biological explanation of criminal behaviour- FORENSICS Flashcards
Genetic explanation- twin studies research
BARTOL
- 55% concordance for MZ twins
- 12% concordance for DZ twins
GROVE
- aim= concordance rate for criminal behaviour in separated pairs of MZ twins
- method= 31 sets of MZ twins, 1 set of triplets, interviewed individually
- interviews scored for=
>psychiatric disorders
>alcohol problems
>antisocial personality
>child and adult antisocial behaviour
- result= drug score ad antisocial scores showed heritability
- conc= these traits have a genetic component
Genetic explanation- adoption studies
- children w criminal parents are adopted by non-criminal individuals, if child shows later criminal behaviour it must be genetic
MEDNICK
- took all court convictions between 1927-1947 found 14000 by adoptees
- investigating the biological parents of these people for criminal convictions
——–> found strong positive correlation
What considerations have to be made when looking at adoption studies?
- children who’re adopted tend to be placed in an environment similar to those of their biological parents
- some children adopted at a later age, could be their early life experiences are the cause of their criminality
Genetic explanation- family studies research
- Cambridge study if delinquent development, 411 males living in London from 400 families were monitored from age 3-32
- used interviews and records from 10-40 in crime records
- conviction rates of these men were compared with convictions of their biological parents and close family members
FOUND-
- 64% of families had at least 1 convicted person
- 75% of convicted parents had a convicted child
- about 75% of families with convicted daughters also had convicted sons
conc= offending is strongly concentrated in families, and is demonstrated from 1 generation to the next
AO3- genetic explanation
- research results shows affects on offending behaviour can be caused by family, but doesn’t show that offending behaviour runs in families, doesn’t mean it’s due to genetic transmission, could be social learning or environmental
- stress of adoption could explain offending behaviour so hard to conclude if it genetic transmission or not, stress prior to birth can affect the development of the foetus, environmental influences pre-birth can’t be controlled for
- twin studies show genetic transmission–> but MZ twins are treated more similarly than DZ could explain high concordance
- no single gene has been identified as causing criminal behaviour
Chromosomal explanation
- XYY hypothesis, chromosomal abnormality of an extra Y chromosome in males is linked to above average height and low intelligence
- suggestion made that prison and hospital populations have a higher proportion of these individuals as they have a disproportionate inclination towards violent crime
Danish study on chromosomal explanation
- 4591 men screened for XYY chromosome pattern, only 12 cases found
- these individuals were more likely to be involved in crime (but not violent crime)
conc=
- over representation of XYY males in prisons more likely due to the result of other characteristics like low intelligence
theory is rejected
Biochemical explanation- 3 neurotransmitters involved
NEUROADRENALINE
- fight or flight response
- high levels linked to aggression and violence
SEROTONIN
- regulates mood and impulse control
- low levels cause more impulsivity
DOPAMINE
- link to addiction, substance abuse
- dopaminergenic activity in the limbic system means pleasure is experienced, great the activity, greater the pleasure, makes addiction more likely
Biochemical explanation research evidence
HIGLEY
- levels of testosterone positively correlated with aggressiveness but not impulsivity
- serotonin negatively correlated with impulsive behaviour and extreme behaviour
———-> results suggest how biochemical levels may underpin offender behaviour
BRUNNER
- examined effects of MAOA gene which alters the levels of neuro-transmitters of those have a shortened version of the gene.
—–> this is then linked to aggressive behaviour so could equally be applied to violent crime
Biochemical explanation- AO3
- biochemical explanations are more relevant to everyday behaviour and they may lead to offending behaviour in some circumstances—> may also underpin a mental illness and that’s what increases the likelihood crimes being committed rather than chemical levels. suggest relationship is indirect
- most research into neurotransmitters has been done on animals questions of validity
- biochemical explanations are reductionist, simplifying criminal behaviour
Brain physiology- limbic system
- central part of the brain
- primitive area
- where emotions are regulated, case w criminal psychopaths
- problems processing emotions and empathy
- leads to lack of guilt or remorse
—–> fault in their limbic system means that lack of emotional reactions could lead to planned and organised offending behaviour as they lack remorse
Brain physiology- brain development
- RAINE= frontal lobe volumes of people with anti-social personality disorder is less than those without
—> reduced activity could be why people with the disorder don’t feel guilt or appear to have a conscience - KENT= fMRI scanning to observe any abnormalities in psychopathic brain activity during an emotion based task, criminals showed less activity in the limbic system, psychopaths also seemed to use their frontal lobe more
- RAINE= investigated brain differences of murderers and non-murderers , 41 violent murderers who’d claimed not guilty due to insanity were assessed on a PET scanner, brain differences found in areas linked to aggression
- FALLON=
his work showed that an unusual pattern of low brain function in the frontal lobes commonly associated with empathy and self-control is found in the brains of psychopaths
AO3 - brain physiology
- a clear link between abnormal processing and crime may not be appropriate, functioning could be due to brain trauma, cause and effect isn’t clear
- Brain functioning issues could be due to abuse in offender’s childhood
- sample sizes for research are small, target population are hard to access and using scanning is time consuming gand expensive
