during the erotic videotape. Though sensitive, skin conductance appeared to he unreliable. Areas for further research were identified.     

Sexual arousal patterns of bisexual men revisited

Men who identify themselves as bisexual report feeling sexually aroused by both men and women. However, past research has not demonstrated that such men exhibit substantial genital arousal to both male and female erotic stimuli, suggesting that they identify as bisexual for reasons other than their genital arousal pattern. The purpose of the present study was to examine arousal patterns among bisexual men who were recruited using stringent criteria involving sexual and romantic experience with both men and women in order to increase the likelihood of finding a bisexual arousal pattern. Bisexual men in the present study demonstrated bisexual patterns of both subjective and genital arousal. It remains unclear which pattern is most typical of contemporary bisexual men: the present results supporting a bisexual arousal pattern, or previous results not finding one. In either case, understanding men with bisexual arousal patterns could help illuminate the etiology and development of male sexual orientation.     

Attentional Effects on Sexual Arousal

Lang's theory on emotions was applied to the sexual response: the cognitive processing of information on sexual responses (in contrast to information on sexual stimuli) was predicted to elicit the sexual response. Each of 48 men and 48 women imagined a sexual interaction, looked at a series of slides, and listened to an erotic story. Subjects were instructed to attend to images of sexual stimuli or to images of sexual stimuli plus responses. During imagery the genital response and the experience of sexual arousal were stronger when subjects focused on stimuli plus responses than when they focused on stimuli only. This effect occurred in both men and women. During slides and story a similar effect was found in men, but not in women. The genital response and the experience of sexual arousal were found to correlate more strongly when attentional focus was on stimuli plus responses instead of on stimuli only: in women, and, although marginally significant, also in men.     

Testing cognitive predictors of individual differences in the sexual psychophysiological responses of sexually functional women

The literature on sexual responses shows a large and not fully understood between‐women variance in sexual responses and in strength of coherence between physiological and subjective sexual responses. This study investigated cognitive factors theorized to be associated with sexual responses that could explain such variance. Specifically, we investigated the predictive value of sexual excitation/inhibition and sexual schemas on sexual response and coherence. Vaginal photoplethysmography and continuous subjective sexual arousal were collected from 29 young women while they watched a control/erotic video sequence. Hierarchical linear modeling revealed that high sexual excitation and schemas related to passion and romance were related to higher coherence. These findings support the notion that cognitive factors that enhance sexual arousal contribute to the large variation seen in the coherence of sexual response as measured in the laboratory.     

The time course of pupil dilation evoked by visual sexual stimuli: Exploring the underlying ANS mechanisms

The early processing of visual sexual stimuli shows signs of automaticity. Moreover, there is evidence for sex‐specific patterns in cognitive and physiological responding to erotica. However, little is known about the time course of rapid pupillary responses to sexual stimuli and their correspondence with other measures of autonomic activity in women and men. To study pupil dilation as an implicit measure of sexual arousal at various stages of picture processing, we presented 35 heterosexual participants with pictures showing either erotic couples or single (male/female) erotic nudes, contrasted with people involved in everyday situations. Brightness‐adjusted grayscale pictures were shown for a duration of 2,500 ms within the central visual field, alternating with perceptually matched patches. Left pupil diameter was recorded at 500 Hz using a video‐based eye tracker. Skin conductance and heart rate were coregistered and correlated with latent components of pupil dilation (dissociated by temporal PCA). Whereas stimulus‐evoked changes in pupil size indicated virtually no initial constriction, a rapid effect of appetence emerged (dilation to erotica within 500 ms). Responses at early stages of processing were remarkably consistent across both sexes. In contrast, later phases of pupil dilation, subjective ratings, and skin conductance responses showed a sex‐specific pattern. Moreover, evidence for an association of early‐onset pupil dilation and heart rate acceleration was found, suggestive of parasympathetic inhibition, whereas the late component was mainly related to sympathetically mediated skin conductance. Taken together, our results indicate that different temporal components of pupil responses to erotic stimuli may reflect divergent underlying neural mechanisms.     

