Key points: Diathesis-stress model
• The nature-nurture debate: Concerned with the extent to which • The diathesis-stress model suggests behaviour is caused by a
aspects of behaviour are a product of inherited or acquired biological or environmental vulnerability (diathesis) which is
characteristics only expressed when coupled with a biological or
• Heredity: the genetic transmission of both mental and physical environmental ‘trigger’ (stressor).
characteristics from one generation to another • For example, the biological explanations of OCD. A person who
• Environment: Any influence on human behaviour that is non-genetic. inherits a generic vulnerability for OCD (nature) may not
This may ranger from prenatal influences in the womb through to develop the disorder, but, combined with psychological trigger
cultural and historical influences at a societal level. It includes (e.g. traumatic experience) this may result in the disorder
biological influences, e.g. the food you eat may affect your mental appearing (nurture)
development and physical growth
• Interactional approach: A way to explain the development of behaviour Epigenetic’s
in terms of a range of factors, including both biological and • Epigenetic’s refers to a change in our genetic activity
psychological ones. Most importantly such factors don’t simply add without changing the genes themselves. It is a process that
together but combine in a way that can’t be predicted by each one happens throughout life and is caused by interaction with the
separately i.e. they interact environment. Aspects of our lifestyle or events we encounter
(from smoking and diet to trauma and war) leave ‘marks’ on
The Nature-nurture debate our DNA (genes), which switch genes on or off. This explains
why factors such as smoking have a lifelong influence even
The interactionist approach after you actually stop - they have changed the way your
• The nature-nurture debate seeks to answer the question of whether genes will be expressed
our behaviour is influence more by nature or nurture • Even more remarkably these epigenetic changes may go on
• For example, John Bowlby claimed that a baby’s attachment type is and influence the genetic codes of our children, as well as
determined by the warmth and continuity of parental love (an their children. Epigenetics therefore introduces a third
environmental influence). element into the nature-nurture debate - the life experience
• Kagan proposed that a baby’s innate personality (temperament) also of previous generations.
affects the attachment relationship. Thus, nature (the child’s • Brian Dias and Kerry Ressler gave male lab mice electric
temperament), in a real sense, creates nurture (the parents response), shocks every time they were exposed to the smell of
so environment and heredity interact. acetophenone, a chemical used in perfume. As any
• For this reason, psychologist are now more likely to ask what the behaviourist would predict, the mice showed a fear reaction
relative contribution of each influence is. Therefore, the nature- as soon as the scent was presented. Surprisingly the mice’s
nurture debate is really about discussing how nature and nurture children showed similar fear of the smell - even though they
interact - an interactionist approach had not been exposed to the smell before or received an
shocks and so did their grandchildren
, Key concepts of the debate -
nurture
Nature ↳
• Nature refers to inherited influences, or heredity. Early nature
>
nurture
-
nativists such as René Descartes (1596-1650) argued that all
human characteristics - and even some aspects of knowledge - - nature
are innate. Psychological characteristics like intelligence or
nurture
-
personality are determined by biological factors (genes), just
as physical characteristics like eye colour or height are. -
nature
-
nature
Nurture
• Nurture refers to the influence of experience and the -
nurture
environment. Empiricists including the philosopher John Locke -
>
nature
(1632-1704) argued that the mind is a blank slate at birth
which is then shaped by the environment. This view later >
-
nature
became an important feature of the behaviourist approach. -
• Richard Lerner (1986) has identified different levels of the
environment. This includes prenatal factors, such as how
physical influences (smoking) or psychological influences (music)
affect a feotus. More generally development is influenced
postnatally in terms, for example, of the social conditions a
child grows up in.
Measuring nature and nurture
• The degree to which t wo people are similar on a particular
trait can be represented by a correlation coefficient and is
called concordance. Such concordance provides an estimate
!morogia)
(g)
about the extent to which a trait is inherited - called
heritability. Heritability is the proportion of differences
bet ween individuals in a population, with regards to a
particular trait, that is due to genetic variation. A figure of
.01 (or 1%) means genes contribute almost nothing to
undunm
individual differences and 1.0 (or 100%) means genes are the
approach
only reason for individual differences.
• The general figure for heritability in IQ is about 0.5 across
multiple studies in varying populations (Plomin 1994). This
means that about half of a person's intelligence is determined
by genetic factors and the other half must be environmental.