Arousal is a state of sexual excitation marked by increased blood flow to the genitals, elevated heart rate, and the tumescence (swelling) of the clitoris and penis. Arousal can be initiated by physical and mental stimuli and is profoundly impacted by individual psychology and cultural conditioning.
Also called the excitement phase, arousal is the first stage of the human sexual response cycle developed by William H. Masters and Virginia E. Johnson (1966). Arousal is followed by the plateau stage, in which tensions initiated by arousal are intensified. The third stage, orgasm, involves the sudden release of this tension, and the final resolution stage incorporates the gradual reduction of physiological tension and often includes a period of emotional calm and well-being.
Sexual arousal engenders a variety of physiological responses. Women experience erection of the nipples and, as arousal moves toward the plateau stage, an increase in breast size resulting from vasocongestion, or the swelling of tissues owing to increased blood flow. The heart rate and blood pressure both increase in direct relation to increasing tension. Late in the excitement phase, a female may experience some muscle tension, including expansion of the vaginal wall and tensing of the abdominal muscles. The late excitement phase may also include the sex flush, a red rash that begins on the upper abdomen and spreads quickly to the breasts.
Within the first thirty seconds of arousal, vaginal lubrication appears. The clitoral glans becomes tumescent and vasocongestion increases the diameter of the clitoral shaft, engorges the labia, expands and lengthens the vaginal barrel, and alters the vaginal wall to a darker, purplish color. Expansion and separation of the vaginal walls causes the folded pattern of the vagina to smooth out. Finally, the uterus begins to elevate into the greater pelvis, which lies above and in front of the pelvic brim.
The initial physiological response to sexual stimuli in males is the erection of the penis. Once the penis is fully erect, arousal may continue for only a few moments or for several minutes. When the excitement phase is prolonged, the penis may lose and regain its erection one or more times. Penile erection is often extremely sensitive to the discontinuation and resumption of physical sexual stimulation. The penis is also sensitive to asexual stimuli, which may cause a partial or complete loss of the erection even when physical stimulation is constant.
During arousal, males also experience a thickening of the scrotal covering and an elevation of the scrotal sac and testes. As with females, males experience an increased heart rate and elevated blood pressure when sexually aroused. Men also experience muscle tension, including partial elevation of the testicles and contraction of the abdominal and intercostals muscles (the latter being the muscles that run between the ribs). About 60 percent of men also experience nipple erection, though it is inconsistent and may not appear until the plateau phase.
Though the precise role of the brain in sexual arousal has not been determined, studies have consistently found increased right-brain activity in response to arousal. More complex studies have found that a variety of cortical and subcortical brain regions are implicated in sexual arousal, and some researchers have argued that this demonstrates the complexity of the cognitive, physiological, emotional, and psychological processes involved in sexual arousal.
Though Masters and Johnson have been greatly influential in the conceptions of human sexual response, many researchers have taken issue with their exclusive focus on physiological response. Helen Singer Kaplan (1974) modifies their model to a three-stage model that includes desire, excitement, and orgasm. Some find this model more useful in that it allows for a consideration of the psychological effects of desire and motivation on arousal.
Further modifications of sexual response models have suggested distinguishing between spontaneous desire, or libido, and stimulus-driven desire, or arousability. Some researchers find that this distinction allows for an evolutionary explanation of differing modes of male and female desire, wherein men experience a biological drive to successfully disseminate their genetic material whereas female success, which is tied to the rearing of offspring, depends on selecting an appropriate mate, a selection that will be driven by external cues. For some clinicians, this model of sexual response has proved useful in that it allows for the complex mediation between internal and external stimuli that occurs in sexual arousal, as well as for consideration of the physiological, psychological, and relationship factors that affect arousal.
Ultimately, sexual arousal is dictated by an exceedingly complex interaction of psychological, cultural, behavioral, neurological, cognitive, physiological, and interpersonal factors. Though certain kinds of stimulation (of the genitals, for example) seem to be universally interpreted as sexual, whether or not such stimulation is arousing depends on individual and cultural conditioning, as well as situational and relationship factors—all of which are mediated by the central nervous system.
