Editing Sexual orientation (section)

==Assessment and measurement==

Varying definitions and strong [[sexual norm|social norms about sexuality]] can make sexual orientation difficult to quantify.

===Early classification schemes===

One of the earliest sexual orientation classification schemes was proposed in the 1860s by [[Karl Heinrich Ulrichs]] in a series of pamphlets he published privately.<ref>{{cite book|last=Ulrichs|first=Karl Heinrich|title=The Riddle of Man-Manly Love|year=1994|publisher=Prometheus Books|isbn=978-0-87975-866-0}}</ref> The classification scheme, which was meant only to describe males, separated them into three basic categories: ''dionings, urnings'' and ''uranodionings''. An ''urning'' can be further categorized by degree of [[effeminacy]]. These categories directly correspond with the categories of sexual orientation used today: ''heterosexual'', ''homosexual'', and ''bisexual''. In the series of pamphlets, Ulrichs outlined a set of questions to determine if a man was an ''urning''.  The definitions of each category of Ulrichs' classification scheme are as follows:

:* Dioning – Comparable to the modern term "heterosexual"

:*Urning – Comparable to the modern term "homosexual"
:::Mannling – A manly ''urning''
:::Weibling – An effeminate ''urning''
:::Zwischen – A somewhat manly and somewhat effeminate ''urning''
:::Virilised – An ''urning'' that sexually behaves like a ''dioning''

:*Urano-Dioning – Comparable to the modern term "bisexual"

From at least the late nineteenth century in Europe, there was speculation that the range of human sexual response looked more like a continuum than two or three discrete categories. Berlin sexologist [[Magnus Hirschfeld]] published a scheme in 1896 that measured the strength of an individual's sexual desire on two independent 10-point scales, A (homosexual) and B (heterosexual).<ref>[[Magnus Hirschfeld|Hirschfeld, Magnus]], 1896. ''Sappho und Socrates, Wie erklärt sich die Liebe der Männer & und Frauen zu Personen des eigenen Geschlechts?'' (Sappho and Socrates, How Can One Explain the Love of Men and Women for Individuals of Their Own Sex?).</ref> A heterosexual individual may be A0, B5; a homosexual individual may be A5, B0; an asexual would be A0, B0; and someone with an intense attraction to both sexes would be A9, B9.

===Kinsey scale===

The [[Kinsey scale]], also called the Heterosexual-Homosexual Rating Scale, was first published in ''[[Kinsey Reports|Sexual Behavior in the Human Male]]'' (1948) by [[Alfred Kinsey]], [[Wardell Pomeroy]], and [[Clyde Martin]] and also featured in ''Sexual Behavior in the Human Female'' (1953).<ref>{{cite book|last=Kinsey|title=Sexual Behavior in the Human Female|year=1953|publisher=Indiana University Press|isbn=978-4-87187-704-6|page=499|display-authors=etal}}</ref> The scale was developed to combat the assumption at the time that people are either heterosexual or homosexual and that these two types represent antitheses in the sexual world.<ref>{{cite book|last=Kinsey|title=Sexual Behavior in the Human Male|year=1948|publisher=Indiana University Press|isbn=978-0-253-33412-1|display-authors=etal}}</ref> Recognizing that a significant portion of the population is not completely heterosexual or homosexual and that such people can experience both heterosexual and homosexual behavior and psychic responses, Kinsey et al., stated:
{{blockquote|text=Males do not represent two discrete populations, heterosexual and homosexual. The world is not to be divided into sheep and goats. Not all things are black nor all things white... The living world is a continuum in each and every one of its aspects. The sooner we learn this concerning human sexual behavior, the sooner we shall reach a sound understanding of the realities of sex. |sign=Kinsey et al. (1948) p. 639.}}

The Kinsey scale provides a classification of sexual orientation based on the relative amounts of heterosexual and homosexual experience or psychic response in one's history at a given time.<ref>{{cite book|last=Kinsey|title=Sexual Behavior in the Human Male|url=https://archive.org/details/sexualbehaviorin00kins|url-access=registration|year=1948|page=[https://archive.org/details/sexualbehaviorin00kins/page/639 639]|publisher=Philadelphia, W. B. Saunders Co.|display-authors=etal}}</ref> The classification scheme works such that individuals in the same category show the same balance between the heterosexual and homosexual elements in their histories. The position on the scale is based on the relation of heterosexuality to homosexuality in one's history, rather than the actual amount of overt experience or psychic response. An individual can be assigned a position on the scale in accordance with the following definitions of the points of the scale:<ref>{{cite book|last=Kinsey|title=Sexual Behavior in the Human Male|url=https://archive.org/details/sexualbehaviorin00kins|url-access=registration|year=1948|pages=[https://archive.org/details/sexualbehaviorin00kins/page/639 639–41]|publisher=Philadelphia, W. B. Saunders Co.|display-authors=etal}}</ref>

