Nature/Nurture

• Nature-Nurture Debate


  - argument concerning how much of behaviour is the product of inherited behaviour or acquired characteristics

  
  

  - takes an interactionist approach; what is the relative influence of each component
• Heredity


  - the genetic transmission of both metal and physical characteristics from one generation to another
• Diathesis-Stress Model


  - behaviour is caused by a biological or environmental vulnerability (diathesis)

  
  

  - these are expressed when coupled with a biological or environment trigger
• Interactionist Approach


  - a way of explaining the development of behaviour in terms of the range of factors (e.g. biological, psychological)

  
  

  - these factors interact with each other to form behaviour
• Epigenetics


  - a change in genetic activity without a change to genes themselves

  
  

  - circumstances and lifestyle (e.g. war, smoking, trauma etc.) can cause genes to turn 'on' and 'off
• Nature


  - refers to inherited influences or heredity

  
  

  - all possible behaviours are present from conception

  
  

  - psychological characteristics such as intelligence or personality are determined by biological factors (genes)
• Support for Nature


  - (Gottesman & Shield, 1976) found increased incidence of schizophrenia in adopted children with a schizophrenic biological parent

  
  

  - 'normal' children fostered to a schizophrenic parent and adoptive parents of schizophrenic children showed little evidence of schizophrenia

  
  

  - twin studies found a higher concordance rate for schizophrenia in MZ twins (58%) than DZ twins (12%)
• Nurture


  - refers to the influence of experience and environment

  
  

  - included pre-natal factors such as:

  . physical influences (e.g. smoking)

  . psychological influences (music)
• Support for Nurture


  - 'Little Albert Experiment' (Watson & Raynor, 1920)
• Measuring Nature Nurture


  - the degree to which people share a trait is represented by a correlation coefficient called concordance

  
  

  - concordance provides an estimate of the extent to which a trait is inherited

  
  

  - a figure of 0.1 (1%) means genes contribute almost nothing to individual difference and 1.0 (100%) means genes are the only reason for behaviour
• Adoption Studies: Strength


  - adoption separates the competing influences of nature and nurture

  
  

  - if adoptive children are more similar to their adoptive parents environmental factors are at play

  
  

  - if adoptive children are more similar to their biological parent then genetic factors are presumed to dominate

  
  

  - (Rhee & Waldman, 2002) found genetic influences account for 41% of the variance in aggression

  
  

  - demonstrates how research can separate the influences of nature-nurture
• Adoption Studies: Counterpoint


  - research suggests that this approach may be misguided; nature and nurture can be looked at in isolation

  
  

  - (Plomin, 1994) people create their own 'nurture' by selecting environments that are appropriate for their 'nature' (niche picking)

  
  

  - this then influences their development

  
  

  - this suggests that it doesn't make sense to look at evidence of either nature or nurture
• Epigenetics: Strength


  - environmental factors can span generations

  
  

  - in 1944 the Nazis blocked the distribution of food to the Dutch and 22,000 people died of starvation

  
  

  - (Susser & Lin, 1992) reported that those who were pregnant during the famine gave birth to low birth weight babies

  
  

  - these babies were 2x as likely to develop schizophrenia compared to more typical population rates

  
  

  - supports the view that life experiences of previous generations can leave epigenetic 'markers
• Real-World Application: Strength


  - the debate has a real-world application

  
  

  - (Nesdadt et al, 2010) placed the heritability rate for OCD at 0.76

  
  

  - this understanding can inform genetic counselling

  
  

  - those who have a high genetic risk of a metal disorder due to their family background can receive advice about the likelihood of developing it themselves and how to prevent it

  
  

  - the debate is not only theoretical but also has practical use
• Implications of Debate: Evaluation Extra

  - Nativists: 'anatomy is destiny'; our genetic makeup determines our characteristic and behaviour with little environmental input

  
  

  - Extreme Determinism: has led to controversy (linked to ideas of racial superiority, purity and eugenics)

  
  

  - Empiricists: suggests that any behaviour can be changed by altering environmental conditions; undesirable behaviours are punished and desirable behaviours are reinforced