Nature vs Nurture

What is the nature/ nurture debate concerned with?

the relative contributions of nature (heredity) and nurture (environment, experience and learning) to behaviour.

What is the nature side of the debate associated with in comparison to the nurture side of the debate?

with a nativist theory; they stress the importance of inherited influences on behaviour whereas empiricists (nurture) believe behaviour is due to learning and experience.

What is the nature side of the debate?

• Early Nativists (e.g. Decartes, 17th Century) argued that human characteristics are innate

• They are heritable; the result of our genes

• Psychological characteristics (e.g. IQ or personality) are determined by biological factors, in the same way as eye colour or height

What are examples of the nature debate?

• Limbic System cause of aggression

• Serotonin (neural) explanation of OCD (Psychopathology)

• Dopamine Hypothesis explanation of Schizophrenia

What is the nurture side of the debate?

• Empiricists (e.g. Locke, 17th century) argued that humans are born as ‘blank slates’, and believed that the mind is shaped by trial and error interactions with the environment

• These interactions can be prenatal (e.g. pregnant mothers smoking) or postnatal experiences

What are examples of the nurture debate?

• Operant Conditioning/ Classical Conditioning: Skinner’s Rats / Pavlov’s Dogs

• SLT - Behaviour learnt through imitation and vicarious reinforcement: (Bandura’s Bobo Doll study)

What does relative importance mean?

The nature/nurture debate concentrates on

the Relative Contribution (interaction) of

nature and nurture in determining our

behaviour…

E.g. How much of each concept causes a

behaviour? Which one is dominant in a

particular behaviour?

How can psychologists study measure the contributions of nature and nurture in behaviour?

• Concordance: the degree to which two people are similar on a particular trait

• Heritability: the proportion of differences between individuals in a population, with regards to a particular trait, due to genes.

  0.01 (1%) is very little contribution, 1 (100%) means genes are the only reason. (The figure for IQ heritability is about 0.5)

• Twin studies: MZ twins share 100% of genes, whereas DZ twins share 50% of genes – so we would expect a greater likelihood of both MZ twins developing the same behaviour if it IS genetic.

• Adoption studies: whether a child behaves more similarly to an adopted parent (environmental input only) or a biological parent (biological input only).

Evidence of a necessary Interactionist Approach in Research (AO3): Diathesis-Stress Model

This model states that behaviour is caused by a biological vulnerability (diathesis) which is only expressed when coupled with an environmental trigger (stressor).

E.g. a person who inherits a genetic vulnerability for OCD may not develop the disorder, but, if combined with a psychological trigger (e.g. traumatic experience) this may result in OCD.

= Gene/environment interactions – so the cause of the behaviour is BOTH nature AND nurture.

MAOA gene trigger (childhood abuse) to cause an aggressive response.

SERT/COMT genes need ‘triggering’ by an experience of trauma to produce OCD characteristics.

Example of a necessary Interactionist Approach in Research (AO3): Epigenetic

• Lifestyle and events we encounter (e.g. smoking, diet, exercise, pollution) leave ‘epigenetic marks’ on our DNA

• These ‘epigenetic marks’ stay in our genes and can be passed down to our children, and down our genetic lines

• These marks can tell our bodies which genes can switch into high or low function if triggered (by diathesis stress).

• So, life experiences of our previous generations causes a nature AND nurture interaction

Example of a necessary Interactionist Approach in Research (AO3): Constructivism

People create their own ‘nurture’ by actively seeking and selecting environments that suit their ‘nature’.

E.g. a naturally aggressive or shy child is likely to feel comfortable around children who show similar behaviours and will choose their environment accordingly. This environment then affects their development. Plomin (1994) refers to this as niche-building.

This is further evidence of why it’s illogical and impossible to try to separate the nature and nurture influences on behaviour. Thus rendering a separation of the sides of the debate meaningless.