Abstract

Introduction

Among sexually reproducing species, each parent contributes a random sample of only half of their genes to their offspring. As a consequence, both parents have a vested interest in the other 50 percent of each child's genes. Mate choice is not a trivial issue. One of the best ways to ensure that genes find their way into subsequent generations is to pair them with a member of the opposite sex who is healthy, reproductively viable, and has high quality genes. Growing evidence clearly shows that features people find attractive in members of the opposite sex function as indicators of good genes and act as signals for health and fertility (for a review, see Gallup and Frederick, 2010). Because the costs of reproduction are higher for females, particularly human females, selection for making judicious mate choices would be expected to have had a greater impact on women. Included among recent suggestions concerning mate choice are mechanisms that range from romantic kissing (Hughes, Harrison, and Gallup, 2007) to semen sampling (Gallup and Reynolds, 2014).

A growing number of studies show that the occurrence and frequency of female orgasm may be related to characteristics of their partner. Women with more bilaterally symmetrical partners have more orgasms (Thornhill, Gangestad, and Comer, 1995). The same is true for those with more attractive partners (Puts, Welling, Burriss, and Dawood, 2012; Shackelford et al., 2000), wealthier partners (Pollet and Nettle, 2009; but see Pollet and Nettle, 2010), more masculine partners (Puts et al., 2012), and those who have extra-pair/clandestine partners (Baker and Bellis, 1993). Female orgasm frequency also increases with partner MHC compatibility (Garver-Apgar, Gangestad, Thornhill, Miller, and Olp, 2006). All of these features have been implicated as proxies for male health, fertility, and good genes.

Based on evidence such as this, Puts and Dawood (2012) contend that female orgasm may be a covert mate choice mechanism. Consistent with this notion, Puts et al. (2012) report that measures of men's facial masculinity and facial attractiveness predict female orgasm timing and frequency. The present paper is based on an attempt to examine a broader and more diverse set of indicators that bear on whether orgasms provide women with feedback about whether it would be in their reproductive best interests to enter into and/or remain in a committed relationship with a particular man.

Participants in our study consisted of sexually active female college students who were in a committed relationship with a member of the opposite sex and agreed to fill out an anonymous survey concerning targeted features of their past and present sexual behavior. Questions about orgasm (e.g., orgasm frequency, orgasm intensity, multiple orgasms) were restricted to orgasms that occurred as a result of vaginal-penile intercourse. From an evolutionary perspective, orgasms induced by other means (e.g., mutual masturbation, oral sex) are not reproductively relevant unless they promote sperm retention (e.g., Pham, Shackelford, Sela, and Welling, 2013), enhance fertility, and/or lead directly or indirectly to an increase in the incidence of heterosexual intercourse. Included in our survey were questions about various physical and psychological characteristics of their committed male sexual partner and how their friends felt about their partner.

As this was a preliminary study, our primary objective was to determine whether women who were in committed sexual relations with high quality, opposite-sex mates experienced more frequent orgasms, orgasms of higher intensity, and to see if they were more sexually satisfied.

Materials and Methods

Fifty-four female undergraduate students enrolled at the University at Albany volunteered to participate in an anonymous online survey. Participation was restricted to those who were in a committed sexual relationship with a member of the opposite sex. Participants chose the survey from an online database posted on www.surveymonkey.com that was only accessible to students enrolled in the Introduction to Psychology course, and were given credit for participating. The research was reviewed and approved by the local/campus Institutional Review Board.

The survey consisted of questions concerning the participants' sexual behavior, prior sexual experience, feelings toward their committed partner, and various physical and psychological features of their partner (see Appendix 1). There was no time limit imposed on the completion of the survey. Participants were able to complete the survey only if they indicated being in a committed sexual relationship that involved penile-vaginal intercourse.

Results

Participant descriptive statistics are presented in Table 1. All data were initially analyzed using Pearson correlations. Due to the possibility that participants might inflate their ratings of their partner based on positivity bias (Gagne and Lydon, 2004) or a halo effect (see Nisbett and Wilson, 1977), a composite attractiveness variable was formed by combining the participants' ratings of partner attractiveness with her friend's ratings of his attractiveness. It was assumed that by combining an external measure with a self-report measure, at least some of the error in the self-report measure would be offset. This composite was substituted for all regression analyses and correlations pertaining to partner attractiveness.

