Human sexual behaviour

human sexual behaviour, any activity—solitary, between two persons, or in a group—that induces sexual arousal. There are two major determinants of human sexual behaviour: the inherited sexual response patterns that have evolved as a means of ensuring reproduction and that are a part of each individual’s genetic inheritance, and the degree of restraint or other types of influence exerted on the individual by society in the expression of his sexuality. The objective here is to describe and explain both sets of factors and their interaction.

It should be noted that taboos in Western culture and the immaturity of the social sciences for a long time impeded research concerning human sexual behaviour, so that by the early 20th century scientific knowledge was largely restricted to individual case histories that had been studied by such European writers as Sigmund Freud, Havelock Ellis, and Richard, freiherr von Krafft-Ebing. By the 1920s, however, the foundations had been laid for the more extensive statistical studies that were conducted before World War II in the United States. Of the two major organizations for sex study, one, the Institut für Sexualwissenschaft in Berlin (established in 1897), was destroyed by the Nazis in 1933. The other, the Institute for Sex Research (later renamed Kinsey Institute for Research in Sex, Gender, and Reproduction), begun in 1938 by the American sexologist Alfred Charles Kinsey at Indiana University in Bloomington, undertook the study of human sexual behaviour. Much of the following discussion rests on the findings of the Institute for Sex Research, which comprise the most comprehensive data available. The only other country for which comprehensive data exist is Sweden.

Types of behaviour

Human sexual behaviour may conveniently be classified according to the number and gender of the participants. There is solitary behaviour involving only one individual, and there is sociosexual behaviour involving more than one person. Sociosexual behaviour is generally divided into heterosexual behaviour (male with female) and homosexual behaviour (male with male or female with female). If three or more individuals are involved it is, of course, possible to have heterosexual and homosexual activity simultaneously.

In both solitary and sociosexual behaviour there may be activities that are sufficiently unusual to warrant the label deviant behaviour. The term deviant should not be used as a moral judgment but simply as indicating that such activity is not common in a particular society. Since human societies differ in their sexual practices, what is deviant in one society may be normal in another.

Solitary behaviour

Self-masturbation is self-stimulation with the intention of causing sexual arousal and, generally, orgasm (sexual climax). Most masturbation is done in private as an end in itself but is sometimes practiced to facilitate a sociosexual relationship.

Masturbation, generally beginning at or before puberty, is very common among males, particularly young males, but becomes less frequent or is abandoned when sociosexual activity is available. Consequently, masturbation is most frequent among the unmarried. Fewer females masturbate; in the United States, roughly one-half to two-thirds have done so, as compared to nine out of ten males. Females also tend to reduce or discontinue masturbation when they develop sociosexual relationships. There is great individual variation in frequency, so that it is impractical to try to define what range could be considered “normal.”

The myth persists, despite scientific proof to the contrary, that masturbation is physically harmful. Neither is there evidence that masturbation is immature behaviour; it is common among adults deprived of sociosexual opportunities. While solitary masturbation does provide pleasure and relief from the tension of sexual excitement, it does not have the same psychological gratification that interaction with another person provides; thus, extremely few people prefer masturbation to sociosexual activity. The psychological significance of masturbation lies in how the individual regards it. For some, it is laden with guilt; for others, it is a release from tension with no emotional content; and for others it is simply another source of pleasure to be enjoyed for its own sake.


Since the masturbating person is in sole control of the areas that are stimulated, the degree of pressure, and the rapidity of movement, masturbation is often more effective in producing sexual arousal and orgasm than is sociosexual activity, during which the stimulation is determined to some degree by one’s partner.

Orgasm in sleep evidently occurs only in humans. Its causes are not wholly known. The idea that it results from the pressure of accumulated semen is invalid because not only do nocturnal emissions sometimes occur in males on successive nights, but females experience orgasm in sleep as well. In some cases orgasm in sleep seems a compensatory phenomenon, occurring during times when the individual has been deprived of or abstains from other sexual activity. In other cases it may result from external stimuli, such as sleeping prone or having night clothing caught between one’s legs. Most orgasms during sleep are accompanied by erotic dreams.

A great majority of males experience orgasm in sleep. This almost always begins and is most frequent in adolescence, tending to disappear later in life. Fewer females have orgasm in sleep, and, unlike males, they usually begin having such experience when fully adult.

Orgasm in sleep is generally infrequent, seldom exceeding a dozen times per year for males and three or four times a year for the average female.

Most sexual arousal does not lead to sexual activity with another individual. Humans are constantly exposed to sexual stimuli when seeing attractive persons and are subjected to sexual themes in advertising and the mass media. Response to such visual and other stimuli is strongest in adolescence and early adult life and usually gradually declines with advancing age. One of the necessary tasks of growing up is learning to cope with one’s sexual arousal and to achieve some balance between suppression, which can be injurious, and free expression, which can lead to social difficulties. There is great variation among individuals in the strength of sex drive and responsiveness, so this necessary exercise of restraint is correspondingly difficult or easy.

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