Masters and Johnson’s Four-Phase Model

Masters and Johnson distinguish four phases in the sexual response patterns of both men and women: excitement, plateau, orgasm, and resolution. I Figures 6.3 and 6.4 illus­trate these four phases of sexual response. These charts provide basic maps of com­mon patterns characterized by strong similarities in the responses of men and women to sexual stimuli. Masters and Johnson did, however, note one significant difference between the sexes: the presence of a refractory period (a recovery stage in which there is a temporary inability to reach orgasm) in the male resolution phase.

The simplified nature of these diagrams can easily obscure the richness of individual variation that does occur. Masters and Johnson were charting only the physiological responses to sexual stimulation. Biological reactions might follow a relatively predict­able course, but the variability in individual responses to sexual arousal is considerable. These variations are suggested in the several individual reports of arousal, orgasm, and resolution included later in this chapter.

Two fundamental physiological responses to effective sexual stimulation occur in both women and men. These are vasocongestion and myotonia. These two basic reactions are the primary underlying sources for almost all biological responses that take place during sexual arousal.

Vasocongestion is the engorgement with blood of body tissues that respond to sexual excitation. Usually the blood flow into organs and tissues through the arteries

I Figure 6.3 Female sexual response cycle. Masters and Johnson identified three basic patterns in female sexual response. pattern a most closely resembles the male pat­tern, except that a woman can have one or more orgasms without dropping below the plateau level of sexual arousal. Variations of this response include an extended plateau with no orgasm (pattern B) and a rapid rise to orgasm with no definitive plateau and a quick resolution (pattern C).

SOURCE: Human Sexual Response, by W. H. Masters and V. E. Johnson. Copyright © 1966

Sexual arousal and response

I Figure 6.4 Male sexual response cycle. Only one male response pattern was identified by Masters and Johnson. However, men do report considerable variation in their response pattern. Note the refractory period; males do not have a second orgasm immediately after the first.

SOURCE: Human Sexual Response, by W. H. Masters and V. E. Johnson. Copyright © 1966

is balanced by an equal outflow through the veins. During sexual arousal, however, the arteries dilate, increasing the inflow beyond the capacity of the veins to carry blood away. This results in widespread vasocongestion in both superficial and deep tissues. The vis­ible congested areas might feel warm and appear swollen and red as a result of increased blood content. The most obvious manifestations of this vasocongestive response are the erection of the penis in men and blood engorgement of the clitoris and lubrication of the vagina in women. In addition, other body areas can become engorged—the labia, testes, clitoris, nipples, and even the earlobes.

As described in Chapter 2, Masters and Johnson and other researchers have used devices such as the vaginal photoplethysmograph and the penile strain gauge to electroni­cally measure vasocongestion during sexual arousal. Investigators have also used functional magnetic resonance imaging (fMRI) technology to study sexual response. This approach to assessing the physiology of sexual arousal is described in the Spotlight on Research box.

The second basic physiological response is myotonia (my-uh-TOH-nee-uh), the increased muscle tension that occurs throughout the body during sexual arousal. Myo­tonia is evident in both voluntary flexing and involuntary contractions. Its most dra­matic manifestations are facial grimaces, spasmodic contractions of the hands and feet, and the muscular spasms that occur during orgasm.

The phases of the response cycle follow the same general patterns, regardless of the method of stimulation. Masturbation, manual stimulation by one’s partner, oral pleasuring, penile-vaginal intercourse, dreaming, fantasy, and, in some women, breast stimulation can all result in completion of the response cycle. Often the intensity and rapidity of response vary according to the kind of stimulation.

■ Table 6.3 on p. 166 summarizes the major physiological changes that occur in women and men during the four phases of the sexual response cycle. Note the similarities in the sexual response patterns of men and women. We discuss some important differences in greater detail at the conclusion of this chapter. In the following paragraphs we provide a few observations regarding each of the four phases of sexual response and some personal reports.

During the excitement phase both sexes experience an increase in myotonia, vaso­congestion, heart rate, and blood pressure. Although the appearance of a sex flush (a pink or red rash on the chest or breasts) can occur in either sex, it is more common in females. The length of this phase is highly variable in both sexes, ranging from less than a minute to several hours, and the degree of arousal can fluctuate between low and high. The following two reports, the first by a woman and the second by a man, give some indication of subjective variations in how people describe their sexual arousal.

chapter 6

Monitoring Genital Changes During Sexual Arousal With Functional Magnetic Resonance Imaging

The term plateau phase is somewhat of a misnomer in that in the behavioral sciences the term plateau is typically used to describe a leveling-off period during which no observ­able changes in behavior can be detected. For example, it might refer to a flat spot in a learn­ing curve where no new behaviors occur for a certain period of time. The plateau stage has been diagrammed in just this manner in the male chart (Figure 6.4) and in pattern A of the female chart (Figure 6.3). In actuality, the plateau level of sexual arousal involves a powerful surge of sexual tension in both sexes (e. g., increase in blood pressure and heart and breath­ing rates) that continues to mount until it reaches the peak that leads to orgasm.

