FEMALE ORGASM ACROSS the MENSTRUAL CYCLE by Jesse B

Home , Fertility

FEMALE ORGASM ACROSS THE MENSTRUAL CYCLE

Jesse B. Marczyk

A Thesis Submitted to the Faculty of

The Charles E. Schmidt College of Science

in Partial Fulfillment of the Requirement for the Degree of

Master of Arts

Florida Atlantic University

Boca Raton, FL

August 2011

ABSTRACT

Author: Jesse B. Marczyk

Title: Female Orgasm Across the Menstrual Cycle

Institution: Florida Atlantic University

Thesis Advisor: Dr. David Bjorklund

Degree: Master of Arts

Year: 2011

Forty-one women filled out surveys about their heterosexual sexual behavior over the course of 30 days. These surveys tracked their menstrual cycles, sexual behavior, sexual desires, and orgasm frequency. Although the sample size was small, a number of borderline statistically significant (p < .10) trends emerged from the analysis: women experienced more copulatory orgasms on average when fertile and women who were not in relationships tended to have more frequent non-copulatory orgasms. Naturally cycling women also experienced significantly more non-copulatory orgasms when fertile.

Although no strong conclusions can be drawn from the current sample, the results suggest many avenues for future research.

iii FEMALE ORGASM ACROSS THE MENSTRUAL CYCLE

List of Tables ...... vi

List of Figures ...... vii

Introduction ...... 1

The Adaptive Account ...... 1 The Byproduct Account ...... 4 Research and Evidence ...... 8 The Heritability of Female Orgasm ...... 12 The Current Study ...... 14 Method ...... 15

Participants ...... 15 Methods and Procedure ...... 16 Results ...... 19

Analyses Overview ...... 19 Copulatory Orgasms ...... 20 Non-Copulatory Orgasms ...... 20 Copulatory Frequency, Birth-Control Use, and Fertility Status ...... 21 Copulatory Orgasm Frequency, Birth-Control Use, and Fertility Status ...... 22 Perceived Partner Attractiveness, Fertility Status, and Copulatory Orgasms ...... 23 Non-Copulatory Orgasm Frequency, Birth-Control Use, and Fertility Status ...... 24 Non-Copulatory Orgasm Frequency, Fertility Status, and Relationship Status ...... 25 Perceived Partner Attractiveness, Fertility Status, and Non-Copulatory Orgasms ...... 26 Discussion ...... 27

Conclusion ...... 31 Tables ...... 32

Figures...... 34

References ...... 41

v LIST OF TABLES Table 1. Mean Scores and Ranges of Demographic Variables ...... 32

Table 2. Mean Scores and Ranges for Daily Survey Variables ...... 33

vi LIST OF FIGURES Figure 1. Mean Proportion of Copulatory Days During the Fertile and Non-Fertile

Periods...... 34

Figure 2. Mean Number of Orgasms Achieved per Copulation During the Fertile and

Non-Fertile Periods ...... 35

Figure 3. Proportion of Copulatory Days During Which a Copulatory Orgasm was

Reported for the Fertile and Non-Fertile Periods ...... 36

Figure 4. Mean Number of Copulatory Orgasms per Copulation Reported for the Fertile

and Non-Fertile Periods Relative to Partner-by-Self Attractiveness Ratings .....37

Figure 5. Mean Number of Days During Which Non-Copulatory Orgasms Were Reported

for the Fertile and Non-Fertile Period ...... 38

Figure 6. Mean Number of Non-Copulatory Orgasms Experienced per Day for the Fertile

and Non-Fertile Periods ...... 39

Figure 7. Mean Number of Days Non-Copulatory Orgasms Were Reported for the Fertile

and Non-Fertile Periods ...... 40

vii

INTRODUCTION

Over the past several decades, a debate has been waged in the scientific literature over female orgasm. The central question of this debate focuses on whether or not female orgasm in humans – as well as other species – shows evidence of having been designed by an evolutionary process to perform one or more functions, or whether female orgasm can be better conceptualized as a functionless – albeit pleasurable - potential in women , resulting from shared embryological development with males. Put more succinctly, should female orgasm be regarded as an evolutionary adaptation in its own right, or a byproduct of selection occurring on the adaptive male orgasm?

The Adaptive Account

Currently, the most favored adaptive hypothesis concerning a possible function of the female orgasm is the sperm retention hypothesis. Smith (1984) suggested that the occurrence of female orgasm may serve to actively transport sperm into the female’s reproductive tract. This active transport could serve women by allowing them an opportunity to affect the probability of insemination by a given male. It is not difficult to imagine the ways this could benefit a female: it could allow her some ability to favor the sperm of a preferred male over that of a rival male in the case of multiple matings, or it could allow a woman some degree of control in manipulating the likelihood of conception with a single male. In support of this hypothesis, Smith (1984) cites an experiment by Fox et al. (1970) that showed a decrease in intrauterine pressure following female orgasm that might create circumstances favorable for active sperm transport.

While the results of Fox et al. (1970) are consistent with the notion that the female orgasm may play a role in active sperm transport, there are a number of shortcomings: first, the participant size consists of only one couple measured over a short period of time; because of this issue, it is unclear as to how representative these findings are either between other women, or even within a single woman over the course of her menstrual cycle or life. Second, Fox et al. (1970) did not actually observe the transport of any fluids or sperm over the course of this experiment, so it is also unclear as to whether the observed pressure changes would have an effect on the active transport of sperm, transport that may occur naturally without female orgasm. Finally, both Grafenberg

(1950) and Masters and Johnson (1966) failed to find any transport of radio-opaque fluid into a female’s reproductive tract following coitus or orgasm. However, the results of these papers were criticized by Fox and Fox (1967) on the basis that both studies placed a cap containing this fluid over the female’s cervix, which may have had an effect on the ability of female orgasm to create the pressure change observed by Fox et al. (1970).

The sperm retention hypothesis was later expanded on by Baker and Bellis (1993), who studied the orgasm timing among 11 heterosexual couples and subsequent flowback rates – seminal fluid, sperm, and female secretions ejected from the female’s reproductive tract following copulation. Towards this end, Baker and Bellis (1993) collected ejaculates resulting from copulations in condoms to estimate average sperm counts for each couple. They then collected the flowback results from intercourse without a condom

The women were also asked to estimate the flowback volume, as being normal, heavier or lighter than normal, or none.

