Sexual Psychology – Pop Culture Sexual Health Composition – Due Fri 12/3

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The Psychology of Human Sexuality, Second Edition. Justin J. Lehmiller. © 2018 John Wiley & Sons, Ltd. Published 2018 by John Wiley & Sons, Ltd. Companion Website: www.wiley.com\go\lehmiller2e

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CHAPTER OUTLINE

Introduction, 88 Factors That Influence Sexual Arousal, 88

The Brain, 88 The Senses, 90 Hormones, 98 Substances, 102

The Sexual Response Cycle, 105 The Masters and Johnson Model, 105 Psychological Models of Sexual Response, 110

Human Sexual Response: Understanding Arousal and Orgasm

©Milles Studio. Used under license from Shutterstock.com.

Lehmiller, J. J. (2017). The psychology of human sexuality. John Wiley & Sons, Incorporated. Created from umuc on 2021-11-03 20:09:05.

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4 Human Sexual Response: Understanding Arousal and Orgasm88

Introduction

If you have ever looked at the magazines sitting beside the checkout line at the grocery store, you have probably noticed that at least half of them feature stories about “how to turn him on” or “what you need to know to drive her wild.” To be perfectly honest, these stories are usually garbage: they are not always based upon sound scientific research, they are not necessarily written by experts, and they tend to reinforce gender stereotypes. Such articles drive psycholo- gists crazy, and not in a good way.

The purpose of this chapter is to tell you what you really need to know about the topic of sex- ual arousal. We will explore the biological, psychological, and social factors that lead to arousal and consider the accompanying changes that occur in the male and female body during sexual activity. Knowledge of the factors that generate arousal and an appreciation of how the body normally reacts to sexual stimuli are both vital for understanding the basis of sexual difficul- ties and the ways in which a sex therapist might go about treating them (chapter 13 will cover sexual dysfunction and therapy in detail). This information is also important for understanding similarities and differences in male and female sexuality. This chapter will give you far more valuable insight than you could get from any magazine at the supermarket and will hopefully serve as a valuable reference guide for you in the future.

Factors That Influence Sexual Arousal

Is your brain really your biggest sex organ? It most certainly is! Sexual arousal is contingent upon the way your brain perceives a given sexual stimulus. It does not matter whether the most sensitive parts of your body are being touched, or how little clothing the person in front of you is wearing, because if your brain does not interpret that stimulus as arousing, you are unlikely to have a sexual response. We will therefore begin our discussion of sexual arousal with the brain and our senses, and subsequently consider the myriad other factors that can affect arousal, including hormones and substances.

The Brain

The brain is the control center for sexual arousal. Through cognitions, mood states, and fanta- sies, we are able to turn ourselves off and on, independent of any sensory input. However, the degree of control a person has, as well as the way that person responds to sexual stimuli, varies considerably across individuals. For example, emotions such as depression and anger can make sexual arousal difficult in some people, but pose little problem for others. Likewise, some peo- ple may not notice the sound of traffic outside the window while they are having sex, but others may find the same noise so distracting that it kills the mood. In addition, neuroscience research has found that some people’s brains are just more sensitive to sexual cues than others (Prause et al., 2014). What this means is that some people have a low threshold for sexual arousal—it might not take much to get them interested in sex; by contrast, the threshold for others is set much higher—they might only be responsive to really potent sexual cues.

In this section, we will consider the sections of the brain that are most important for arousal. First is the limbic system, a set of structures deep within the brain that exerts a profound influence on both animal and human sexual behavior. The limbic system is composed of sev- eral important elements, including the hypothalamus (which controls autonomic processes and sexual responses), hippocampus (which assists in learning and memory), and amygdala (which plays a role in emotion regulation and the processing of social information). As early as

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­aators Tat nnluenae Sexual Arousal 89

the 1950s, scientists identified the limbic system as the “pleasure center” of the brain through studies of rats (Liebowitz,  1983). In one of these studies, rats had tiny electrodes implanted into their brains through which they were able to administer a small electric jolt to their own limbic system by pressing on a lever. Scientists soon observed those rats pressing the lever hundreds of times per hour! Subsequent research on human participants revealed similar effects and, believe it or not, humans pressed the lever even more frequently than did the rats (Heath, 1972)! In addition, subjective reports from human patients indicate that electrical stimulation of the limbic system is highly pleasurable and can sometimes generate orgasmic responses.

The role of the limbic system in sexual arousal has been further established in recent years by functional magnetic resonance imaging (fMRI). Through fMRI scanning, we can see what areas of the brain “light up” (i.e., become neurologically active) when we experience arousal. For example, in studies of individuals exposed to erotic films during an fMRI scan, male and female participants showed significant activation of the amygdala (Karama et al., 2002) and, at least for men, activation of the hypothalamus as well (Arnow et al., 2002). Other neuroimaging studies have reported similar results (e.g., Ferretti et al., 2005). Of all of the limbic structures, the hypothalamus appears to be one of the most important for normal sexual functioning, par- ticularly in the males of most species. Destruction or chemical inactivation of certain portions of the hypothalamus (especially a region known as the medial preoptic area, or MPOA) results in a significant decrease in sexual behavior (Hurtazo, Paredes, & Agmo, 2008), whereas electri- cal stimulation to this same area generally increases such behavior (Rodriguez-Manzo, Pellicer, Larsson, & Fernandez-Guasti, 2000).

Beyond the limbic system, the cerebral cortex also plays an important role in sexual arousal. The cerebral cortex is the outer layer of the brain, and it is this region that controls our thoughts, memories, imagination, and use of language. Given that it controls such a large number of mental processes, it is plain to see that the cerebral cortex can be used to either facilitate or inhibit sexual arousal in a variety of ways. Among the many sexual functions of the cerebral cortex is sexual fantasy, a topic we will return to in chapter 9.

Neocortex

Basal ganglia

Hypothalamus

Amygdala

Hippocampus

Figure 4.1 In this diagram you can see the cerebral cortex and the major structures of the limbic system depicted. ©Blamb, 2016. Used under license from Shutterstock.com.

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4 Human Sexual Response: Understanding Arousal and Orgasm90

One other important way the brain influences sexual arousal is through the production of neurotransmitters, substances that transmit signals between nerve cells. Perhaps the two most potent neurotransmitters that affect sexual arousal are dopamine and serotonin. The pres- ence of dopamine has the effect of enhancing sexual arousal and increasing the odds of sexual behavior. As some evidence of this, women who have taken drugs that reduce dopamine levels (e.g., certain antipsychotics) often report difficulties reaching orgasm (Shen & Sata, 1990). In contrast, women who have taken drugs that increase dopamine levels (e.g., the antidepressant bupropion) typically report more sexual arousal and greater ability to reach orgasm (Segraves, Clayton, Croft, Wolf, & Warnock, 2004).

The sexual effects of serotonin are the opposite of dopamine. The presence of serotonin tends to reduce sexual arousal and inhibit orgasm. This probably does not come as a surprise to anyone who has seen advertisements for Prozac or any other antidepressant in the class of selective serotonin reuptake inhibitors (SSRI). These ads frequently mention potential sexual side effects of taking SSRIs, such as low libido. Indeed, research has found that patients taking SSRIs typically report lower levels of arousal and delayed orgasm (Serretti & Chiesa,  2009). Thus, while keeping higher levels of serotonin in the brain may be good for one’s mood, it can be bad for one’s sex life. On an interesting side note, these inhibitory side effects of serotonin may be desirable in some patients, particularly for persons who typically reach orgasm more quickly than desired (an issue we will return to in chapter 13).

The Senses

Another way the brain contributes to sexual arousal is by interpreting sensory input from our skin, eyes, nose, ears, and mouth. The way our brains interpret sensory information is complex and takes into account psychological and social factors, including prior learning experience and cultural values. As input comes in, the brain also releases different types of neurotransmit- ters that can either facilitate or inhibit arousal. Given all of the factors at play here, it should be easy to understand why a given stimulus may be perceived as sexual by some people but not by others.

