Evidence for a curvilinear relationship between sympathetic nervous system activation and women's physiological sexual arousal

There is increasing evidence that women's physiological sexual arousal is facilitated by moderate sympathetic nervous system (SNS) activation. Literature also suggests that the level of SNS activation may play a role in the degree to which SNS activity affects sexual arousal. We provide the first empirical examination of a possible curvilinear relationship between SNS activity and women's genital arousal using a direct measure of SNS activation in 52 sexually functional women. The relationship between heart rate variability (HRV), a specific and sensitive marker of SNS activation, and vaginal pulse amplitude (VPA), a measure of genital arousal, was analyzed. Moderate increases in SNS activity were associated with higher genital arousal, while very low or very high SNS activation was associated with lower genital arousal. These findings imply that there is an optimal level of SNS activation for women's physiological sexual arousal.     

A Psychophysiological Exploration of Sexual Arousal Patterns in Females and Males

Fifty-nine female and 39 male undergraduates completed 3 sessions of a psychophysiological study on sexual arousal. Subjects were assigned to one of six experimental groups. Subjects within each group were exposed to a series of four audio-tapes, and were asked to fantasize before and after the tape series. Tapes varied in their erotic and romantic content, and two sex role dimensions were also varied across tapes. Dependent measures included scaled subjective reports, genital pulse amplitude and blood volume responses, heart rate, and finger pulse amplitude. Erotic contents were significantly more sexually arousing than nonerotic contents for both sexes. Romantic content did not significantly enhance the facilitation of sexual arousal. Nontraditional sex roles were significantly more arousing for females, with a similar nonsignificant trend for males. There were significant correlations between genital pulse amplitude and subjective reports of arousal; however, for females the genital blood volume measure showed less reliable agreement with subjective report. Genital pulse amplitude was the most reliable and precise indicator of arousal and accounted for the most variance across conditions. No significant changes occurred on the heart rate and finger pulse amplitude measures. Although subjects were able to become aroused by fantasy alone, listening to erotic tapes did not facilitate their ability to be sexually aroused during fantasy.     

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.     

Cardiovascular and endocrine alterations after masturbation-induced orgasm in women.

OBJECTIVE: The present study investigated the cardiovascular, genital, and endocrine changes in women after masturbation-induced orgasm because the neuroendocrine response to sexual arousal in humans is equivocal. METHODS: Healthy women (N = 10) completed an experimental session, in which a documentary film was observed for 20 minutes, followed by a pornographic film for 20 minutes, and another documentary for an additional 20 minutes. Subjects also participated in a control session, in which participants watched a documentary film for 60 minutes. After subjects had watched the pornographic film for 10 minutes in the experimental session, they were asked to masturbate until orgasm. Cardiovascular (heart rate and blood pressure) and genital (vaginal pulse amplitude) parameters were monitored continuously throughout testing. Furthermore, blood was drawn continuously for analysis of plasma concentrations of adrenaline, noradrenaline, cortisol, prolactin, luteinizing hormone (LH), beta-endorphin, follicle-stimulating hormone (FSH), testosterone, progesterone, and estradiol. RESULTS: Orgasm induced elevations in cardiovascular parameters and levels of plasma adrenaline and noradrenaline. Plasma prolactin substantially increased after orgasm, remained elevated over the remainder of the session, and was still raised 60 minutes after sexual arousal. In addition, sexual arousal also produced small increases in plasma LH and testosterone concentrations. In contrast, plasma concentrations of cortisol, FSH, beta-endorphin, progesterone, and estradiol were unaffected by orgasm. CONCLUSIONS: Sexual arousal and orgasm produce a distinct pattern of neuroendocrine alterations in women, primarily inducing a long-lasting elevation in plasma prolactin concentrations. These results concur with those observed in men, suggesting that prolactin is an endocrine marker of sexual arousal and orgasm.     

Uncovering category specificity of genital sexual arousal in women: The critical role of analytic technique

