Week 15 Twin Studies

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Week 15 Twin Studies

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  • The nature side of the debate suggests behaviour is cause by characteristics we are born with- the innate characterisitcs, which are usually physiological or biological. People behave the way they do because they are animals who act in accordance with their animal instincts (innate characteristics) and are determined by their biology.These characteristics are inherited from our ancestors, and form our genetic makeup
  • On the other hand, the nature side of the debate suggests that people behave the way they do because they are determined by the things other people teach them, the things they observe, and because of the different situations they are in.Like the nature side, the nurture side is also a determinist view as it proposes all human behaviour is the result of interactions with the environment.
  • Week 15 Twin Studies

    1. 1. True of False
    2. 2. Learning Objectives By the end of this lesson you: • Must be able to describe (AO1) the use of twin studies in psychology . • Should be able to describe (AO1) concordance rates.
    3. 3. Nature Behaviour is caused by innate characteristics : • The physiological/biological characteristics we are born with. • Behaviour is therefore determined by biology. • Determinist view - suggests all behaviour is determined by hereditary factors: Inherited characteristics, or genetic make-up we are born with.
    4. 4. Nurture • An individuals behaviour is determined by the environment- the things people teach them, the things they observe, and because of the different situations they are in. • Also a determinist view - proposes all human behaviour is the result of interactions with the environment.
    5. 5. Do twins hold the answer?
    6. 6. Genes Shared MZ Twins 100% DZ Twins 50% (approx) Siblings 50% (approx) Adopted Children None
    7. 7. Steve and Sue are non identical twins. Steve’s bedroom is painted blue, he likes playing football and his favourite television programme is Formula 1 racing. Sue’s bedroom is painted pink, she likes dancing and her favourite film is Sleeping Beauty. Use explanations of gender behaviour from both the Learning Approach and the Biological Approach to explain why Steve and Sue behave differently. [6] (2010)
    8. 8. Consolidation TASK Using page 5-7 summarise twin and adoption studies with 2 strengths and 2 weaknesses for each. - 15 minutes Twin / Adoption Studies - + - +
    9. 9. Concordance Feature Interpretation MZ concordance is significantly higher than DZ concordance MZ concordance is same or similar to DZ concordance MZ concordance is 100% The disorder has a genetic component. MZ concordance is significantly less than 100% The disorder is environmentally caused. The disorder is genetically caused. The disorder has an environmental component.
    10. 10. • Must be able to describe (AO1) the use of twin studies in psychology . • Should be able to describe (AO1) concordance rates. »
    11. 11. Twins & Adoption Studies 1. What are identical twins? 2. Why are they useful to study in Psychology? 3. If Identical twins behave in similar ways and share traits, what does this tell us about these behaviours? 4. However, might there be another reason as to why identical twins behave in similar ways or share traits? 5. Why are identical twins reared apart (adoption studies) useful to study?
    12. 12. Learning Objectives By the end of this lesson you: • Must be able to describe (AO1) the Gottesman and Shields study. • Must be able to describe (AO1) and evaluate (AO2) twin studies as a method in psychology.
    13. 13. Genes Shared MZ Twins 100% DZ Twins 50% (approx) Siblings 50% (approx) Adopted Children None
    14. 14. Concordance Feature Interpretation MZ concordance is significantly higher than DZ concordance MZ concordance is same or similar to DZ concordance MZ concordance is 100% The disorder has a genetic component. MZ concordance is significantly less than 100% The disorder is environmentally caused. The disorder is genetically caused. The disorder has an environmental component.
    15. 15. Consolidation Task [twin studies] 1. Describe one research method used in the study of schizophrenia (6) 2. Evaluate one research method used in the study of schizophrenia (6)
    16. 16. A P R C • Aim • What did they hope to find? What was their research question? What theory is the study attempting to support? How is it going to support it? • Procedure • What did they do? How did they do it? Who did they do it to? When did they do it? • Results • What did they find out? What data did they collect? • Conclusion • What does this mean? Did the results support the aim? Do the results support the theory the study is based on? Page 47-48
    17. 17. Aim(s) To investigate the relative importance of genetic and environmental influences on schizophrenia by comparing MZ and DZ twins. • 1.Wanted to know the extent to which Schizophrenia was genetic • 2.Wanted to replicate other studies that had found a genetic link with schizophrenia
    18. 18. Procedure Collected secondary data from hospital records of twins from the Maudsley and Bethlem Royal Joint Hospital as well as collecting primary data by interviewing and giving personality (psychometric) tests. From a sample of 392 patients 57 twin pairs were selected aged between 19 –64yrs (average age 37) where at least one of the twins were on the register of the hospital as suffering from schizophrenia (5 pairs were both on the register).
    19. 19. Participants MZ Male Female Total DZ (same sex) Total 13 11 24 17 16 33 30 27 57 The following information was obtained: • Case histories based on a self-report questionnaire and interview with the twins and their parents to provide a record of verbal behaviour • A personality test • A test used to measure disordered thinking conducted on twins and parents.
    20. 20. Results Analysis of the data has looked for similarities between each patient and their twin. Concordance was assessed in three different ways: • Grade 1: both the patient and co-twin had been hospitalised and diagnosed with schizophrenia. • Grade 2: both patient and co-twin have had psychiatric hospitalisation but the cotwin has a different diagnosis. Grade 1 2 MZ (%) 42 12 DZ (%) 9 9 3 Normal 25 21 27 55 • Grade 3: The co-twin has some psychiatric abnormality (e.g. out-patient care, GP care, neurotic or psychotic personality profile or being abnormal on interview)
    21. 21. Conclusions NATURE • Genes appear to play an important role in schizophrenia because the concordance rate is higher in MZ twins than DZ twins. (MZ twins are at least 48 times more likely to have schizophrenia than someone in the general population) • There is some evidence to suggest that there is a set of genes responsible but not one in particular. NURTURE • Environmental factors must also be important. The Diathesisstress model suggests that individuals have a genetic predisposition for schizophrenia which is in part triggered from the environment. • Gottesman (1991) went on to investigate the influence of genes on by combining the results of 40 investigations spanning over 60 years. Concordance rate for schizophrenia was 48% for MZ and 17% for DZ twins.
    22. 22. Twin sisters Zara and Elizabeth shared everything as they were growing up, dolls, secrets, boyfriends. Recently, Zara has been diagnosed with schizophrenia and now Elizabeth is terrified that she’ll be next. Use psychological concepts, theory and studies to discuss whether Elizabeth is right to be worried.(8) Tip: your answer must include an evidence based argument that Elizabeth should be worried but also a counter-argument, presenting reasons why Elizabeth may be okay, thoughts about how Elizabeth could protect herself further, evidence which refuters the role of genetics in schizophrenia, possibly drawing upon theories which suggest schizophrenia is caused by environmental experiences, limitations of studies which support the genetic base of schizophrenia
    23. 23. • Must be able to describe (AO1) the Gottesman and Shields study. • Must be able to describe (AO1) and evaluate (AO2) twin studies as a method in psychology.

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