{| class="wikitable"
|-
! Rating !! Description
|-
| 0 || ''Exclusively heterosexual''. Individuals make no physical contact which results in erotic arousal or orgasm and make no psychic responses to individuals of their own sex.
|-
| 1 || ''Predominantly heterosexual/incidentally homosexual''. Individuals have only incidental homosexual contacts which have involved physical or psychic response or incidental psychic response without physical contact.
|-
| 2 || ''Predominantly heterosexual but more than incidentally homosexual''. Individuals have more than incidental homosexual experience or respond rather definitely to homosexual stimuli.
|-
| 3 || ''Equally heterosexual and homosexual''. Individuals are about equally homosexual and heterosexual in their experiences or psychic reactions.
|-
| 4 || ''Predominantly homosexual but more than incidentally heterosexual.'' Individuals have more overt activity or psychic reactions in the homosexual while still maintaining a fair amount of heterosexual activity or responding rather definitively to heterosexual contact.
|-
| 5 || ''Predominantly homosexual/only incidentally heterosexual.'' Individuals are almost entirely homosexual in their activities or reactions.
|-
| 6 || ''Exclusively homosexual.'' Individuals who are exclusively homosexual, both in regard to their overt experience and in regard to their psychic reactions.
|}

The Kinsey scale has been praised for dismissing the dichotomous classification of sexual orientation and allowing for a new perspective on human sexuality. Despite seven categories being able to provide a more accurate description of sexual orientation than a dichotomous scale, it is still difficult to determine which category individuals should be assigned to. In a major study comparing sexual response in homosexual males and females, [[Masters and Johnson]] discuss the difficulty of assigning the Kinsey ratings to participants.<ref>{{cite book|last=Masters and Johnson|title=Homosexuality in Perspective|year=1979|isbn=978-0-316-54984-4|url=https://archive.org/details/homosexualityinp00mast}}</ref> Particularly, they found it difficult to determine the relative amount heterosexual and homosexual experience and response in a person's history when using the scale. They report finding it difficult to assign ratings 2–4 for individuals with a large number of heterosexual and homosexual experiences. When there are a substantial number of heterosexual and homosexual experiences in one's history, it becomes difficult for that individual to be fully objective in assessing the relative amount of each.

Weinrich et al. (1993) and Weinberg et al. (1994) criticized the scale for lumping individuals who are different based on different dimensions of sexuality into the same categories.<ref name="Weinrich 1993 157–168">{{cite journal|last=Weinrich|first=J.|title=A factor analysis of the Klein Sexual Orientation Grid in two disparate samples|journal=Archives of Sexual Behavior|year=1993|volume=22|issue=2|pages=157–68|doi=10.1007/bf01542364|pmid=8476335|s2cid=34708645|display-authors=etal}}</ref><ref>{{cite book|last=Weinberg|title=Dual Attraction|year=1994|publisher=Oxford University Press|isbn=978-0-19-508482-5|display-authors=etal|url=https://archive.org/details/dualattractionun00wein}}</ref>  When applying the scale, Kinsey considered two dimensions of sexual orientation: overt sexual experience and psychosexual reactions. Valuable information was lost by collapsing the two values into one final score. A person who has only predominantly same sex reactions is different from someone with relatively little reaction but much same sex experience. It would have been quite simple for Kinsey to have measured the two dimensions separately and report scores independently to avoid loss of information. Furthermore, there are more than two dimensions of sexuality to be considered. Beyond behavior and reactions, one could also assess attraction, identification, lifestyle, etc. This is addressed by the [[#Klein Sexual Orientation Grid|Klein Sexual Orientation Grid]].

