Physiology: The Nature of Sexual Response

Though billions of human beings down the ages have experienced sex, the question persists: What is it? The average man’s or woman’s answers are as uninformative as the paeans of poets, and not until a century ago did medical science tackle the question. Then even such pioneers as Krafft-Ebing, Freud and Kinsey relied on what their subjects told them — and gathered mostly emotion-laden impressions.

To Gynecologist William Howell Masters, 50, this sort of thing is not sufficiently precise or scientific. Ever since he graduated from the University of Rochester medical school in 1943, Masters has been determined to chart the basic physiology of sex. Next spring Little, Brown & Co. will publish Human Sexual Response, the extraordinarily detailed results of Dr. Masters’ eleven years’ work with his research associate, Psychologist Virginia E. Johnson.

Bed & Camera. Dr. Masters deliberately delayed his primary sex research until he was almost 40, a husband and father of two, a specialist in obstetrics and gynecology, and a medical professor at Washington University in St. Louis. In 1954 he persuaded the university to set up special laboratories containing a bed, electrocardiographs, electroencephalographs, biochemical equipment, flood lights and color-movie cameras. A primary purpose was to study sexual inadequacy in both sexes.

To avoid public controversy, Dr. Masters published nothing for five years, then reported his first findings in the relatively obscure Western Journal of Surgery, Obstetrics and Gynecology.

Now the controversy is unavoidable. To permit filming of detailed physiologic changes, many of Dr. Masters’ subjects necessarily engage in what he calls “automanipulation,” generally known as masturbation, and other stimulating techniques. As a result, the research program has made unique progress in mapping the sexual response of both men and women — in some cases, during coitus. Dr. Masters divides the female response into four phases that vary in both duration and intensity among different women, and even for the same women at different times. The typical progression:

∙EXCITEMENT. The first physiologic response is erection of the nipples, from contraction of their muscular fibers. It occurs in both breasts, though not necessarily at the same time. Second, the pattern of veins in the surface of the breasts stands out more clearly, and this may extend to the adjoining chest wall. The breasts gradually increase in size as a result of the filling-up of blood vessels. In addition, the labia minora (the vulva’s inner folds) turn bright pink, a process that Dr. Masters compares biologically with changes in female monkeys’ exposed “sex skin.” A lubricant appears in the vagina. As excitement proceeds to the next phase, the pigmented rings around the nipples (areolae) become engorged and impinge upon the erect nipples. The breasts increase in size by 20% to 25%. ∙PLATEAU. A pink mottling appears over the chest, spreads to the breasts and “actually coalesces in the terminal stages, to suggest an advanced state of measles.” The mottling may spread over the abdomen, shoulders, and even the hollows inside the elbows. The labia minora become enlarged to about twice their normal size as tension increases, and turn a deeper, scarlet hue (purplish in a woman who has borne several children). The intensity of sexual response is directly proportional to this color change; in no observed case has a woman reached a deep-color phase without proceeding to a satisfactory orgasm. Engorgement of the labia minora and the outer third of the vagina creates an “orgasmic platform.” ∙ORGASM. With the physiologic stage thus set, a woman should experience an orgasm even more intense than a man’s and marked by strong contractions of the engorged pelvic structures. The contractions usually occur at one-second intervals, continue for three to four seconds and up to ten or twelve seconds of “agonized physical effort.” ∙RESOLUTION. After an unusually intense orgasm, this phase may drop a woman into deep sleep within a minute or two. (“Postorgasmic sleep” had previously been regarded as a male characteristic.) The measles-like rash fades, the engorged vessels of the pelvis and breasts relax to permit the resumption of normal blood flow, and the vagina subsides into a state that facilitates the movement of sperm to ovum for conception.

The Lethal Vagina. A major controversy in female physiology has concerned the source of the all-important vaginal lubricant. Some authorities have traced it to the uterine cervix; others, to the Bartholin glands flanking the vagina. In fact, says Dr. Masters, the normal cervix secretes nothing of any importance; the Bartholin glands secrete only a minute quantity of lubricant. According to Dr. Masters, the vaginal walls themselves supply nearly all the vaginal lubricant. How they do so is unclear, since there are no glands in the vaginal walls, and this is a subject of continuing study.

As Gynecologist Marion H. Sims suggested in 1888, says Dr. Masters, the vagina seems to be a functioning as well as a functional organ. In some cases, at least, its biochemical activity may completely defeat nature’s purpose. In 39 patients, Dr. Masters has found a vaginal secretion that was absolutely lethal for spermatozoa; three more patients had an equally deadly cervical secretion. The chemical nature of these substances is not yet known, but since some of them kill all accessible sperm within ten seconds, Dr. Masters says, “research in this direction is important both from a conceptive and a contraceptive point of view.”

Teaching Conception. How to help supposedly infertile couples conceive has always been among Dr. Masters’ major concerns. As a result of his physiologic research, Dr. Masters has developed a gratifyingly successful method. Husband and wife must both agree to remain under treatment for at least a year. Dr. Masters and Psychologist Johnson start from the assumption that many couples “don’t know where babies come from”—or at least don’t know how they’re made.

Johnson and Masters have to explain basic physiology. Often they have to reassure the husband that infertility does not mean impotence. They explain the best timing for intercourse in relation to ovulation and the best position to increase the likelihood of conception. It may take months of laboratory work to pinpoint and correct the cause of infertility. But in at least one case out of eight, Masters and Johnson report, learning about conception and the assurance that something is being done about their problem are enough to start a couple toward parenthood within three months.