PSYC 2850 - Human Sexuality - Class 10

Course Code
Psychology 2800
Thisis P S Y C2850- Human Sexuality N O T P S Y C2800

Sexual Orientation
The prenatal hormone hypothesis of Sexual orientation
How androgen levels influence sexual development
Homosexuals not exposed to enough testosterone prenatally at a critical point in
Androphilic: Variable in males and females
Threshold: if below the threshold line males have not received enough androgens so
they develop sexual preferences in an androphilic way
Females who produce more androgens than threshold develop gynephilic tendencies
Experimentally manipulation testosterone levels prenatally in animal models results in
sex-atypical brain development and sex-atypical sexual partner preference in adulthood
SDN: sexually dimorphic nucleus
Amount of testosterone is only influential in sexual preference when injected
around the time of birth
If injected around puberty would just become more interested in sex
Women affected with CAH are much more likely to express sexual interest in same-
sex sexual partners than unaffected women
Prenatal exposure to hormones but there are likely only things influencing sexual
Sexual orientation is not an isolated trait
Gay men and lesbians are gender-atypical for various behavioural, cognitive,
personality, physiological and morphological traits
This is what we would predict based on the prenatal hormone hypothesis
Childhood behaviour
Childhood gender-atypicality in boys is highly predictive of adult homosexuality
Retrospective studies: as adults about their childhood on a scale of 1-7
Prospective: more difficult, start with kids and follow them into adulthood
Adult behaviour
Sex difference is gait
Swagger (men move shoulders more)
Sway/sashay (women hip movement)
Gay men and lesbians are gender-atypical in terms of their gait
Gender-atypical gait, voice, posture used when spotting someone whom you think
is homosexual without explicit knowledge of that person’s sexual orientation
Sex differences in targeting accuracy
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Hetero men > hetero women
Testosterone exposure increase = increase in accuracy
CAH women better targeting accuracy than non-CAH women
Gay men and lesbians are sex-atypical for targeting accuracy one
Body morphology
Long bones
Increase prenatal testosterone = increase long-bone
Increase length in rates
Hetero male > hetero females
Lesbians > hetero females
Gay men < hetero males
Otoacoustic emissions: weak sounds produced by the cochlea (inner ear)
OAE: hetero women > hetero men
Increase testosterone exposure = decrease OAE strength
OAE in lesbians < hetero women
No difference in gay men vs straight men
Amgydala: clusters of nuclei in the left and right temporal lobes involved in
regulating emotion, sexuality, social information
In hetero men right amygdala more richly connected with other parts of the
brain, than the left
In hetero women opposite pattern
Sex differences in the main functional connections to other parts of the brain
The amygdalas of homosexual men and women are sex-atypical
Fraternal Birth Order (older brother) effect
The number of loder biological brothers increases the chances of male androphilia
in later born male siblings
For every older biological brother the odds that a male will be androphilic increased
by 33%
Sexual Disorders
All information from the Diagnostic Statistical Manual of Mental Disorders
What is a disorder?
Different for each disorder
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