Forensic Psychology Flashcards
(177 cards)
2 Biological Explanations
- Atavistic form
- Genetic and neural explanations
3 Genetic Explanations
- Twin and adoption studies
- Candidate genes
- Diathesis-stress model
Twin Study - Christiansen - 6 Points
- Studied over 3,500 twin pairs in Denmark
- Found concordance rates for offender behaviour of 35% for identical twin males and 13% for non-identical twin males
- Slightly lower rates for females
- Included all twins born between 1880 and 1910 in a region of Denmark
- Offender behaviour was checked against Danish police records
- Data indicates that its not just the behaviour that might be inherited but the underlying predisposing traits as well
Adoption Study - Crowe - 2 Points
- Found that adopted children whose biological mother had a criminal record had a 50% risk of having a criminal record by 18
- Adopted children whose biological mother did not have a criminal record only had a 5% risk
Candidate Genes - 4 Points
- Tiihonen et al - genetic analysis of almost 800 Finnish offenders suggested that two genes, MAOA and CDH13, may be associated with violent crimes
- MAOA gene regulates serotonin in the brain and has been linked to aggressive behaviour
- CDH13 gene has been linked to substance abuse and ADHD
- Analysis found that about 5 - 10 % of all severe violent crime in Finland is attributable to these two genotypes
Diathesis - Stress Model - 2 Points
- If genetics do have some influence on offending, it seems likely that this is at least partly moderated by the effects of the environment
- A tendency towards offending behaviour may come about through the combination of genetic predisposition and biological or psychological trigger
2 Neural Explanations
- Prefrontal cortex
- Mirror neurons
Prefrontal Cortex - 4 Points
- Raine - conduced many studies of the APD brain
- Reported that there are several dozen brain-imaging studies demonstrating that individuals with antisocial personalities have reduced activity in the prefrontal cortex
- Part of the brain that regulates emotional behaviour
- 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
What is APD?
Anti-social personality disorder, formerly known as psychopathy
Mirror Neurons - 3 Points
- Recent research suggests offenders with APD can experience empathy, but they do so more sporadically than the rest of us
- Keysers - found that only when they were asked to emphasise with a person depicted on film experiencing pain, did their empathy reaction activate, controlled by mirror neurons
- Suggests that APD individuals are not totally without empathy, but may ave a neural ‘switch’ that can be turned on and off, unlike the ‘normal’ brain, which has the empathy switch permanently on
Genetic Explanation of Criminal Behaviour A03 - Issues with Twin Evidence - 5 Points
- Often assumed that the twins grew up in equal environments
- Assumed by researchers studying twins that environmental factors are held constant because twins are brought up together and must experience similar environments
- This ‘shared environment assumption’ may apply more to MZ twins than DZ twins
- MZ twins look identical and people tend to treat them more similarly, which in turn, affects their behaviour
- Higher concordance rates for MZs in twin studies may simply be because they are treated much more similarly than DZ twins
Genetic Explanation of Criminal Behaviour A03 - Support for Diathesis - Stress - 6 Points
- Mednick et al - study of 13,000 Danish adoptees
- When the biological and adoptive parents didn’t have any convictions, the percentage of adoptees that did was 13.5%
- 20% when either of the biological parents had convictions
- 24.5% when both biological and adoptive parents had convictions
- Shows that genetic inheritance plays an important role in offending, but environmental influence is clearly important as well
- Provides support for diathesis-stress model of crime
Genetic Explanation of Criminal Behaviour A03 - Nature and Nurture - 4 Points
- Presumed that adoption studies are a good way of separating nature and nurture
- If crime has a genetic component, then an adopted child should still experience the influence of the biological parent
- However, many adoptions take place when the child is older, so they spend several years with their biological parents
- Many adoptees are also encouraged maintain contact with their biological family, so biological parents may still exert an environmental influence
Neural Explanation of Criminal Behaviour A03 - Brain Evidence - 5 Points
- Support for the link between crime and the frontal lobe
- Kandel and Freed - reviewed evidence of frontal lobe damage, including the prefrontal cortex, and anti-social behaviour
- People with such damage tended to show impulsive behaviour, emotional instability, and an inability to learn from their mistakes
- Frontal lobe is associated with planning behaviour
- Supports the idea that brain damage may be a casual factor in offending behaviour
Neural Explanation of Criminal Behaviour A03 - Intervening Variables - 5 Points
- The link between neural differences and APD may be more complex and other factors may contribute to APD and offending behaviour
- Farrington et al - studied a group of men who scored highly on psychopathy
- These individuals had experienced various risk factors during childhood, such as being raised by a convicted parent and being physically neglected
- Could be that these early childhood experiences caused APD and some of the neural differences associated with it, such as reduced activity in the frontal lobe from trauma - Rauch et al
- Suggests the relationship between neural differences, APD and offending is complex, and there may be other intervening variables that have an impact
Neural Explanation of Criminal Behaviour A03 - Biological Determinism - 5 Points
- Biological approach suggests that offending behaviour is determined by genetic or neural factors which cannot be controlled by the person
- Suggests a person should not be held responsible for a crime
- Our justice system is based on the notion that we have responsibility for our actions
- Only in extreme cases is an individual judged to lack responsibility
- The identification of possible biological precursors to crime complicates this principle
4 Psychological Explanations
- Eysenck’s theory
- Cognitive
- Differential association theory
- Psychodynamic
Definition of the Criminal Personality
A feature of Eysenck’s theory of crime, where an individual who scores highly on measures of extraversion, neuroticism, and psychoticism, and cannot be easily conditioned and is cold and unfeeling, is likely to engage in offending behaviour
Personality Theory - 3 Points
- Eysenck proposed that behaviour could be represented along two dimensions - introversion - extraversion and neuroticism - stability
- Two dimensions combined to form a variety of personality characteristics or traits
- Later added a third dimension - psychoticism - - sociability
Biological Basis of Personality Theory
According to Eysenck, our personality traits are biological in origin and come about through the type of nervous system we inherit
Extravert - 3 Points
- Have an underactive nervous system, which means they constantly seek excitement, stimulation, and are likely to engage in risk-taking behaviours
- Tend not to condition easily, and do not learn from their mistakes
- Seek more arousal and engage in dangerous activities
Neurotic - 3 Points
- Have a high level of reactivity in the sympathetic nervous system, meaning they respond quickly to threatening situations
- Tend to be nervous, jumpy, over anxious, and their general instability means their behaviours are often difficult to predict
- Unstable and prone to overact to threatening situations
Psychotic - 3 Points
- Suggested to have higher levels of testosterone
- Unemotional and prone to aggression
- Lack empathy
3 Traits Needed for a Criminal Personality
- Extravert
- Neurotic
- Psychotic