Forensic Psychology - Biological explanations of criminal behaviour Flashcards
The 4 lobes of the brain and their functions
- Frontal lobe - deals with conscious thought, source of emotions through amygdala, decision-making, personality, it is what divides us from the rest of the animal kingdom
- Parietal lobe - sensory behaviour, somatosensory cortex and motor cortex
- Occipital lobe - visual information
- Temporal lobe - auditory and spatial information
Physiological explanations
- Phrenology
1876 - Franz Gall suggests that certain skull and brain structures give rise to different behaviours
- Studied 4000 people and 400 skulls and determined behaviour patterns by correlating skull shapes to the behaviour associated with that area of the skill
- By studying skull shape you can determine which behaviours will be dominant
- The area often associated with criminal behaviour via this disproven science was found around the ear, with behaviours such as combativeness, secretiveness, vitative wit, destructiveness, alternativeness and acquisitiveness - behaviours of greed, violence and adrenaline
Lombroso (phrenology) - The Atavistic Form
- He suggested that criminals were of an earlier evolutionary stage, and cannot be blamed for crimes caused by their physiology
- As a positivst criminologist, he wanted to examine the link between physical traits and criminal behavior - he found criminals to be more primitive in their features and therefore their behavior, allowing criminality to develop, and as these features survived natural selection, criminals are ‘genetic throwbacks’
- He coined the features of criminals as the atavistic form, containing the following identifiers:
1) Heavy brow
2) Large strong jaw
3) Large ears
4) Extra digits or nipples - This has links to Postman’s train study of the eyewitness testimony - a black man and a white man were in a staged argument, and those on the train were asked to give a testimony of the incident - 90% of witnesses named the black man to be more aggressive despite the white man pulling a knife on him.
- It also has links to Loftus’ studies on schema in memory and links to the influence this has on eyewitness testimonies
- Stereotyping of criminals based on assumptions of what a criminal is
Evaluating Lombroso - Supporting and contradicting evidence
Support - Hooton:
- 13,873 US males were studied who were suggested to have degeneration and unattractive physical characteristics led into criminal behaviour
Contradicting - Goring:
- 2,348 London criminals did not replicate Lombroso’s findings after being studied for phrenological characteristics and having no correlation found
Evaluation of the theory:
- Weakness - causality; Is it appearance that causes crime, or the social isolation because of stereotypes about someone’s appearance
- Strength - increasing use of scientific identification for criminals, forming the basis of the ‘why?’ of criminal behaviour and emphasized looking at a range of factors in criminal behavior
- Weakness - Control groups are needed (Hooton did, but only 3,000)
- Weakness - leads to stereotyping of people and because of a lack of technology, he could only look at physical characteristics, and so there is no control for genetic factors
The genetic explanation - 1) twin studies
- MZ and DZ twins - traits are measured with the dichotomy of criminal or not criminal, and concordance rates are calculated
- The difference between the correlation coefficients when doubled provides the proportion of variance in criminality that can be attributed to genetic influences (Falconer, 1965)
Raine (1993):
- A review of all twin studies of crime before 1993 showed that although there is variance in crime, age, sex and culture, all 13 studies identified a greater concordance rate of criminal behaviour / criminality in MZ twins than DZ twins
- 51.5% concordance for MZ, and 20.6% for DZ - further studies have confirmed this hypothesis, finding concordance for antisocial behaviour and aggressive actions (Slutske et al, 1997 and Eley, Lichtenstein and Stevenson in 1999)
Grove et al (1990)
- 32 MZ twin sets separated and reared apart shortly after birth had statistically significant heritabilities for antisocial behaviour as children and adults - suggested there is a stronger genetic factor than environmental
Studies have shown a link between genetics and aggression - Christiansen (1977) found:
1) Male identical twins had a 35% concordance for criminality, compared to 12% of DZ male twins
2) Female identical twins had a 21% concordance for criminality, and 8% for DZ twins
Evaluation of twin studies:
- Allen et al (1976) - they ignore the similar environments MZ twins have which means there is an artificial concordance rate because they are raised the same and will show the same behaviour as a result
The genetic explanation - 2) Adoption studies
- Environmental/ adoptive family influence is lower than twin studies
- we can examine offspring who have been separated from their criminal, biological parents early in life and sent out to other families. If these offspring grow up to become criminal at greater rates than foster children whose biological parents were not criminal, this would indicate a genetic influence with its origin in the subject’s biological parents
-Mednick, Gabrielli, and Hutchings (1984), examined 14,427 adoptees and their biological and adoptive families to determine genetic and environmental influences on criminal behavior. The study’s results indicated that 13.5% of adoptees for whom neither adoptive or biological parents had been convicted of a crime were convicted. 14.7% of those for whom only their adoptive parents had been convicted became convicts. - These numbers spiked when the biological parents had been convicted of a crime. 20% of those whose biological parents had been convicted became convicted, and 25% of those for whom both biological and adoptive parents had become convicted became convicted
- These results suggest that the traits that lead to criminality are somewhat heritable, but those who are reared in an environment where they are exposed to criminal behavior are even more likely to engage in it themselves (Newsome, 2014). More recent criminality adoption studies have supported these findings
- There is a genetic link to criminality - but concordance is still low, so there are other factors
The genetic explanation - 3) Family studies and Y chromosome studies
- Offending is strongly concentrated within families from one generation to the next - Cambridge Delinquency Study (Farrington) found that criminality was concentrated in families, with women carrying and men presenting aggression due to their Y chromosome
Y chromosome studies are also used to identify genetic influences:
- Males are supposed to have an XY chromosome pattern
- Jacobs et al (1965) examined a prison population and found there to be a higher percentage of prisoners with the atypical chromosome pattern (XYY) compared to a non-prisoner population
- The study stated that the extra Y chromosome could be linked with increased testosterone production and therefore more violent behavior, which could lead to criminal behavior
- Other studies have found that chromosomal patterns result in hyperactivity, increased impulsivity and a lower IQ, which can also be linked to criminal behavior
The genetic explanation - Rhee and Waldman - Twin and Adoption Studies support
- Rhee and Waldman (2002) conducted a review of twin and adoption studies and found that there are substantial genetic and environmental influences on antisocial behavior.