Baker and Bellis (1993) found a positive relationship between the estimated number of sperm a male inseminated a female with and the number of sperm ejected, calculated from the flowback data. A median value of 65% of the sperm being retained from any given copulation was calculated, though females appeared capable of ejecting nearly all the sperm that were estimated to have been inseminated in some instances. Of the women who were taking hormonal contraceptives during this study, there was no significant trend over their menstrual cycle to retain different amounts of sperm; however, those women who were not taking hormonal contraceptives showed a significant decrease in sperm retention during days 6 to 15 of their cycle.

While female orgasm in general was not associated with greater sperm retention, this could be expected, given that the timing of female orgasms would need to occur in proper temporal proximity to male ejaculations to be effective. When considering the timing of female orgasm, Baker and Bellis (1993) found that female orgasms occurring prior to 1 minute before male ejaculations were associated with low sperm retention, whereas those occurring up to one minute before, at, or immediately after male ejaculation were associated with greater sperm retention. These results appear consistent with the results of Fox et al. (1970), suggesting a possible role for female orgasm in active sperm transport.

While this study is perhaps the most suggestive of a direct role of female orgasm in sperm retention, there are some potential problems to consider. The first is the small sample size and possible skewed nature of the data: Of the 127 flowback samples provided by 11 couples, 93 of those samples came from 1 couple. Worryingly, that one couple also had a substantially lower rate of overall sperm retention than every other

3 couple, barring one; this range varied from being 16% to 57% lower, being about 30% lower on average. While Baker and Bellis (1993) insist that proper statistical techniques were used to protect against issues of skewed results, Lloyd (2005) disagrees that this is the case. Nevertheless, despite the validity of lack thereof of their statistical methods, the results of Baker and Bellis (1993) beg for replication with a larger sample size. Finally, the results should also be replicated with respect to the women’s menstrual status; if female orgasm does play a role in sperm retention, one would expect that role to be pronounced at times when women are most likely to be fertile. However, almost all the flowback data was collected from women taking hormonal birth control, which could preclude that analysis.

The Byproduct Account

The long-standing alternative to the adaptive hypothesis of female orgasm is that female orgasm is a non-functional byproduct. The byproduct hypothesis was initially proposed by Donald Symons (1979), who suggested that female orgasm be viewed as a potential in women that resulted from selection pressures on the male ability to orgasm.

This potential for orgasm exists in females due to a shared embryological development with males; the same embryonic tissue will either develop into a penis or a clitoris, given the proper prenatal environment. The penis and clitoris are thus said to be homologues.

Unsurprisingly, stimulation of these homologous organs is primarily responsible for generating orgasms in later life for both sexes. A parallel could be drawn to male nipples, which, while non-functional, results from a shared embryological development with females, for whom they are functional.

In support of this hypothesis, Symons (1979) notes that the available data at the time on non-human species experiencing female orgasm seemed tenuous at best, especially with regard to heterosexual intercourse. Experimentally, female rhesus monkeys were genitally stimulated to the point where they appeared to experience an orgasm (Burton, 1971). However, this orgasm response was achieved only after the monkeys had be stimulated by a method unlikely to be found in natural matings

(involving direct clitoral stimulation) for an extended period of time – roughly fifteen minutes, whereas normal copulations only last a few seconds.

One could make the case that such unnatural conditions do not tap into the proper psychological contexts that are most likely to elicit orgasm in female monkeys naturally

(for these objections, see Lloyd, 2005). On the other hand, this pattern seems to hold true for many human females as well; extended periods of stimulation – especially clitoral stimulation- is often required to achieve orgasm (Kinsey, 1953).

Given a more natural setting, some species may be more likely to respond to sexual stimulation, relative to laboratory stimulation. Troisi and Carosi (1998) conducted a series of naturalistic observations on a group of 56 sexually mature Japanese macaques, living in an outdoor enclosure. Heterosexual copulations were observed, the amount of stimulation each monkey received was recorded, and dominance rank of each of the monkeys was assessed. Troisi and Carosi (1998) used a clutching reaction – a female turning her head to look back at her partner while grasping him - as their index of female orgasm. In total, 240 copulations between 68 different heterosexual pairs were used as the data set for this research. Out of those 240 copulations, 61% of the females displayed the clutching reaction, which occurred in about 33% of the copulations.

Troisi and Carosi (1998) found that, after controlling for the amount of physical stimulation each female received – which was predictive of the clutching response - the clutching reaction was predicted by the status differential between the male and female involved in the mating. When the mating pair included a high-status male and a low- status female, the clutching reaction occurred most often; when that status differential was reversed, the clutching reaction occurred the least. Troisi and Carosi (1998) – as well as Lloyd (2005) - note that these clutching reactions may well not actually represent female orgasm, though they might at least indicate female arousal. These results suggest that, in addition to the amount of stimulation a female receives, the nature of that stimulation may be a determining factor in the resulting pleasure.

There is some further evidence that females from some non-human species may experience orgasm during sexual activity, or at least be capable of experiencing orgasm.

However, much of this evidence comes from sources other than heterosexual intercourse, largely restricted to female-female mounts (Symons, 1979; Lloyd, 2005). Definitive evidence of non-human female orgasm from heterosexual copulations appears to have been found in stump-tailed macaques (Goldfoot et al., 1980), data that was unavailable to

Symons, though its occurrence appeared infrequent. While these results highlight the need for more naturalistic research, the ease of conducting such research is a substantial impediment.

Symons (1979) further notes that the cross-cultural record is very variable with respect to female orgasm; in some cultures it appears common, whereas in others the concept itself appears to be missing. However, some caution is also warranted when considering ethnographer’s reports, given the potential risks of bad sources, inaccurate

6 information, or many other such factors that could affect the reliability of such reports.

Indeed, it has been observed that some women may experience orgasm, but did not identify it as such (Lloyd, 2005). Such a potential barrier could lead to false negatives in the ethnographic record.

Kinsey (1953) found that when masturbating, females often do not make use of techniques that simulate heterosexual intercourse – such as the insertion of fingers or any other object into the vagina – and, when they do, they normally do so in addition to direct clitoral stimulation – not in place of it. During masturbation, women are often much quicker to respond to orgasm, relative to heterosexual intercourse; typically within 4 minutes when not intentionally prolonging the act. Taken together, these two facts suggest that women are, on average, slower to respond to orgasm during heterosexual intercourse due to the ineffectiveness of the stimulation that it often provides for achieving such an end.

