Developmental psychology.pdf

292 Motivation and Emotion
Species Survival
As one would expect, Robin's parents were extremely concerned about his survival.
His mother even considered legal efforts to prevent the voyage. His father was "really
worried" when he left. And for good reason. At sea Robin was washed overboard,
battered by storms, threatened by sharks, and nearly crushed when his small boat was
almost struck by a freighter passing in the night. On land he was stalked by an aroused
rhinoceros, bitten by poisonous shellfish, and susceptible to various diseases.
Sexual Motivation The survival of the species depends initially upon propagation,
and here the limits of behavior among human beings, and even among apes, are so
broad that universal patterns cannot be identified. There is no universal sexual response.
If there were, it would be readily evident among all human adults.
Among rats and guinea pigs, there is little variation in sexual activity because
this behavior depends chiefly upon hormonal secretions, the androgens and estrogens
in the male and female, respectively. Withdrawal of androgen hormones in males distinctly
alters sexual activity as well as aggressive and scent-making behavior, and this
result occurs regardless of the age at which the hormone is withdrawn (Hart, 1974).
A related topic of considerable interest concerns the role of these hormones
in newborn animals. When androgen is administered to young female rats or guinea
pigs, as adults they behave like males, demonstrating mounting behavior instead of the
customary bending response. When newborn and even prenatal males are deprived of
androgenic hormones, their sexual behavior in adulthood is like that of females. These
findings indicate that the genetic constitution of young mammals is highly susceptible
to early hormonal influences. They suggest that, even at the human level, hormones
predispose the young individual to acquire certain sex-specific behavior patterns, raising
numerous questions about the ultimate basis of the distinction between the sexes
(Goy, 1970).
At a higher level, in the chimpanzee, there is no stereotyped mating behavior,
such as that in the rat. The pattern that finally emerges in the individual adult chimpanzee
is largely learned (Figure 11.6).
In the human being, the testes secrete the sex hormone in the male, and when
they are removed before puberty, sexual development is commonly disrupted. After
puberty, castration usually does not result in a cessation of sexual behavior, showing
the influence of learning. Sexual interests and activities may continue for years, although
perhaps at a reduced rate. In the human female, the sex hormones come from
the ovaries, and the effects of removing these organs are difficult to predict. Generally,
there is some decrease of sexual interest, but again the result is not as significant as
in lower animals.
Both men and women whose gonads have degenerated late in life may continue
to participate in sexual activities, and some women who have passed through
menopause actually increase their sexual activity. In the male, contrary to popular
thought, sexual activity can occur even into the seventh and eighth decades. In fact,
the more regular and frequent sexual intercourse has been in earlier years, the greater
is the likelihood of a sustained responsiveness in later life (Masters & Johnson, 1966).
Sexual behavior at the human level clearly illustrates the relationship between
inborn and acquired factors in motivation. A readiness for sexual activity is provided
by hormonal secretions, and certain reflexes are involved, such as the erection of nipples
in the female and ejaculation in the male. But the expression of sexual motivation
is molded by the environment. Apart from the basic reflexes and nature of the organs
involved, human sexual activity is directed chiefly by prior experience and current circumstances.
There is no human sexual instinct. Anyone doubting the absence of such
an instinct need only to consult the sex magazines and books at the corner store, which
give ample testimony to the role of psychological factors in human sexual motivation.