Biological Explanations for Aggression
- Created by: jessmccamley
- Created on: 13-06-18 13:12
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- Biological Explanations for Aggression
- Limbic System
- Hippocamus
- Stores LTM, responsible for comparing the current stimuli to past experiences
- Bacardi et al
- Multiple violent offenders show abnormal hippocampal functioning.
- Unrepresentative sample - all prisoners
- Correlative - cannot establish causation
- Multiple violent offenders show abnormal hippocampal functioning.
- Bacardi et al
- Stores LTM, responsible for comparing the current stimuli to past experiences
- Amygdala
- Responsible for determining an emotional response
- Pardini et al.
- Connection between low amygdala volume in boys and later aggressive character traits in adulthood
- Gender bias - all male sample could lead to androcentrism
- Connection between low amygdala volume in boys and later aggressive character traits in adulthood
- Has been shown to work with the OFC - which is not part of the limbic system. This shows the theory may be incomplete.
- OFC - Orbitofrontal Cortex
- Removing the amygdala in monkeys results in loss of status in the group
- Animal model, cannot be extrapolated
- Gospic et al.
- Pps playing the Ultimate Game (a bidding game involving rejection) had fewer aggressive responses when the amygdala was suppressed using a drug
- Used fMRI (functional magnetic resonance imaging) to directly study inactivity - increasing validity
- Drug also suppressed the entire ANS (autonomic nervous system) - which could have lead to another responsible region being suppressed
- Pps playing the Ultimate Game (a bidding game involving rejection) had fewer aggressive responses when the amygdala was suppressed using a drug
- Pardini et al.
- Responsible for determining an emotional response
- Hypothalamus
- Responsible for regulating the release of hormones in response to aggressive stimuli
- Hippocamus
- Neurotransmitters
- Serotonin is thought to play an inhibitory role in the response to stimuli
- Virkkunen
- Compared the amount of serotonin breakdown fluid in the cerebrospinal fluid of impulsive non-violent offender and impulsive violent offenders.
- Violent offenders had a lower concentration of serotonin breakdown fluid that non-violent
- Correlative - cannot establish causation
- Violent offenders had a lower concentration of serotonin breakdown fluid that non-violent
- Compared the amount of serotonin breakdown fluid in the cerebrospinal fluid of impulsive non-violent offender and impulsive violent offenders.
- Berman
- Drugs that increased serotonin activity decreased frequency and severity of electric shocks in a Milgram-esque game
- Use of a control group increases internal validity, allowing for a comparison
- Ethics - protection from harm infringed due to electric shocks
- Drugs that increased serotonin activity decreased frequency and severity of electric shocks in a Milgram-esque game
- Virkkunen
- Serotonin is thought to play an inhibitory role in the response to stimuli
- Deterministic
- Aggression is the result of biological factors beyond the control of the individual
- Hormones
- Testosterone is associated with high levels of aggression
- Mehta and Joseph
- Measured testosterone in men before and after they lost a competitive game
- Pps were allowed to re-challenge the opponent. Those whose T had increased were more likely (73%) to re-challenge than those whose T had decreased (22%)
- Measured testosterone in men before and after they lost a competitive game
- Mehta and Joseph
- Testosterone is associated with high levels of aggression
- Genes
- Twins
- Coccaro et al.
- In adult male twins, the concordance for direct physical aggression was 50% for MZ (monozygotic) twins and 19% for DZ (dizygotic) twins
- Not 100% - other factors must be in play
- Adult model - there is significant evidence to suggest that the genome changes over the course of someone's life, meaning at birth concordance of genes could have been higher
- Environmental factors - MZ twins tend to be treated the same way due to being identical whereas DZ twins are distinguishable and will be treated differently
- In adult male twins, the concordance for direct physical aggression was 50% for MZ (monozygotic) twins and 19% for DZ (dizygotic) twins
- Coccaro et al.
- MAOA
- The MAOA gene codes for the creation of an enzyme that breaks down neurotransmitters after impulses are fired.
- A variant of this gene lowers the activity of the MAOA enzyme, which is associated with aggression
- Brunner
- 28 men in a large Dutch family with a history of violent, impulsive crime all had the gene variant
- One family, cannot generalise
- Correlation not causation
- 28 men in a large Dutch family with a history of violent, impulsive crime all had the gene variant
- Frazetto et al.
- Diathesis-Stress may play more of a role
- Found that the MAOA variant must be accompanied by trauma in the first 15 years of life in order to create aggression
- Brunner
- Twins
- Limbic System
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