A third concern with the Kinsey scale is that it inappropriately measures heterosexuality and homosexuality on the same scale, making one a tradeoff of the other.<ref name="Sell 1997 43–58">{{cite journal|last=Sell|first=R.L.|title=Defining and measuring sexual orientation: A review|journal=Archives of Sexual Behavior|year=1997|volume=26|issue=6|pages=643–58|pmid=9415799|doi=10.1023/A:1024528427013|s2cid=29774549}}</ref> Research in the 1970s on masculinity and femininity found that concepts of masculinity and femininity are more appropriately measured as independent concepts on a separate scale rather than as a single continuum, with each end representing opposite extremes.<ref>{{cite book|last=Bem|first=S.L.|title=Bem sex-rol inventory professional manual|year=1981|publisher=Consulting Psychologists Press|location=Palo Alto, CA}}</ref>  When compared on the same scale, they act as tradeoffs such, whereby to be more feminine one had to be less masculine and vice versa. However, if they are considered as separate dimensions one can be simultaneously very masculine and very feminine. Similarly, considering heterosexuality and homosexuality on separate scales would allow one to be both very heterosexual and very homosexual or not very much of either.  When they are measured independently, the degree of heterosexual and homosexual can be independently determined, rather than the balance between heterosexual and homosexual as determined using the Kinsey Scale.<ref>{{cite journal|last=Shively|first=M.G.|author2=DeCecco, J.P. |title=Components of sexual identity|journal=Journal of Homosexuality|year=1977|volume=3|issue=1|pages=41–48|doi=10.1300/j082v03n01_04|pmid=591712}}</ref>

===Klein Sexual Orientation Grid===

{{main|Klein Sexual Orientation Grid}}
In response to the criticism of the Kinsey scale only measuring two dimensions of sexual orientation, [[Fritz Klein (sex researcher)|Fritz Klein]] developed the Klein sexual orientation grid (KSOG), a multidimensional scale for describing sexual orientation. Introduced in Klein's book ''[[The Bisexual Option]]'' (1978), the KSOG uses a 7-point scale to assess seven different dimensions of sexuality at three different points in an individual's life: past (from early adolescence up to one year ago), present (within the last 12 months), and ideal (what the individual would choose if it were completely their choice).

===The Sell Assessment of Sexual Orientation===

The Sell Assessment of Sexual Orientation (SASO) was developed to address the major concerns with the Kinsey Scale and Klein Sexual Orientation Grid and as such, measures sexual orientation on a continuum, considers various dimensions of sexual orientation, and considers homosexuality and heterosexuality separately. Rather than providing a final solution to the question of how to best measure sexual orientation, the SASO is meant to provoke discussion and debate about measurements of sexual orientation.<ref name="Sell 1997 43–58" />

The SASO consists of 12 questions. Six of these questions assess sexual attraction, four assess sexual behavior, and two assess sexual orientation identity. For each question on the scale that measures homosexuality there is a corresponding question that measures heterosexuality giving six matching pairs of questions. Taken all together, the six pairs of questions and responses provide a profile of an individual's sexual orientation. However, results can be further simplified into four summaries that look specifically at responses that correspond to either homosexuality, heterosexuality, bisexuality or asexuality.<ref name="Sell 1996 295–310">{{cite journal|last=Sell|first=R.L.|title=The Sell assessment of sexual orientation: Background and scoring|journal=Journal of Lesbian, Gay, and Bisexual Identity|year=1996|volume=1|pages=295–310}}</ref>

Of all the questions on the scale, Sell considered those assessing sexual attraction to be the most important as sexual attraction is a better reflection of the concept of sexual orientation which he defined as "extent of sexual attractions toward members of the other, same, both sexes or neither" than either sexual identity or sexual behavior. Identity and behavior are measured as supplemental information because they are both closely tied to sexual attraction and sexual orientation. Major criticisms of the SASO have not been established, but a concern is that the reliability and validity remains largely unexamined.<ref name="Sell 1996 295–310" />

===Difficulties with assessment===

Research focusing on sexual orientation uses scales of assessment to identify who belongs in which sexual population group. It is assumed that these scales will be able to reliably identify and categorize people by their sexual orientation. However, it is difficult to determine an individual's sexual orientation through scales of assessment, due to ambiguity regarding the definition of sexual orientation. Generally, there are three components of sexual orientation used in assessment. Their definitions and examples of how they may be assessed are as follows:

{| class="wikitable"
|-
! Component !! Definition !! Questions
|-
| Sexual attraction || Attraction toward one sex or the desire to have sexual relations or to be in a primary loving, sexual relationship with one or both sexes || "Have you ever had a romantic attraction to a male? Have you ever had a romantic attraction to a female?"<ref>{{cite journal|last=Udry|first=J.|author2=Chantala, K. |title=Risk factors differ according to same sex and opposite-sex interest|journal=Journal of Biological Sciences|year=2005|volume=37|issue=4|pages=481–97|doi=10.1017/s0021932004006765|pmid=16086450|s2cid=33902115}}</ref>
|-
| Sexual behavior || "Any mutually voluntary activity with another person that involves genital contact and sexual excitement or arousal, that is, feeling really turned on, even if intercourse or orgasm did not occur"<ref>{{cite book|last=Laumann|title=The Social Organization of Sexuality|year=1994|publisher=University of Chicago Press|isbn=978-0-226-46957-7|page=67|display-authors=etal}}</ref>   || "Have you ever had a relationship with someone of your own sex which resulted in sexual orgasm?"<ref>{{cite journal|last=Eskin|first=M.|title=Same-sex sexual orientation, childhood sexual abuse, and suicidal behaviour in university students in Turkey|journal=Archives of Sexual Behavior|year=2005|volume=34|pages=185–95|doi=10.1007/s10508-005-1796-8|issue=2|display-authors=etal|pmid=15803252|s2cid=2103633}}</ref>
|-
| Sexual identity || Personally selected, socially and historically bound labels attached to the perceptions and meaning individuals have about their sexual identity. || "Pick from these six option: gay or lesbian; bisexual, but mostly gay or lesbian; bisexual equally gay/lesbian and heterosexual; bisexual but mostly heterosexual; heterosexual; and uncertain, don't know for sure."<ref>{{cite journal|last1=D'Augelli|title=Suicidality patterns and sexual orientation-related factors among lesbian, gay, and bisexual youths|journal=Suicide and Life-Threatening Behavior|year=2001|volume=31|pages=250–64|doi=10.1521/suli.31.3.250.24246|pmid=11577911|last2=Hershberger|first2=SL|last3=Pilkington|first3=NW|issue=3|s2cid=12852593|display-authors=etal|url=https://semanticscholar.org/paper/a5a4f3aec208d80a1feacb9c9a2b0176a8458dde}}</ref>
|}

Though sexual attraction, behavior, and identity are all components of sexual orientation, if a person defined by one of these dimensions were congruent with those defined by another dimension it would not matter which was used in assessing orientation, but this is not the case. There is "little coherent relationship between the amount and mix of homosexual and heterosexual behavior in a person's biography and that person's choice to label himself or herself as bisexual, homosexual, or heterosexual".<ref>{{cite book|last=Rust|first=Paula|title=Bisexuality in the United States: A Social Science Reader|year=2000|publisher=Columbia University Press|isbn=978-0-231-10226-1|page=167}}</ref>  Individuals typically experience diverse attractions and behaviors that may reflect curiosity, experimentation, social pressure and is not necessarily indicative of an underlying sexual orientation. For example, a woman may have fantasies or thoughts about sex with other women but never act on these thoughts and only have sex with opposite gender partners. If sexual orientation was being assessed based on one's sexual attraction then this individual would be considered homosexual, but her behavior indicates heterosexuality.

As there is no research indicating which of the three components is essential in defining sexual orientation, all three are used independently and provide different conclusions regarding sexual orientation. Savin Williams (2006) discusses this issue and notes that by basing findings regarding sexual orientation on a single component, researchers may not actually capture the intended population. For example, if homosexual is defined by same sex behavior, gay virgins are omitted, heterosexuals engaging in same sex behavior for other reasons than preferred sexual arousal are miscounted, and those with same sex attraction who only have opposite-sex relations are excluded.<ref name="Savin-Williams 2006 40–44">{{cite journal|last=Savin-Williams|first=R.|title=Who's Gay? Does it Matter?|journal=Current Directions in Psychological Science|year=2006|volume=15|pages=40–44|doi=10.1111/j.0963-7214.2006.00403.x|s2cid=40586896|url=https://semanticscholar.org/paper/9a770397ab1e5f2dfed9b6a52bf1367fe5b33ce2}}</ref>  Because of the limited populations that each component captures, consumers of research should be cautious in generalizing these findings.