We will begin by discussing touch, which is an important source of sexual stimulation for most people. However, as we discuss the remaining senses, you will see much wider variabil- ity in response and preference emerging. Before we go on, please note that some people have impairments affecting one or more of their senses, such as complete or partial blindness and hearing loss or deafness. Given the powerful role that the senses can play in sexual arousal, an impaired sense can have important implications for a person’s sexual development and/or functioning.

Touch Touch is usually an integral part of sexual arousal and pleasure, regardless of whether an indi- vidual is engaging in solo or partnered sexual activity. However, the type and nature of touch that is sexually pleasing can be quite different from one person to the next, due to biological, psychological, and sociocultural factors. Of course, most people find it arousing when one of their primary erogenous zones is touched. Primary erogenous zones are portions of the body where nerve endings are present in large quantities, such as the genitals, perineum, nip- ples, lips, and inner thigh. Type of touch is very important, though. Some people prefer lighter touch (e.g., gentle kissing and stroking of the nipple), whereas others prefer to be more aggres- sively handled (e.g., having their nipples clamped or twisted). The key is for partners to discuss with each other what does and does not feel good. Do not leave it up to your partner to guess, because some people are poor guessers!

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­aators Tat nnluenae Sexual Arousal 91

Sometimes, people enjoy having portions of the body other than their primary erogenous zones touched during sexual activity. These body parts are known as secondary erogenous zones, or regions of the body that have taken on sexual significance as a result of condition- ing. For instance, if you were to have the back of your knee caressed and licked during sexual activity, this body part might eventually come to be its own erogenous zone for you. Second- ary erogenous zones may take on heightened importance for persons with physical disabilities (e.g., spinal cord injuries that affect genital responses). For such individuals, these erogenous zones can be one way of maintaining an active sex life when genital sensation or function is impaired.

Vision Reflecting on the value that our society places on physical attractiveness and the immense popularity of sexually explicit films, magazines, and websites, it should come as no surprise that for many people, vision is almost as important as touch in generating sexual arousal. How- ever, the types of visual stimuli that generate arousal vary across persons and cultures. Broadly speaking, cultures and societies shape individual preferences by dictating what is and is not sexually attractive (e.g., in the Western world, the popular media typically depicts the “ideal” woman as having an hourglass figure and the “ideal” man as being tall and muscular). Those individual preferences are further refined as a result of our own learning and experience and, in some cases, people’s preferences may barely resemble the cultural standard. While vision can play a powerful role in shaping perceptions of attractiveness, it is important to note that some persons have visual impairments. For these individuals, what is considered to be attractive may be a function of other forms of sensory input (e.g., attractiveness may depend more on the sound of a person’s voice or their scent than their physical appearance).

There is a widely held belief that men are more strongly aroused by visual stimuli than are women and, on the surface, research seems to support this idea. For example, when shown a variety of pornographic video clips, male participants consistently report experiencing more sexual arousal than female participants on subjective self-reports (e.g., Koukounas &

Figure 4.2 Physical touch is perhaps the strongest sexual sense, although the type and nature of touch that is considered desirable varies across persons. ©Frenk Kaufmann/123RF.COM.

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4 Human Sexual Response: Understanding Arousal and Orgasm92

McCabe,  1997). However, when sexual arousal is assessed by physiological indicators (i.e., penile strain gauges and vaginal photoplethysmographs), this sex difference starts to dis- appear: both men and women show significant arousal in response to visual erotic stimuli. In fact, these physiological measures reveal that women actually show more arousal than men to certain kinds of sexual stimuli (Chivers, Rieger, Latty, & Bailey,  2004). For example, whereas heterosexual men show significant genital arousal only in response to porn featuring women in some way, heterosexual women register strong levels of genital arousal in response to several different types of porn, including videos of lesbians, gay men, and heterosexual couples having sex. Compared to men, women are more likely to have a nonspecific genital response pattern (i.e., they demonstrate arousal in response to a wider range of sexual stimuli), which some have interpreted as an indicator that they have greater erotic plasticity than men (more on this in chapter 6).

You may be wondering what accounts for the disconnect between the subjective and the physiological reports of sexual arousal in women in response to visual stimuli. We cannot say for sure, but some have argued for a cultural explanation. As mentioned in the previous chapter, there is a sexual double standard in many modern cultures, in which women are evaluated more negatively than men for pursuing and enjoying sexual activity. It could be that social pressure either consciously or unconsciously leads women to report lower levels of sexual interest and arousal than men. An alternative possibility that others have proposed is that male sexual arousal (i.e., erection and pre-ejaculate) is more obvious or is easier to detect and interpret than female sexual arousal (i.e., clitoral blood flow and vaginal lubrica- tion). Yet another possible explanation is that women’s greater genital responsiveness is sim- ply a learned behavior. Specifically, perhaps heterosexual women demonstrate physiological arousal to stimuli of other women because they have grown up in a world that has taught them that women are sex objects.

Figure 4.3 Men have long been thought to be more visually stimulated than women, but recent research suggests that this may not be the case after all. ©Lucky Business, 2016. Used under license from Shutterstock. com.

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So which is the more valid indicator of women’s sexual arousal: genital measures or subjec- tive self-reports? This has been the subject of great debate, with some arguing that we should focus on genital measures because “genitals don’t lie.” However, it is important to keep in mind that people—both male and female—can experience signs of genital arousal without necessarily “feeling” aroused. Sometimes our bodies have responses to stimuli that are dis- connected from our actual feelings and desires. Psychologist Meredith Chivers—one of the most widely published researchers on women’s sexual arousal—has frequently made the anal- ogy that although vegans might salivate at the smell or sight of bacon, it does not necessarily mean that vegans truly want to eat bacon. Thus, we must be careful to avoid concluding that women’s nonspecific genital response pattern means that they are psychologically “turned on” by a wider range of stimuli. Perhaps women’s genitals are responding for an entirely different reason. For example, some have argued that women evolved a nonspecific pattern of sexual arousal because it was adaptive. Known as the preparation hypothesis, the basic idea is that women became genitally responsive to all sexual cues in order to reduce the risk of injury (e.g., vaginal tears) in the event that sex is forced upon them. As some support for this idea, one study found that women demonstrated similar levels of genital arousal in response to consensual and non-consensual sexual scenarios, as well as violent and non-violent sexual scenarios; however, women’s self-reported sexual arousal told a different story, with women only feeling aroused by sex that was described as consensual and non-violent (Suschinsky & Lalumiere, 2011). These results do not necessarily mean that the preparation hypothesis is cor- rect, but they do suggest that genital and self-reported arousal are both important to consider and may not always tap into the same thing.

Smell “I’m coming home. Don’t bathe.” According to legend, Napoleon Bonaparte wrote this to the empress Josephine after winning a military campaign (Williams, 2013)

Our sense of smell can contribute to sexual arousal in two ways: consciously or unconsciously. Sometimes we breathe in a scent and consciously think “her perfume smells lovely,” or “his feet reek like moldy cheese,” and these thoughts either put us in or out of the mood. Other times, however, a scent can affect our brain and behavior in ways we do not realize.

Conscious effects are determined by our prior learning experiences and cultural standards. For example, if you previously dated a man you found very sexy and who happened to wear Abercrombie and Fitch cologne every day, you might come to think of that scent as being very sexually pleasing and get turned on any time you catch a whiff of someone wearing that cologne in the future. Thus, the scents you have learned to associate with sex (a la classical conditioning processes) can become powerful triggers of future arousal. However, keep in mind that these need not be artificial scents—some people find natural body odors sexually pleasing, and this is where cultural values and standards come into play. In cultures that do not mask body scents, a person’s own odors or the “smell of sex” may be considered the ultimate turn on (as exempli- fied by the quote from Napoleon Bonaparte that opened this section). In societies that value covering up any natural bodily scents through deodorants, perfumes, mouthwashes, and soaps, those scents will be preferred and “natural” scents may be considered a turn-off. However, there is a double standard when it comes to masking body scents, in that there is a huge market for “feminine hygiene products” designed to cleanse the female genitals, while similar products for men are not nearly as ubiquitous.

