1. Debate: Nature and Nurture
The degree to which human behaviour is
determined by genetics/biology (nature)
or learned through interacting with the
environment (nurture)
2. Aims of lesson
To 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.
3. Nature
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.
4. Nature
All 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.
5. Nurture
An 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.
6. 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.
7. Support for Nature
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)
8. 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.
9. 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%.
10. 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. Video
11. Results Support for Nature
- 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%).
Conclusion
Significant genetic input into the onset of
schizophrenia. Genes responsible for predisposing a
person to schizophrenia.
12. IQ scores Support for Nature
-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.
13. 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.
14. Support for Nurture
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.
15. 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)
16. Support for Nurture- Zimbardo
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.
Video
17. Support for Nurture
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.
18. 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.
19. Can you think of any
other studies that show
the effect a situation can
have on behaviour?
20. Nature Nurture Interaction
Behaviour 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.
21. Nature Nurture Interaction
Evidence
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.
22. 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
23. 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.
25. Problems with Nature-Nurture Debate
1. It is reductionist
2. It is deterministic
3. 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).
26. Applications
Nature
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.
Nurture
If 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.
27. Summary
Nature: 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.
28. 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.
Notas del editor
The nature side of the debate suggests behaviour is cause by characteristics we are born with- the innate characterisitcs, which are usually physiological or biological. People behave the way they do because they are animals who act in accordance with their animal instincts (innate characteristics) and are determined by their biology.
These characteristics are inherited from our ancestors, and form our genetic makeup
The nature argument suggests that our genes pre-programmed all our behaviours. All possible behaviours are present from conception however whilst some are expressed from birth others are pre-programmed to emerge as we mature. The nature side of the debate is therefore a developmental approach, behaviour change is caused by age and maturation.
On the other hand, the nature side of the debate suggests that people behave the way they do because they are determined by the things other people teach them, the things they observe, and because of the different situations they are in.
Like the nature side, the nurture side is also a determinist view as it proposes all human behaviour is the result of interactions with the environment.
Developmental approach example
Twin and adoption studies are used to show how much of a behaviour or trait is due to genetics or due to the environment. Identical twins have identical twins- this means they share 100% of their genes, where as non-identical fraternal twins share only half of their genes- 50%.
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 as parents share 50% of their genes, siblings share 25%, and cousins share 12.5%.
Adoptive children are included in analysis to help separate the effects of growing up in shared environments. Adopted children’s similarity to their biological parents reflects genetic similarity and eliminates environmental factors. Adopted children with adopted parent similarity reflects environmental similarity and eliminates genetic similarity.
Variations between identical twins must be the consequences of the shared environmental influences.
In order to determine whether schizophrenia, a serious mental illness has a genetic link, Gottesman and shields carried out a compreshensive review of twin and adoption studies. The concordance rates – how often both twins were diagnosed with schizophrenia was compared for monozygotic- identical, and dyzgotic- non-identical twins. In adoption studies, biological parents and siblings and adoptive parents and siblings were compared to separate out the contribution of genetics and environment on the development of the disorder.
All adoption studies found an increased incidence of schizophrenia in adopted children with a schizophrenic biological parent, whereas normal children fostered to schizophrenic parents and adoptive parents of schizophrenic children showed little evidence of schizophrenia.
Twin studies found a higher concordance rate for schizophrenia in monozygotic- or identical twins, than dyzygotic- or non-identical twins. Significantly there was a concordance rate of 58% in monozygotic twins which means that if one twin had schizophrenia there was a 58% chance the other would have it, compared against a 12% chance in non-identical dyzgotic twins.
Both these comparisons indicate that there is a significant genetic input into the onset of schizophrenia, but with concordance rates less than 100% there must be some interaction with the environment. Certain genes appear to predispose a person to schizophrenia.
Twin studies have also been used to show the heritability of IQ. Plomin found that when the IQ scores of identical and non-identical twins living both together or apart were studied the overall heritability of IQ was about 0.68, or another way, 68% of IQ was due to genetic influences.
When only identical twins who were raised apart were studied the correlation increased to 0.74, meaning twins who share 100% of their DNA but grow up in different environments still have IQ scores that are 74% similar- the genetic influence is greater than the environmental influence.
