Editing Sexual orientation (section)

====Sexual arousal====
Studying human [[sexual arousal]] has proved a fruitful way of understanding how men and women differ as genders and in terms of sexual orientation. A clinical measurement may use [[penile plethysmograph|penile]] or [[vaginal photoplethysmograph]]y, where genital engorgement with blood is measured in response to exposure to different erotic material.<ref name="BornGay-p21" />

Some researchers who study sexual orientation argue that the concept may apply differently for men and women. A study of sexual arousal patterns<ref name="Arousal and orientation">{{cite journal
|first=Meredith L.
|last=Chivers
|author2=Gerulf Rieger
|author3=Elizabeth Latty
|author4=J. Michael Bailey
|title=A Sex Difference in the Specificity of Sexual Arousal
|year=2004
|doi=10.1111/j.0956-7976.2004.00750.x
|pmid=15482445
|journal=Psychological Science
|volume=15
|issue=11
|pages=736–44
|s2cid=5538811
|url=https://www.gaylawnet.com/ezine/gender/sex_difference.pdf
|access-date=2017-12-10
|archive-date=2018-08-18
|archive-url=https://web.archive.org/web/20180818085417/https://www.gaylawnet.com/ezine/gender/sex_difference.pdf
|url-status=live
}}</ref> found that women, when viewing erotic films which show female-female, male-male and male-female sexual activity (oral sex or penetration), have patterns of arousal which do not match their declared sexual orientations as well as men's.  That is, heterosexual and lesbian women's sexual arousal to erotic films do not differ significantly by the genders of the participants (male or female) or by the type of sexual activity (heterosexual or homosexual). Men's sexual arousal patterns tend to be more in line with their stated orientations, with heterosexual men showing more penis arousal to female-female sexual activity and less arousal to female-male and male-male sexual stimuli, and homosexual and bisexual men being more aroused by films depicting male-male intercourse and less aroused by other stimuli.

Another study on men and women's patterns of sexual arousal confirmed<ref name="Arousal and orientation #2">{{cite journal
|first=Meredith L.
|last=Chivers
|author2=J. Michael Bailey.
|title=A sex difference in features that elicit genital response
|year=2005
|doi=10.1016/j.biopsycho.2004.12.002
|pmid=16168255
|journal=Biological Psychology
|volume=70
|issue=2
|pages=115–20|s2cid=7637198
}}
</ref> that men and women have different patterns of arousal, independent of their sexual orientations.  The study found that women's genitals become aroused to both human and nonhuman stimuli from movies showing humans of both genders having sex (heterosexual and homosexual) and from videos showing non-human [[primates]] (bonobos) having sex.  Men did not show any sexual arousal to non-human visual stimuli, their arousal patterns being in line with their specific sexual interest (women for heterosexual men and men for homosexual men).

These studies suggest that men and women are different in terms of sexual arousal patterns and that this is also reflected in how their genitals react to sexual stimuli of both genders or even to non-human stimuli. Sexual orientation has many dimensions (attractions, [[Human sexual activity|behavior]], [[sexual identity|identity]]), of which sexual arousal is the only product of sexual attractions which can be measured at present with some degree of physical precision. Thus, the fact that women are aroused by seeing non-human primates having sex does not mean that women's sexual orientation includes this type of sexual interest. Some researchers argue that women's sexual orientation depends less on their patterns of sexual arousal than men's and that other components of sexual orientation (like emotional attachment) must be taken into account when describing women's sexual orientations. In contrast, men's sexual orientations tend to be primarily focused on the physical component of attractions and, thus, their sexual feelings are more exclusively oriented according to [[sex]].

More recently,{{Vague|date=October 2020}} scientists have started to focus on measuring changes in brain activity related to sexual arousal, by using [[Neuroimaging|brain-scanning techniques]]. A study on how heterosexual and homosexual men's brains react to seeing pictures of naked men and women has found<ref name="Arousal and orientation #3">{{cite journal
|first1=Adam
|last1=Safron
|last2=Bennett
|first2=Barch
|last3=Bailey
|first3=J. Michael
|last4=Gitelman
|first4=Darren R.
|last5=Parrish
|first5=Todd B.
|last6=Reber
|first6=Paul J.
|title=Neural Correlates of Sexual Arousal in Homosexual and Heterosexual Men
|year=2007
|doi=10.1037/0735-7044.121.2.237
|pmid=17469913
|journal=Behavioral Neuroscience
|volume=121
|issue=2
|pages=237–48
|s2cid=16030669
|url=https://semanticscholar.org/paper/e795b53c48ce8c9869cd1e54f20596d739eb5b5b
|access-date=2019-12-01
|archive-date=2021-08-24
|archive-url=https://web.archive.org/web/20210824071649/https://www.semanticscholar.org/paper/Neural-correlates-of-sexual-arousal-in-homosexual-Safron-Barch/e795b53c48ce8c9869cd1e54f20596d739eb5b5b
|url-status=live
}}</ref> that both hetero- and homosexual men react positively to seeing their preferred sex, using the same brain regions. The only significant group difference between these orientations was found in the [[amygdala]], a brain region known to be involved in regulating [[fear]].<ref>LeDoux JE, ''The Emotional Brain'' (New York: Simon & Schuster, 1996).</ref>