In terms of unconscious effects of smell, a growing amount of research suggests that phero- mones affect humans. Pheromones are chemicals secreted by the body that play a role in sexual communication. Anyone who has ever been to a zoo knows that pheromones affect animals, because when the female of a given species is “in heat,” all of the nearby males start going crazy.

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As scientific evidence of this, when male apes and monkeys are exposed to pheromones from the urine of females of their species, the males experience increases in testosterone and exhibit more frequent erections (Snowdon, Ziegler, Schultz-Darken, & Ferris, 2006). As you will see below, human pheromones seem to exist, but the effects do not appear to be quite as dramatic, perhaps because we have a less developed sense of smell than most other animal species.

The portion of the olfactory (i.e., smell) system that processes pheromones in animals is the vomeronasal organ (VNO). We know this because in cases where the VNO has been removed or surgically damaged, sexual behaviors tend to drop off quickly, which further high- lights the important role of smell in animal sexual behavior (Wysocki & Lepri,  1991). Many scientists believe that humans also possess a VNO that is responsive to pheromones (Monti- Bloch, Jennings-White, & Berliner, 1998). The primary source of human pheromones are the apocrine (i.e., sweat) glands in the armpits and pubic region, although scientists are now able to manufacture synthetic versions of human pheromones in the lab, which some companies are bottling and selling.

What evidence do we have that pheromones affect human sexual behavior? The earliest sup- port for this idea came from research by Martha McClintock (1971) who found that female college students who lived together in close quarters exhibited menstrual synchrony. That is, the women eventually started to get their periods around the same time, which was thought to stem from women’s exposure to each other’s pheromones. In a subsequent study, female participants had the sweat of another woman regularly applied to their upper lip several times per week for four months. (The things people will do for science!) Over time, the women who received the sweat applications showed more menstrual synchrony than control subjects (Preti et al., 1986).

The concept of menstrual synchrony has been questioned in recent years, though. Other studies have failed to replicate the effect and concerns have been raised about the method- ological and statistical procedures employed in earlier research (Strassman,  1999); however,

Figure 4.4 Other people’s scents can turn us off or on; however, we may not always consciously recognize when this is happening. ©Inspirestock International/123RF.COM.

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lay-belief in the idea remains strong, largely because people do not seem to understand how far apart the onset of menstruation should be for women with independent cycles. As explained by Strassman (1999), “given a cycle length of 28 days (not the rule—but an example), the maxi- mum that two women can be out of phase is 14 days. On average, the onsets will be 7 days apart. Fully half the time they should be even closer. . .Given that menstruation often lasts 5 days, it is not surprising that friends commonly experience overlapping menses, which is taken as personal confirmation of menstrual synchrony” (p. 579). In other words, while many people have personal experiences that lead them to believe in menstrual synchrony, the reality is that the observed “effect” may simply be due to random chance.

That said, more convincing evidence for the effects of human pheromones comes from two placebo-controlled studies in which men (Cutler, Friedmann, & McCoy,  1998) and women (McCoy & Pitino,  2002) were randomly assigned to wear either synthetic phero- mones or a non-pheromone, placebo solution on a daily basis for several weeks. During this time period, participants regularly reported on their sexual activities. For both male and female participants, those who wore pheromones reported having more sex than those who wore the placebo.

Naturally, you might wonder whether these pheromone effects are specific to heterosexual individuals, or if they might also have effects in gays and lesbians. There is some fascinating research suggesting that people of all sexual orientations pick up on pheromones. For instance, in one study, participants were asked to rate the pleasantness of armpit sweat collected from heterosexual and homosexual men and women (Martins et al.,  2005). Without knowing the source of the odors, heterosexual men and women least preferred the odors of gay men, while gay men least preferred the odors of heterosexual men. Pheromones may thus represent a sub- tle way of helping us to identify compatible sexual partners. Further evidence for this idea comes from neuroscience research finding that the way people’s brains process pheromones depends upon both their sex and sexual orientation (Lübke, Hoenen, & Pause, 2012).

In light of such findings, some people have actually started hosting so-called “pheromone parties,” in which all attendees bring a tee-shirt they have worn for several days. The shirt is placed in a sealed plastic bag that has an identification number on it. Other attendees sniff the contents of the bags without knowing who they belong to and choose their date based solely on smell. Whether these parties actually lead people to select partners with whom they have better relationships remains an open scientific question, though.

It is important to emphasize that the effects of pheromones on sexual behavior are often completely unconscious (McClintock, 2000). That is, we do not have to consciously perceive a scent in order for it to change our behavior, which means that pheromones may be driving sexual behavior more than we possibly know. For more information on the potential sexual effects of pheromones, see the Digging Deeper 4.1 box.

On a side note, what happens when someone’s sense of smell is not working? Research on isolated congenital anosmia (ICA), a condition in which a person lacks a sense of smell from the time of birth, has revealed that men with ICA report fewer sexual partners as adults than men with a functional sense of smell (Croy, Bojanowski, & Hummel, 2013). To the extent that ICA prevents men from picking up on pheromones, that could explain the lower number of partners; however, this effect may also be attributable to the fact that the lack of a sense of smell may make people feel more socially insecure because they are unable to determine if they have unpleasant breath or body odor.

Hearing The role of sound in sexual arousal is perhaps the most variable of all of the senses. Many peo- ple like to hear their partners moan and groan, others enjoy “dirty talk” or listening to music,

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Digging Deeper 4.1 Do Birth Control Pills Make Exotic Dancers Less Appealing To Men?

Most women know that being on “the pill” may have sexual side effects, such as decreased libido and reduced sexual enjoyment. However, the sexual side effects of oral contraceptives do not stop there. In fact, being on the pill can potentially impact the amount of money a woman can make from a night of exotic dancing!

In a titillating study (pun intended) of professional female lap dancers, researchers found that naturally ayaling women (i.e., women who were not taking a hormonal contraceptive) experienced an increase in tips when they were ovulating; women on the pill did not show a similar peak in their earnings at any time of the month (Miller, Tybur, & Jordan, 2007). This difference translated to real money too—naturally cycling women earned an average of just over $354 (USD) per shift while ovulating, compared to a more modest $200 per shift for women on the pill.

However, we cannot definitively say why some of these women made more money than others. Did ovulating lap dancers alter their behavior in ways that made them more attractive and tip-worthy? Or were their male customers able to detect when the dancers were ovulating, and this made them more willing to part with their cash? It is probably a bit of both. For instance, research shows that ovulating women tend to dress more sexily and show more skin (Haselton, Mortezaie, Pillsworth, Bleske-Rechek, & Frederick, 2007). So, perhaps the ovulating dancers chose to wear more sensual or revealing outfits (or no outfits at all!). The answer may also be a function

Figure 4.5 Being on the pill can potentially impact the amount of money women make from exotic dancing. ©chaoss/123RF.COM.

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and some prefer no sound at all when they are between the sheets (or where ever it is that they like to have sex). These individual preferences for sound are often established through learning (e.g., if a partner repeatedly talks dirty to you when you are aroused, or if you watch porn with a lot of raunchy language while masturbating, you may come to prefer this kind of sound during future sexual activity).

Making sounds during sex can be helpful for letting your partner know what does and does not feel good. Thus, you can use it to enhance your own sexual experience. However, sounds can also be used to facilitate your partner’s sexual response. In fact, research has found that, among heterosexual couples, men perceive the sounds that women make during sex (known scientifically as female copulatory vocalizations) to be very sexually arousing and these noises help to facilitate men’s orgasms (Levin, 2006). Women seem to know this because they consciously report vocalizing during sex in order to increase a male partner’s enjoyment and help him climax faster (Brewer & Hendrie, 2011).

On an interesting side note, researchers have found that the females of most species are much more vocal than the males during sexual activity (Hamilton & Arrowood,  1978). We do not know why females make more noise, but some scientists have suggested that this finding is evi- dence of a non-monogamous approach to mating among both humans and primates, whereby the female “announces” her sexual availability to other potential suitors (Ryan & Jetha, 2010).