Based on analytic techniques that collapse data into a single average value, it has been reported that women lack category specificity and show genital sexual arousal to a large range of sexual stimuli including those that both match and do not match their self‐reported sexual interests. These findings may be a methodological artifact of the way in which data are analyzed. This study examined whether using an analytic technique that models data over time would yield different results. Across two studies, heterosexual (N = 19) and lesbian (N = 14) women viewed erotic films featuring heterosexual, lesbian, and gay male couples, respectively, as their physiological sexual arousal was assessed with vaginal photoplethysmography. Data analysis with traditional methods comparing average genital arousal between films failed to detect specificity of genital arousal for either group. When data were analyzed with smoothing regression splines and a within‐subjects approach, both heterosexual and lesbian women demonstrated different patterns of genital sexual arousal to the different types of erotic films, suggesting that sophisticated statistical techniques may be necessary to more fully understand women's genital sexual arousal response. Heterosexual women showed category‐specific genital sexual arousal. Lesbian women showed higher arousal to the heterosexual film than the other films. However, within subjects, lesbian women showed significantly different arousal responses suggesting that lesbian women's genital arousal discriminates between different categories of stimuli at the individual level. Implications for the future use of vaginal photoplethysmography as a diagnostic tool of sexual preferences in clinical and forensic settings are discussed.     

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.     

Cardiovascular and Electrodermal Responses Conditioned to Fear-Relevant Stimuli

This study examined heart rate, finger pulse volume, and skin conductance responses in subjects conditioned to fear-relevant (snakes and spiders) and fear-irrelevant (flowers and mushrooms) slide stimuli by an electric shock unconditioned stimulus. A differential conditioning paradigm with an interstimulus interval of 8 sec was used. There were 4 habituation, 8 acquisition, and 20 extinction trials with each of the two cues. The results demonstrated reliable acquisition for finger pulse volume and skin conductance responses, with superior resistance to extinction for the fear-relevant conditioned stimuli. The heart rate data showed no differentiation between reinforced and nonreinforced cues during acquisition and extinction, and no effect of fear-relevance. This discrepancy between skin conductance and finger pulse volume responses, on the one hand, and heart rate, on the other, was interpreted as due to differences in innervation, with the former measures mainly reflecting sympathetic and the latter parasympathetic effects.     

Paranoid-nonparanoid differences--psychophysiological parallels.

It was predicted that the psychological differences between paranoids and nonparanoids would be parallelled by differences in psychophysiological responses to stimuli varying along both informational and motivational dimensions. Skin conductance and heart rate responses to stimuli in a guessing task were measured in a group of paranoid patients and compared with those from non-paranoid and non-patient controls. A group of nonschizophrenic patients on phenothiazine medication served as drug-matched controls. Skin conductance level, response frequency and amplitude data are reported; heart rate response changes were examined by means of times series analysis and reported as first and second deceleration and first and second acceleration components. It was predicted that paranoid patients would show a greater increase in skin conductance measures with cognitive demand, and an increase in acceleratory components of the heart rate to increases in motivational variables. The normal pattern of greater electrodermal responding to the negative stimuli than the positive, and greater heart rate acceleration to the positive stimuli but not the negative (Fowles, 1980) was predicted to be reversed in schizophrenic patients, and possibly more marked in paranoids. Cognitive manipulations showed the predicted increase in electrodermal and heart rate responding in normal controls. The paranoid subjects showed a similar increase as a function of task demands, but there was no significant difference between the other groups. Motivational manipulations produced increased skin conductance responding and increases in heart rate acceleration components in normal controls, this was not parallelled in the patient groups. All subject groups failed to show greater electrodermal activity to negative than to positive stimuli. Normal controls showed significant heart rate acceleration to positive as compared to negative stimuli, this pattern was reversed in paranoid patients.     

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.     

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.     

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.     

Cardiovascular and Skin Conductance Correlates of a Fixed-Foreperiod Reaction Time Task in Retarded and Nonretarded Youth

Changes in heart rate (HR), digital and cephalic pulse amplitude, and skin conductance were studied during a fixed-foreperiod reaction time (RT) task. Mentally retarded adolescents with a mean mental age of 9 yrs, 10 mos were compared with two nonretarded groups matched on mental age (MA) and chronological age (CA), respectively. AH subjects received 20 RT trials with distractors (music) during the 4-sec preparatory interval (PI) and 20 trials without music in a counterbalanced design. The warning signal was a 1 sec light presentation and the reaction signal was an 82 dB tone. Retarded subjects had longer and more variable RTs than the controls. Retarded subjects had smaller HR accelerations and decelerations during the PI than the CA group but not less than the MA group. Further, the retarded group had a marginally lower tonic skin conductance level, smaller skin conductance responses, and smaller constrictions in cephalic pulse amplitude than the CA controls. The results are discussed in terms of attentional and arousal deficits in retarded persons. Some comments are focused on the developmental findings (MA vs CA groups) and on the discrepancies among the skin conductance and cardiovascular measures.     

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.     

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.     