- Specifically, the researchers found that about 32% of the variation in antisocial behavior is due to additive genetic effects, 9% due to nonadditive genetic effects, 16% due to environmental influences shared by the twins, and 43% due to unique environmental influences not shared by the twins.
- After Rhee and Waldman, Moffitt (2005) conducted a review that concluded that about 50% of the population’s variation in antisocial behavior was due to genetic influence
Evaluation of adoption studies
Strengths:
- Important in the nature v nurture debate as they separate out genetic and environmental influences, and so the Mednick study is powerful
- Sample size was very large, increasing the validity of results
Weaknesses:
- However, the study only looked at criminal convictions, not crimes committed - people could have committed crimes but not been convicted, which could have given different results
Neural explanations - Noradrenaline and criminality
- Part of the fight or flight response to threats; crimes are underpinned by an overly aggressive response to a threat e.g. crimes of passion
- Reduced noradrenaline has been linked to sexually inappropriate behaviour and anti-social behaviour
- Brunner - ‘warrior gene’; mutation on the X chromosome leading to an increase in MAOA, which in turn results in reduced noradrenaline and more aggressive behaviour expected in a fight or flight response as it does not modulate arousal, attention and aggression correctly
- Wright et al (2015) - very high or low levels of noradrenaline has been associated with aggression, violence and criminality
- Evaluation - not all serial killers are in stressful situations; psychopaths do not tend to feel stress
Neural explanations - Serotonin
- Low levels of serotonin functioning predisposes individuals to impulsive and aggressive behaviour
- Affects our mood as a regulator and too little of it results in a lack of control over negative impulsions - also linked to anxiety and depression
- Higley et al (1996) - found levels of testosterone correlated to aggression but not impulsivity; the intersection of serotonin and testosterone caused this impulsive and aggressive behaviour
Neural explanations - Dopamine
- Dopamine is the reward system and deals with behaviour such as motivation, mood and attention
- Couppis -> argues some individuals who engage in certain criminal behaviours may experience an increase in dopamine and as a result seek out these experiences again due to the reward feeling
- Buitelaar - found juvenile delinquents given dopamine antagonists which reduce dopamine levels showed a decrease in aggressive behaviour
- Low dopamine levels can cause tiredness, lack of motivation and annoyance
Biological explanations - Brain physiology
- Research into reduced frontal lobes suggests that a lack of conscience means some people do not know when they need to stop
Evidence -
- Raine has conducted research using PET scanning and found abnormalities in some parts of the brain in violent criminals.
- Most of the criminals in these studies have been diagnosed with Antisocial Personality Disorder (APD). Raine has discovered that these individuals have reduced activity in the prefrontal cortex of the brain, the part of the brain that regulates emotional behavior; they find it difficult to control their impulses and do not suffer from guilt or remorse.
- Raine studied 41 violent offenders and compared the activity in their prefrontal cortex to 41 non-criminals (including 6 schizophrenics) using PET scans. The violent offenders showed significantly less activity in prefrontal lobe than the other participants suggesting less control over impulsive behavior.
- The prefrontal lobe develops relatively late, sometimes not fully developed until early 20s and later in males. This may explain the peak in antisocial behavior by male teenagers
Brain physiology - the limbic system
The limbic system controls your emotions. There is an argument that the lack of empathy leads to criminal behaviour
Evaluating the biological explanations of criminal behaviour
1) Neurotransmitters underpin mental illness which has a high correlation
2) Generalisability of research is difficult - tend to study animals
3) Reductionist - ignore environment
4) Cause and effect are difficult to determine
5) Brain function may be due to other things, a deciding factor on whether they are culpable is difficult (can we blame somebody whose learning difficulties or brain structures make it hard to understand morals)