There are differences in cerebral activation between females in distinct menstrual phases during viewing of erotic stimuli: a fMRI study

There is evidence that men experience more sexual arousal than women but also that women in mid-luteal phase experience more sexual arousal than women outside this phase. Recently, a few functional brain imaging studies have tackled the issue of gender differences as pertaining to reactions to erotica. The question of whether or not gender differences in reactions to erotica are maintained with women in different phases has not yet been answered from a functional brain imaging perspective. In order to examine this issue, functional MRI was performed in 22 male and 22 female volunteers. Subjects viewed erotic film excerpts alternating with emotionally neutral excerpts in a standard block-design paradigm. Arousal to erotic stimuli was evaluated using standard rating scales after scanning. Two-sample t-test with uncorrected P<0.001 values for a priori determined region of interests involved in processing of erotic stimuli and with corrected P<0.05 revealed gender differences: Comparing women in mid-luteal phase and during their menses, superior activation was revealed for women in mid-luteal phase in the anterior cingulate, left insula, and orbitofrontal cortex. A superior activation for men was found in the left thalamus, the bilateral amygdala, the anterior cingulate, the bilateral orbitofrontal, bilateral parahippocampal, and insular regions, which were maintained at a corrected P in the amygdala, the insula, and thalamus. There were no areas of significant superior activation for women neither in mid-luteal phase nor during their menses. Our results indicate that there are differences between women in the two cycle times in cerebral activity during viewing of erotic stimuli. Furthermore, gender differences with women in mid-luteal phases are similar to those in females outside the mid-luteal phase.     

Does the Menstrual Cycle Play a Role in Sexual Arousal?

Menstrual cycle effects on erotic arousability were tested in 13 women aged 20–28. Vaginal blood volume and pulse amplitude were measured with a light emitting diode photoplethysmograph, labial temperature was measured by a small thermistor, and subject self-report of arousal was estimated on a 7-point Likert scale in response to audio erotic tapes and fantasy over five different phases of the menstrual cycle. Pre-session levels of blood volume and labial temperature showed no important changes across the cycle, but pooled blood volume, pulsatile blood volume and labial temperature reliably demonstrated sexual arousal during tape and fantasy sessions. Repeated measures analyses of variance and covariance of physiological change scores from baseline and subjective ratings failed to demonstrate that significant changes in self-reports, vaginal blood volume, vaginal pulse amplitude, or labial temperature occurred as a function of menstrual cycle phase. This study provides objective physiological evidence that there appears to be no one phase in the menstrual cycle during which women are more sexually arousable to erotic stimuli as detected by these physiological measures.     

Assessment of female sexual arousal: Response specificity and construct validity

Specificity of vaginal pulse amplitude and vaginal blood volume in reaction to visual sexual stimuli was investigated by comparing responses to sexual, anxiety-inducing, sexually threatening, and neutral film excerpts. Subjective sexual arousal, body sensations, emotional experience, skin conductance, and heart rate were monitored along with the genital measures. Self-report data confirmed the generation of affective states as intended. Results demonstrated response specificity of vaginal vasocongestion to sexual stimuli. In terms of both convergent and divergent validity, vaginal pulse amplitude was the superior genital measure. Skin conductance discriminated among stimuli only to a small degree, whereas heart rate failed to discriminate among stimuli altogether.     

Modulation of spinal reflexes by sexual films of increasing intensity

Sexual arousal can be viewed as an emotional state generating sex-specific autonomic and general somatic motor system responses that prepare for sexual action. In the present study modulation of spinal tendious (T) reflexes by sexual films of varying intensity was investigated. T reflexes were expected to increase as a function of increased film intensity. Through use of a between-subjects design, participants were exposed to three erotic films of low, moderate, and high intensity or to three films of moderate intensity. Self-report and genital data confirmed the induction of increasing versus stable levels of sexual arousal. Exposure to the films of increasing intensity resulted in increasing T reflexes. The results indicate that T reflex modulation is sensitive to varying levels of sexual arousal and may be of use in research on behavioral mechanisms underlying appetitive motivation.     

Women with hypoactive sexual desire disorder compared to normal females: a functional magnetic resonance imaging study

Lack of sexual interest is the most common sexual complaint among women. However, factors affecting sexual desire in women have rarely been studied. While the role of the brain in integrating the sensory, attentional, motivational, and motor aspects of sexual response is commonly acknowledged as important, little is known about specific patterns of brain activation and sexual interest or response, particularly among women. We compared 20 females with no history of sexual dysfunction (NHSD) to 16 women with hypoactive sexual desire disorder (HSDD) in a functional magnetic resonance imaging (fMRI) study that included assessment of subjective sexual arousal, peripheral sexual response using a vaginal photoplethysmograph (VPP), as well as brain activation across three time points. Video stimuli included erotic, sports, and relaxing segments. Subjective arousal to erotic stimuli was significantly greater in NHSD participants compared with HSDD. In the erotic-sports contrast, NHSD women showed significantly greater activation in the bilateral entorhinal cortex than HSDD women. In the same contrast, HSDD females demonstrated higher activation than NHSD females in the medial frontal gyrus (Brodmann area (BA) 10), right inferior frontal gyrus (BA 47) and bilateral putamen. There were no between group differences in VPP-correlated brain activation and peripheral sexual response was not significantly associated with either subjective sexual response or brain activation patterns. Findings were consistent across the three experimental sessions. The results suggest differences between women with NHSD and HSDD in encoding arousing stimuli, retrieval of past erotic experiences, or both. The findings of greater activation in BA 10 and BA 47 among women with HSDD suggest that this group allocated significantly more attention to monitoring and/or evaluating their responses than NHSD participants, which may interfere with normal sexual response.     