Whilst genetics seem to be the biggest influence on IQ the environment must also have an influence, in identical twins 26% of the difference in scores must be due to environmental factors
On the side of nurture, it is argued that behaviour can be a result of exposure to certain situations and environments.
A case study on one child ‘Little Albert’, under controlled laboratory conditions was carried out to see if it is possible to induce a fear of a previously unfeared object through classical conditioning.
Before the experiment little albert showed no fear response to any objects including a white rat. In the first session, when aged 11 months, little albert was presented with a rat, but each time he reached for it a steel bar was hit. The 1st time this happened he jumped and fell forward, the 2nd time he began to cry. In session 2, after 5 rat-bar presentations, Albert reacted to the rat alone by immediately crying, leaning and crawling away quickly.
In session 3 Albert was tested to see if the fear had been transferred to other previously unfeared, but similar looking objects. When give toy blocks Albert played happily, however when the rat was presented and was immediately followed by either a rabbit, a dog, a fur-coat, Watson’s hair, or a santa clause beard Albert showed negative responses of crying and moving away from the stimulus.
Session 4 tool this future, and presented the new similar stimuli paired with the steel bar, as originally done with the rat. Albert showed a definite pronounced fear response to all.
One month later Albert was brought back to see if the fear response had subsided, but albert continued to show fear reactions to all similar stimuli. Transference of the fear had been made to similar objects. Albert unfortunately was never returned to be desensitised to the objects!
The behaviour of the apparenly normal students was affected the roles they were assigned to, they appeared to believe in and take on their newly allocated positions. The guards became more and more verbally and physically aggressive towards the prisoners, whilst the prisoners became increasingly depersonalised and deindividuated- several showed signs of extreme depression, with crying, rage and acute anxiety.
Because of the extreme, unanticipated reactions, the experiment had to be cut short after only 6 days, instead of the planned 14 days.
It is more often accepted that behaviour is a result of the interaction between nature and nurture, or biology and the environment.
One view is that people may construct or contribute to their own environments. For example, an individual’s characteristics (which may be innate) such as temperament, gender, or level of aggression, may ellicit particular responses from other people, which may in turn influence the individual’s behaviour.
Others take a view which states that an individuals genes are seen as setting upper and lower limits for their potential behaviour. Where within these limits an individual’s behaviour falls may be determined by the environment.
Rutter and Rutter thought that it was too simplistic to just say that children are either born aggressive or learn aggression, and instead suggested that children pay exhibit aggressive characteristics which in turn causes people around them to respond in a hostile or aggressive manner. This aggressive response then acts to reinforce the child’s aggressive behaviour, beliefs and tendencies.
They suggest that aggressive children tend to experience aggressive environments partly because they elicit aggressive responses in others.
Whilst some behaviours can be traced to physiology research does indicate that the environment can create brain changes.
Research by Maguire et al. Found that the structure of the hippocampus in the brains of taxi drivers change as a result of their environment- which suggests than an interaction between nature and nurture affects brain structure.
The physiological approach focuses on biological influences on behaviour, so is therefore influenced by nature.
Much social research takes the Nurture side of the debate: showing that behaviour is influenced by the social environment. Research by Piliavin et al. Demonstrated that it was not the nature of the passengers that influenced whether they helped, but the situation of the victim that motivated helping behaviour.
A key application of the nature debate is the development of drug thereapies to target and treat behavioural and psychological problems that have a physiological origin. For example, SSRI’s can be used to treat depression and anxiety disorders, whilst Ritalin can be used to help ADHD.
You can use the AS and A2 textbooks to find studies and examples to support and expand on the applications of the nature-nurture debate. The studies can also be used to reinforce important evaluative points, for example- with learning, both nature and nurture offer practical applications to understanding. Whilst developmentalists such as Piaget suggest that a childs development happens at predetermined age-related stages, behaviourists such as Skinner disagree and instead propose that children learn through imitation and reinforcement. Therefore, to best understand and help facilitate child development it would be important to understand what they are capable of at certain stages of development, but how best to help them reach their maximum potential.