Lloyd (2005) takes note of those facts when voicing her support for the byproduct hypothesis, raising the point that many studies – some of which will be examined shortly

– fail to take into account the methods by which orgasm during heterosexual copulations are achieved. She questions whether orgasms during intercourse are achieved through

“assisted” means, (through additional direct stimulation of the clitoris by either a female or her partner) or “unassisted” means (strictly through penetration). If female orgasm only occurs reliably in the presence of assisted intercourse, it is unlikely to be the case that female orgasm is a frequent occurrence in cultures where assisted intercourse is not common practice. It is also less likely to occur during any given sex act unless the male or female take direction action to further stimulate the female’s clitoris.

All of this is not to say that female sexual excitement and pleasure may not be adaptive; indeed, it likely is. However, this evidence does suggest that female orgasm itself may not serve any direct function. Despite the tentative evidence by Baker and

Bellis (1993) that female orgasm may play a role in sperm transportation, Lloyd (2005) notes that there has yet to be any definitive link made between female orgasm and actual fertility rates. However, if Baker and Bellis (1993) are correct in their conclusion that the timing of orgasm is the key variable in sperm retention, the research that would be required to demonstrate a link – or lack of a link – between female orgasm and fertility has yet to be conducted.

Research and Evidence

It is against these background theories – adaptive and byproduct – that other evidence concerning female orgasm can be better evaluated and understood. In addition to the research presented previously, a number of other important studies in humans require further scrutiny.

The first two pieces of research concern the role of mate quality with respect to female orgasm. Thornhill, Gangestad, and Comer (1995) reasoned that if Baker and

Bellis (1993) are correct – that female orgasm serves to transport sperm – women should be more likely to experience high sperm retention orgasms when partnered with males of higher phenotypic quality, as it would be in a woman’s reproductive best interests to choose a sire of high genetic quality for her offspring. To assess this possibility, Thornhill,

Gangestad, and Comer (1995) recruited 86 heterosexual adult couples and measured the males on a number of traits on the right and left sides of their bodies to determine the

8 overall degree of symmetry their bodies displayed - better symmetry being a good marker of better genetic quality. In addition, each participant also filled out a survey about the contexts during which the female experienced orgasm in any given instance of sexual intercourse. Controlling for other demographic variables, the authors found that only fluctuating asymmetry predicted reports of female orgasm during copulation. Further, these copulatory orgasms were more likely to be the high sperm retention orgasms postulated by Baker and Bellis (1993).

The paper does contain many faults, however. The first and perhaps most glaring issue is that the reports of female copulatory orgasm were averaged across the men and women’s reports. It is unclear that this led to greater, as opposed to lesser, accuracy; one could assume that women have a better handle of their estimated orgasm frequency, and several participants actually had to be excluded, due to the male and female reports diverging so widely. Secondly, these accounts are retrospective in nature, asking people to estimate orgasm frequency and timing in general, raising doubts as to the veracity of these estimates. Further, it introduces the additional problem of blinding the results to any effects of the menstrual cycle; female orgasm would only be functional when a woman could conceive, suggesting that the study should have examined orgasm with respect to the menstrual cycle.

Relatedly, Shackelford et al. (2000) examined a similar aspect of mate quality: perceived physical attractiveness. Shackelford et al. (2000) asked 340 women about their most recent sexual encounter only, specifically asking women to assess their partner’s physical and sexual attractiveness and report whether or not they experienced an orgasm.

About 75% of the women reported experiencing an orgasm, and those who rated their

9 partner as being more attractive were more likely to have experienced an orgasm, even after controlling for relationship satisfaction and duration. Unfortunately, the timing of these orgasms was not assessed, leaving the results inconclusive with respect to the sperm retention hypothesis.

While the results of Thornhill, Gangestad, and Comer (1995) and Shackelford et al. (2000) are consistent with the adaptive hypothesis of female orgasm, they can also be viewed as being consistent with the byproduct account; simply put, women could be more sexually aroused by more attractive partners, higher-fitness partners, or more desirous of intercourse with them, and it is that increase in sexual arousal that results in more frequent orgasms during copulation. Interestingly, these results are also consistent with the results of Troisi and Carosi (1998), suggesting that male quality is an important variable in female excitement.

Singh et al. (1998) approached the sperm retention hypothesis from a slightly different angle, examining women’s conscious desire for pregnancy relative to the frequency and timing of their orgasms. Sixty-nine women were assessed using the same questions employed by Thornhill et al. (1995) regarding orgasm timing and frequency. In addition, each woman was asked to rate how important it was to them to eventually give birth to a child on a 5-point scale. The results showed that while desire for pregnancy did not predict coital orgasm frequency before male ejaculation, desire for pregnancy did predict orgasm frequency following a partner’s ejaculation.

Though these results appear consistent with the sperm retention theory – though by no means conclusive - they also suffer many of the same problems as Thornhill et al.

(1995), namely they are only retrospective estimates of orgasm frequency that pay no mind to daily variations. It is also unclear why a conscious desire for pregnancy should be predictive of female orgasm; surely, female orgasm should work in a similar fashion for women, irrespective of any conscious desire for pregnancy, given that the explicit link between intercourse and pregnancy may not have been present for most of our evolutionary history.

In support of the byproduct hypothesis, Wallen and Lloyd (2008) examined the variability in the organs most responsible for generating orgasm, the penis and the clitoris, hypothesizing that if female orgasm is indeed a byproduct, there should be more variability in the clitoris than the penis, since adaptive traits tend to show lower phenotypic variation than non-adaptive traits. Wallen and Lloyd (2008) found just that; their measures of clitoral length appeared more variable than their measures of penile length, whereas vaginal and penile length variability was not significantly different.

There are a number of problems with this claim. First, Hosken (2008) notes than the logic employed by Wallen and Lloyd (2008) about phenotypic variation is lacking.

Lynch (2008) raises the point that clitoral length appears to be unrelated to the ability of females to achieve orgasm, undermining the logic of Wallen and Lloyd’s (2008) conclusion completely. Lynch (2008) further notes that clitoral volume, as compared to penile volume, does not differ significantly, posing the possibility that length measurements – while easier to obtain – may not be the most valid measure of the traits in question.

Most interestingly, a good critic of the conclusion reached by Wallen and Lloyd

(2008) that, “…this marked variability in clitoral size suggests little or no selective pressure on clitoral structure, and consequently, on female orgasm itself” (p.1), would be

Lloyd (2005), who wrote,”…[B]ecause no one is arguing that the clitoris – in its role of producing sexual excitement in females, thereby promoting her to engage in sexual activity – does not play an important role in female fitness” (p. 159). While Lloyd (2005) cautions against conflating the clitoris with female orgasm, Wallen and Lloyd (2008) apparently discard caution and do just that. This is a fine example of how interpretations of the data surrounding female orgasm can be influenced heavily by the bias of the author doing the interpreting. Given that Lloyd (2005) accuses researchers who favor the possibility of the sperm retention hypothesis of being biased when interpreting evidence, it is ironic that Lloyd herself is hardly an exception to bias affecting her claims.

