Introductory Psychology: Behavior Genetics

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lecture 10 from a college level introduction to psychology course taught Fall 2011 by Brian J. Piper, Ph.D. (psy391@gmail.com) at Willamette University,

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  • Preview Question 2: What is heritability, and how does it relate to individuals and groups?
  • Preview Question 4: How do evolutionary psychologists use natural selection to explain behavior tendencies?
  • Preview Question 5: How might and evolutionary psychologist explain gender differences in mating preferences?
  • Preview Question 6: What are the key criticisms of evolutionary psychology?
  • Introductory Psychology: Behavior Genetics

    1. 1. Behavioral Genetics Brian J. Piper, Ph.D. 1
    2. 2. Goals• Genetics Primer• Behavioral Genetics Methods – Selective Breeding – Pedigree Analysis – Twins (& Adopted Twins!)• Evolutionary Psychology 2
    3. 3. 3
    4. 4. Gregor Mendel • Austrian friar who studied pea plants (29K!) 1822-1884 • Dichotomous traits 4http://www.accessexcellence.org/RC/AB/BC/Gregor_Mendel.php
    5. 5. Gregor Mendel • Homozygote versus Heterozygote • Dominant versus Recessive 1822-1884 5http://www.accessexcellence.org/RC/AB/BC/Gregor_Mendel.php
    6. 6. Examples of Mendelian PatternsS = spherical, s = wrinkled 6
    7. 7. Huntington’s Disease • Neurodegenerative Disease – Loss of motor function H h – dementia h Hh hh h Hh hh1 min video: http://www.youtube.com/watch?v=JzAPh2v-SCQ 7http://en.wikipedia.org/wiki/Huntington%27s_Disease
    8. 8. Terminology Chromosomes containing DNA(deoxyribonucleic acid) are situated in the nucleus of a cell. 8
    9. 9. Genes: Our Codes for Life Segments within DNA consist of genes that make proteins to determine our development. 9Chromosome 4: Huntingtin gene;
    10. 10. Pedigree Rife (1940) collected info from 2,200 college students and their parents Parent Child RXR= 7.6 R x L or L x L = 21.6Rife (1940) Genetics, 25, 178-186.
    11. 11. Aggression• Brunner described an extended family in which 5 males had impulsive aggression including: – Exhibitionism – Arson – Rape 11
    12. 12. Limitations of Pedigree• Paternity• Best for Dichotomous Characteristics• Families share environments too 12
    13. 13. Selective Breeding• Simple procedure with extended history• May involve controlling environment• Has been completed for emotions and drug preference• Limitations: – Generalizability – Ethics 13
    14. 14. Twin Studies Studying the effects of heredity andenvironment on two sets of twins, identical and fraternal, has come in handy. 14
    15. 15. LogicRelationship Genetic Relationship Predicted SimilarityMonozygotic Twins 100% HighDizygotic Twins (same 50% Moderatesex)Siblings 25% LowerUnrelated Minimal Modest 15
    16. 16. LogicRelationship Genetic Relationship Predicted SimilarityMonozygotic Twins 100% HighDizygotic Twins (same 50% Moderatesex)Siblings 25% LowerUnrelated Minimal Modest 16
    17. 17. 17
    18. 18. Temperament and Heredity Temperament refers to a person’s stable emotional reactivity and intensity. Identicaltwins express similar temperaments, suggesting heredity predisposes temperament. 18
    19. 19. Separated Twins A number of studies compared identical twinsreared separately from birth, or close thereafter, and found numerous similarities. Separated Twins Personality, Intelligence Abilities, Attitudes Interests, Fears Brain Waves, Heart Rate 19
    20. 20. Limitations of Twin Studies• Is postnatal environment equivalent? – Non-randomness of adoptive families• Is prenatal environment equivalent? – Solution: Assisted Reproductive Technology• Mechanism? 20
    21. 21. Evolutionary Psychology: Understanding Human NatureEvolutionary psychology studies why we ashumans are alike. In particular, it studies the evolution of behavior and mind using principles of natural selection. 21
    22. 22. Topics of Evolutionary PsychologyA number of human traits have been identified as a result of pressures afforded by natural selection. Why do infants fear strangers when they become mobile? Why do people fear spiders and snakes and not electricity and guns? How are men and women alike? How and why do men’s and women’s sexuality differ? 22
    23. 23. Natural Selection Natural selection is an evolutionary processthrough which adaptive traits are passed on to ongoing generations because these traits help animals survive and reproduce. 23
    24. 24. Sex Differences in Cognitive Functions 24Yasen et al. (in review) Neuropsychobiology.
    25. 25. Sex Differences in Cognitive Functions Explanation: Males = Hunters Females = not 25
    26. 26. Human Sexuality Gender Differences in Sexuality Males and females, to a large extent, behaveand think similarly. Differences in sexes arise in regards to reproductive behaviors. Question (summarized) Male Female Casual sex 58% 34% Sex for affection 25% 48% Think about sex everyday 54% 19% 26
    27. 27. Natural Selection & Mating PreferencesNatural selection has caused males to send their genes into the future by mating with multiplefemales since males have lower costs involved.However, females select one mature and caringmale because of the higher costs involved with pregnancy and nursing. 27
    28. 28. 28
    29. 29. Mating Preferences Males look for youthful appearing females inorder to pass their genes into the future. Females,on the other hand, look for maturity, dominance, affluence and boldness in males. Data based on 37 cultures. 29
    30. 30. Critiquing the Evolutionary Perspective Evolutionary psychologists take a behavior and work backward to explain it in terms of natural selection.Evolutionary psychology proposes genetic determinism and undercuts morality in establishing society. 30
    31. 31. Summary• Genetics Primer• Behavioral Genetics Methods – Selective Breeding – Pedigree Analysis – Twins (& Adopted Twins!)• Evolutionary Psychology 31
    32. 32. Video: Genetics versus Environment in Dogs• Behavioral Genetics: Dogs Decoded: Nova, 30:00 to 34:30 32

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