The plateau phase is often brief, typically lasting a few seconds to several minutes. However, many people find that prolonging sexual tensions at this high level produces greater arousal and ultimately more-intense orgasms. This is reported in the following subjective accounts:

Sexual arousal and response

■ TABLE 6.3 Major Physiological Changes During Each of the Four Phases of the Sexual Response Cycle Phase Reactions Common to Both Sexes Female Responses Male Responses Excitement ■ Increase in myotonia, heart rate, ■ Clitoris swells. ■ penis becomes erect. and blood pressure. ■ Sex flush and nipple erections occur (more common in females). ■ Labia majora separate away from vaginal opening. ■ Labia minora swell and darken in color. ■ Lubrication begins. ■ Uterus elevates. ■ Breasts enlarge. ■testes elevate and engorge. ■ Scrotal skin thickens and tenses. Plateau ■ Myotonia becomes pronounced, and involuntary muscular contrac­tions may occur in hands and feet. ■ Heart rate, blood pressure, and breathing increase. ■ Orgasmic platform (engorgement of outer third of the vagina) forms. ■ Clitoris withdraws under its hood. ■ Uterus becomes fully elevated. ■areola becomes more swollen. ■ engorgement and eleva­tion of testes becomes more pronounced. ■ Cowper’s gland secretions may occur. Orgasm ■ Involuntary muscle spasms throughout body. ■ Blood pressure, breathing, and heart rates at maximum levels. ■ Involuntary contractions of rectal sphincter. ■ Orgasmic platform contracts rhyth­mically 3 to 15 times. ■ Uterine contractions occur. ■ Clitoris remains retracted under its hood. ■ No further changes in breasts or nipples. ■ During emission phase, inter­nal sex structures undergo con­tractions, causing pooling of seminal fluid in urethral bulb. ■ During expulsion phase, semen expelled by contrac­tions of muscles around base of penis. Resolution ■ Myotonia subsides, and heart rate, blood pressure, and breath­ing rates return to normal imme­diately after orgasm. ■ Sex flush disappears rapidly. ■ Nipple erection subsides slowly. ■ Clitoris descends and engorgement slowly subsides. ■ Labia return to unaroused size. ■ Uterus descends to normal position. ■ Lack of orgasm after period of high arousal may dramatically slow resolution. ■ erection subsides over a period of a few minutes. ■testes descend and return to their normal size. Scrotum resumes wrinkled appearance. ■ resolution quite rapid in most men.

CHAPTER 6

As effective stimulation continues, many people move from plateau to orgasm. Orgasm is the shortest phase of the sexual response cycle, typically lasting only a few seconds. Men almost always experience orgasm after reaching the plateau level of sex­ual response. In contrast to men, women sometimes obtain plateau levels of arousal without the release of sexual climax (Wallen et al., 2011). This is often the case during penile-vaginal intercourse when the man reaches orgasm first or when effective man­ual or oral stimulation is replaced with penetration as the female approaches orgasm.

The NSSHB (National Survey of Sexual Health and Behavior) found that 64% of adult females experienced orgasm during their most recent sexual experience with another person (most commonly a sex partner of the other sex). The comparable figure for adult males was 85% (Reece et al., 2010a). Adult females were most likely to have an orgasm when they engaged in a variety of sex acts, such as oral sex, partnered masturba­tion, and vaginal intercourse. Another study reported that women typically experience orgasm during partnered sex via manipulation of the clitoris or oral sex, and much less frequently during vaginal penetration (Brewer & Hendrie, 2010).

For both sexes the experience of orgasm can be an intense mixture of highly pleasur­able sensations, but whether that experience differs from male to female has been the subject of considerable debate. This question was evaluated in two separate experimen­tal analyses of orgasm descriptions provided by college students (Wiest, 1977; Wiest et al., 1995). When compared using a standard psychological rating scale, women’s and men’s subjective descriptions of orgasm were indistinguishable in both investigations. Similar results were obtained in an earlier study, in which 70 expert judges were unable to distinguish reliably between the written orgasm reports of men and women (Proctor et al., 1974). Another investigation found that when men and women were asked to use adjectives to describe their subjective experience of orgasm, similarities in description significantly outweighed differences (Mah & Binik, 2002).

Beyond the question of sex differences in orgasmic experiences, it is clear that great individual variation exists in how people, both men and women, describe orgasms. The following Sexuality and Diversity discussion provides some indication of the varied ways people experience and describe their orgasmic experiences.