METHODS: Twin Studies
- Created by: krist-vincu
- Created on: 31-01-17 12:42
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- METHODS: Twin Studies
- NATURE Vs NURTURE DEBATE
- Asit shows how its unlikely that any characteristic is solely due to either nature or nurture.
- There is always some influence from the environment. Genetic characteristic/ Should show it.
- In practice, no characteristic is shared completely (MZ)
- Monozygotic (MZ), Identical, share 100% of their genes as they came from one fertile egg.
- some characteristics, such as IQ and personality might become more alike as the twins age.
- Start: Physical differences /fingerprints, develop differently in the womb, despite their DNA being the same.
- Some characteristics that genetic are triggered by the environment, so identical twins can become less identical overtime, although their DNA does not change.
- EPIGENETIC MODIFICATION: Overtime, different environmental differences. 50 years old MZ have over 300 times the epigenetic differences compared to you MZ twins.
- Dizygotic (DZ)
- Not identical (fraternal)
- Come from two separate eggs that are fertilised at the same time.
- Share 50% of their genes.
- Can be different genders.
- This means that if a characteristics is genetic, DZ twins would be expected to hare that characteristic to an extent but not as much as MZ twins would share it.
- Psychologists are able to compare behaviour between a group of identical twins and fraternal twins to see which group shared the most similarity between each set of twins. To which extent the same behaviour is the same between twins is known as CONCORDANCE RATE.
- Concordance Rate: An agreement rate- when both twins have the same characteristic
- Evidence: Gottesman & Shields (1966)
- (MZ): Concordance Rate: 35% to 58%, on average 42%
- (MZ): Concordance Rate: 35% to 58%, On average 42%
- they studied twins over 16 years period using data from 5 twins studies.
- When only the most severe cases of Schizophrenia were considered, the concordance rate for MZ twins was between 75% to 91%.
- Researchers concluded hat genes do play a role in the development of Schizophrenia
- Aim: to see if there is any relationship between genetic make-up and the development of Schizophrenia, by looking at the concordance rate for he disorder in groups of twins. The researchers waned to see how common it is for both twins to show signs of Schizophrenia.
- To do this they obtained information: Patients treated for Schizophrenia and whether or not they were born a twin.
- 57 twin airs were chosen for the study.
- 33 DZ and 24 MZ
- 57 twin airs were chosen for the study.
- ETHICS
- - Generalisability: Twins are unique
- + Valid: Time period: Face validity: criticism wold be that they expect 100% concordance rate / that its not down to genetics but the environment
- + Appication: MZ have high concordance rate than DZ
- Triangulation : Reliability: different research telling the same results/ increase reliability
- (MZ): Concordance Rate: 35% to 58%, on average 42%
- NATURE Vs NURTURE DEBATE
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