Erotic stimulation in both men and women appears to be largely the result of conditioning in which certain kinds of stimuli become associated with positive sexual outcomes. Though some stimuli are more easily eroticized, studies have demonstrated that people can be quite readily conditioned to respond sexually to neutral objects. Sexual arousal, moreover, is almost always context-dependent; what may carry an erotic charge in one situation does not necessarily in another. Men and women report arousal increases with the sexual explicitness of the stimuli, though men and women are excited by different sexual situations. Men, for example, are more excited by viewing group sex than women, while women report greater arousal in response to films that emphasize the desire and enjoyment of both partners. Sexual fantasy is an important source of arousal for both men and women. Fantasy alone can generate moderately high sexual excitement and a concomitant physiological response; it can moreover serve as mechanism for exerting control over a physiological function often considered involuntary.
Emotional states greatly impact sexual arousal, though the nature of this impact is often complex and little understood. Emotions themselves are multidimensional and can be experienced in varying degrees of intensity. Certain negative emotions, such as guilt or embarrassment, inhibit arousal, while others, such as sadness, do not necessarily. Emotions that themselves invoke a certain physiological arousal, such as anger, often increase sexual arousal, though only to a certain limit. Additionally, the source of the emotion—whether it occurs outside of the sexual situation or arises out of it—changes its relation to sexual arousal. And the valence of certain emotions changes greatly depending on the situation: Anxiety surrounding body image may inhibit sexual arousal, whereas anxiety about getting caught having sex in a public place may be sexually arousing. Finally, there is some evidence that sexual arousal itself may be considered a sort of emotional state, in which persons experience an extremely heightened, positive state of being.
Sexual arousal is intimately related to the culture in which it occurs. The particular stimuli that people find arousing are culturally inflected, either by societal taboos or eroticized representations. Edward Shorter (2005), for example, links the newly common practice of deep tongue kissing in the late nineteenth century to kinetoscope depictions of male-female kissing. Shorter finds a similar tendency at work in the eroticization of various body parts, arguing that an earlier emphasis on the face and genitals as the primary sites of sexual attraction was replaced in the twentieth century with an erotic interest in other body parts, including the breasts, nipples, and buttocks. This shift in the erotic charge of particular parts of the body occurs in tandem with the production of art, photography, and pornography that call attention to these areas of the bodies as legitimate stimuli for sexual arousal. Similarly, an increase in experimentation with different sexual techniques, including oral sex, appears to have followed its depiction in popular pornographic works of the period.
The correspondence between erotics and popular culture has been one of the hallmarks of the film industry, which has legimated as much as it has reflected the cultural eroticization of certain kinds of sexual stimulation. Similarly, the sexual liberation movement of the 1960s and 1970s has been consistently linked to the increasing visibility of men's magazines, such as Playboy, which valorized alternative forms of sexual expression. Since at least the 1970s, sexual arousal has been an important component of mainstream depictions of sexuality. Sex manuals and men and women's magazines alike emphasize the importance of arousal to sexual expression, often providing detailed instructions for pleasing one's partner. Mainstream films, magazines, romance novels, and soft-core porn often attempt to incite sexual arousal by depicting individuals who are themselves sexually aroused, as marked by parted lips, heavy breathing, and splayed limbs. One effect of this kind of representation is that sexual arousal is constructed as itself sexually arousing.
see also Foreplay.
Kaplan, Helen Singer. 1974. The New Sex Therapy: Active Treatment of Sexual Dysfunctions. New York: Brunner/Mazel.
Masters, William H., and Virginia E. Johnson. 1966. Human Sexual Response. Boston: Little, Brown.
McAnulty, Richard D., and M. Michele Burnette, eds. 2006. Sex and Sexuality. Vol. 2: Sexual Function and Dysfunction. Westport, CT: Greenwood Press.
Shorter, Edward. 2005. Written in the Flesh: A History of Desire. Toronto: University of Toronto Press.
1. The transition from the sleeping to the waking state.
2. An increase in the responsiveness of an animal to sensory stimuli.