Given the important role that hearing plays in both sexual communication and sexual arousal, it should not be surprising to learn that persons who develop hearing loss often report changes in sexual functioning. For instance, research has found that men who acquire bilateral hearing loss report having more erectile difficulties than men who have not lost hearing (Bakir et al., 2013).

Taste Taste can affect sexual arousal, although its effects can be somewhat hard to separate from those of smell because these two senses are highly intertwined. For example, you have probably found that food does not have nearly as much flavor when you have a stuffy nose, because your sense of smell is diminished. As with smell and hearing, taste can be very specific to the indi- vidual in terms of what is sexually pleasing. For example, some people enjoy the taste of natural bodily secretions (e.g., semen, vaginal fluids), whereas others find them to be a turn off. In fact, some people insist on covering up any natural bodily tastes through the use of flavored lubri- cants, mouthwashes, and mints. Taste can also contribute to arousal to the extent that people incorporate food with sex. If you try this, just be careful not to condition yourself to experience arousal every time you eat!

of pheromones. Research shows that men experience a bigger increase in testosterone levels after sniffing shirts worn by ovulating women than after sniffing shirts worn by nonovulating women (Miller & Maner, 2010), suggesting that men may subconsciously pick up on female ovu- lation through their noses. Thus, the amount that men tip an exotic dancer may not only depend upon her looks, but how she smells.

Either way, whatever it is that leads ovulating dancers to receive bigger tips appears to be wiped out when women are on the pill.

Note: Reprinted with permission from Saienae on RelationsTips (www.scienceofrelationships.com).

Digging Deeper 4.1 (Continued)

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Hormones

In addition to the brain and sensory processes, several hormones play an important role in sexual arousal. In particular, we will consider the effects of testosterone, estrogen, and oxytocin.

Testosterone Testosterone is a steroid hormone secreted by both the gonads and the adrenal glands. Many people think of testosterone as a “male” sex hormone; however, this could not be further from the truth. Both men and women produce testosterone, and it has a number of impor- tant effects in each sex. Most testosterone is produced in the testes and ovaries, with a much smaller amount released by the adrenal glands. Although men produce more testosterone than women, women do not need the same amount as men for normal functioning because women’s bodies are more sensitive to it (Bancroft, 2002).

As we will discuss in the next chapter, the presence or absence of testosterone prenatally affects internal and external development of the genital structures. In addition, prenatal expo- sure has important effects on how the brain is organized. Testosterone is thus vital during certain critical periods in order for typical sexual development to proceed. Unusually high or low testosterone levels during these critical periods, may contribute to variations in gender identity, sexual orientation, and degree of psychological masculinity and femininity. We will explore these effects in more detail in chapters 5 and 6.

Our primary concern in this chapter is with the effects of circulating levels of testoster- one on people’s sexual behaviors in adolescence and adulthood (i.e., testosterone’s activating effects). Testosterone has clear effects on men’s levels of sexual desire and their sexual behav- iors. For example, men who have had their testes (i.e., their primary source of testosterone) removed through castration (known in medical terms as orchidectomy) typically experience a loss of libido and have a more difficult time achieving erections (e.g., Shabsigh, 1997). Not all castrated men experience these effects, though; at least a few of them retain some degree of sexual interest and behavior afterward. Such findings indicate that while testosterone

Figure 4.6 Why do female humans and animals vocalize more during sexual activity than their male counterparts? ©PhotoMediaGroup, 2016. Used under license from Shutterstock.com.

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production by the testes has important sexual effects in most men, it is not the sole factor influencing sexual behavior.

Additional evidence for the important role of testosterone in male sexual arousal comes from studies of men with hypogonadism, a physical condition in which testosterone produc- tion is significantly diminished. This may occur as a result of a specific disease process, or as a natural result of aging (although there is no true “male menopause,” men usually expe- rience a gradual decrease in the production of sex hormones with age). Regardless of the reason, men with very low levels of testosterone typically have less sexual desire (Hintikka et al., 2009). Low testosterone is also linked to depression, though, which means it is possible that mood changes might really be the key factor affecting desire here; however, it might also be the case that low desire negatively impacts mood. Either way, these effects can potentially be reversed through testosterone replacement therapy, in which supplementary testosterone is administered (Wang et al., 1996). This has become an increasingly common treatment for low libido in men, although the potential long-term health implications and side effects are not well-understood yet.

Testosterone is also related to sexual desire in women. For instance, women who have their ovaries (i.e., their primary source of testosterone) removed through an oophorectomy fre- quently experience low libido and difficulties becoming sexually aroused (McPherson et al.,  2005). However, testosterone replacement therapy reverses these effects, increasing both sexual desire and activity (Simon et al.,  2005). Likewise, older women who have gone through menopause naturally appear able to restore lost sexual desire through supplementary testoster- one (Spark, 2002). However, more recent research suggests that testosterone replacement is only effective at increasing women’s libido when administered jointly with estrogen, suggesting that testosterone is not the only hormone involved in female sexual desire (Cappelletti & Wallen, 2016).

Figure 4.7 Testosterone replacement is sometimes used as a treatment for low libido in both men and women. ©Public domain image, via Wikimedia Commons.

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While the above discussion might lead you to believe that there is a perfectly linear relation- ship between testosterone and sexual desire (i.e., as testosterone levels increase, so does libido), this does not appear to be the case. In fact, testosterone is really only linked to difficulties with sexual arousal and desire when hormone levels are extremely low, such as when some- one’s gonads have been removed or when one is very advanced in age. When scientists look at healthy young adults with testosterone levels in the normal range, they do not see a positive correlation between testosterone and desire for partnered sex in either men or women (van Anders,  2012). This tells us that the amount of testosterone necessary for producing sexual desire can vary considerably from person to person.

Physical and Chemical Castration as Treatments for Sex Offenders Because testosterone plays such an important role in generating sexual arousal and behavior, many legal systems around the world have contemplated instituting treatments that would significantly reduce testosterone levels in convicted sex offenders with the hope of decreasing the likelihood of convicts committing future crimes. Physical castration is obviously a drastic and controversial step, and public opinion about it is very polarized. Some people see castra- tion as cruel and unusual, while others think it is a fitting punishment for sex crimes. Physical castration for sex offenders is relatively rare these days and is generally only performed on a voluntary basis. For example, in Germany, the Czech Republic, and certain parts of the United States, convicted sex offenders can voluntarily seek castration as a means of bargaining for reduced sentences (BBC News Europe, 2012; Sealey, 2012).

Lately, the trend has been to offer chemical castration instead of or as an alternative to physi- cal castration. Chemical castration involves administering anti-androgen drugs that block the production of testosterone. One of the most commonly used drugs of this nature is Depo- Provera. While some countries offer chemical castration on a voluntary basis (e.g., the United States and several European nations), others, such as South Korea (Woo-young,  2011), have enacted laws that force convicted sex offenders to take these drugs. Chemical castration is con- troversial, with some people questioning whether it is a violation of human rights and others worried about its effectiveness, because both physical and chemical castration do not always have predictable results when it comes to sexual behavior. As a result, castration should not necessarily be the only treatment considered for sex offenders. We will consider other options in chapter 14.

Estrogen Like testosterone, estrogen is also a steroid hormone produced by the gonads and adrenal glands. Although it is often described as a “female” sex hormone, it is produced in both men and women; however, women’s bodies make more of it than men. For a long time, scientists— and pharmaceutical companies, too, for that matter—did not think estrogen played much of a role in sexual desire, which led them to focus primarily on developing testosterone-only thera- pies for treating low libido. However, recent research suggests that testosterone and estrogen each have important roles to play in this area.

As some evidence of this, consider a tightly controlled experiment in which healthy men aged 20–50 allowed scientists to tinker with their hormone levels (Finkelstein et al.,  2013). These researchers found that deficient levels of testosterone and estrogen were each linked to problems with sexual desire and arousal, indicating that men do not need just one hormone or the other—they need both. Likewise, studies of hormone replacement in postmenopausal women reveal that, while estrogen-only therapies can increase sexual desire, administering tes- tosterone jointly augments the effectiveness of these treatments (Cappelletti & Wallen, 2016).

