Psychology of Gender and Sex Differences
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Transcript Psychology of Gender and Sex Differences
Psychology 320:
Psychology of Gender
and Sex Differences
Lecture 17
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Office Hour Invitations
October 23rd, 1:30-2:30, Kenny 2517
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Announcement
Jacqueline-Marie (TA for students with last names A-M)
must cancel her office hour today due to a missed airline
flight on return from a conference.
Please feel free to contact her with questions via e-mail
over the weekend or early next week.
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Biological Theories of Sex Differences
1. What biological theories have been proposed to
explain sex differences? (continued)
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By the end of today’s class, you should be able to:
1. review evidence that supports genetic contributions
to sex differences in psychological characteristics.
2. discuss the causes and symptoms of Klinefelter
syndrome.
3. identify the three classes of sex-related hormones.
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4. review evidence that supports hormonal contributions
to sex differences in psychological characteristics.
5. define the “challenge hypothesis.”
6. discuss the causes and symptoms of congenital
adrenal hyperplasia.
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What biological theories have been proposed to explain
sex differences? (continued)
2. Genetic Theories (continued)
Example 2: Genetic Atypicalities
Klinefelter Syndrome
• Results from an extra X chromosome in males (XXY).
• Incidence: 1/1000 – 3/1000 live births.
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• Physical symptoms include:
small firm testes
small penis
underdeveloped muscles
rounded body type (i.e.,
wide hips)
atypical body
proportions
tall build
gynecomastia
reduced facial/body hair
language learning impairment
decreased libido
infertility
epilepsy
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• Psychological symptoms include: “incomplete
masculinization” and “feminization.”
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3. Hormonal Theories
There are three classes of sex-related hormones:
Estrogens (e.g., estradiol; relatively high among
females).
Progestins (e.g., progesterone).
Androgens (e.g., testosterone; relatively high among
males).
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Estrogens and androgens are particularly important
in sex differentiation, in utero and at puberty.
Research suggests, in addition to sex differentiation,
hormones influence the psychological and behavioural
characteristics of the sexes.
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Example 1: Non-Human Animal Experiments
vom Saal, Grant, McMullen, and Laves (1983)
• Contrasted the behaviour of male mice exposed to high
prenatal testosterone levels and male mice exposed to
low prenatal testosterone levels.
• Target embryos were “placed” between male siblings or
female siblings.
• Males exposed to higher testosterone levels
displayed more aggressive behaviour postnatally.
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Example 2: Correlational Studies
Dabbs, Carr, Frady, and Riad (1995);
Dabbs, Ruback, Frady, Hopper, and Sgoutas (1988)
• Found that male and female prison inmates who had
relatively high levels of testosterone displayed higher
levels of negative masculinity (e.g., impulsiveness,
aggression, disobedience; vs. positive masculinity).
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Example 3: Meta-Analytic Studies
Book, Starzyk, and Quinsey (2001)
• Conducted a meta-analysis of 45 studies that examined
the relationship between testosterone and aggression
among females and males.
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• Average correlation was +.23; correlation was
strongest among males aged 13 – 20 years, at +.58.
• The authors proposed the “challenge hypothesis” to
explain the latter finding.
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Example 4: Hormonal Atypicalities
Congenital Adrenal Hyperplasia (CAH)
• CAH is a genetically-based disorder that results in
excessive androgen production in utero.
• Male fetuses are relatively unaffected by CAH. Female
fetuses develop ”masculinized” genitalia.
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Congenital
Adrenal
Hyperplasia
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Ehrhardt, Epstein, and Money (1968)
• Examined 15 girls diagnosed with CAH.
• The behavioural profiles of the CAH participants were
more “masculine” than those of controls, as indicated by:
lower levels of anticipation of marriage, preference for
career over marriage, less preference for doll play, less
interest in infant care, a preference for boy’s clothes, a
greater interest in outdoor activity.
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Hines, Brook, and Conway (2004)
• Examined 16 women and 9 men diagnosed with CAH.
• CAH women recalled more male-typical play behavior,
reported less satisfaction with female sex assignment,
and showed less heterosexual interest than female
controls.
• CAH men did not differ significantly from male controls.
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Biological Theories of Sex Differences
1. What biological theories have been proposed to
explain sex differences? (continued)
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