forensic: bio explanation: genetic and neural Flashcards
define candidate gene
studying genetic influence by focusing on one particular gene that is thought to be of interest
explain Tiihohen et al research into candidate genes
he conducted a genetic analysis of almost 800 Finnish offenders> he suggested two genes (MAOA and CDH13) may be associated with violent crime
MAOA gene > (criminal gene) regulates serotonin in the brain and has been linked to aggressive behaviour
CDH13 gene > linked to substance abuse and ADHD
explain the diathesis-stress model for offending
a tendency towards offending may be due to a combination of genetic predisposition and a biological or psychological trigger
eg: being raised in a dysfunctional environment or having criminal role models
outline the twin study
Christiansen 1977 > studied over 3500 twin pairs in Denmark
found concordance rates for offender behaviour > 35% in MZ males 13% in DZ males> slightly lower rates in females
study included all twins in Denmark born between 1880-1910
indicates that behaviour might be inherited or there may be underlying predisposing traits
outline adoption studies
Crowe 1972 > found that adopted children whose bio mother had a criminal record had a 50% risk of having a criminal record by the age of 18
adopted children whose bio mother didnt have a record only had a 5% risk
shows there is a biological predisposition
AO3: cause and effect twin studies
using twin studies as genetic evidence assumes equal environments
researchers assume environmental factors are constant
this idea applies more to MZ twins than DZ because MZ look identical and are treated the same
limitation as concordance rates for MZ twins might be because they’re treated more similarly than DZ twins > can’t seperate nature and nurture
AO3: research to support
support for diathesis stress model of offending
Mednick et al conducted a study on 13,000 Danish adoptees
when neither biological nor adoptive parents had convictions 13.5% of adoptees did (quite high)
figure rose to 20% if bio parents had convictions
and 24.5% if bio and adoptive had convictions
shows genetic inheritance plays a part but environmental influence is also important > suggests being adopted may increase chances of offending
define a neural explanation
refers to any explanation of behaviour in terms of dysfunction of brain and nervous system
outline the neural explanation
evidence suggests neural differences in brains of offenders and non offenders
most evidence involved people diagnosed with antisocial personality disorder (APD)
behaviour associated with APD
reduced emotional responses
lack of empathy for others feelings
found in many offenders
what area of the brain is involved in offending behaviour
frontal lobe > prefrontal cortex
responsible for decision making and controlling emotional responses
there is lack of activity in the prefrontal cortex of a murderer > brain scans provide evidence for offenders having a lack of remorse and empathy for others
Raine’s research
conducted many studies of APD brain
reports that there are several dozen brain-imaging studies showing that people with APD have reduced activity in the prefrontal cortex
in 2011 Raine and his colleagues found an 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD compared to controls
> show people with APD have reduced emotional ability and empathy > supports bio explanation
explain the mirror neuron
Rizzolatti et al studied electrical activity in a monkey’s motor cortex
when one researcher reached for his lunch in front of the monkey his motor cortex became activated in the same way it did when the monkey itself reached for food > further investigation showed that the same brain cells fired when the monkey reached for food of watched someone else reach > these are called mirror neurons as the neurons mirror activity in another individual
define a mirror neuron
special brain cells that fire both in response to a personal reaction and in response to actions of others > this allows us to interpret intention and emotion in others
link between APD and mirror neurons
recent research shows offenders with APD can experience empathy but do so more sporadically than the rest of us
Keyers found that only when offenders were asked to empathise (with a person depicted on film experiencing pain) did their empathy (controlled by mirror neurons in the brain) activate
suggests people with APD are not totally lacking empathy > instead they may have a neural ‘switch’ that can be turned on and off > this is different to the normal brain which has the empathy switch permanently on
AO3: research to support neural explanation
evidence supports the link between crime and the frontal lobe
Kandel and Freed reviewed evidence of frontal lobe damage (including the prefrontal cortex) and antisocial behaviour > people with such damage tended to show:
impulsive behaviour,
emotional instability,
an inability to learn from their mistakes
supports the idea that brain damage may be a causal factor in offending behaviour
AO3: causal relationship neural explanation
limitation > link between neural differences and APD may be complex
Farrington et al 2006 studied a group of men who scored high on psychopathy (APD) > they had various factors in childhood like physical neglect or having convicted parents
the APD could be caused by their childhood experiences or some neural differences > eg: reduced activity in the frontal lobe due to trauma (Rauch et al 2006)
relationship between neural differences, APD and offending is complex and there may be intervening variables