The Heritability of Female Orgasm

While evidence of heritable components to female orgasm does not directly support either the adaptive or byproduct accounts, it is still relevant information. Dawood et al. (2004) conducted a twin study including over 3000 women. The women were asked about how frequently they experienced orgasm during penetrative sexual intercourse, how frequently they have orgasms with a partner in ways other than sexual intercourse, and how frequently they experience orgasm from masturbation.

Dawood et al. (2004) found that roughly 30% of orgasm frequency with partners across both conditions could be accounted for by additive genetic factors, leaving the remaining 70% accounted for by non-shared environment. Perhaps unsurprisingly,

12 masturbatory orgasm was slightly more heritable, likely due to constraints on underlying female sexuality encountered during heterosexual intercourse (Matteo & Rissman, 1984).

This pattern of results was replicated by Dunn, Cherkas, and Spector (2005), suggesting these are fairly good estimates.

The only study that manages to avoid the retrospective accounts of female orgasm was conducted by Matteo and Rissman (1984). Noting that heterosexual relationships can result in compromises between a male and female’s interests, Matteo and Rissman (1984) examined 7 lesbian couples over a 14-week period. Each participant kept a daily record of her sexual thoughts, behaviors, and orgasms, in addition to tracking her menstrual cycle. The results showed a peak in orgasm frequency during mid-cycle, despite masturbation remaining constant across the cycle, as well as a peak in self-initiated intercourse.

While the results are certainly interesting, they appear to be consistent with both the byproduct and adaptive accounts. Women could be experiencing more orgasms during mid-cycle because that is when they are most likely to be adaptive, or due to a more general interest in sexual activity. It is also unclear how well these results would generalize to heterosexual women; not only is the sample size very small, but as Matteo and Rissman (1984) note, there could be different factors at play during heterosexual intercourse. To the extent that female orgasm is functional for sperm retention, it would only be functional in heterosexual contexts, which require a similar examination.

The Current Study

As the state of the scientific literature currently stands, the debate over the adaptive and byproduct accounts of female orgasm is unlikely to be resolved. The research done in this area suffers from many flaws, resulting in the literature not having examined key variables that bear on the matter, such as accurate accounts of orgasm frequency, timing, or menstrual cycle effects. Without accurate, day-to-day accounts of female orgasm during heterosexual intercourse, this debate will be unable to be resolved.

Further, the existing literature can be interpreted as being consistent within the adaptive or byproduct framework.

The current research was designed to capture the everyday variation in women’s copulatory and non-copulatory orgasms in a way that avoided relying on retrospective estimates of general orgasm frequency. The primary research question of this study was to determine whether women are more likely to experience copulatory orgasms during the fertile period - defined as days 9 through 15 – of their cycle, as opposed to the non- fertile period. If the sperm-retention hypothesis (Smith 1984; Baker and Bellis 1993) is correct, we would expect women to experience proportionately more copulatory orgasms when fertile, all other factors being equal, since it is during that fertile period that sperm retention should be most functional; retaining additional sperm at a time when a woman is unlike to conceive serves no reproductive function. Further, we would expect the relationship between women’s copulatory orgasm frequency when fertile to be moderated by her partner’s attractiveness, since women should be more likely to preferentially retain the sperm of higher-quality males.

Additionally, we would expect only naturally cycling women to show this effect, whereas those on hormonal birth control would not, since hormonal birth control has

14 been known to have an effect on menstrual cycle-dependent behaviors (Miller, Tybur, &

Jordan, 2007).

METHOD

Participants

One hundred seven women recruited from the internet and Florida Atlantic

University campus filled out at least 1 day of the daily survey. In compensation for their participation, the participants were informed that $5 would be donated to the Avon

Foundation for Women for each participant to complete the full survey. The inclusion criteria for the present study required women to have given at least one response from her fertile period and one response from her non-fertile period. The final sample available for analysis was comprised of 41 women, ages 19-42 (M = 23.88), who reported on 1064 total days (M=25.95). An independent-samples t test was conducted to assess whether the included sample different from the non-included sample across any of the demographic variables. The results indicated that the only variable to differ significantly was sexual orientation, t(107) = 2.04, p < 0.05, with 9.76% of the included sample reporting a bisexual orientation and 26.09% of the excluded sample reporting a bisexual orientation.

The sample was largely Caucasian (n = 30; 73.2%), followed by Hispanic (n = 7; 17.1%),

Black (N = 2; 4.9%), and Asian/Other (n = 2; 4.9%).

Materials and Procedure

The materials for this study were two surveys hosted through Surveymonkey: an introductory survey and a daily survey. A link to the website containing both the surveys was posted online on various cooperating websites. The instructions for the survey explained that the participants would never be asked for any information that could identify them personally; this was done because the degree of anonymity women have when completing surveys of sexual matters can affect their answers (Wittrock, 2004). It was my hope that hosting the survey online would grant a further degree of privacy, allowing the women to fill out their surveys in a setting and time of their choice. In order to protect the participants anonymity while tracking their responses across different surveys, they were instructed to create a 7-digit ID for the survey, the first four digits representing the month and day the survey was started, and the final three being self- generated; this ID was entered at the beginning of every survey. Unfortunately, without any identifying information, contacting the participants with reminders to complete their surveys was not an option. Accordingly, the instructions for the survey made it clear that it would be the participant’s responsibility to log in each day to the appropriate survey and complete it.

The first survey was an introductory survey filled out at the beginning of the study.

This survey collected various demographic and background variables, including age, weight, height, sexual orientation, ethnicity, relationship status and satisfaction, number of short and long-term sexual partners, birth control use, perceptions of partner and self attractiveness, the importance of orgasms for sexual satisfaction, and the first day of a woman’s last menstrual cycle. Means, sample size, ranges, and standard deviations for each of these measures are presented in Table 1.

Twenty women (48.78%) in the sample reported currently using a form of hormonal birth control; the remaining 21 (51.22%) were cycling naturally. Thirty-five

(85.37%) women reported a heterosexual orientation and 6 (14.63%) reported a bisexual orientation. Previous sexual experience was broken down into long- and short-term components. Women in the sample ranged from having 0 to 30 (M = 5.98) short-term male sexual partners, and from 0 to 8 (M = 2.24) long-term male sexual partners.