Using one-tailed tests, factors that emerged as significant predictors of the topics of interest (e.g., orgasm frequency, orgasm intensity, sexual satisfaction) are presented in subsequent tables. Other unanticipated but interesting clusters of factors (e.g., age of first sex, partner sense of humor) were analyzed using two-tailed tests.

Frequency and intensity of female orgasm

Our primary hypothesis that partner characteristics indicative of good genes would lead to higher penile-vaginal orgasm frequency/intensity was supported.

Correlational analyses of the frequency of penile-vaginal orgasm indicated that the best predictors of how often participants experienced orgasm was the intensity of their orgasms, sexual satisfaction with their partner, physical attraction to their partner, their partner's family income, and partner self-confidence (see Table 2 for a complete list of correlates). Factors that predicted multiple orgasms during a single encounter are given in Table 4.

Table 2.

Factors that predicted how often females experience orgasm

Factor	r
Orgasm intensity	.816****
Sexual satisfaction with partner	.482****
Physical attraction to partner	.411***
Partner's family income	.291**
Partner's self-confidence	.270**

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Note. *p < .05,

^**p < .025,

^***p < .01,

^****p < .001

Table 4.

Factors that predicted multiple orgasms

Factor	r
Orgasm frequency	.525****
Orgasm intensity	.511****
Sexual satisfaction	.454****
Partner age	.286**

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Note. *p < .05,

^**p < .025,

^***p < .01,

^****p < .001

Likewise, in terms of orgasm intensity, correlational analyses indicated that number of orgasms per encounter, sexual satisfaction with partner, frequency of intercourse, and partner attractiveness were all significantly correlated with the intensity of orgasm (see Table 3).

Table 3.

Factors that predicted female orgasm intensity

Factor	r
Orgasm frequency	.816****
Number of orgasms per encounter	.511****
Sexual satisfaction with partner	.505****
Partner attractiveness	.427***
Frequency of sex	.275**

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Note: *p < .05,

^**p < .025,

^***p < .01,

^****p < .001

To examine the relative importance of each variable while controlling for others, a hierarchical multiple regression was conducted on orgasm frequency. Partner attractiveness was controlled for in the first step, and partner self-confidence and partner family income were entered in the subsequent step. An overview of the regression results is provided in Table 5. Women experienced more frequent penile-vaginal orgasm with partners who were more attractive. This was true when partner attraction was examined in isolation and with the inclusion of partner self-confidence and partner family income, β = .37, t = 2.84, p < .05. However, after controlling for partner attractiveness, only partner's family income remained significant, β = .27, t = 2.21, p < .05.

Table 5.

Summary of hierarchical regression analysis examining the relationship between orgasm frequency and mate-value characteristics

Model		B	SE B	β
Step 1
	Partner attractiveness	.72	.24	.39***
Step 2
	Partner attractiveness	.62	.23	.33**
	Partner self-confidence	.30	.20	.19
	Partner family income	.45	.20	.27*
	Partner family income	.45	.20	.27*

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Note. R² = .15 for Step 1; ΔR² =.109 for Step 2.

^*p < .05,

^**p < .025,

^***p < .01,

^****p < .001

Female sexual satisfaction

Women who experienced more penile-vaginal orgasms and who had more attractive partners were also more sexually satisfied. As shown in Table 6, sexual satisfaction increased with partner physical attractiveness, shoulder breath, and how much of a catch they thought he was. In addition, sexual satisfaction was related to higher intercourse frequency, though not self-initiated intercourse.

Table 6.

Factors that predicted female sexual satisfaction

Factor	r
Partner attractiveness	.579****
Protection by partner	.379***
How much of a catch her partner is	.347***
Age of first sex	−.328**
Love for partner	.315**
Intercourse frequency	.311**
Partner's shoulder width	.299**
Number of sex partners	.267*

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Note. *p < .05,

^**p < .025,

^***p < .01,

^****p < .001

The relative importance of each of the significant variables on sexual satisfaction was assessed through multiple regression analysis with partner catch, penile-vaginal orgasm frequency, partner shoulder breath, and the attraction composite as the primary predictors (see Table 7). Results indicated that when the shared variance of all variables was taken into account, only orgasm frequency (β = .33, t = 2.85, p < .05) and partner attractiveness (β = .41, t = 3.13, p < .001) contributed unique variance to sexual satisfaction.

Table 7.