Orienting and Defensive Responses to Visual Stimuli

Physiological responses were recorded while 10 females who feared spiders (Group SP) and 10 females who did not (Group NP) viewed 24 neutral and 6 spider slides. Group NP responded to the spider stimuli with heart rate (HR) deceleration and cephalic vasodilation (increase in pulse amplitude), while Group SP responded with HR acceleration and cephalic vasoconstriction. Neither group gave appreciable or systematic cardiovascular responses to the neutral stimuli. Palmar and dorsal skin conductance (SC) responses to the spider stimuli were larger than those given to the neutral slides, and tended to be larger and more resistant to habituation in Group SP than in Group NP. When considered along with post-experimental reports, the responses given by Group NP to the spider slides could be considered to be indicative of an orienting response (OR), while those given by Group SP were consistent with recent conceptions of the defensive response (DR). These response patterns, especially the latter one, were evident in both group data and in individual records.     

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.     

Amplitude and Habituation of the Orienting Reflex as a Function of Stimulus Intensity

Two within-S experiments involving 20 Ss each and one between-S experiment employing 100 Ss were performed to examine effects of stimulus intensity on orienting response amplitude and habituation. Five intensities of a 1000 Hz tone were presented, ranging from 0 to 40 dB in Experiment I and from 0 to 80 dB in Experiments II and III. Response measures were skin conductance response (SCR) and heart rate (HR). Skin conductance response amplitude increased monotonically with stimulus intensity while HR deceleration was a generally decreasing function which tended to decrease, increase, and finally decrease again as intensity increased. Not only was deceleration greatest at 0 dB but it was more resistant to habituation. Several intensities of test stimulation were presented after habituating stimuli in the between-S experiment. Skin conductance response to test stimuli was facilitated by habituation at 0 dB and depressed by habituation at 80 dB. The results suggest a direct relationship between stimulus intensity and development of habituation.     

Blood pressure changes highlight gender differences in emotional reactivity to arousing pictures

The current study was aimed at investigating the effects of gender on the magnitude and patterning of blood pressure responses to specific pleasant and unpleasant, arousing visual stimuli. Systolic and diastolic blood pressure (SBP and DBP), as well as heart rate (HR) and skin conductance (SCR) responses were investigated during picture viewing in 21 female and 25 male students. The pattern of SCR and HR reactivity across emotional categories was found to be similar for men and women. Gender was found to be an effective moderator of BP responses specifically to sexual stimulus content, which prompted greater reactivity in men than in women. These findings extend prior research on gender differences in autonomic responding to emotional visual stimuli and suggest that BP changes might reflect sexual peripheral arousal more than other autonomic measures.     

Facial electromyographic reactions and autonomic activity to auditory stimuli

This study explored whether high- and low-intensity auditory stimuli evoke different facial electromyographic reactions and autonomic responses. Subjects were repeatedly exposed to 95-dB and 75-dB tones (1000 Hz, 40 ms rise and fall times) while their facial electromyograms from the corrugator and zygomatic muscle regions, heart rate, skin conductance responses, skin conductance half recovery time and ratings were measured. The 95-dB tone evoked a "negative" reaction with increased corrugator activity and an autonomic response pattern that carried aspects of a defense reaction, that is, slowly habituating skin conductance responses with retarded recovery rate and an initial tendency to heart rate acceleration. Furthermore, the 95-dB tone was rated as unpleasant. The 75-dB tone elicited an orienting response indicated by a distinct heart rate deceleration and fast habituating skin conductance responses with a relatively short recovery time. Thus, the present study demonstrated that the facial electromyographic technique is sensitive to simple environmental stimuli such as auditory stimuli and that the facial response is consistent with the autonomic response patterns and the experience of the stimuli.     

Habituation and the Orienting Response in the Auditory Cortical Evoked Potential

Habituation of the auditory cortical evoked potential, the GSR, and heart rate was measured in 100 male subjects. Stimuli were 31 tones of 1 sec duration with an ISI of 33 sec. All stimuli were sinusoidal, at a frequency of 1000 Hz, and at an intensity of 95 dB (re 20 N/cm²). The EEG was measured from bipolar electrode placement to the C_z and T₃ scalp locations. Evoked potentials were averaged over 3 successive blocks of 10 stimuli. The GSR habituation scores were the regression coefficients over trials of the response amplitude in square root conductance. Significant habituation of all evoked potential amplitude components was found. This was a rapid process occurring between the first and the second 10 stimuli. The habituation score for the most significant evoked potential variable (P200) was found to correlate significantly with the GSR and heart rate habituation scores. These results were interpreted as suggesting that the amplitude of the evoked potential was enhanced by the orienting reaction.