Of the 41 women in the sample, 21 (51.22%) reported currently being involved in a committed heterosexual relationship; 20 women (48.78%) were not in a relationship.

Satisfaction with a participant’s current relationship status – single or involved - was broken down into a sexual and emotional dimension on a ten-point scale, ranging from 0 to 9 (representing completely unsatisfied to completely satisfied). Those women currently involved in committed relationship ranged in the sexual satisfaction from 3 to 9 (M =

7.38), and ranged in their emotional satisfaction from 1 to 9 (M = 7.05); those women who were not currently in relationship ranged in their sexual satisfaction from 0 to 8 (M =

3.15), and ranged in their emotional satisfaction from 0 to 9 (M = 4.9). Of those women who were in a committed relationship, the length of that relationship varied from 7 to 132 months (M = 44.05).

Women in the sample were asked to rate their self-perceived attractiveness across a physical and sexual dimension on a ten-point scale, ranging from 0 to 9. Responses varied from 0 to 9 across both dimensions (M physical = 6.83; M sexual = 6.71). Those women currently involved in a relationship were asked to assess those same dimensions in their partner using the same scale; responses for a partner’s physical attractiveness ranged from 5 to 9 (M = 7.67), and responses for a partner’s sexual attractiveness ranged

17 from 6 to 9 (M = 7.61). A further variable was created by combining the ratings of partner- and self-attractiveness, then dividing the overall ratings of partner’s attractiveness by overall ratings of self-attractiveness. A score of 1 on this measure would indicate a woman perceives herself as being equally attractive as her partners, whereas a score below 1 would indicate a woman perceives herself being more attractive and a score above 1 would indicate a woman perceives her partner as being more attractive than she herself is. The partner-by-self attractiveness scores ranged from 0.82 to 1.6 (M =

1.09).

Women were asked to rate the importance of orgasm in their sexual satisfaction on a 10-point scale, ranging from 0 to 9 (representing completely unimportant to extremely important); the responses ranged from 0 to 9 (M = 6.76).

The second survey was a daily survey; it was filled out each day concerning events that happened the day prior for a maximum of 30 days. The daily survey assessed women’s perceived stress levels, their sexual desire for their committed partner if they had one, their sexual desire for men who were not a committed partner, whether or not they had sex (defined as penis-in-vagina sex), whether or not they had an orgasm, and, if they did, how many orgasms they had. The number of orgasms they had was further divided into those that occurred during copulation with a partner and ones that did not; the former were coded as copulatory orgasms, while the latter were coded as non- copulatory orgasms. The means and ranges for the daily survey are found in Table 2.

Since all the daily survey results were time-stamped, I was able to count forward from the reported date of last menstruation to estimate each woman’s current position in

18 her menstrual cycle. Following Miller, Tybur, and Jordan (2007), responses on days 1-5 and days 18-28 were coded as “non-fertile,” while days 9-15 were coded as “fertile.”

Days 6-8 and 16-17 were dropped from the analysis because it is unclear whether or not women are likely to be fertile during those times; this left a total of 262 fertile days and

613 non-fertile days for analysis.

RESULTS

Analyses Overview

Initial analyses examined the frequency of both copulatory and non-copulatory orgasms and frequency of copulation. Orgasm data, both copulatory and non-copulatory, were examined with respect to both the proportion of days women reported experiencing one or more of either type of orgasm and the mean number of orgasms experienced per day. Orgasm frequency was evaluated as a function of fertility period (fertile period vs. non-fertile period) and birth control status (no birth control vs. using birth control). Of those women in relationships, all types of orgasms were assessed with respect to their perceptions of their partner’s attractiveness, relative to their own. The data from one outlier who reported up to 18 non-copulatory orgasms on a single day was excluded from the non-copulatory data set.

Effects on each dependent measures were also assessed as a function of sexual orientation (i.e., heterosexual vs. bisexual). No significant effects involving sexual orientation reached significance, all Fs < 1, and therefore will not be reported in the analyses below.

Copulatory Orgasms

Orgasms reported by a participant occurring during penetrative vaginal intercourse were considered copulatory orgasms. Copulatory orgasms accounted for

18.15% of all reported orgasms (n = 100). The number of reported copulatory orgasms ranged from 0 to 8 a day (M = 0.09). Twenty-six women (63.41%) in the sample did not report any copulatory orgasms.

Since copulatory orgasms require sexual intercourse to occur, we further considered copulatory orgasms only on days when intercourse was reported (n = 116;

10.9%). On days when women reported having sexual intercourse, women averaged

0.862 copulatory orgasms per day. However, women only reported experiencing one or more orgasms on 44% of the days they copulated. Of those women who reported having sex at least once (n = 25), 10 (40%) did not report any copulatory orgasms.

Non-Copulatory Orgasms

Any orgasms reported by a participant that were not the result of copulation were considered non-copulatory orgasms. This category of orgasms included all orgasms that occurred outside of penetrative vaginal intercourse, and could include penetrative anal intercourse or masturbation. These orgasms were the most common type experienced by women in the current sample, representing 81.85% of all reported orgasms (N = 451).

The number of reported non-copulatory orgasms ranged from 0 to 18 a day (M = 0.43).

Women reported having one or more non-copulatory orgasms on 29.14% of the days available for analysis. Five women (12.12%) in the sample did not report any non- copulatory orgasms.

Copulatory Frequency, Birth-Control Use, and Fertility Status

The proportion of days women reported copulating was computed separately for their fertile and non-fertile periods as a function of birth-control use (see Figure 1). These data were analyzed in a 2 (fertility status: fertile vs. non-fertile) x 2 (birth-control use: no birth control vs. birth control) analysis of variance with repeated measure on the fertility status. The results indicated that the mean proportion of days during which copulation took place was not significantly greater for either period, F(1,39) = 0.63, p = 0.43 (fertile:

M = 0.13, SD = 0.22; non-fertile: M = 0.11, SD = 0.16). The main effect of birth-control use F(1, 39) = 0.65, p = 0.43 (birth control: M = 0.14, SD = 0.04; naturally cycling: M =

0.10, SD = 0.04) and the interaction, F (1,39) = 1.15, p = 0.29, were also not significant.

