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Psychology 320: Psychology of Gender and Sex Differences

Lecture 18

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Office Hour InvitationsOctober 23rd, 1:30-2:30, Kenny 2517

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Reminder

I will hold additional office hours in preparation for the midterm exam:

Monday, October 22:  11:30AM-1:30PMTuesday, October 23: 1:30-3:30PM

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Midterm Exam

• October 24: 30 multiple choice questions (1 point each).

• October 26: 5 extended response questions (2-6 points each, totaling 20 points).

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

• The exam will be scored out of 50 points.

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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 before the start of the exam.

• Bags and backpacks should be left at the front of the room. Valuables (e.g., laptops, wallets) may be placed under your seat.

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

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From last class ….

• Lecture 17: Non-human animal experiments suggest that high levels of testosterone cause aggression.

• Brannon (2011, p. 96): “Thus, the evidence is weak that testosterone is the underlying cause of aggression.”

• Reconciliation?

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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. identify differences in the neuroanatomical features of the female brain and the male brain.

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4. Neuroanatomical Theories

Sex differences have been identified in brain structure.

Example 1: Interhemispheric Differences

• The functions of the brain are “lateralized.”

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

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• Left hemisphere: Language production/comprehension, mathematics, and analytical reasoning.

• Right hemisphere: Visual-spatial problem solving, pattern recognition, perceptual/nonverbal skills, and musical ability.

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• A number of studies suggest that male brains are more lateralized than female brains:

Voyer (1996): Conducted a meta-analysis of 396 studies; found greater brain lateralization among males

than females for linguistic and visual-spatial abilities.

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• Notably, some studies (e.g., Sommer et. al., 2004) have failed to replicate this finding.

• 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: Hemispheric Connectivity

• Corpus callosum: A band of neural fibers that connects the right and left hemispheres of the brain.

• Some studies suggest that there are sex differences in the size of the corpus callosum:

The posterior portion (i.e., splenium) 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 argue that the brain hemispheres communicate more effectively among females than males.

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Other Neuroanatomical Differences

• The brains of males are larger than the brains of females.

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

• Neurons are more densely packed in the brains of females than in the brains of males.

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• Long-term memory of emotional events: Associated with activity of the left amygdala in females and the right amygdala in males (Cahill et al., 2004).

• Memory of object location: Associated with activity of the left hippocampus in females and the right

hippocampus 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.

The function of this nucleus is unknown.

The region in which it is located is associated with sexual and parental behaviour, gender identity, and the regulation of gonadal hormones (Breathnach, 1990).

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Community Service Learning (CSL) Information

• Supplementary syllabus, application, and organization information sheets are now available on the course website.

• Graded requirements: Discussion group attendance, articulated learning journal entries, end of placement paper.

• Application due date: Monday, November 5th, 2012 (submit in class). Requires letter of intent and resume/CV.

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• Eight partner organizations:

Beauty Night Society: Life Makeover Program Ending Violence Association Frog Hollow Neighbourhood House Health Initiative for Men QMUNITY: BC’s Queer Resource Centre Vancouver and Lower Mainland Multicultural Family

Support Service Society West Coast Legal Education & Action Fund (LEAF) YWCA Metro Vancouver

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Biological Theories of Sex Differences

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