One of the uses for scales that assess sexual orientation is determining what the prevalence of different sexual orientations are within a population. Depending on subject's age, culture and sex, the prevalence rates of homosexuality vary depending on which component of sexual orientation is being assessed: sexual attraction, sexual behavior, or sexual identity. Assessing sexual attraction will yield the greatest prevalence of homosexuality in a population whereby the proportion of individuals indicating they are same sex attracted is two to three times greater than the proportion reporting same sex behavior or identify as gay, lesbian, or bisexual. Furthermore, reports of same sex behavior usually exceed those of gay, lesbian, or bisexual identification.<ref>{{cite book|last=Laumann|title=The Social Organization of Sexuality|year=1994|publisher=University of Chicago Press|isbn=978-0-226-46957-7|page=301|display-authors=etal}}</ref> The following chart demonstrates how widely the prevalence of homosexuality can vary depending on what age, location and component of sexual orientation is being assessed:

{| class="wikitable" style="text-align: center;"
|+ Prevalence of homosexuality
|-
!  !! colspan="2" |  Attraction   !! colspan="2" | Behaviour   !! colspan="2" | Identity
|-
| Country: Age group || Female
|Male|| Female
|Male|| Female
|Male
|-
|
:US: Youth<ref>{{cite journal|last=Mosher|first=W |author2=Chandra, A. |author3=Jones, J.|title=Sexual behaviour and selected health measures: Men and women 15–44 years of age, United States, 2002|journal=Advance Data from Vital and Health Statistics|volume=362}}</ref>
 || 6%
|3%|| 11%
|5%|| 8%
|3%
|-
|
:US: Young adults<ref>{{cite journal|last=Savin-Williams|first=R.|author2=Ream, G.L.|title=Suicide attempts among sexual-minority male youth|journal=Journal of Clinical Child and Adolescent Psychology|year=2003|volume=32|pages=509–22|pmid=14710459|issue=4|doi=10.1207/S15374424JCCP3204_3|s2cid=24999339|url=https://semanticscholar.org/paper/2f1f4316ab48b647d9aaf8fc823369b75672880b|access-date=2019-12-01|archive-date=2021-08-24|archive-url=https://web.archive.org/web/20210824071647/https://www.semanticscholar.org/paper/Suicide-Attempts-Among-Sexual-Minority-Male-Youth-Savin-Williams-Ream/2f1f4316ab48b647d9aaf8fc823369b75672880b|url-status=live}}</ref>
 || 13%
|5%|| 4%
|3%|| 4%
|3%
|-
|
:US: Adults<ref>{{cite book|last=Laumann|title=The Social Organization of Sexuality|year=1994|publisher=University of Chicago Press|isbn=978-0-226-46957-7|display-authors=etal}}</ref>
 || 8%
|8%|| 4%
|9%|| 1%
|2%
|-
| Australia: Adults<ref>{{cite journal|last=Dunne|first=M.|author2=Bailey, J. |author3=Kirk, K. |author4=Martin, N. |title=The subtlety of sex –atypicality|journal=Archives of Sexual Behavior|year=2000|volume=29|pages=549–65|doi=10.1023/A:1002002420159|issue=6|pmid=11100262|s2cid=17955872}}</ref>  || 17%
|15%|| 8%
|16%|| 4%
|7%
|-
| Turkey: Young adults<ref>{{cite journal|last1=Eskin |first1=M. |last2=Kaynak-Demir |first2=H. |last3=Demis |first3=S.|title=Same-sex sexuall orientation, childhood sexual abuse, and suicidal behaviour in university students in Turkey|journal=Archives of Sexual Behavior|year=2005|volume=34|pages=185–95|doi=10.1007/s10508-005-1796-8|issue=2|pmid=15803252|s2cid=2103633 }}</ref>  || 7%
|6%|| 4%
|5%|| 2%
|2%
|-
| Norway: Adolescents<ref>{{cite journal|last1=Wichstrom |first1=L. |last2=Hegna |first2=K.|title=Sexual orientation and suicide attempt: A longitudinal study of the general Norwegian adolescent population|journal=Journal of Abnormal Psychology|year=2003|volume=112|pages=144–51|doi=10.1037/0021-843X.112.1.144|pmid=12653422|issue=1}}</ref>  || 21%
|9%|| 7%
|6%|| 5%
|5%
|}

