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Psychology 320: Gender Psychology

Lecture 16

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Midterm

• The exam is worth 20% of your final grade.

• The exam will be scored out of 75 points.

• October 21: 35 multiple choice questions (1 point each), 5 definitions (2 points each).

• October 23: 7 short answer questions (2-7 points each).

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• Please arrive on time to facilitate rapid distribution of the exams.

• Bring a pencil, eraser, pen, and your student ID to the exam.

• All electronic devices must be put away; the time will be monitored in 5 minute increments on the overhead projector.

• Students may not leave the exam room during the last 10 minutes of the exam.

• Hats (e.g., baseball caps) should not be worn during the exam.

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1. What biological theories have been proposed to explain gender differences? (continued)

Biological Explanations of Gender Differences:

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What biological theories have been proposed to explain gender differences? (continued)

3. Hormonal Theories (continued)

Example 4: Hormonal Abnormalities

Congenital Adrenal Hyperplasia (CAH)

• CAH is a genetically-based disorder that results in inadequate synthesis of cortisol by the fetus.

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• Cortisol converts androgens into estrogens.

• Male fetuses are relatively unaffected by CAH. However, 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 the controls.

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Select Findings from Ehrhardt et al. (1968)

CAH Participants

Control Participants

Slacks, shirts, and shorts only 0 0

Slacks, shirts, and shorts strongly preferred over dresses

9 0

Dresses strongly preferred over slacks, shirts, and shorts

5 11

Dresses only 1 4

A. Interest in Physical Appearance: Clothing Preference

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CAH Participants

Control Participants

Intense outdoor activity 11 5

Periodic outdoor activity 4 9

Little outdoor activity 0 1

B. Physical Energy Expenditure: Athletic Interests and Skills

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CAH Participants

Control Participants

Never 3 11

Passing Episode 1 4

Always 11 0

C. Tomboyism: Known to Self and Mother as Tomboy

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CAH Participants

Control Participants

Content or prefers to be a girl 7 14

Ambivalent 5 0

Desires expressly to be a boy 3 1

D. Tomboyism: Satisfaction with Sex Role

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4. Neuroanatomical Theories

Sex differences have been identified in the structure of the brain.

Example 1: Interhemispheric Differences

• The functions of the brain are “lateralized.”

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• The brain areas responsible for language production and comprehension, mathematics,

and analytical reasoning are largely located in the left hemisphere.

• The brain areas responsible for visual-spatial problem solving, facial and pattern recognition, perceptual and nonverbal skills, and musical ability are largely located in the right hemisphere.

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• The results of several studies suggest that male brains are more lateralized than female brains:

Voyer (1996): Conducted a meta-analysis of 396 studies; revealed greater brain lateralization among males than females for both linguistic abilities and visual-spatial abilities.

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• Notably, however, some studies have failed to demonstrate sex differences in brain lateralization.

• Sommer et al. (1994): Conducted a meta-analysis of 14 studies; revealed that brain lateralization for linguistic abilities did not differ

for males and females.

• Sex differences in performance on verbal tasks and visual-spatial tasks have been attributed to sex differences in brain lateralization.

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Example 2: Intrahemispheric Differences

• Within each hemisphere of the brain, distinct regions are responsible for distinct functions.

• The results of some studies suggest that there are sex differences in the organization of these regions within each hemisphere of the brain.

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• Kimura (1987, 1992, 1999): Found that both the language and manual dexterity areas in the left hemisphere were more focally organized among females and more diffusely organized among males.

Females afflicted with aphasia and apraxia were more likely to suffer damage to the anterior region of the left hemisphere.

Males afflicted with aphasia and apraxia were more likely to suffer damage to the anterior, central, parietial, temporal, and posterior regions of the left hemisphere.

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71% of females and 12% of males who suffered apraxia had sustained lesions to the anterior region of the left hemisphere

7% of females and 44% of males who suffered apraxia had sustained lesions to the posterior region of the left hemisphere

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Example 3: Hemispheric Connectivity

• The corpus callosum is a band of neural fibers that connects the right and left hemispheres of the brain.

• The results of some studies suggest that there are sex differences in the size of the corpus callosum:

The posterior portion of the corpus callosum is larger in females than males.

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Corpus Callosum

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• On the basis of this difference, some researchers have argued that the brain hemispheres

communicate more effectively among females than males.

• Notably, however, some studies have failed to demonstrate sex differences in the size of the corpus callosum.

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Other Neuroanatomical Differences

• The brains of males are slightly larger than the brains of females. However, neurons are more densely packed in the brains of females than in the brains of males.

• Right vs. left hemisphere weight differences are smaller for females than for males.

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• Activity of the left amygdala is associated with long-term memory of emotional events in

females; activity of the right amygdala is associated with long-term memory of emotional

events in males (Cahill et al., 2004).

• Activity of the left hippocampus is associated with memory of object location in females; activity of the right hippocampus is associated with memory of object location in males (Frings et al., 2006).

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• The sexually dimorphic nucleus is 2.5 times larger in adult males than adult females. Although its

function is unknown, the area in which it is located (the anterior hypothalamic preoptic area) is associated with sexual and maternal behaviour, gender identity, and the regulation of gonadal hormones (Breathnach, 1990).

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1. What biological theories have been proposed to explain gender differences? (continued)

Biological Explanations of Gender Differences: