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June 12, 2003
Study on Differences in Female, Male Sexuality
EVANSTON, Ill.
--- Three decades of research on men’s sexual
arousal show patterns that clearly track sexual orientation --
gay men overwhelmingly become sexually aroused by images of men
and heterosexual men by images of women. In other words, men’s
sexual arousal patterns seem obvious.
But a new
Northwestern University study boosts the relatively limited research
on women’s sexuality with a surprisingly
different finding regarding women’s sexual arousal.
In contrast to men, both heterosexual and lesbian women tend
to become sexually aroused by both male and female erotica, and,
thus, have a bisexual arousal pattern.
“These findings likely represent a fundamental difference
between men’s and women’s brains and have important
implications for understanding how sexual orientation development
differs between men and women,” said J. Michael Bailey, professor
and chair of psychology at Northwestern and senior researcher of
the study “A Sex Difference in the Specificity of Sexual
Arousal.” The study is forthcoming in the journal Psychological
Science.
Bailey’s
main research focus has been on the genetics and environment
of sexual orientation, and he is one of the principal
investigators of a widely cited study that concludes that genes
influence male homosexuality.
As in many
areas of sexuality, research on women’s sexual
arousal patterns has lagged far behind men’s, but the scant
research on the subject does hint that, compared with men, women’s
sexual arousal patterns may be less tightly connected to their
sexual orientation.
The Northwestern study strongly suggests this is true. The Northwestern
researchers measured the psychological and physiological sexual
arousal in homosexual and heterosexual men and women as they watched
erotic films. There were three types of erotic films: those featuring
only men, those featuring only women and those featuring male and
female couples. As with previous research, the researchers found
that men responded consistent with their sexual orientations. In
contrast, both homosexual and heterosexual women showed a bisexual
pattern of psychological as well as genital arousal. That is, heterosexual
women were just as sexually aroused by watching female stimuli
as by watching male stimuli, even though they prefer having sex
with men rather than women.
“In fact, the large majority of women in contemporary Western
societies have sex exclusively with men,” said Meredith Chivers,
a Ph.D. candidate in clinical psychology at Northwestern University
and a psychology intern at the Centre for Addiction and Mental
Health and the study’s first author. “But I have long
suspected that women’s sexuality is very different from men’s,
and this study scientifically demonstrates one way this is so.”
The study’s results mesh with current research showing
that women’s sexuality demonstrates increased flexibility
relative to men in other areas besides sexual orientation, according
to Chivers.
“Taken together, these results suggest that women’s
sexuality differs from men and emphasize the need for researchers
to develop a model of the development and organization of female
sexuality independent from models of male sexuality,” she
said.
The study’s four authors include Bailey and three graduate
students in Northwestern’s psychology department, Chivers,
Gerulf Rieger and Elizabeth Latty.
“Since most women seem capable of sexual arousal to both
sexes, why do they choose one or the other?” Bailey asked. “Probably
for reasons other than sexual arousal.”
Sexual arousal is the emotional and physical response to sexual
stimuli, including erotica or actual people. It has been known
since the early 1960s that homosexual and heterosexual men respond
in specific but opposite ways to sexual stimuli depicting men and
women. Films provoke the greatest sexual response, and films of
men having sex with men or of women having sex with women
provoke the largest differences between homosexual and heterosexual
men. That is because the same-sex films offer clear-cut results,
whereas watching heterosexual sex could be exciting to both homosexual
and heterosexual men, but for different reasons.
Typically,
men experience genital arousal and psychological sexual arousal
when they watch films depicting their preferred sex, but
not when they watch films depicting the other sex. Men’s
specific pattern of sexual arousal is such a reliable fact that
genital arousal can be used to assess men’s sexual preferences.
Even gay men who deny their own homosexuality will become more
sexually aroused by male sexual stimuli than by female stimuli.
“The fact that women’s sexual arousal patterns are
not all predicted by their sexual orientations suggests that men’s
and women’s minds and brains are very different,” Bailey
said.
To rule out
the possibility that the differences between men’s
and women’s genital sexual arousal patterns might be due
to the different ways that genital arousal is measured in men and
women, the Northwestern researchers identified a subset of subjects:
postoperative transsexuals who began life as men but had surgery
to construct artificial vaginas.
In a sense,
those transsexuals have the brains of men but the genitals of
women. Their psychological and genital arousal patterns
matched those of men -- those who like men were more aroused by
male stimuli and those who like women were more aroused by the
female stimuli -- even though their genital arousal was measured
in the same way women’s was.
“This shows that the sex difference that we found is real
and almost certainly due to a sex difference in the brain,” said
Bailey. |