The previous analysis focused on the proportion of days women reported either copulating or not copulating. However, on some days women reported copulating multiple times. Accordingly, the number of times women reported copulating during the fertile and non-fertile periods was calculated. The number of times women reported copulating during the fertile period was multiplied by 2.29 to compensate for the fact that the non-fertile period is much longer than the fertile period. These data were analyzed in a 2 (fertility status: fertile vs. non-fertile) x 2 (birth-control use: no birth control vs. birth control) analysis of variance with repeated measure on the fertility status. The results indicated that the mean number of copulations did not differ as a function of fertility period, F(1,39) = 1.54, p = 0.7 (fertile: M = 2.86, SD = 0.71; non-fertile: M = 2.61, SD =

0.5). The main effect of birth-control use, F(1, 39) = 0.27, p = 0.61 (birth control: M =

3.01, SD = 0.74; naturally cycling: M = 2.46, SD = 0.74), and the interaction, F (1,39) =

0.35, p = 0.56, were also not significant.

Copulatory Orgasm Frequency, Birth-Control Use, and Fertility Status

In order to assess whether the participants were significantly more likely to experience copulatory orgasms when fertile, a mean value of copulatory orgasms experienced per day of reported copulation was calculated for each participant. That number was then divided by the number of times each participant reported having intercourse. In order to be included in this analysis, a woman must have reported having sex at least once during the fertile and non-fertile periods (N = 15; 8 using birth control, 7 not using birth control). The range of mean number of copulatory orgasms experienced per intercourse when fertile was in between 0 to 1.5 (M = 0.41); the range for the non- fertile period was in between 0 to 0.5 (M = 0.16).

Figure 2 presents the mean number of orgasms achieved during copulation during the fertile and non-fertile periods as a function of their birth-control status. These data were assessed in a 2 (fertility status) x 2 (birth-control use) analysis of variance with repeated measure on the fertility status variable. The analysis produced a non-significant trend for women to experience more copulatory orgasms when fertile, F (1,13) = 3.89, p

= 0.07, ƞ² = 0.23 (fertile: M = 0.4, SD = 0.47; non-fertile: M = 0.16, SD = 0.17). The main effect of birth-control use, F(1, 13) = 1.92, p = 0.19 (birth control: M = 0.37, SD = 0.38; naturally cycling: M = 0.19, SD = 0.23), and the interaction of birth-control use and fertility status, F(1,13) = 0.79, p = 0.39, were not significant.

Perceived Partner Attractiveness, Fertility Status, and Copulatory Orgasms

Women in the sample who were in a committed relationship had rated themselves and their partners on two scales of attractiveness: physical and sexual. These scores were averaged, giving an overall mean attractiveness score for both the women and their

22 committed partners. By dividing the mean partner attractiveness score by the mean self- rated attractiveness score, a partner-by-self rating of attractiveness score was calculated for each participant. The mean partner-by-self score for all participants was then calculated, and participants were classified as having high (n = 6) or low (n = 8) perceptions of partner attractiveness, relative to their own. These data are presented in

Figure 3 and were entered into a 2 (fertility status) x 2 (hi/low partner-by-self ratings) analysis of variance with repeated measure on the fertility status variable. The results indicated no significant main effect of fertility status, F(1,12) = 0.89, p = 0.37, or for an interaction, F(1,12) = 0.86, p = 0.37. Although women in the high-partner-attractiveness group reported experiencing copulatory orgasms on a higher proportion of days (M =

0.75; SD = 0.36) than women in the low-partner-attractiveness group (M = 0.45, SD =

0.47), the main effect of partner-by-self attractiveness ratings failed to reach significance,

F(1,12) = 2.08, p = 0.18.

In addition to the proportion of days women reported copulatory orgasms, the mean number of orgasms women achieved during copulation was also examined as a function of partner-by-self attractiveness ratings. These data are presented in Figure 4 and were assessed in a 2 (fertility status) x 2 (hi/low partner-by-self ratings) analysis of variance with repeated measure on the fertility status variable. The analysis yielded a marginally significant main effect of fertility status, F(1,12) = 3.89, p = 0.07, ƞ² = 0.25 with women reporting marginally more copulatory orgasms during the fertile period (M =

0.46, SD = 0.48) than during the non-fertile period (M = 0.18, SD = 0.17). There was no significant main effect of partner-by-self attractiveness ratings, F(1,12) = 2.45, p = 0.14, though women reported more copulatory orgasms per instance of intercourse when

23 partnered to a more attractive partner (high attractive: M = 0.42, SD = 0.29; low attractive: M = 0.21, SD = 0.32). The interaction was also not significant, F(1,12) = 0.002, p = 0.97.

Non-Copulatory Orgasm Frequency, Birth-Control Use, and Fertility Status

The data from one outlier (18 non-copulatory orgasms in one day) were excluded from subsequent analysis. In order to assess whether the participants (N = 40) were significantly more likely to experience more non-copulatory orgasms when fertile or non- fertile, a mean value of non-copulatory orgasms was calculated for each period as a function of birth-control status. The range of non-copulatory orgasms experienced on average by women on days when they were estimated to be fertile ranged from 0 to 2 (M

= 0.39, SD = 0.43); when non-fertile, the range of non-copulatory orgasms experienced on average ranged from 0 to 1.62 (M = 0.43, SD = 0.38).

Mean number of days during which non-copulatory orgasms were reported as a function of fertility status and birth-control use are reported in Figure 5. These data were analyzed in a 2 (fertility status) x 2 (birth control) analysis of variance with repeated measure on the fertility status variable. The analysis produced no significant main effect for fertility status, F(1,38) = 2.31, p = 0.14, or birth-control status, F(1,38) = 2.24, p =

0.14. The interaction effect was also non-significant, F(1,38) = 2.11, p = 0.15.

A second 2 x 2 analysis of variance with repeated measure on the fertility status variable was conducted to evaluate whether naturally cycling women or hormonal birth control users experienced a greater number of non-copulatory orgasms per day, on average (see Figure 6). The results showed no main effect of fertility status, F(1,38) =

0.51, p = 0.48, but a significant interaction effect, F(1, 38) = 5.37, p < 0.05, ƞ² = 0.12. As seen in Figure 6, naturally cycling women experienced more non-copulatory orgasms on average when fertile (M = 0.56, SD = 0.49) compared to women using hormonal birth control (M = 0.22, SD = 0.29). However, when non-fertile, naturally cycling women did not experience significantly more orgasms per day (M = 0.46, SD = 0.43) compared to birth control users (M = 0.41, SD = 0.34). An independent-samples t test was conducted to assess this relationship. The results yielded significant differences during the fertile period, t(1,38) = 2.26, p < 0.05, but not during the non-fertile period, t (1,38) = 0.35, p =

0.73.

