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The Nature-Nurture debate - Coggle Diagram
The Nature-Nurture debate
The interactionist approach
nature-nurture debate isn't really a debate about one or the other because behaviour/characteristics arise from the combination of both.
....even eye colour isn't 100% nature (it's about .80 inheritable, Brauer and Chopra 1978)
John Bowlby (1958) claimed a baby's attachment types is determined by the warmth and continuity of parental love (environmental influence)
Kagan (1984) proposed that baby's innate personality (temperament) also affects the attachment relationship. thus, nature (child's temperament), in a real sense, creates nurture (the parent's response), so env and heredity interact.
for these reasons psychologist now more likely to ask what the
relative contribution
of each influence is. therefore nature-nurture debate is really about discussing how nature & nurture interact -
an interactionist approach
Diathesis-stress model
suggests behaviour is caused by a biological or environmental vulnerability (diathesis) which is only expressed when coupled with a biological or environmental 'trigger' (
stressor
).
e.g. we previously studied explanation of OCD in year 1. a person who inherits genetic vulnerability for OCD may nor develop the disorder. but combined with psychological trigger (e.g. traumatic exp) this may result in the disorder appearing
epigenetics
refers to the change in our genetic activity without changing the genes themselves.
it's a process which happens throughout life & is caused by interaction with the env.
aspects of our lifestyle or events we encounter (from smoking & diet to trauma and war) leave 'marks' on our DNA (genes), which switch genes on or off. this explains why factors such as smoking have a lifelong influence even after you actually stop - they've changed the way your genes will be expressed.
epigenetic changes may even go on and influence the genetic codes of our children as well as their children. epigenetics therefore introduces a 3rd element into nature-nurture debate - the life experience of previous generations.
evaluation
adoption studies
P: adoption studies = useful because separate the competing influences of nature & nurture.
E: if adopted children found to be more similar to their adoptive parent , suggests env is bigger influence whereas if adoptive child is more similar to biological parent (no influence on the env) then genetic factors = dominant. meta-analysis of adoption studies by Soo Rhee & Irwin Waldman (2002) found genetic influences accounted for 41% of the variance in aggression.
E: strength - shows how research can separate influences of nurture and nature.
counterpoint
P: research suggests this approach may be misguided, that nature-nurture aren't 2 entities that can simply be pulled apart
E: according to Plomin (1994) people create own 'nurture' by actively selecting env that is appropriate for their 'nature'. thus, naturally aggressive child is likely to feel more comfortable with children who show similar behaviour and will 'choose' their env accordingly. then chosen companions further influence their development. Plomin refers to this as
niche-picking
E: weakness - suggests that is doesn't make sense to look at evidence of either nature or nurture.
epigenetics
P: debate supports epigenetics. one example of how env effects can span generations presumably through epigenetic effect comes from events of WW2.
E: 1994 Nazi's blocked distribution of food to Dutch people & 22,000 died of starvation, in what was called
Dutch Hunger Winter
. Ezra Susser and Shang Lin (1992) report that women who became pregnant during the famine had low birth weight babies. whilst this may be unsurprising, what's more interesting is that these babies were x2 likely to develop schizophrenia when they grew up compared to more typical population rates
E: strength - supports view that life exp of previous generations can leave epigenetic 'markers' which influence health of offspring.
real-world application
P: debate had real-world application. research suggest OCD is highly heritable mental disorder.
E: Nestadt et al. (2010) put heritability rate at .76. such understanding can inform genetic counselling because it's important to understand that high heritability doesn't mean it's inevitable that the individual will go on to develop the disorder. meaning people with high genetic risk of OCD because of family background can receive advice about likelihood of developing disorder & how they might prevent this.
E: strength - shows debate isn't just a theoretical one but that it's important, at a practical level, to understand the interaction between nature and nurture.
key concepts of the debate
nature
refers to inherited influences, or heredity. early nativists such as Descartes argued that all human characteristics - & even some aspects of knowledge - are innate. psychological characteristics like intelligence or personality are determined by biological factors (genes), just as physical characteristics like eye colour or height are.
nurture
nurture refers to influence of experiences & the env.
empiricists including John Locke argued mind is a blank slate at birth (tabula rasa) which is shaped by env. - this view later became important feature of behaviourist approach
Richard Lerner (1986) identified different levels of the env. including prenatal factors such as how physical influences (smoking) or psych influences (music) affect a foetus. more generally development is influences postnatally in terms, for example, of the social conditions a child grows up in.
measuring nature and nurture
degree to which 2 people are similar on a particular trait can be represented by a correlation coefficient & is called concordance.
such concordance provides an estimate about the extent to which a trait is inherited - called heritability.
heritability = proportion of differences between individuals in a population, with regards to a particular trait, that is due to genetic variation.
figure of .01 (or 1%) means genes contribute almost nothing to individual differences and 1.0 (or 100%) means genes are the only reason for individual differences.
general figure for heritability in IQ = .5 across multiple studies in varying populations (Plomin 1994). meaning about half a person's intelligence is determined by genetic factors & the other half must be env