The variance in prevalence rates is reflected in people's inconsistent responses to the different components of sexual orientation within a study and the instability of their responses over time. Laumann et al. (1994) found that among U.S. adults 20% of those who would be considered homosexual on one component of orientation were homosexual on the other two dimensions and 70% responded in a way that was consistent with homosexuality on only one of the three dimensions.<ref name="Laumann 1994 303">{{cite book|last=Laumann|title=The Social Organization of Sexuality|year=1994|publisher=University of Chicago Press|isbn=978-0-226-46957-7|page=303|display-authors=etal}}</ref> Furthermore, sexuality may be fluid; for example, a person's sexual orientation identity is not necessarily stable or consistent over time but is subject to change throughout life. Diamond (2003) found that over seven years, two-thirds of the women changed their sexual identity at least once, with many reporting that the label was not adequate in capturing the diversity of their sexual or romantic feelings. Furthermore, women who relinquished bisexual and lesbian identification did not relinquish same sex sexuality and acknowledged the possibility for future same sex attractions or behaviour. One woman stated "I'm mainly straight but I'm one of those people who, if the right circumstance came along, would change my viewpoint".<ref>{{cite journal|last=Diamond|first=L.M.|title=Was it a phase? Young women's relinquishment of lesbian/bisexual identities over a 5-year period|journal=Journal of Personality and Social Psychology|year=2003|volume=84|pages=352–64|doi=10.1037/0022-3514.84.2.352|pmid=12585809|issue=2}}</ref>  Therefore, individuals classified as homosexual in one study might not be identified the same way in another depending on which components are assessed and when the assessment is made making it difficult to pin point who is homosexual and who is not and what the overall prevalence within a population may be.<ref name="AmPsycholAssn-whatis" />

====Implications====
Depending on which component of sexual orientation is being assessed and referenced, different conclusions can be drawn about the prevalence rate of homosexuality which has real world consequences. Knowing how much of the population is made up of homosexual individuals influences how this population may be seen or treated by the public and government bodies. For example, if homosexual individuals constitute only 1% of the general population they are politically easier to ignore or than if they are known to be a constituency that surpasses most ethnic and minority groups.  If the number is relatively minor then it is difficult to argue for community based same sex programs and services, mass media inclusion of gay role models, or Gay/Straight Alliances in schools.  For this reason, in the 1970s [[Bruce Voeller]], the chair of the [[National Gay and Lesbian Task Force]] perpetuated a common myth that the prevalence of homosexuality is 10% for the whole population by averaging a 13% number for men and a 7% number for women.  Voeller generalized this finding and used it as part of the modern gay rights movement to convince politicians and the public that "we [gays and lesbians] are everywhere".<ref>{{cite book|last=Laumann|title=The Social Organization of Sexuality|year=1994|publisher=University of Chicago Press|isbn=978-0-226-46957-7|page=289|display-authors=etal}}</ref>

====Proposed solutions====
In the paper "Who's Gay? Does It Matter?", psychologist [[Ritch Savin-Williams]] proposes two different approaches to assessing sexual orientation until well positioned and psychometrically sound and tested definitions are developed that would allow research to reliably identify the prevalence, causes, and consequences of homosexuality.<ref name="Savin-Williams 2006 40–44" />
He first suggests that greater priority should be given to sexual arousal and attraction over behaviour and identity because it is less prone to self- and other-deception, social conditions and variable meanings. To measure attraction and arousal he proposed that biological measures should be developed and used. There are numerous biological/physiological measures that exist that can measure sexual orientation such as [[#Sexual arousal|sexual arousal]], brain scans, eye tracking, body odour preference, and anatomical variations such as [[Digit ratio|digit-length ratio]] and right or left-handedness.
Secondly, Savin-Williams suggests that researchers should forsake the general notion of sexual orientation altogether and assess only those components that are relevant to the research question being investigated. For example:
* To assess STIs or HIV transmission, measure sexual behaviour
* To assess interpersonal attachments, measure sexual/romantic attraction
* To assess political ideology, measure sexual identity

=== Means of assessment ===

Means typically used include surveys, interviews, cross-cultural studies, physical arousal measurements<ref name="Gonsiorek-Weinrich">{{cite web|url=http://psycnet.apa.org/?fa=main.doiLanding&fuseaction=showUIDAbstract&uid=1996-16078-001|title=PsycNET|website=psycnet.apa.org|access-date=2010-03-20|archive-date=2021-05-11|archive-url=https://web.archive.org/web/20210511080204/https://psycnet.apa.org/?fa=main.doiLanding&fuseaction=showUIDAbstract&uid=1996-16078-001|url-status=live}}</ref> sexual behavior, sexual fantasy, or a pattern of erotic arousal.<ref name="BornGay-p21">Wilson, G., & Q. Rahman, ''Born Gay: The Psychobiology of Human Sex Orientation'' (London: Peter Owen Publishers, 2005), p. 21.</ref> The most common is verbal self-reporting<ref name="Gonsiorek-Weinrich" /> or self-labeling,<ref name="BornGay-p21" /> which depend on respondents being accurate about themselves.<ref name="Gonsiorek-Weinrich" />

====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>