twin and adoption studies suggest
that a large component of the variation
in IQ is due to genetic factors
however, there's equally strong
evidence for the effects of nurture
Flynn effect; the observation that IQs all over the
world have increased by 20 points in 30 years
must be due to environmental enrichment
Mental illness
twin and adoption studies show that the closer 2
individuals are genetically, the more likely that both
of them will develop the same mental disorder
EG. concordance rate for
schizophrenia is 40% for MZ
and 7% for DZ
however, clearly a significant
environmental component
diathesis-stress model; individuals who have a
genetic vulnerability (diathesis) for a disorder only
develop is under certain conditions (stress)
Evolutionary explanations
natural selection; behaviour that leads to increased
survival/reproduction will be selected and passed on
via genes to subsequent generations
however genetic behaviours
are modified by culture
Buss found 22% of
females did NOT
value ambition an
industriousness
more than males
(cultural relativism)
Environmental Influences
Aggression
Bandura's view was that
aggressive behaviour is mainly
learned through observation
and vicarious reinforcement
the key concepts of
social learning theory
(SLT)
Bandura suggested
that this enables us to
learn the specifics of
aggressive behaviour
however, a person's
biological make-up creates
a potential for aggression
and it is the actual
expression of aggression
that is learned
Coccaro (1997) studied twin pairs
and found that nearly 50% of the
variance in aggressive behaviour
could be attributed to genetic factors
Neural plasticity
the ability of the brain, both in development and
adulthood to be changed by the environment
Pascual-Leone (1995) - the region of the
brain that controls finer movement
increased in size in PP's required to play
a piano finger exercise daily over 5 days
Edwards and Cline (1999) - studies with
non-human animals have observed the way
neurons shrink and grow in response to
changing environmental conditions