Non-Copulatory Orgasm Frequency, Fertility Status, and Relationship Status

In order to assess whether women in committed relationships (N = 21) were more likely to experience one or more non-copulatory orgasms on any given day on average than women not in relationships (N = 19), a 2 (fertility status) x 2 (relationship status: in committed relationship vs. not in committed relationship) analysis of variance with repeated measure on the fertility status variable was conducted. These data are presented in Figure 7. The results indicated no significant main effect for fertility status, F(1,38) =

2.01, p = 0.16, and no interaction effect, F(1,38) = 1.19, p = 0.28. Although women who were not in relationships tended to have non-copulatory orgasms on a slightly greater proportion of days (M = 0.38, SD = 0.37) than women in relationships (M = 0.22, SD =

0.23), the main effect of relationship status failed to reach conventional levels of significance, F(1,38) = 3.23, p = 0.08, ƞ² = 0.08.

In order to assess whether women in committed relationships (N = 21) were more likely to experience more non-copulatory orgasms on any given day on average than women not in relationships (N = 19), a final 2 (fertility status) x 2 (relationship status) analysis of variance with repeated measures on the fertility status variables was conducted. The analysis yielded no main effect for fertility status, F(1,38) = 0.38, p =

0.54, relationship status, F(1,38) = 1.85, p = 0.18, or an interaction, F(1,38) = 2.87, p =

0.10.

Perceived Partner Attractiveness, Fertility Status, and Non-Copulatory Orgasms

In order to assess whether women in committed relationships with partners of higher perceived attractiveness (N = 9) were more likely to experience more non- copulatory orgasms on any given day on average than women in relationships with partners of lower perceived attractiveness (N = 12), a 2 (fertility status) x 2 (high/low partner attractiveness) analysis of variance with repeated measures on the fertility status variables was conducted. The analysis yielded no significant main effect for fertility status, F(1,19) = 3.09, p = 0.10, attractiveness ratings, F(1,19) = 0.32, p = 0.58, or an interaction, F(1,19) = 0.59, p = 0.45.

Finally, in order to assess whether women in committed relationships with partners of higher perceived attractiveness (N = 9) were proportionately more likely to experience one or more non-copulatory orgasms on a given day than women in relationships with partners of lower perceived attractiveness (N = 12), a 2 (fertility status) x 2 (high/low partner attractiveness) analysis of variance with repeated measures on the fertility status variable was conducted. The analysis yielded a significant main effect for

26 fertility status, F(1,19) = 5.07, p < 0.05, ƞ² = 0.21, but no main effect for attractiveness ratings, F(1,19) = 0.04, p = 0.85, or an interaction, F(1,19) = 0.92, p = 0.35.

DISCUSSION

I was interested in addressing some of the methodological shortcomings in the literature concerning female orgasm generally and copulatory orgasms, specifically with an eye towards tracking responses over the menstrual cycle. With the exception of Matteo and Rissman (1984), who dealt exclusively with lesbian couples, female orgasm has not been examined across the menstrual cycle in a day-to-day form. This lack of daily reports potentially calls into question the accuracy of estimates provided by women in prior studies. Even if the estimates of those previous studies can be considered accurate in general, they fail to capture any potential menstrual cycle effects – effects that are a likely to be of importance if one believes female orgasm could serve a functional role in affecting sperm retention. While the current study by no means resolves the question of adaptation or byproduct, it represents the beginning of an effort to create a solid foundation of basic knowledge from which future research and theory can be guided.

This foundation should contain information both about the copulatory and non-copulatory contexts during which orgasms occur to offer a more complete picture of the phenomenon being studied.

The present findings suggest some interesting trends to pursue further, some expected and some not. The first of these findings is that the vast majority of orgasms

(81.85%) occurred in a non-copulatory context. Lloyd (2005) has interpreted similar research findings to indicate that female orgasm is a byproduct, given its infrequent

27 realization during copulation, likely due to the inadequate stimulation that is typically provided during intercourse. According to Puts and Dawood (2006), however, such facts no more condemn the adaptive hypothesis than does that fact that males can, and often do, reliably achieve orgasms more frequently through masturbation than through intercourse.

The non-copulatory contexts that elicit orgasm, such as masturbation, could be byproducts of an adaptive copulatory orgasm, as is the case in males.

There was a non-significant trend for women in this sample to report more copulatory orgasms on average when fertile compared to when not fertile. What is particularly surprising about this trend is that it was carried predominately by women using hormonal birth control. While it is not surprising that women taking hormonal birth control are more likely to experience copulatory orgasms (Caruso et al., 2005) – perhaps due to a decrease in anxiety about becoming pregnant, or an increase in spontaneity when it comes to the contexts immediately preceding intercourse – it is surprising that the trend appears specifically during the fertile period as opposed to throughout the entire cycle.

This is surprising because other cycle-dependent trends (Miller, Tybur, & Jordan, 2007;

Petralia & Gallup, 2002) are often absent in women using hormonal birth control.

However, owing to the small sample size (n = 15) available for analysis, it would be premature to draw any strong conclusions about this effect. Future research should re- evaluate this trend using a larger sample size.

While hormonal birth control may serve to increase the average copulatory orgasm rate, the same cannot be said of non-copulatory orgasms. During the fertile period, in this case, naturally cycling women were significantly more likely to experience a greater number of orgasms, whereas the two groups did not differ during the non-fertile

28 period. Further, naturally cycling women experienced non-copulatory orgasms on a greater percentage of days when fertile. In fact, women experienced non-copulatory orgasms on over twice as many days, on average. These results stand in contrast to

Matteo and Rissman (1984), who found no variations across the menstrual cycle in masturbatory sessions in naturally cycling women. It is unclear at this point whether sexual orientation is a factor possibly affecting these results - as the current sample does not include any self-identified lesbians and only six bisexual women – or whether the non-copulatory orgasms were elicited more frequently by a partner in non-copulatory contexts, including manual, oral, or anal stimulation. While there are good reasons to suspect that these orgasms were elicited most frequently in masturbatory contexts – such as the lack of connection between partner attractiveness and non-copulatory orgasms, as well as the fact that women who were not in relationships reported more non-copulatory orgasms - the question will need to be resolved more fully by future research.

