Debate: Nature and Nurture

The degree to which human behaviour is determined by genetics/biology (nature) or

learned through interacting with the environment (nurture)

Aims of lessonTo understand what is meant by the nature-nurture debate and to identify the main assumptions .To be able to describe at least 1 study which supports nature, and 1 study to support nurture.To be able to identify the applications and problems associated with the debate.To be able to identify the perspectives/ approaches relevant to the debate.To be able to evaluate the debate.

Behaviour is caused by innate characteristics :The physiological/biological characteristics we are born with. Behaviour is therefore determined by biology.Determinist view- suggests all behaviour is determined by hereditary factors:

Inherited characteristics, or genetic make-up we are born with.

Nature

NatureAll possible behaviours are said to be

present from conception.Genes provide the blueprint for all behaviours; some present from birth, others pre-programmed to emerge with age.Is a developmental approach:

E.g. Piaget: children’s thought processes change at predetermined age-related stages

changes in age are related to changes in behaviour.

NurtureAn individuals behaviour is determined by the environment- the things people teach them, the things they observe, and because of the different situations they are in. Also a determinist view- proposes all human behaviour is the result of interactions with the environment.

Behaviourist theories are nurture theories: - Behaviour is shaped by interactions with

the environment.Born an empty vessel- waiting to be filled up by experiences gained from environmental interaction.No limit to what they can achieve:-Depends on quality of external influences and NOT genes.The quality of the environment is KEY:-You can become anything provided the environment is right.

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) - Operational (approx 7 – 11) - Formal operational (approx 11+ years)

Support for Nature

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.

Support for Nature

Identical genes exist in Identical Twins- Monozygotic (MZ) twins share 100% of their genes.

Fraternal Twins- Dyzygotic Twins (DZ), share 50% of their genes.

Genetic effects can therefore be shown when the correlations within each group is compared with the correlations between each group.

This can be added to the correlations found with other relatives. Parents share 50% of genes, cousins share 12.5%.

Support for Nature

Genetic basis of Schizophrenia (Gottesman & Shields, 1976)

- A review of twin and adoption studies into schizophrenia between 1967 and 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 dyzygotic (non-identical) twins.

Support for Nature

Video

Results - 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 rate for schizophrenia in MZ twins (58%) than DZ twins (12%).

ConclusionSignificant genetic input into the onset of schizophrenia. Genes responsible for predisposing a person to schizophrenia.

Support for Nature

IQ scores -Plomin (1988) studied MZ and DZ twins

reared together and apart and found that I.Q. has an overall heritability of 0.68- genetics are responsible for about 68% of the variation in I.Q.

-MZ twins reared apart have I.Q. scores which correlate at about 0.74, or 74%.Evaluation point

However, variations between identical twins must

be due to environmental influences.

Support for Nature

Support for Nurture – Little Albert

Classical conditioning of fear- phobia acquisition: ‘little Albert’ (Watson & Raynor, 1920)-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 + 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.

Session 3: Albert returned to see if the fear had transferred.

- Presentation of toy blocks (neutral stimulus) = playing

- Presentation of the rat followed by a rabbit, dog, fur-coat, Watson’s hair and a Santa Claus = –ve responses of crying, moving away from stimulus and crawling. Session 4: steel bar + rat, steel bar+ rabbit, steel bar+ dog. Fear response was pronounced in all.Session 5: 1 month later Albert continued to show fear reactions to all stimuli. Transference of the fear had been made to similar objects.

Support for Nurture

Conclusion - By session 2, after 5 paired presentations the

conditioning of fear was evident: is possible to condition fear through classical conditioning.

- By sessions 3 & 4, transference of the fear had been made to similar objects.

- By session 5, time had not removed the fear response.

Provides evidence that the environment can be manipulated to create a phobic response & behavioural change.

(See key study: A2 OCR textbook p.115)

Support for 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’ . - A simulated prison was built in the basement of the

psychology building at Stanford University. It comprised of 3 small cells each housing 3 men ,and 1 small unlit room for solitary confinement.

Support for Nurture- Zimbardo

Video

Guards not told how to behave but were explicitly told that they were not allowed to use physical punishment or physical aggression.Uniforms of both groups were intended to increase group identity and reduce individuality.Guards’ uniforms were intended to convey a military attitude, with a baton and whistle for symbols of control and power.  

Support for Nurture

The behaviour of the ‘normal’ students was affected by the assigned role- seemed to believe in their allocated position.Guards became verbally and physically aggressive.Prisoners became increasingly depersonalised- several experienced extreme depression, crying, rage and acute anxiety.The experiment had to be stopped after just six days instead of the planned 14 days.

The study demonstrates the powerful effect roles can have on peoples’ behaviour.

Support for Nurture

Can you think of any other studies that show the effect a situation can have on behaviour?

Nature Nurture InteractionBehaviour is often a result of the interaction

between nature AND nurture.An individuals characteristics may elicit particular responses in other people e.g. Temprament: 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 create particular responses from other people.

Nature Nurture InteractionEvidence

Rutter and Rutter (1993) Aggressionhostility

- 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.

Nature Nurture Interaction

Maguire 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. See AS Psychology textbook:

pp.68

Nature Nurture Interaction

Maguire et al. Conclusion - It appears the brain has the capacity for

plasticity (the ability to change)- the structure of the brain can alter in response to environmental demands.

Supporting Approaches & Perspectives

Supporting NATURE Supporting NURTUREPhysiological Social (e.g. Helping

behaviour)Individual Differences Behavioural

Developmental

Psychodynamic

Problems with Nature-Nurture Debate

1. It is reductionist2. It is deterministic3. It is difficult to control variables

Determinism: The ‘nature’ view of psychology is a determinist one- it suggests behaviour is determined by hereditary factors (e.g. Language development).

Links to other debates

ApplicationsNature

Drug therapies can be developed to treat behavioural or psychological problems that have a physiological origin.

E.g. SSRI’s can be used to treat depression, Ritalin- ADHD.

NurtureIf behaviour is susceptible to environmental influences we need to consider how we adapt our environment.

E.g. To promote helping behaviour, enhance learning, reduce aggression and decrease criminality.

BUT- where does learning fit?? Nature like Piaget, or nurture

like Skinner?

SummaryNature: behaviour is caused by characteristics we are born with e.g. genetic, physiological.Nurture: behaviour is shaped through interactions with the environment.Research supporting nature: language development, IQ scores, predisposition to schizophrenia etc.Research supporting nurture: fear acquisition, effect of the environment on behaviour.

Summary cont...Nature-nurture interaction: Temperament and gender can influence other peoples behaviour.Exposure to certain environmental stimuli can alter physiology e.g. Brain structure, neurochemicals.Applications: Development of drug therapies,adapt environments to increase helping behaviour, enhance learning etc.Link to other debates: Determinism