Download Genetic and Neural Explanations

The Mobley Defence
http://www.independent.co.uk/news/uk/do-your-genes-makeyou-a-criminal-1572714.html
Stephen Mobley (1966-2005) was a convicted murderer executed
by the State of Georgia for the 1991 killing of John C. Collins, a 25year-old college student working nights as a Domino's pizza store
manager. On appeal, Mobley's attorneys advanced a novel
argument that Mobley was genetically predisposed to seeking
violent solutions to conflict. The case was described as "perhaps
the most widely cited case in which defence lawyers used genetic
factors in the defence of their client".
Should genes ever be considered
a legitimate legal defence?
Why/not?
Real world
application/issues
and debates
Genetic and Neural
Explanations of offender
behaviour
Aim: to examine and evaluate the genetic and neural
explanations for crime.
How can we test if genes play a part in criminal behaviour?
Who can we study?
• Twin studies:
• monozygotic twins (MZ-100%)
• dizygotic twins (DZ- 50%)
• Adoption studies:
• Find out the effects of genes and
the environment
• Family studies:
• Study rates of schizophrenia in
different relatives. E.g. compare
concordance rates between mother
and child.
What is a concordance rate?
• This is the coefficient value that is worked
out by correlating the crime rate between 2
groups of people e.g. concordance between
parent and child
• The correlation coefficient tell us the
likelihood of both parent and child engaging in
criminal behaviours
• The higher this number is the more chance
there is of criminal behaviours developing
• This can then be represented as a percentage
value.
Twin studies recap
2 advantages of
studying twins
as a
psychologist
2 disadvantages
of studying
twins as a
psychologist
Lange (1930); 13 MZ twins and 17 DZ
twins where one of the twins in each
pair has spent time in prison. 10 of the
MZ twins and but only 2 of the DZ
twins had a co-twin that had also spent
time in prison.
Christiansen (1977); studies 87 MS and
147 DZ twins and found a concordance
rate of 33% for MZs and only 12% for
DZs which supports the view that
offending may have a genetic
component.
Genetic explanations
– twin studies
Candidate genes
Tiihonen et al (2014) revealed two abnormalities that may be
associated with violent crime – the MAOA gene (controls
dopamine and serotonin) and CDH13 (linked to substance
abuse and attention deficit disorder). Tiihonen’s sample was
900 Finnish offenders. Individuals with this combination were
13 times more likely to have a history of violent behaviour. This
research is in its infancy and has yet to be replicated.
MAOA gene: controls dopamine and serotonin in the brain and
has been linked to aggressive behaviour
Diathesis-stress model
Describe what the D-S model is based on this diagram:
Neural explanations
• Prefrontal cortex: individuals who experience antisocial
personality disorder show reduced activity in the PFC,
the part of the brain that regulates emotional behaviour.
Raine (2000) found an 11% reduction in the volume of
grey matter in the PFC of people with APD compared to
control groups.
• Mirror neurons: Keysers (2011) only when criminals
were asked to empathise with others did their empathy
reactions activate. This is controlled by mirror neurons.
This suggests that criminals do experience empathy,
although it is not an automatic response. These neurons
fire in response to the actions of others.
Ex: can you think of 2
strengths/real world
applications of the biological
explanations?
Biological
reductionism is an
issue within these
studies as criminality
is complex and
environmental
factors must be
considered.
Many adoptees are adopted
late so spend their infancy
with their biological parents
anyway. Some also maintain
regular contact with their
biological parents. This
means that the parents may
have had an environmental
rather than biological impact.
Biological determinism
presents problems for
our legal system since it
negates free will and
raises the ethical
question surrounding
what society does with
people who carry
criminal genes
Twin studied involve
small sample sizes and
the fact that most twins
are raised in the same
environment is a
confounding variable as
concordance rates may
be due to shared
experiences rather than
genetics
Early twin studies are
often unreliable since
zygosity (whether twins
are MZ or DZ) was based
on appearance rather
than DNA testing.
Therefore they may lack
validity.
Jim Fallon – warrior gene video
https://www.ted.com/talks/jim_fallon_exploring_the_mind_of_a_killer
?language=en