Nature v Nurture

• Nature-nurture debate


  Focuses on the relative importance of how much of our behaviour is innate and how much is acquired
• Factors contributing to behaviour

  • Heritability (innate influences)
  • Environmental factors (prenatal influences and societal experience)
• Nature


  The idea that human behaviour is the result of innate influences and that heredity is more influential
• Nature viewpoint

  • Suggests that through the process of heredity, characteristics and traits are genetically transmitted from one generation to the next
  • Is founded in the nativist theory that knowledge/abilities are innate
  • Imposes the belief that humans are pre-programmed therefore 'born this way'
• Heredity


  The process of genetic transmission of mental and physical characteristics from one generation to the next
• Nurture


  The viewpoint that human behaviour is the result of environmental influences
• Nurture viewpoint

  • Is founded in empiricist theory and believes that knowledge comes from learning and experience
  • Proposes that the environment and experience is important therefore humans are 'made this way'
• Environment

  • Everything outside the body which can include people, events and the physical world
  • Includes three levels: pre-natal, post-natal (e.g. upbringing) and historical and cultural context
• Interactionist approach


  • Suggests that both genetics and environment contribute to behaviour
  • Proposes it is more important to study how these factors affect each other rather than how much of an individual's behaviour is a result of nature or nurture
• Models that stem from the interactionist approach tend to be the most persuasive in Psychology
• Diathesis-stress model


  Proposes behaviour is the result of a biological vulnerability triggered by an environmental stressor
• Diathesis-stress model in Psychopathology

  • Explains that schizophrenia results from an interaction between a diathesis (predisposition) such as a biological vulnerability, for example, a neural correlate, faulty dopamine system or genetic abnormality) and a stress factor such as an environmental trigger, for example, a dysfunctional family
• Research evidence to support the importance of the nature argument

  • Research evidence from family, twins and adoption studies show that the closer the relatedness of two people, the more likely it is that they will show the same behaviours
  • Risk of being diagnosed with schizophrenia is approximately 1% of the general population, but increases to 46% for those with two parents who have schizophrenia
  • Average concordance rate of 40% for MZ twins and 7% for DZ twins for schizophrenia, highlighting a significant genetic component and hence support for the nature side of the nature-nurture debate
• Methodological issues concerned with separating nature from nurture

  • Determining the relative importance of how much of behaviour is due to genetics and how much is learnt is very difficult due to it being practically and theoretically impossible to separate the influence of genes from the environment in twin studies
  • The core assumption that the only difference between MZ and DZ twins is their genetic similarity (MZ=100%, DZ=50%) is strongly criticised
  • As MZ twins are the same sex and usually look alike, their parents, and society in general, tends to treat them more similarly than DZ twins
  • DZ twins are more likely to experience differential reinforcers and therefore have more unique experiences
  • These issues increase the difficultly in determining the importance of heredity (nature) and environment (nurture) because it means any 'genetically' explained differences in concordance rates can actually be accounted for by environmental influences
• Research evidence that nurture affects nature

  • Research using both humans and animals has found evidence to show that nurture can affect nature
  • Maguire et al (2000) found evidence for physical changes in the brains of humans (nature) due to environmental experience (nurture)
  • London taxi drivers had significantly bigger hippocampi (associated with spatial awareness) than controls, argued to be due to the increased use of this process rather than being born this way
  • Blakemore & Cooper (1970) gave kittens large collars to restrict vision and raised them in a circular drum with either vertical or horizontal stripes, finding they were unable to see and process lines of the opposite orientation when introduced to the 'real world' at 5 months old, supporting that the kittens' innate visual system had been altered through experience
• Both nature and nurture are deterministic viewpoints
• Regardless of whether behaviour is a product of the environment or biology, the nature-nurture debate excludes the notion of freewill
• Adopting a fatalist position such as the nature-nurture argument is linked with poorer mental health
• Adolescents who believe they have control in their lives were less vulnerable to becoming depressed whereas those who did not believe that they had control over their lives were at a significantly greater risk of developing the disorder
• Understanding human behaviour goes far beyond the nature-nurture debate
• Interactionist approach

  • Strength is that there is research support for it
  • Combines both nature and nurture
• Research support for interactionist approach

  • Tienari et al. (2004) study on schizophrenia
  • Guo et al. (2010) study on treatment of schizophrenia
• It would be far too time consuming to produce personal therapies for unique individuals, so we need to make predictions about the most likely therapeutic solutions