Neural correlates of sexual arousal in homosexual and heterosexual men

Men exhibit much higher levels of genital and subjective arousal to sexual stimuli containing their preferred sex than they do to stimuli containing only the nonpreferred sex. This study used event-related functional magnetic resonance imaging to investigate how this category-specific pattern would be reflected in the brains of homosexual (n = 11) and heterosexual (n = 11) men. Comparisons of activation to preferred sexual stimuli, nonpreferred sexual stimuli, and sports stimuli revealed large networks correlated with sexual arousal, spanning multiple cortical and subcortical areas. Both homosexual and heterosexual men exhibited category-specific arousal in brain activity. Within the amygdala, greater preference-related activity was observed in homosexual men, but it is unclear whether this is a cause or a consequence of their sexuality. In a subsequent analysis of regions hypothesized to support arousal, both participant groups demonstrated widespread increases in evoked activity for preferred stimuli. Aggregate data from these regions produced significant differences between stimulus types in 16 out of 22 participants. Significant activational differences matched reported sexual orientation in 15 of these 16 participants, representing an advance in psychophysiological measures of arousal.     

Shock Threat and Sexual Arousal: The Role of Selective Attention, Thought Content, and Affective States

In an attempt to detail cognitive processes during anxiety and sexual arousal, 16 heterosexual males were presented with brief erotic audiotapes simultaneous with four levels of shock threat (no shock, half tolerance, tolerance, and twice tolerance threat). Subjects were instructed to pay close attention to the audiotapes, following which a sentence recognition task was administered to assess stimulus-focused attention. Additionally at these times, they were given a thought-listing task and completed a series of affect ratings. Tumescence and subjective arousal were monitored continuously during the erotic stimuli. Results revealed that tolerance shock threat decreased tumescence (p<.05). In contrast, recognition memory was greatest during tolerance shock threat and diminished during twice tolerance shock threat, which also produced increased reports of emotional stales. Issues regarding the relation between cognition and sexual arousal are discussed, including implications for understanding sexual dysfunction.     

Physiological and Subjective Sexual Arousal in Pre- and Postmenopausal Women and Postmenopausal Women Taking Replacement Therapy

Twenty premenopausal, 14 postmenopausal, and 14 postmenopausal women receiving replacement estrogen therapy were studied to determine whether differences in hormone status were associated with differences in physiological and subjective sexual responses. All subjects viewed a neutral, an erotic, and a second neutral videotape while photoplethysmographic vaginal pulse amplitude was continuously recorded. Self-report ratings of sexual arousal and affective response were collected. Serum levels of testosterone, estradiol, estrone, and luteinizing hormone were obtained. The three groups did not differ in either average or maximum vaginal pulse amplitude to the videotapes nor in latency of sexual response. The postmenopausal women not taking replacement estrogen reported significantly less vaginal lubrication in response to the erotic videotape than the higher estrogen premenopausal and replacement hormone groups. Estradiol level was significantly correlated with ratings of vaginal lubrication in response to the erotic videotape but not with vaginal pulse amplitude. Results thus suggest that estrogen is important in maintaining vaginal lubrication and the perception of sexual arousal but not in determining vaginal vasocongestion.     

The effect of visual sexual content on the event-related potential

In the present study we investigated the effect of emotional valence and arousal value of non-erotic visual stimuli on event-related potentials. We also directly compared the effects of erotic and non-erotic stimuli of comparable valence and arousal levels. Sixteen sexually functional heterosexual males rated 150 computer screen pictures, selected from the International Affective Picture System, representing five stimulus types differing along dimensions of emotional valence and arousal, and erotic vs. non-erotic content. A positive deflection of the ERP between 300 and 500ms after stimulus onset (P300) was found to be sensitive to stimulus differences, with positive valence and high arousal resulting in larger P300. Furthermore, the positive slow wave (PSW) between 500 and 750ms revealed additive effects of valence and arousal value. High arousal and positive valence of the stimuli resulted in larger PSW. Importantly, an interaction effect was absent here. In addition, sexual content led to a larger P300 and PSW than expected on the basis of a mere additive contribution of high arousal and positive valence.