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Although we still have much more to learn about the complex ways these hormones work together to affect sexual functioning, it seems clear that we can no longer look at just one of them in isolation.

Oxytocin Oxytocin is a neuropeptide hormone manufactured in the brain that has a wide range of effects on human sexual behavior. Perhaps its best known function is to assist in the release of milk during breastfeeding. However, oxytocin is increasingly being recognized as playing a vital role in developing bonds between romantic and sexual partners because it is released during physical intimacy (we will return to this topic in chapter 7 when we discuss sexual attraction). For this reason, oxytocin is sometimes referred to in the popular media as the “love hormone” or “cuddle drug.”

In addition to helping generate bonds and attraction, oxytocin plays at least some role in sexual arousal. For example, research on male rats has found that oxytocin injections pro- duce erections (Gimpl & Fahrenholz,  2001). Likewise, a few recent case studies of humans have found that oxytocin administered via a nasal spray produced unexpected increases in sexual desire and activity. In one study, a woman was given oxytocin to assist in breastfeeding (Anderson-Hunt & Dennerstein, 1994), and in another study, a man with Asperger’s syndrome (a DSM-IV diagnosis, now labeled “Social Communication Disorder,” in which social interac- tion abilities are impaired) was given oxytocin to improve his social functioning (MacDonald & Feifel, 2012). In both cases, the changes in sexual interest and behavior were dramatic. How- ever, these sexual effects disappeared once the hormone treatments stopped. Although these results are far from conclusive (recall the limitations of case studies discussed in chapter  2) and more research on this topic is needed, these findings suggest that oxytocin is involved in sexual arousal and that it could potentially be used as a future treatment for individuals who experience low libido.

Figure 4.8 Oxytocin (often referred to as the “cuddle drug”) facilitates sexual and romantic bonding, but it may also play a role in generating sexual arousal. ©sam100, 2013. Used under license from Shutterstock.com.

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Substances

Another factor that affects sexual arousal is the substances that we put into our bodies (e.g., food, drinks, drugs). Substances vary in terms of whether they have inhibiting or facilitating sexual effects. Some substances are aphrodisiacs, which increase sexual desire and behavior, while others are anaphrodisiacs, which reduce sexual arousal and activity. Substances also very in terms of whether their effects are mediated by physiology or psychology. In other words, some substances have a direct effect on arousal by affecting hormone and neurotransmitter levels, while other substances only change people’s behavior because of the placebo effect. Placebo effects occur when people strongly believe that something they are taking will have an effect on them, even if the substance or treatment is biologically inert. When the belief is strong enough, people often end up showing the expected change in behavior. For example, research has found that when depressed patients take a sugar pill that they believe is an actual medica- tion designed to improve their mood, their symptoms improve 75% as much as people who take genuine antidepressant medication (Kirsch & Sapirstein,  1998)! Placebo effects are rampant when it comes to aphrodisiacs because people are often highly motivated to believe they can restore lost desire or enhance their sexual potency by taking a substance or changing their diet.

Aphrodisiacs For centuries, people have believed that various foods possess aphrodisiac qualities. The com- mon theme uniting the most popular foods of this nature is that they bear a striking resem- blance to the penis. You can test this out by doing a quick online search for “aphrodisiacs.” You will soon be able to compile a long list of food products with reported sexual effects that includes bananas, cucumbers, carrots, and asparagus. Also featuring prominently will be foods that resemble the vulva, such as oysters, open figs, and peaches.

Figure 4.9 Oysters are just one of many foods that have been thought to be an aphrodisiac. However, any sexual effects of such foods are likely a result of faith and the power of suggestion. ©Fedor Kondratenko/123RF.COM.

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Beyond this, animal horns and penises are highly sought after in some Asian cultures because they are thought to enhance sexual potency and virility if consumed (Harding,  2006). While horns are usually ground up or powdered, penises can be served in a variety of ways. You can have a penis pickled, in a soup, or even served as fondue (I kid you not!). One of the rarest deli- cacies of this nature is tiger penis. Tiger parts have long been popular in traditional Chinese medicine and are thought to have medicinal benefits. Although tigers are an endangered spe- cies, and trading their parts is illegal in many parts of the world, they are still pursued because of their supposed health benefits, and some people will pay exorbitant sums to get them. In fact, some restaurants in China charge as much as $6,000 for a tiger penis dinner (Harding, 2006)!

Do any of these foods actually enhance sexual desire? Although many people swear by them, we do not have scientific evidence that consumption of these foods in typical quantities gen- erates physiological arousal. Thus, any reported sexual influences of such foods are likely attributable to the placebo effect.

Beyond food, alcohol and drugs have often been considered aphrodisiacs as well. Some of these substances can affect sexual arousal physiologically and psychologically; however, under- standing the sexual effects of drugs is complicated because different drugs have different effects, and the amount of the drug consumed matters greatly (for a summary of the sexual effects of various drugs, see Table 4.1). We will begin with alcohol, which is indeed an aphrodis- iac, but only when it is consumed in small quantities. Alcohol not only reduces our inhibitions, but it can also create expectancy effects, whereby we come to believe that consuming alcohol will put us “in the mood” or make us feel more sexual (Cooper, 2010). If you have ever taken a course in social psychology, you can think of expectancy effects as a self-fulfilling prophecy (i.e., if we believe that some outcome is likely, we will work consciously and unconsciously to make it a reality). However, when alcohol is consumed in very large quantities it has a depressing effect on sexual arousal and makes it more difficult for both men and women to reach orgasm. Chronic alcohol abuse can also contribute to sexual dysfunction. We will explore the sexual effects of alcohol use in more detail later in this book when we discuss sexual difficulties (chapter 13) and sexually transmitted infections (chapter 12).

Aside from alcohol, people sometimes turn to other drugs (some legal and others illegal) to enhance their sexual experience, including Ecstasy, “poppers,” marijuana, and Viagra. First, Ecstasy (the popular name of methylenedioxymethamphetamine or MDMA): this is a

Table 4.1 Sexual effects of several alleged aphrodisiacs.

Substance Sexual effects

Alcohol Through both a reduction in inhibitions and expectancy effects, alcohol can be a mild aphrodisiac in small doses. In larger quantities, alcohol has a depressant effect on arousal and orgasm in men and women.

Ecstasy (MDMA) Users report enhanced desire and more intense orgasms, but also erectile difficulties and delays in reaching orgasm.

Marijuana About half of users report increased libido and greater sexual pleasure; the other half do not. Effects depend upon the strain of the drug used, the amount consumed, and individual sensitivity to marijuana.

Poppers (amyl nitrate)

Users who inhale poppers report more intense orgasms, but some men experience temporary erectile difficulties.

Viagra Creates a capacity for erection in men. Linked to the release of oxytocin in male rats; unknown if similar hormonal effects occur in humans.

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popular club drug that seems to enhance sexual desire and produce more intense orgasms in recreational users (Zemishlany, Aizenberg, & Weizman, 2001). At the same time, however, it is linked to reports of erectile difficulties in a large number of men and often delays male and female orgasm.

Second, “poppers” (amyl nitrate): this is an inhalant that users have reported as intensifying the experience of orgasm (Everett, 1972). “Poppers” have been used in the club scene for dec- ades, particularly by people who practice anal sex (because it supposedly enhances pleasure from this activity). Common side effects for users include headaches, nausea, and temporary loss of erection (Wood, 1983).

Third, marijuana: this is a widely used drug that does not have consistent sexual effects on those who consume it. For example, in one study of recreational marijuana users in Canada, about half of the participants reported that marijuana increased libido and enhanced sexual pleasure, while the other half reported no such effects (Osborne & Fogel,  2008). In other research, a majority of men reported that marijuana enhanced their sexual stamina (Shamloul & Bella,  2011); however, it is unclear whether the drug actually had that effect or if it simply affected men’s perception of time. In other words, it is possible that marijuana might lead peo- ple to think that sex lasts longer without objectively changing the amount of time people spend on sex. So why does marijuana seem to have inconsistent sexual effects on users? There are at least three reasons for this: people use different strains of marijuana (some are more relaxing, whereas others are more stimulating), they consume it in different quantities (larger doses are linked to more negative effects), and people’s sensitivity to the drug varies (some people’s bod- ies are simply less tolerant of it). Because there are so many variables in play here, it has been difficult to obtain a clear understanding of marijuana’s sexual effects.