Summary of regression analysis for sexual satisfaction and mate-value characteristics

Variables	B	SE B	β
Partner catch	.02	.14	.015
Penile vaginal orgasm frequency	.16	.06	.327***
Partner shoulder/waist ratio	.27	.15	−.210
Partner attractiveness	.39	.13	.411***

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Note. Total R² = .47.

^*p < .05,

^**p < .025,

^***p < .01,

^****p < .001

Female initiation of sex

Frequency of self-initiated intercourse was related to their partner's motivation, focus, and determination. For a complete list of significant correlates of female-initiated sex, see Table 8. To examine the role of partner drive, a composite variable was created comprising these three variables. Reliability analysis indicated sufficient inter-item consistency (α = .82).

Table 8.

Factors that predicted how often females initiated sex

Factor	r
Partner determination	.303*
Partner focus	.303*
Partner sense of humor	.294*
Partner motivation	.287*
Partner intelligence	.285*

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Note. *p < .05,

^**p < .025,

^***p < .01,

^****p < .001

A hierarchical regression of partner drive on frequency of self-initiated intercourse was then conducted, controlling for overall frequency of intercourse. Results indicated no effect for attraction to partner, β = .16, t = 1.16, p > .05. Partner drive, however, predicted frequency of self-initiated intercourse (β = .36, t = 2.63, p < .05), contributing significant variance over and above partner attraction, ΔR = .12, F(1,50) = 6.93, p < .05

Age of first sexual intercourse

Those who began having sexual intercourse at younger ages tended to have more satisfying relationships (see Table 9 for a list of the significant correlations). Participants who engaged in early sex reported being more sexually satisfied, more committed to their partner, and to feeling that their partners were more committed to them in return. Early sexual intercourse was also associated with several variables indicating that they saw their partner in a more favorable light. Participants who had early sex rated their partners as more intelligent and attractive. The possibility that women who had sexual intercourse at younger ages were simply more likely to find a mate with higher mate-value is contrary to findings showing that although early intercourse was associated with finding their partner more attractive, it was not associated with perceptions that their peers found their partner more attractive.

Table 9.

Correlations with age of first sex

Factor	r
Partner attractiveness	−.481****
Commitment to partner	−.434****
Sexual infidelity	−.330**
Sexual satisfaction with partner	−.328**
Ratings of partner intelligence	−.317**
Number of sex partners	−.295*
Orgasm frequency	−.278*
Love for partner	−.278*

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Note. *p < .05,

^**p < .025,

^***p < .01,

^****p < .001

Partner's sense of humor

Another interesting but unanticipated finding was the impact of partner sense of humor on participants' ratings of their partners (see Table 10). Those in relationships with more humorous partners reported he was more popular, intelligent, a better leader, and more creative. In terms of the relationship quality, participants with humorous partners reported initiating sex more often, and having more frequent intercourse in general. They also reported feeling more protected and committed to their partner.

Table 10.

Correlations with partner's sense of humor

Factor	r
Partner popularity	.487****
Partner intelligence	.463****
Protection by partner	.451****
Orgasm frequency with this partner	.408**
Partner leadership quality	.398***
Commitment to partner	.370***
Partner muscularity	.331**
Partner creativity	.320**
Intercourse frequency	.313**
Female initiated sex	.294*
Partner family income	.291*
Partner self-confidence	.276*

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Note. *p < .05,

^**p < .025,

^***p < .01,

^****p < .001

Discussion

Surveys of human sexual behavior rarely address the issue of orgasm intensity. In addition to orgasm frequency, orgasm intensity may bear on the magnitude of vaginal and intrauterine contractions that accompany orgasm, which in turn could promote the movement of sperm up through the female reproductive tract and increase the chances of conception (Baker and Bellis, 1993; Puts and Dawood, 2012). Likewise, if one views female orgasm as an endogenous reinforcement mechanism that functions to promote good mate choices, it seems reasonable to suppose that the magnitude of the reinforcing effect of orgasm would vary in relation to orgasm intensity.

We think there may be parallel effects of orgasm intensity in men. For instance, if sperm donors were asked to rate the intensity of the orgasm they experienced upon providing a semen sample, we would predict that sperm count would be proportional to orgasm intensity. Variation in orgasm intensity in males may be a reflection of underlying sperm recruitment mechanisms (Gallup, Burch, and Petricone, 2012). Evidence shows, for example, that the method of harvesting semen for artificial insemination affects the potency of the ejaculate (i.e., likelihood of impregnation). Semen harvested from men who watch visual pornography while masturbating is significantly more potent than samples collected from those who are required to rely on their imagination to achieve sufficient arousal in order to ejaculate (Yamamoto, Sofikitis, Mio, and Miyagawa, 2000).

