Nature & Nurture Debate

Research supporting nurture:

Fear acquisition, effect of the environment on behaviour.

Debate: Nature and Nurture - Maquire et al, 2000: Taxi Driver Study

Structural MRI scans of the brains of licensed London taxi drivers were compared with controls who did not drive taxis. • Hippocampal volume correlated with the amount of time spent as a taxi driver. • The posterior hippocampi of taxi drivers were significantly larger relative to those of control subjects. • The posterior hippocampus stores a spatial representation of the environment and can expand regionally in people with a high dependence on navigational skills.

Nature-nurture interaction:

Temperament and gender can influence other people's behaviour.

Debate: Nature and Nurture

The degree to which human behaviour is determined by genetics/biology (nature) or learned through interacting with the environment (nurture).

Diathesis Stress Model:

The diathesis stress model is a psychological theory that attempts to explain a disorder, or its trajectory, as the result of an interaction between a predispositional vulnerability, the diathesis, and a stress caused by life experiences.

Tabula Rasa (John Locke):

The theory that individuals are born without built-in mental content, and therefore all knowledge comes from experience or perception.

Nature and Nurture - Evaluation: Real-world Application

A further strength of the nature-nurture debate is that it has real world application. Research suggests that OCD is a highly heritable mental disorder. For example Gerald Nestadt et al, 2010, put the heritability rate at .76. Such understanding can inform genetic counselling because it is important to understand that high heritability does not mean it is inevitable that the individual will go on to develop the disorder. This means that people who had a high genetic risk of OCD because of their family background can receive advice about the likelihood of developing the disorder and how they might prevent this (e.g. learn to manage stress). This shows that the debate is not just a theoretical one but that it is important, at a practical level, to understand the interaction between nature and nurture.

Nature and Nurture - Evaluation: Epigenetics

Another strength of the debate is support for epigenetics. One example of how environmental effects can span generations presumably through epigenetic effects comes from events of the Second World War. In 1944, the Nazis blocked the distribution of food to the Dutch people and 22,000 died of starvation, in what became called the Dutch Hunger Winter. Ezra Susser and Shang Lin, 1992, report that women who became pregnant during the famine went on to have low birth weight babies. Whilst this may be unsurprising, what is more interesting is that there babies were twice as likely to develop schizophrenia when they grew up compared to the norm. This supports the view that the life experiences of previous generations can leave epigenetic 'markers' that influence the health of their offspring.

Nature:

Behaviour is caused by characteristics we are born with, e.g. genetic, physiological.

Nurture:

Behaviour is shaped through interactions with the environment.

The nature-nurture debate definition

Concerned with the extent to which aspects of behaviour are a product of inherited or acquired characteristics.

Debate: Nature and Nurture - Rutter and Rutter (1993) Aggression Hostility

Described how aggressive children think and behave in ways that lead other children to respond to them in a hostile manner. This then reinforces the antisocial child's view of the world. Thus, aggressive children tend to experience aggressive environments partly because they elicit aggressive responses.

Nurture definition

Due to environmental influences and learning.

Nature definition

Due to inherited characteristics and innate drives.

Relative Contribution:

Genes can predispose our shared humanity and individual differences and how we react to situations. Environment can amplify our genetic predispositions, and can also shape the way we react to different situations and the way we act and think. Combination of both factors. Rather than asking which approach is responsible, psychologists now try to understand which has more of a relative contribution.

Epigenetics:

How nature and nurture interact. Epigenetics is the study of changes in the expression of genes that do not result from alterations in the sequence of the genetic code. Each person's DNA lays a groundwork for the development of physical and psychological characteristics, but the activity of genes can be modified by various factors.

Debate: Nature and Nurture - Gottesman & Shields, 1976

In adoption studies: Compared biological parents and siblings and adoptive parents and siblings. • In twin studies: Compared concordance rates (how often both twins were diagnosed with schizophrenia) for monozygotic (identical) and dizygotic (non-identical) twins. • Adoption studies 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 higher concordance rates for schizophrenia in MZ twins (58%) than DZ twins (12%).

Personality - The Jim Twins

Jim Springer and Jim Lewis were separated at birth and adopted by separate families who, by coincidence, named their respective sons James.- Both were adopted by families living in Ohio and grew up within 45 miles of each other. - Both had childhood dogs they named "Toy".- Both were married twice - first to women named Linda, and then to women named Betty.- Both had boys - one called his James Allan and the other James Alan.- Both smoked the same cigarettes.- Both bite their nails and suffer from migraines. - Both enjoyed leaving letters to their wives around the home.- Both had been employed as a Sheriff at one point in their life.