We do not fully understand why any of these drugs have the sexual effects they do, but at least part of the reason is likely attributable to neurochemical changes (indeed, many of these drugs have been linked to increased dopamine release) and, just as with alcohol, expectancy effects probably play a role. As you can see from this discussion, there appear to be at least some aphrodisiac-like properties of many recreational drugs, but the effects are not necessarily con- sistent across persons and are often counterbalanced by negative effects on sexual response.

One other drug we should mention here is the erectile dysfunction medication Viagra, which is available by prescription only. A growing number of men are taking Viagra or one of its sister medications (e.g., Cialis, Levitra) recreationally because they believe it will increase their sex- ual pleasure. The primary effect of the drug (which we will discuss in more detail in chapter 13) is to create the capacity for an erection. Contrary to popular belief, Viagra does not give men an automatic erection—sexual stimulation is still required. Traditionally, the medical commu- nity has not viewed Viagra as an aphrodisiac because there was no evidence that it increased sexual desire. However, research has found that Viagra stimulates the release of oxytocin in the brains of male rats (Zhang, Klyachko, & Jackson, 2007). If subsequent research confirms that Viagra leads to the release of more oxytocin in humans, we may one day see it discussed as an aphrodisiac.

Anaphrodisiacs In recent years, some scientists have shifted their focus from identifying substances that increase sexual desire to those that curb it. Why would anyone want a lower sex drive? There is medical and political interest in uncovering safe and effective anaphrodisiacs that could poten- tially be used to stop rapists and other sex offenders from committing future crimes, but also to help reduce sexual desire in people with hypersexuality (i.e., “excessive” sexual behavior that causes personal distress). Right now, the most promising anaphrodisiacs available for dealing

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with such issues are Depo-Provera and SSRIs. Drugs like these can successfully lower sexual desire by reducing levels of testosterone (Depo-Provera) or enhancing the amount of serotonin in the brain (SSRIs).

The Sexual Response Cycle

Now that you have an understanding of the factors that affect sexual arousal, let us turn to the topic of sexual response and consider the internal and external bodily processes that occur once sexual arousal begins.

The Masters and Johnson Model

The most widely known and discussed model of human sexual response was developed by Masters and Johnson (1966). As the basis for their model, they observed more than 10,000 complete sexual cycles of men and women and found that sexual arousal and response followed a predictable pattern. There are certainly many individual differences when it comes to sex and sexuality, but with respect to patterns of physical responding, human beings are more similar than you might expect.

Masters and Johnson specified four phases in their model: excitement, plateau, orgasm, and resolution. In reality, it may be hard to pinpoint exactly when one phase ends and another begins, so you should not think of these as four truly separate phases—rather, these phases are labeled to help simplify and explain the numerous processes that occur in the body during sexual activity. Please keep in mind that although many of Masters and Johnson’s observa- tions have held up over time, some have not, which means that their model is not universally accepted. After detailing this model, we will address its limitations and consider a few alterna- tive models.

Excitement The excitement phase marks the start of sexual arousal and is characterized by two physiologi- cal processes that begin here and are carried through the remaining phases. First, vasocon- gestion refers to an increase in blood flow to bodily tissues (in this case, the genital tissues). The most obvious physical manifestation of this in men is erection of the penis, which occurs as the cavernous and spongy bodies fill with blood. In women, the clitoris, labia, and uterus become engorged and increase in size. Across the sexes, these physical changes ebb and flow throughout the excitement phase (e.g., a man’s penis may vacillate between partially and fully erect) depending upon the level of stimulation. Second, myotonia refers to the voluntary and involuntary tensing and contracting of muscles both in the genital region and throughout the rest of the body.

Other physical changes that occur during excitement include increases in heart and breath- ing rate, as well as the sex flush, the increasingly reddish appearance of the chest and torso during arousal. The sex flush does not occur in everyone and often appears more prominently in women than it does in men. Additional changes that men experience include a tightening of the scrotal skin and elevation of the testes closer to the penis. In women, the vagina expands in length and the vaginal walls begin to lubricate.

The trigger for sexual excitement and the length of this phase varies widely across per- sons and situations, lasting from a few moments to a few hours. In some cases, excitement may  be preceded by physical stimulation from the self (e.g., masturbation) or from a partner

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(e.g., kissing). Alternatively, excitement may be the result of a visual stimulus (e.g., pornogra- phy), a substance (e.g., an aphrodisiac), or a cognitive process (e.g., sexual fantasy). Excitement is thus a biopsychosocial event.

Plateau As excitement continues, an individual enters the plateau phase, during which sexual tensions continue to mount. The plateau phase is really an extension of the excitement phase, and is charac- terized by vasocongestion and myotonia becoming more pronounced. Several sex scientists have argued that discussing excitement and plateau as two separate events is unnecessary (e.g., Levin & Riley, 2007), which is why some textbook authors combine their descriptions of these phases.

In men, the major bodily changes that occur during this stage include a complete erection, fully engorged and elevated testes, and the secretion of pre-ejaculate by the Cowper’s gland. In women, the major changes include swelling of the nipples and areola, complete expansion and lengthening of the vagina, retraction of the clitoris into the body, and the development of the orgasmic platform, which refers to the increased swelling of the outer third of the vagina. In addition, both men and women experience continued increases in heart and breathing rates and a deepening of the sex flush. Overall, the plateau phase can last anywhere from a few sec- onds to a few minutes depending upon the individual and the situation. However, prolonging this phase (known colloquially as “edging”) may enhance the pleasure of a subsequent orgasm.

Orgasm If appropriate sexual stimulation continues, an individual may experience orgasm, during which the muscles around the genitals make a series of brief, rhythmic contractions. In men, orgasm usually coincides with ejaculation; however, it is possible for men to orgasm without ejaculating and, in very rare cases, ejaculate without orgasming (known as ejaculatory anhedonia). Ejacula- tion occurs when the accumulated secretions of the vas deferens, seminal vesicles, and prostate gland are released into the urethra and expelled from the body. In women, the orgasmic platform and uterus contract several times, and this may or may not be accompanied by an expulsion of fluid (as discussed in chapter 3). Bodily changes during orgasm are not limited to the genitals, though. Other changes that may occur include increases in heart rate and breathing rate, as well as various forms of myotonia, including facial grimaces (i.e., the “O” face) and contractions of muscles in other parts of the body (e.g., the toes or fingers may curl). For men, orgasm pretty consistently follows the plateau phase. In fact, it is rare for men not to experience orgasm during sexual activity. In comparison, many women do not regularly reach climax, especially when vagi- nal intercourse is the only form of stimulation (Fugl-Meyer, Oberg, Lundberg, & Lewin, 2006).

When orgasm occurs, it is quite brief, lasting just a few seconds in most cases. Male and female orgasms are similar in length, although there is significant variability both within and between persons, with orgasms varying in intensity, number of contractions, and duration. Even though orgasms are quite brief, those few seconds are usually extremely pleasurable to both men and women. In fact, research suggests that the psychological experience of orgasm is virtually identical across the sexes. Several studies have been conducted in which participants have been asked to guess whether written descriptions of what an orgasm feels like were pro- vided by men or by women (Vance & Wagner, 1976; Wiest, 1977). Regardless of whether the judges in these studies were college students or clinical psychologists, participants were unable to reliably determine which descriptions were written by which sex, indicating that orgasms appear to be processed by the brain similarly among men and women.

It is worth noting that orgasms are not always preceded by sexual activity or masturbation— indeed, they can happen independent of any genital stimulation at all! For example, some people can reach orgasm through thought and mental imagery alone (Komisaruk & Whipple, 2012). In addition, many people—both male and female—have experienced orgasms during

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sleep, sometimes referred to as nocturnal orgasms or nocturnal emissions. Although Kinsey’s research suggested that nocturnal orgasms were far more common among men than women, it is possible that this sex difference is not quite as large as it seems due to the fact that female orgasms tend to produce less physical “evidence” than male orgasms.