Consistent with this analysis, orgasm intensity in the present study was highly correlated with how often women experienced orgasm, and related to how attracted they were to their partner and how many times they had sex per week (see Table 4). Another reason to distinguish between orgasm intensity and orgasm frequency is that orgasm intensity accounts for things that frequency did not, such as how many times women had sexual intercourse per week, and how the respondent's friends rate her partner (compare Table 2 and Table 4).

The fact that how one's friends feel about her partner is important suggests that social confirmation by significant others may also serve as feedback about mate choice. Thus, input from close friends may help validate the respondent's choice and affect how they experience sex with their partner. Consistent with this interpretation, sexual satisfaction was also related to how friends rate their partner (see Table 6). Likewise, how friends perceived her partner was highly correlated with his muscularity (r = .459, p < .001), determination (r = .478, p < .001), popularity (r = .423, p < .001), and leadership qualities (r = .343, p < .01).

As an extension of the findings by Baker and Bellis (1993) showing that females were more likely to experience orgasm as a consequence of extra-pair copulations, Gallup, Burch, and Berens-Mitchell (2006) found that women who were party to extra-pair sexual liaisons reported more intense orgasms as well. In fact, women were three times more likely than men to report more intense orgasms during extra-pair encounters.

How often participants experienced orgasm was also related to how physically attractive they thought their partner was, their partner's family income, and ratings of his self-confidence (see Table 2). The relationship between physical attraction and orgasm frequency replicates and extends previous findings showing that partner attractiveness predicts the likelihood of orgasm in women (Puts et al., 2012; Shackelford et al., 2000).

Women in committed relationships with older men reported more sex partners (r = .418, p < .01) and more orgasms per sexual encounter (see Table 5). How many times respondents had sexual intercourse per week was correlated with the width of her partner's shoulders (r = .273, p < .025). Broad shoulders predict many important parameters of male sexual behavior (Hughes and Gallup, 2003), and they are positively correlated with grip strength (Gallup, White, and Gallup, 2007). Grip strength is a testosterone-sensitive trait that is an omnibus index of health and vitality in both males and females (Atkinson et al., 2012). The breadth of a man's shoulders is also correlated with how women independently rate his facial attractiveness (Shoup and Gallup, 2008).

Female orgasm intensity, orgasm frequency, and sexual satisfaction were all related to how physically attracted participants were to their partner. Physical attraction is a well-documented signal for partner health, fertility, and good genes (Gallup and Frederick, 2010). The frequency of female orgasm was also related to her partner's family income, his level of self-confidence, and his sense of humor, all of which may be related in different ways to his ability to compete with other males for scarce resources.

The role of their partner's family income in predicting orgasm frequency represents an interesting parallel to the Pollet and Nettle (2009) study, where women with wealthier partners reported more orgasms. We suspect that among male college students who have yet to enter the job market, family income is a proxy for their income potential. Income potential is no doubt also related to their partner's intelligence, determination, and focus (see Table 8). Although Pollet and Nettle (2010) retracted their findings showing a relationship between female orgasm and partner wealth because of the influence of confounding variables such as youth and level of education, confounding due to youth and level of education does not apply to our sample of college undergraduates in the way it did to theirs. Indeed, we discovered that after controlling for partner attractiveness, partner family income was the only factor that accounted for a significant proportion of the remaining variance in orgasm frequency (see Table 4). These results suggest that it may be prudent to revisit the relationship between partner income and orgasm frequency.

As shown in Table 6, sexual satisfaction was related to how physically attracted women were to their partner, the intensity of their orgasms, how many orgasms they have per encounter, how protected they feel by their partner, how much of a catch they think he is, how old they were when they had sexual intercourse for the first time, how much they love their partner, how often they have intercourse with their partner, the width of their partner's shoulders, and how many sex partners they had. It is interesting that when one ranks the factors that predicted female sexual satisfaction, how much they loved their partner comes in far behind partner attractiveness, orgasm intensity, and number of orgasms per encounter.

