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Human Sexuality
The scientific study of sexuality is multidimensional—
biological, psychological, social, and cultural factors
must all be taken into account
Human Sexual Response
• First mapped by sex research pioneers
William Masters and Virginia Johnson during
the 1950s and 1960s
• Human sexual response can be described as
a cycle with four stages:
• Stage 1: Excitement—beginning of sexual arousal
• Stage 2: Plateau—increased physical arousal
• Stage 3: Orgasm—male ejaculates, female vaginal
contractions
• Stage 4: Resolution—arousal subsides
What Motivates Sexual Behavior
• Necessary for the survival of the species but
not of the individual
• Lower animals motivated by hormonal
changes in the female (estrus)
• Higher species less influenced by hormones
and more by learning and environmental
influences
Hormones & Sexual Response
Women
• A woman’s fertility is regulated by
monthly hormonal cycles but these
hormonal changes seem to have little or
no effect on a female’s sexual
motivation.
• Even when a woman’s ovaries, which
produce the female sex hormone
estrogen, are surgically removed or stop
functioning during menopause, there is
little or no drop in sexual interest.
Hormones & Sexual Response
Men
• When human males experience lowered
levels of testosterone because of illness
or castration (removal of the testes), a
drop in sexual interest tends to occur,
although the effects vary among
individuals
• In both men and women, sexual
motivation is biologically influenced by
levels of testosterone in the body
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Evolution and Mate
Preferences
David Buss coordinated a large-scale survey of more
than 10,000 people in 37 different cultures
• Men and women across all 37 cultures generally
agreed that they wanted a mate who was kind and
understanding, intelligent, emotionally stable, and
healthy, and who had a pleasing personality
• Men were more likely to value youth and physical
attractiveness; women valued financial security,
access to material resources, high status and
education, and good financial prospects
• Evolutionary psychology’s explanation for these
gender differences is that mating behavior is adaptive
to the degree that it furthers the reproductive success
of transmitting one’s genes to the next generation
and beyond
Sexual Behavior over
the Lifespan
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Sexuality During Infancy &
Childhood
The capacity of the human body to show reflexive sexual
responses is present at birth.
Infants as young as three or four months of age will smile or
coo as they engage in genital play.
Signs of sexual activation or genital play should not cause
alarm in parents, because such behaviors reflect completely
normal developmental patterns.
Young children become keenly attuned to parental attitudes,
especially negative attitudes, concerning nudity, genital
touching, and genital exploration.
Awareness of sexual matters expands during middle and late
childhood. By about age eight, most children are aware that
certain behaviors produce erotic feelings.
Sexuality During Adolescence
• Puberty—stage where an individual reaches sexual
maturity and is physically capable of sexual
reproduction
• Primary sex characteristics—sex organs directly
involved in reproduction
• Secondary sex characteristics—develop during puberty,
not directly involved in reproduction, but distinguish
male from female
• Adolescent growth spurt—period of accelerated growth
during puberty
• Menarche—female’s first menstrual period
• Romantic and sexual relationships become
increasingly important in adolescence
Timing of Puberty
• Both genetics and environmental factors
play a role in the timing of puberty
• Girls often experience menarche at about
the same age as their mothers did.
• Generally, well-nourished and healthy
children begin puberty earlier than do
children who have experienced serious
health problems or inadequate nutrition.
• In general, heavy children begin puberty
earlier than do lean children, and girls
involved in physically demanding athletic
activity can experience delays in menarche
Romantic Love and the Brain
• Research results suggest that love activates
brain areas that are involved in other positive
emotions, such as happiness, but in a way
that represents a unique pattern.
• Looking at a photo of one’s romantic partner
produced heightened activity in four brain
areas associated with emotion: the anterior
cingulate cortex, caudate nucleus, putamen,
and insula.
• These are the same brain areas that are
activated by euphoria-producing drugs, such
as opiates and cocaine.
Sexuality in Adulthood
• Majority of adults (80%) report having none or one
sexual partner in the past year (marriage factor)
• Majority of men ages 18-59 have sex about seven times
per month
• Majority of women ages 18-59 have sex about six
times per month
• Vaginal intercourse is nearly universal as the most
widely practiced sexual activity among heterosexual
couples
• 50 percent of older Americans reported sexual activity
at least once per month.
How Often Do You Think About Sex ?
The percentages shown here were derived from a national
survey based on a random sample of American adults
between the ages of 18 and 59. As you can see, although
most men seem to think about sex more often than most
women do, there is overlap between the sexes in this
respect.
Sexuality in Late Adulthood
• According to one survey, among older
Americans nearly half reported engaging in
sexual activity at least once a month
• Older men and women take longer to become
sexually aroused and achieve orgasm
• For older women, probably the biggest
obstacle to enjoying sexual relations
throughout old age is the lack of a sexual
partner
• In late adulthood, dating fills the need for
companionship and sexual intimacy