Sex
Like hunger and thirst, the sex drive involves the hypothalamus, but unlike hunger and
thirst, the sex drive can be aroused by almost anything at any time and is not necessary
for survival of an individual. Sex drive increases at puberty with an increase in male sex
hormones, such as testosterone, in males and estrogen, as well as small amounts of testos-
terone, in females. Secretion of hormones by the hypothalamus stimulates the pituitary
gland to secrete luteinizing hormone (LH) and follicle stimulating hormone (FSH) into the
bloodstream, which stimulate gonads (testes in males and ovaries in females) to secrete
testosterone and estrogen that initiate and maintain arousal. Without these two hormones,
sexual desire is greatly reduced in all species, but testosterone levels in humans seem related
to sexual motivation in both sexes. Humans seem less instinctively driven to have children
than other animals. Many learned cues are involved in this drive. Societies attempt
to regulate sexual behavior by imposing sanctions against incest and encouraging or
discouraging masturbation, premarital intercourse, marital intercourse, extramarital inter-
course, and homosexuality. Sexual orientationrefers to the direction of an individual’s
sexual interest. Homosexualityis a tendency to direct sexual desire toward another person
of the same sex, and bisexualityis a tendency to direct sexual desire toward people of both
sexes. Heterosexualityis a tendency to direct sexual desire toward people of the opposite
sex. While most people are heterosexual, about 10% are estimated to be homosexual.
Researchers attribute the causes of homosexuality to biological, psychological, and sociocul-
tural factors.
Although the sex drive is not necessary for survival of an individual, it is necessary for
survival of the species. According to evolutionary psychologists, mammalian females lack
incentive to mate with many males because they optimize reproductive success by being
selective in mating, choosing a male who has resources to provide for children. On the other
hand, males optimize reproductive success by mating with many females, choosing young,
healthy, fertile females.
Masters and Johnson described a pattern of four stages in the biological sexual
response cycleof typical men and women, including excitement characterized by sexual
arousal; plateau, which involve increased breathing rate, muscle tension, heart rate, and
blood pressure; orgasm, which is characterized by ejaculation in males and pleasurable sen-
sations induced by rhythmic muscle contractions in both sexes; and resolution as blood
leaves the genitals and sexual arousal lessens, followed in most males by a refractory period
during which another erection or orgasm is not achieved. Females show less tendency for
a refractory period and are often capable of multiple orgasms.Social Motivation
Achievement
According to David McClelland, the achievement motive is a desire to meet some
internalized standard of excellence. McClelland used responses to the Thematic
Apperception Test (TAT)to measure achievement motivation. He suggested that people
with a high need for achievement choose moderately challenging tasks to satisfy their need.
They avoid easy goals that offer no sense of satisfaction and avoid impossible goals that offer
no hope of success. People low in need for achievement select very easy or impossible goals
so that they do not have to take any responsibility for failure. College students high in
this need attribute success to their own ability, and attribute failure to lack of effort.
Some people fear success because success can invite envy or criticism that strains social
relationships, or even rejection.152 ❯ STEP 4. Review the Knowledge You Need to Score High