Our study also goes beyond issues related to orgasm frequency and sexual satisfaction by identifying an ensemble of partner psychological attributes that predict other dimensions of female sexual behavior and experience. As shown in Table 8, the only features that predicted how often women initiated penile-vaginal sex were certain partner psychological/personality traits. This is particularly interesting because the timing of sex is crucial when it comes to reproduction. Sex itself will not suffice in order to reproduce. Impregnation requires relatively close temporal continuity between insemination and ovulation. Because sperm viability is short lived (for details see Gallup, Finn, and Sammis, 2009), if these two events are separated by more than +/− 24 hours the likelihood of impregnation is remote. Since female-initiated sex is more likely to occur during the fertile/mid-phase portion of the menstrual cycle (Adams, Gold, and Burt, 1978), female-initiated sex may do as much or even more than orgasm to promote impregnation.

These findings suggest that women in committed relations with high quality opposite-sex mates are putting a premium (wittingly or not) on traits that would confer an advantage in the psychological domain when it comes to how well her partner and, by implication, how well her male descendants could compete with other males for scarce resources. The fact that intelligence and motivation are featured by many women as playing an important role in mate choice lends support to the claim that mate choice puts women at the cutting edge of the selective pressure that may have given rise to the evolution of bigger human brains (see Ash and Gallup, 2008).

Another interesting finding concerns the impact of early/precocial sexual experience (i.e., age of first sex). How old women were when they began having sexual intercourse was correlated with a surprising number of factors (see Table 9). The younger they were when they experienced sexual intercourse for the first time, the more sex partners they had, the more likely they were to admit having been sexually unfaithful, the more sexually satisfied they were with their current partner, the more likely they were to experience orgasm, the more committed they were to their partner, the more physically attracted they were to their partner, the higher they rated their partner's intelligence, and the more they loved their partner.

As is true in other domains, one account of some of the facilitating effects of prior sexual experience may be that informed choices emerge from prior experience. Thus, as the number of sexual encounters with a variety of prospective mates increases, so does the capacity to make more informed mate choices (for how this may apply to semen, see Gallup and Reynolds, 2014). These results also replicate previous findings (e.g., Belsky, Steinberg, and Draper, 1991; Hughes, Dispenza, and Gallup, 2004; Hughes and Gallup, 2003) in showing that women who begin having sex at earlier ages report more sex partners and are more prone to engage in extra-pair copulations.

Finally, it is interesting to draw attention to the mate value that females ostensibly attach to their partner's sense of humor (see Table 10). As ratings of their partner's sense of humor increased, so did the frequency of sex, the likelihood of female-initiated sex, her feelings of commitment to her partner, ratings of her partner's self-confidence, feelings of protection in his presence, and estimates of his family's income. Women with partners who they felt had a good sense of humor also tended to rate their partners as more intelligent, more popular, more creative, and reported experiencing orgasms more often with him than with other men (r = .408, p < .01). Not surprisingly, there is growing evidence that a sense of humor is a proxy for intelligence (Howrigan and MacDonald, 2008; Miller, 2000).

In closing, it is important to acknowledge several limitations of the present study. Because this was a preliminary investigation, the number of respondents in our sample (N = 54) was modest. Not unrelated to the sample size is the problem of Type I error inflation as a consequence of computing multiple correlations. For these reasons, correlations that are marginally significant need to be viewed with some caution. Ultimately, it is not so much a question of statistical significance; it is a question of whether these effects can be replicated.

Furthermore, since the respondents provided information about their sexual experiences as well as their partners' characteristics, it is possible that variation in sexual satisfaction might have influenced how they rated their partners. However, this would not apply in all instances. For example, it seems unlikely that how often women experience orgasm would affect ratings of their partner's family income, nor would orgasm frequency be expected to increase the width of his shoulders or influence how they rate his intelligence, sense of humor, muscularity, creativity, focus, etc. By including how their friend's rated their partner's attractiveness as part of the composite score for attractiveness, this also helped minimize exaggeration of partner features due to sexual satisfaction.

Acknowledgements:

Appendix

Contributor Information

Gordon G. Gallup, Jr., Department of Psychology, University at Albany, State University of New York, Albany, NY, USA.

Benjamin C. Ampel, Department of Psychology, University at Albany, State University of New York, Albany, NY, USA.

Nicole Wedberg, Department of Psychology, University at Albany, State University of New York, Albany, NY, USA.

Arutjun Pogosjan, Department of Psychology, University at Albany, State University of New York, Albany, NY, USA.

References