Research supporting nature:

Language development, IQ scores, Predisposition to schizophrenia etc.

Nativism and empiricism

Nativism and empiricism are two different approaches. Nativism places an emphasis on being born with certain innate traits and empiricism states that all knowledge is derived from experience.

Nature and Nurture - Evaluation: Implications of the debate

Nativists suggest that 'anatomy is destiny' in that our genetic make-up determines our characteristics and behaviour, with little environmental input. This extreme determinism stance has led to controversy, such as linking ethnicity, genetics and intelligence and the application of eugenic policies. In contrast - but also controversially - empiricists suggest that any behaviour can be changed by altering environmental conditions. Behaviour shaping, a behaviourist concept, has had practical application in therapy. Desirable behaviours are selectively reinforced, and undesirable behaviours are punished or ignored. Carried to an extreme this could lead to complete social control by the state for the 'good' of everyone.

Nature and Nurture - Evaluation: Adoption Studies

One strength of research into the nature-nurture debate is the use of adoption studies. Adoption studies are useful because they separate the competing influences of nature and nurture. If adopted children are found to be more similar to their adoptive parents, this suggests the environment is the bigger influence. Whereas, if adopted children are more similar to their biological parents, then genetic factors are presumed to dominate. A meta-analysis of adoption studies by Soo Rhee and Irwin Waldman, 2002, found that genetic influences accounted for 41% of the variation in aggression. This shows how research can separate the influences of nature and nurture. However, research suggests that this approach may be misguided, that nature and nurture are not two entities that can simply be pulled apart. According to Robert Plomin, 1994, people create their own 'nurture' by actively selecting environments that are appropriate for their 'nature'. Thus, a naturally aggressive child is likely to feel more comfortable with children who show similar behaviours and will 'choose' their environment accordingly. Then, their chosen companions further influence their development. Plomin refers to this as niche-picking. This suggests that it does not make sense to look at evidence of either nature or nurture.

Heredity definition

The genetic transmission of both mental and physical characteristics from one generation to another.

Interactionist Approach:

The interactionist approach is the view that both nature and nurture work together to shape human behaviour.

Heritability Coefficient:

The measure of how much of the variation in a given trait is due to genetic variation.

Exposure to certain environmental stimuli can alter...

physiology, e.g. Brain structure, Neurochemicals.

Eugenics:

Was the science of improving the genetic composition of a population.

Debate: Nature and Nurture - Zimbardo (1973) Stanford Prison Experiment

• 24 participants, described as 'normal, healthy male college students, predominantly middle class and white'. • Randomly assigned to the role of 'prisoner' or 'guard'. The behaviour of the 'normal' students was affected by the assigned role - seemed to believe in their allocated position. Guards become verbally and physically aggressive. • Prisoners became increasingly depersonalised - several experienced extreme depression, crying, rage and acute anxiety.

Debate: Nature and Nurture - Piaget

• Children's thought processes change at predetermined age-related stages. • Changes in age are related to changes in behaviour: Sensorimotor (Birth - 2 years) Pre-Operational (Approx 2-7 years) Operational (Approx 7-11 years) Formal Operational (Approx 11+ years)

Debate: Nature and Nurture - Language Acquisition (Chomsky, 1968)

• Chomsky maintained language is the result of innate cognitive structures in the mind. • Biologically based inborn brain mechanism. • Children are predisposed to make sounds and understand grammar. This does not happen from birth but language skills develop rapidly after a certain period of time. • Language acquisition follows the same sequence in all children = An inbuilt genetic mechanism is responsible.

Debate: Nature and Nurture - 'Little Albert' (Watson & Raynor, 1920)

• Classical condition of fear-phobia acquisition. Before the study little Albert showed no sign of fear response in any situation. Session 1: Aged 11 months, Albert was presented with a rat. Each time he reached for the rat a steel bar was hit. 1st time he jumped and fell forward. 2nd time he began to whimper. • Session 2: After 5 paired presentations, Albert reacted to the rat alone by immediately crying, turning, and crawling away quickly.

Debate: Nature and Nurture - An individual's characteristics may elicit particular responses in other people, e.g:

• Temperament: How active, responsive or emotional an infant is influences in part determines their caregivers' responses. • Gender: People tend to react differently to boys and girls due to expectations of masculine and feminine characteristics. • Aggression: Displaying aggressive behaviour creates particular responses from other people.