Theories of orgasm It should be pretty obvious why men experience orgasm. By typically co-occurring with ejacu- lation and the release of semen, orgasm helps to make sexual reproduction become possible. Thus, the male orgasm has a vital biological function. What about the female orgasm? It is not necessary for a woman to reach orgasm in order to get pregnant, which has prompted many to wonder whether it has a purpose. This question has been a topic of debate among sex scientists for decades. Below is an overview of the major theories that have been proposed.

The earliest theories of female orgasm suggested that it served as a “sperm retention mecha- nism.” The thought is that because some amount of sperm is naturally ejected from the vagina after intercourse, orgasm might serve the purpose of retaining as much sperm as possible. There are two main arguments for how this might occur. One is that orgasm increases the like- lihood that a woman will fall asleep after sex, and as a result of lying down, sperm loss will be minimized (Levin, 1981). The other main argument is that the female orgasm induces a “blow– suck” mechanism in which the uterine contractions draw sperm further inside the reproduc- tive tract (Fox, Wolff, & Baker, 1970). (By the way, “blow–suck” is a technical term used in an actual research paper, so you can stop snickering!)

Some research has found support for the sperm retention idea. For example, in one study, researchers asked a sample of women to collect “flowback” (i.e., ejaculate that seeps out after sex), which was then analyzed by the researchers for sperm content (Baker & Bellis,  1993). They found that when women experienced orgasm just before or after her male partner, her flowback contained less sperm than when women did not orgasm at all or had an orgasm well before their partner. Studies like this, although admirable for their creativity, are fraught with some important problems. For instance, how do we know that women collected all of their flowback and did it consistently? We also have no idea how much sperm was initially released in each ejaculation to draw firm conclusions about how much sperm was retained.

The sperm retention evidence is thus not entirely convincing. In addition, this perspective has been criticized on the grounds that if the female orgasm is so adaptive for reproduction, why does it often take women so much longer to climax than men, and why do so few women regularly reach orgasm during vaginal penetration alone? Another evolutionary theory that attempts to account for the fact that the female orgasm does not happen consistently is the mate-choice hypothesis, which argues that the female orgasm is only likely to occur with those men who are the most genetically fit, or who represent the best long-term prospects (Puts, Dawood, & Welling, 2012). The theory is that by reserving orgasm only for the highest-quality mates, orgasm then becomes a reinforcing variable (think operant conditioning here) that encourages continued copulation with those partners, thereby promoting reproductive suc- cess. This might help to explain the fact that women in long-term relationships report having far more orgasms than single women (see chapter 8). Perhaps women are more likely to persist in relationships with those partners who help them reach the most orgasms.

One alternative to these evolutionary theories suggests that women’s climaxes may not serve any biological purpose and may instead be a byproduct of the fact that the male orgasm is so heavily favored by our biology (Lloyd, 2005). To understand this idea, consider that everyone looks the same when they are initially developing in the womb. During the first two months of development, our genital structures are undifferentiated and can potentially develop toward the male or female form depending upon the hormones we are exposed to (see chapter  5). Because everyone’s genitals develop from the same tissues and because nerve structures are

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laid out in such a way as to ensure orgasm if a male develops, the female orgasm may simply by a byproduct of that, much like the male nipple is a byproduct of the fact that women require nipples for breastfeeding. Proponents of this theory thus argue that the female orgasm is noth- ing but a “fantastic bonus” for women.

Sex differences in orgasm Aside from their theorized purpose, male and female orgasms differ in a number of other ways. First, men are more likely to reach orgasm than women, especially during vaginal intercourse. Second, some researchers have suggested that whereas men seem to have just one type of orgasm, women’s orgasms vary considerably in terms of bodily location, intensity, and whether there is an emotional aspect to it (e.g., Hite, 1976). For example, as discussed in chapter 3, some women reach orgasm during vaginal insertion, while others require clitoral or G-spot stimula- tion, and yet others require nipple stimulation. Moreover, researchers have found that women have both “good sex” and “not-as-good-sex” orgasms, which have very different physical and psychological components (King, Belsky, Mah, & Binik, 2011). Third, it appears that women are more likely than men to reach orgasm without any genital stimulation at all. For example, scientists have found that some women are able to literally “think themselves to orgasm” and that these thought-induced orgasms produce bodily responses that are very similar in nature to those experienced during genitally induced orgasms (Komisaruk & Whipple, 2012).

Fourth, while women are often able to experience multiple orgasms (i.e., having two or more orgasms during the same sexual event in close succession), this ability has rarely been documented among men. As some evidence of this, a study of over 800 female college graduates found that approximately 43% reported having had multiple orgasms (Darling, Davidson, & Jennings, 1991). By contrast, research on men has found that fewer than 10% have reported this experience (Wibowo & Wassersug, 2016). So why do women seem more likely to have multiple orgasms? This difference is most commonly attributed to sex differences in the refractory period. The refractory period is a span of time following orgasm during which no additional orgasms are possible, regard- less of whether sexual stimulation continues. It is thought that men usually experience a refractory period, whereas women typically do not. Surprisingly little is known about the refractory period, but it is thought that it might have its basis in neurological and hormonal changes that occur in the body following orgasm, such as an increase in oxytocin levels (Levin, 2009). In has been suggested that this period can last anywhere from a few minutes to a few days, depending upon a range of factors, such as age and sexual desire. While some have argued that the male refractory period may be an adaptive trait designed to replenish men’s sperm reserves, research suggests that this is an unlikely explanation due to the fact that it would take quite a while to build sperm levels back up and men are often able to reach orgasm again before that happens.

One other way that male and female orgasms differ is that women are more likely to fake orgasms than are men. Studies have found that between one-half and two-thirds of women have “faked it” at one time or another (Wiederman, 1997), while the percentage of men who admit having done so is much lower (Muehlenhard & Shippee, 2010). Why do women fake orgasms so frequently? Women report a variety of reasons, with some research suggesting that at least some women fake orgasms as part of a “mate retention strategy” to keep their partners from cheating (Kaighobadi, Shackelford, & Weekes-Shackelford, 2012). In this research, the women who were the most likely to fake orgasms were also the most likely to fear that their partners would cheat on them. Could faking orgasms really help keep your partner around? Theoretically, it is possi- ble. As previously discussed, men tend to find women’s moaning and groaning sexually exciting and this may even enhance men’s own orgasms (Levin, 2006). Thus, if a man does not know he is being deceived and his pleasure and excitement is enhanced by his partner’s pretend orgasms, faking may indeed reduce the likelihood that he will stray. To learn more about faking orgasms and to reflect on your own views on this issue, see the Your Sexuality 4.1 box.

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The aforementioned differences in likelihood of orgasm and ability to experience multiple orgasms have the effect of generating substantial variation in how the typical male and female sexual response cycle plays out. Whereas men’s responses tend to follow the sequential pat- tern of excitement, plateau, orgasm, and resolution, women’s responses have the potential to be far more variable. Table 4.2 provides an overview of some of the different patterns that may emerge in women’s sexual response.

Resolution The last phase of the sexual response cycle is resolution, which occurs once all stimulation stops. Resolution involves the return of the genitals to their nonaroused state (e.g., the penis becomes flaccid again, the orgasmic platform disappears, heart rate and breathing rate slow). Resolution can follow any of the previous phases (i.e., you do not necessarily have to reach orgasm to enter resolution). The length of this phase can take anywhere from a few minutes to a few hours, but it typically occurs more quickly in older adults than it does in younger persons (Nusbaum, Lenahan, & Sadovsky,  2005). Behaviors during the resolution phase vary. Some people relax or sleep, others make a sandwich or have a snack, and yet others express physical intimacy (if resolution follows a partnered sexual act). Contrary to popular belief, there is no scientific evidence to support the stereotype that men typically fall asleep immediately after sex while women stay awake wanting to cuddle. In fact, research finds that men and women

Your Sexuality 4.1 Faking Orgasms: Who Benefits More From a False Finish?

