Sexual Motivation
Sex Is Natural
• We are all motivated to have sex.
• Without that motivation, none of us would
be here.
How do we (as scientists) find out about sex?
We ask!!!!
Alfred Kinsey’s Studies
• Held confidential interviews
with 18,000 people (in early
1950’s) about their sexual
behavior and attitudes.
• He found most men and half of
all women of that time had
premarital sex and did other
various sex acts.
• His study and results shocked
many and angered others
Why??
Why was Kinsey important?
#1
 first
to use scientific method to study sex
 showed us that our perceptions about what
others are doing are a whole lot different than
the reality

#2
i.e. – sex and certain sexual behaviors where only
done by a few deviants – but actually they are done
by most normal people – even your parents!!
 he
denounced, in his opinion, the “repressive
social attitudes” of his time

This opened the flood-gates to research in this field
Good Start- but major problems with
his study- sampling, questions etc….
 Sample was not random
 mostly well-educated, white city dwellers
 Asked many leading questions to gather data
Misinformation effect
 May have let his own beliefs influence his
results
Experimenter bias
Masters and Johnson
The Physiology of Sex
 Set out to explore the physiology (biology) of
sex.
 Started a study with 382 females and 312
males.
 Filmed more than 10,000 sex cycles over a 20
year period
 Only people who were willing to have sex in a lab
environment were asked to participate.
 This was a big problem for the test as far as
reliability and validity
Results of M & J Study
The highlight of their research was the biological
breakdown of sex called…
The Sexual Response Cycle
1. Excitement Phase
2. Plateau Phase: excitement phase peaks, breathing,
pulse increases
3. Orgasm
4. Resolution Phase: body returns to normal resting
states
– men MUST experience a refractory period
– time must elapse before the cycle can repeat
– women do not have a similar refractory period and can
repeat the cycle immediately
The Psychology of Sex
• Many studies point to psychological rather
than biological factors for sexual motivation
– Unlike many animals, our sexual desire is not
motivated strictly by hormones
• Only some people are externals when it comes
to hunger - but we are all externals when it
comes to sex.
– People can find sexually explicit images either
pleasing or disturbing- but they are none the less
biologically arousing.
Can External Sexual Stimuli have
negative effects?
• Movies of women being coerced or forced into
sex tend to increase the viewer’s acceptance of
the false idea that women can enjoy it.
• Viewing X-Rated films can diminish people’s
satisfaction with their own partners.
– Expectations change.
– After viewing attractive women or men on TVpeople judge their own partners as less attractive.
Adolescent Sexuality
Culture
•About ½ of all high school kids in US report having sex- rates are higher in Western
Europe but lower in Arab or Asian countries.
Also change over time in the same culture: in 1900 3% of women reported having
sex by 18. Now that number is around half.
We have discussed the energizing of sexual
motivation but have yet to discuss its direction:
Sexual Orientation
• A sexual attraction toward members of
either one's own gender or the other
gender.
How is Sexual Orientation
Determined
• There has been NO evidence that sexuality is
socially determined.
• Kids raised by gay parents are no more likely
to be gay that if they were raised by hetero
parents.
Thus, it may be likely that sexuality
is biologically determined.
The Brain
Simon LeVay
• discovered a cluster of cells in the
hypothalamus that is larger in heterosexual
men than in heterosexual women or
homosexual men.
• However, this cluster could be socially
developed or by some other biological
factor.
Genetics and Sexual Orientation
• If one identical twin is homosexual, the
other twin has about a 50% chance of
being gay (about 20% for fraternal twins).
Prenatal Environment and Sexual
Orientation
• Current research points to
hormonal levels in the prenatal
environment could impact SO