ological recording devices and motion picture cameras, the physician William H.
Masters and the psychologist Virginia E. Johnson studied the actual sexual
responses of volunteer subjects. Their trailblazing book, Human Sexual Response,
was published in 1966, and summarizes the results of their investigations. Until
the publication of this book and associated articles by the same authors in scien-
tific journals, very little factual information was available concerning the physio-
logical facts associated with the sexual response cycle.
Here are the four stages of the sexual response cycle: (1) excitement, (2)
plateau, (3) orgasm, and (4) resolution. Excitementis characterized by increases
in blood pressure, pulse, and respiration rate. The individual is highly responsive
to erotic stimulation. This varies greatly, of course, from person to person, and is
largely a matter of individual differences, perception, and sexual preferences. In
males, the penis becomes erect. In females, the clitoris swells in size. In general,
there is an intensified flow of blood to the genital area.
During the stage ofplateau,prior increases in physiological activity are main-
tained at a more or less constant level. In males, the penis becomes somewhat
larger. In females, the clitoris retracts a little. The variation in the time associated
with the plateau stage is considerable. The stage can last two minutes, twenty min-
utes, or more. Some of this is under the control of the individual. Plateau can be
shortened or increased based on voluntary responses, responses that aim to dimin-
ish or amplify the momentary intensity of erotic stimulation.(a) The first stage of the sexual response cycle is characterized by increases in blood pres-
sure, pulse, and respiration rate. What is this stage called?(b) In the second stage of the sexual response cycle, prior increases in physiological activity
are maintained at a more or less constant level. What is this stage called?
Answers: (a) Excitement; (b) Plateau.Theorgasmis an involuntary response in both sexes. Although it can be
induced by sexual behavior, it cannot be directly willed. Brief in duration, it
is experienced as intensely pleasurable. Blood pressure and similar measures
increase in intensity. In the male, there is an ejaculation accomplished by com-
pressor muscles in the penis. In the female, there are waves of contractions in
thepubococcygeus (PC) muscle,a muscle surrounding the channel of the
vagina.
During the stage of resolutionthe individual becomes temporarily unre-
sponsive to sexual stimulation. Stimulation that had erotic value only a few min-
utes ago has no capacity to induce excitement. Blood pressure and other
physiological measures decline. The duration of the stage of resolution varies from
individual to individual. For some individuals in some instances, it may last for
only a few minutes. For others, the duration may be twenty minutes, an hour or
two, or longer.176 PSYCHOLOGY