When the non-copulatory figure is compared to the non-significant trends for women to report an increase in the percentage of days they experienced a copulatory orgasm and the mean number of copulatory orgasms they experience when fertile and having intercourse, some possible explanations come to mind. The first is that the smaller sample size of women who could provide copulatory data for both the fertile and non- fertile period allows greater measurement error to enter into the data and reducing statistical power, masking what the true effect would be, given a larger sample. A second possibility is that the increase in non-copulatory orgasms, as compared to copulatory orgasms, represents the compromises of heterosexual intercourse (Lloyd, 2005); simply put, women are able to stimulate themselves more effectively than their male partners can

29 through intercourse. Further, when stimulating themselves without a partner, women may not be affected by the concerns and anxieties that accompany heterosexual mating, such as fearing pregnancy, contracting an STD, or concerning themselves with their partner’s feelings.

What is particularly interesting about the trends for women to experience more orgasms – copulatory and non-copulatory – on a greater percentage of days when fertile, is that there were nearly identical mean reports of desire for their partners during the fertile and non-fertile periods. It would thus seem that the increase in orgasm frequency cannot be accounted for by a consciously reported, global increase in desire.

However, it is unclear whether questioning women about their overall desire in such a fashion was a sensitive enough measure. The matter may again return to the inherent compromises of heterosexual intercourse; despite a woman’s overall desire throughout the day, her interest in any particular sexual act may be contingent on the way her partner approaches or handles a specific situation. Even if a woman desires intercourse, her partner may not approach the situation in a satisfying manner, leading to a degree of disappointment that affects the chance a woman will reach orgasm. Further, regardless of how skillfully – or poorly – a male partner may approach or initiate intercourse, the intercourse itself may still not provide enough physical stimulation for the woman to achieve orgasm. Future research would do well to follow the example set by Matteo and Rissman (1984) and ask instead about whether their sexual encounters were self-, partner-, or mutually initiated. Such a measure may be more sensitive to the more immediate desires of women and the skill of their mates in initiating.

Contrary to the findings of Shackelford et al. (2000) and Thornhill, Gangestad, and Comer (1995), there was no significant relationship between perceptions of partner attractiveness and copulatory orgasm frequency. However, the trend was in the predicted direction, with women partnered to more attractive males experiencing more consistent copulatory orgasms. Unfortunately, there were not enough women reporting intercourse during both the fertile and non-fertile periods to draw any strong conclusion about this effect. These results require further testing with a larger sample of copulating women, testing that focuses specifically on generating more copulatory data.

Conclusion

Female orgasm is currently still a poorly understand phenomenon, despite competing theories about its function, or lack of one. This debate cannot yet be resolved with any degree of satisfaction. While the small sample size of the current research precludes any strong conclusions from being reached at this point, there are a number of trends that warrant future investigation. These trends include, but are not limited to: the effect of partner attractiveness on copulatory orgasms, the effect of fertility status on copulatory and non-copulatory orgasms, and the effects of birth control on the frequency and consistency of orgasm achievement. Future research should be conducted with an eye towards gathering more copulatory data, as its occurrence is somewhat infrequent, making it more difficult to collect data on.

Table 1

Mean scores and ranges of demographic variables

N Minimum Maximum Mean Std.Deviation

______

Age 41 19.00 42.00 23.88 5.15

Weight 41 104.00 250.00 145.27 30.46

Height 41 61.00 71.00 65.55 2.68

Relationship Satisfaction 21 1.00 9.00 7.05 2.13

Emotional

Relationship Satisfaction 21 3.00 9.00 7.38 1.50

Sexual

Single Satisfaction Emotional 20 0.00 9.00 4.90 2.88

Single Satisfaction Sexual 20 0.00 8.00 3.15 2.52

Number of Short-Term Sexual 41 0.00 30.00 5.98 8.31

Parnters

Number of Long-Term Sexual 41 0.00 8.00 2.24 1.85

Partners

Physical Attractiveness (Self) 41 0.00 9.00 6.83 1.87

Sexual Attractiveness (Self) 41 0.00 9.00 6.71 1.74

Partner-by- Self Attractiveness 21 0.82 1.60 1.11 0.20

Orgasm Importance 41 0.00 9.00 6.76 2.28

Table 2

Mean scores and ranges for daily survey variables

N Minimum Maximum Mean Std.Deviation

______

Desire for Partner 21 0.00 9.00 4.58 2.75

Desire for Non-Partner 41 0.00 9.00 1.06 2.66

Sex 41 0.00 1.00 0.11 0.31

Orgasm 41 0.00 18.00 0.53 1.11

Copulatory Orgasm 41 0.00 8.00 0.09 0.52

Non-Copulatory Orgasm 41 0.00 18.00 0.42 1.01

Figure 1. Mean proportion of copulatory days during the fertile and non-fertile periods by birth-control status

0.16

0.14

0.12

0.1 Proportion of Copulatory 0.08 Naturally Cycling Days 0.06 Birth Control

0.04

0.02

0 Fertile Non-Fertile

Figure 2. Mean number of orgasms achieved per copulation during the fertile and non- fertile periods by birth-control status

Figure 3. Proportion of copulatory days during which a copulatory orgasm was reported for the fertile and non-fertile periods relative to partner-by-self ratings

0.8

0.7

Proportion of 0.6 Copulatory 0.5 Days with One High Partner-by-Self or More 0.4 Rating Copualtory 0.3 Low Partner-by-Self Orgasms Rating Reported 0.2

0.1

0 Fertile Non-Fertile

Figure 4. Mean number of orgasms per copulation reported for the fertile and non-fertile periods relative to partner-by-self ratings

Figure 5. Mean number of days during which non-copulatory orgasms were reported for the fertile and non-fertile periods by birth-control use

0.4

0.35

0.3

0.25

Percent of Days 0.2 Naturally Cyling One of More Non-Copulatory 0.15 Birth Control Orgasms Were 0.1 Reported 0.05

0 Fertile Non-Fertile

Figure 6. Mean number of non-copulatory orgasms experienced per day for the fertile and non-fertile periods by birth-control use

0.6

0.5

0.4

Average 0.3 Naturally Cyling Number of Non- Birth Control Copulatory 0.2 Orgasms Reported per 0.1 Day

0 Fertile Non-Fertile

Figure 7: Mean number of days non-copulatory orgasms reported for the fertile and non- fertile periods by relationship status

0.4

0.35 Percent of 0.3 Days One or 0.25 More Non- Copulatory 0.2 No Relationship Orgasms 0.15 Relationship Were Reported 0.1

0.05

0 Fertile Non-Fertile

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