According to Meg Ryan’s character in WTen Harry Met Sally, “Most women at one time or another have faked it.” By “it” she was referring to the seemingly elusive female orgasm. And she was right—studies consistently show that most women have faked a climax at some point (Wieder- man, 1997). What may surprise you is that men fake orgasms at least some of the time too. In fact, one study found that one in four male college students admitted pretending to orgasm at least once (Muehlenhard & Shippee,  2010). It makes sense that men fake it less often than women, given that men are much more likely to reach orgasm in the first place and because men produce more physical “evidence” when it happens, making it harder to fool a sexual partner.

So why would someone pretend to climax? People report a variety of reasons for faking it, from the understandable (e.g., lack of sexual experience) to the unfortunate (e.g., lack of attraction to one’s partner). However, when it comes to discussing motivations for faking, it is important to recognize that men and women are similar in some ways, but very different in others.

For instance, the sexes are equally likely to report having pretended orgasm because they felt an actual orgasm was unlikely to happen (e.g., they were overly intoxicated or it was just taking too long). In comparison, men are more inclined to say they faked it because they just wanted sex to end (e.g., they were tired), whereas women are more inclined to say they did so because they wanted to improve a partner’s self-esteem or avoid hurt feelings.

To sum it up, both men and women fake orgasms sometimes, but women do it more often and frequently see it as a way to protect their partners from getting hurt. When men fake it, they are more likely to see it as a way to exit an undesirable or uncomfortable situation. Thus, no matter who fakes it, the resulting “show” would appear to benefit men (or their egos) more than it does women.

What do you think about fake orgasms? Have you ever or would you ever “fake it?” Do you think faking can potentially be a good thing in some cases, or would honest communication always be preferable? If one of your partners had faked an orgasm with you, would you want to know?

Note: Reprinted with permission from Saienae on RelationsTips (www.scienceofrelationships.com).

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are equally likely to report being the first one to fall asleep after sex (Kruger & Hughes, 2011)! Those who stay awake to express intimacy may be better off than those who sleep, though. In fact, longitudinal research has found that the more cuddling, “spooning,” and intimacy that couples engage in after sex, the more satisfied they are with both their sex lives and relation- ships (Muise, Giang, & Impett, 2014).

Psychological Models of Sexual Response

As previously noted, the Masters and Johnson model of sexual response is not universally accepted. One of the most common criticisms of it is that it is purely biological, giving no con- sideration to the psychological aspects of sexual arousal and response. For example, how does sexual desire factor into this equation? In this section, we will consider two theories that have attempted to incorporate psychology into the Masters and Johnson approach.

The Triphasic Model of Sexual Response Noted sex therapist and author Helen Singer Kaplan (1974) introduced a three-stage model of sexual response that streamlined the Masters and Johnson model, while adding a psychological component. Kaplan also reconfigured the model so as to make it more applicable to the treat- ment of sexual disorders.

The first stage in Kaplan’s model is sexual desire. Kaplan reasoned that sexual response is not likely to occur unless someone wants to have sex—in other words, something needs to precede excitement. Sexual desire is the most novel part of Kaplan’s theory because it is psychological in nature. Desire is a product of many psychological factors, including emotions, stress, prior learning experiences, body image, and so forth. Of course, biological factors (e.g., hormones) play a role in desire as well, but psychology has at least as large of an effect on the drive to pur- sue sexual activity.

Following desire is excitement. In this phase of the model, Kaplan simply combined the excitement and plateau phases of the Masters and Johnson model because she saw little to dis- tinguish between them, especially from the perspective of treating sexual problems. The final phase of this model is orgasm. Kaplan’s discussion of sexual response stopped here because people rarely experience problems during the resolution phase, which makes it of little interest to sex therapists.

Table 4.2 Potential variations in female sexual response.

Variation Sexual response pattern

Four-Phase Pattern (Typical Male Pattern)

Excitement Plateau Orgasm Resolution

Prolonged Plateau, No Orgasm

Excitement Plateau Resolution

Multiple Orgasm (Variation 1)

Excitement Plateau Orgasm Resolution to Plateau

Orgasm Final Resolution

Multiple Orgasm (Variation 2)

Excitement Plateau Orgasm Resolution to Plateau

Orgasm Resolution to Plateau

Orgasm Final Resolution

Note: In the multiple orgasm variations, additional orgasm are experienced most quickly when the resolution phase only lasts long enough to return arousal back to plateau levels. If arousal dips back to excitement levels, producing additional orgasms will require greater stimulation.

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Kaplan’s view was that sexual problems could occur at any stage of the model and that prob- lems in one stage do not necessarily translate to problems in other stages. For example, although one might have hypoactive sexual desire disorder (i.e., low levels of sexual desire), one may still be able to have a physical sexual response. Identifying the stage at which the problem occurs is necessary for understanding and treating cases of sexual dysfunction because different parts of the brain and body are involved at each stage.

Although Kaplan’s model has been a popular alternative to the Masters and Johnson approach, it is not without its detractors. Perhaps its most controversial aspect is the emphasis on sexual desire. Even in someone who is free of sexual dysfunction, desire is not a necessary precursor for sexual response (e.g., desire may develop after sexual activity has begun, a phenomenon known as responsive desire).

The Erotic Stimulus Pathway Theory Building upon the work of both Masters and Johnson and Kaplan, psychiatrist David Reed proposed the Erotic Stimulus Pathway Theory (Keesling, 2004). There are four stages in this model: seduction, sensations, surrender, and reflection. The first phase, seduction, is akin to the desire stage of Kaplan’s model and refers to the set of processes that stimulate sexual activity. In this case, however, desire is viewed as stemming from the behaviors we employ to attract (or “seduce”) other people. This can include spending a lot of time on one’s personal appearance or flirting with someone. Seduction ultimately gives way to sensations, a phase that roughly corresponds to what Masters and Johnson termed excitement and plateau. Here, sensory input (vision, touch, hearing, smell, and taste) and our sexual fantasies combine to create a height- ened sense of arousal that makes us want to continue sexual activity. In these first two phases, psychological factors are seen as propelling physiological responses.

Ultimately, we reach the peak of arousal and give into (or surrender) to orgasm; however, our ability to give up control affects this response. Some people may have a more difficult time “letting go” than others (e.g., they may feel vulnerable or distracted). Following this is the reflection phase, during which we psychologically reinterpret our sexual experiences and give them meaning. Depending upon the individual, that person may attach a positive or negative meaning to the event, which will affect the likelihood of pursuing this partner specifically and sexual activity more generally in the future.

As you can see, although this model shares some degree of overlap with the other models (for a summary of all three models, see Table 4.3), it may have swung too far in the opposite direction, because it focuses almost exclusively on the role of psychology and cognitive factors, while giving little attention to physical responses. Going forward in this book, we will not nec- essarily emphasize one of these models over the other, but rather we will pay attention to the unique points and perspectives that each has to offer. As you will see throughout this text, it is almost never the case that one perspective is “correct” and the others are wrong; rather, differ- ent theories seem to explain different pieces of the puzzle.

Table 4.3 Comparing different models of sexual response.

Researcher(s) Stages of sexual response

William Masters and Virginia Johnson Excitement Plateau Orgasm Resolution Helen Singer Kaplan Desire Excitement Orgasm David Reed Seduction Sensations Surrender Reflection

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Key Terms

limbic system cerebral cortex dopamine serotonin primary erogenous zones secondary erogenous zones female copulatory

vocalizations pheromones

vomeronasal organ (VNO) testosterone castration hypogonadism oophorectomy chemical castration oxytocin aphrodisiacs anaphrodisiacs

placebo effect excitement vasocongestion myotonia plateau orgasmic platform orgasm refractory period resolution

Discussion Questions: What is Your Perspective on Sex?

● Should chemical castration be mandated for sex offenders to reduce the likelihood that they will commit crimes in the future? Explain your answer.

● Have you ever tried an aphrodisiac? Did it work as you expected? Why do you think it turned out the way that it did?

● What is your strongest sexual sense? Why do you think this is the case (e.g., biological or evolved predisposition, social learning)?

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