Aggression Flashcards
Is the limbic system a neural mechanism of aggression
Yes
Explain the limbic system
Brain structures
Amygdala is responsible for rapidly interpreting sensory information and providing an appropriate emotional response - overactive means more aggression
Hippocampus deals with formation of LTM. If animals attacked - long term memory of encounter will be formed. Next time animal has similar experience will respond with fear or aggression. Abnormalities I’m hippocampus appear to prevent amygdala processing sensory info
Limbic communicates with other areas of brain. Believes pre-frontal cortex had an important role in controlling impulsive behaviour such as urge to behave aggressively
Is serotonin inhibitory or exhibitory
Inhibitory - calming effect
Explain why low levels of serotonin may cause aggression
Serotonin has a calming effect on neurons firing in brain, particularly pre frontal cortex. Pre frontal cortex is responsible for resisting urge to behave aggressively when the limbic system is stimulated. Low levels of serotonin disrupt the calming effect resulting in individuals being more likely to behave aggressively
Explain why high levels of serotonin are linked to aggression
During pre natal development the brain may be flooded with serotonin (the prefrontal cortex)
This makes the brain less sensitive to calming effect of serotonin.
When limbic system is stimulated, individual may be more likely to behave aggressively because pre frontal cortex is not acting as a ‘brake’ as usually would
Evaluate serotonin as a cause of aggression
Supporting evidence - role of low level of serotonin for aggression.
Correlation found lower levels of waste product in cerebrospinal fluid of people with aggressive and impulsive behaviour. Suggests individuals that aggressive more likely to have low serotonin than non aggressive.
Supporting evidence - low serotonin levels associated with impulsive aggression in monkeys and also assault, self injury and violent suicide in humans. High levels alcohol reduce serotonin offering a possible explanation for the well documented link between alcohol and aggression
Beta bias - one researcher gave healthy participants drug dexfenfluramine - reduced serotonin levels. Pp’s complete questionnaire to assess aggression before and after drug - taking drug increased score of aggression in males not females. Females do not react same way to decreased serotonin as men
What are genetic theories of aggression
Chromosomal abnormalities
MAOA gene
Explain chromosomal abnormalities
Early psychologists thought aggression lied in Y chromosomes. Interested that individuals who are aggressive with genotype of XYY. Extra Y chromosome would lead to increase of aggression as higher levels of ‘super males’ as possessed two male Y chromosomes
Gene occurs in 1 in 1000 males
Evaluate chromosomal abnormalities
Supporting evidence - Jacobs et al found 3% men in prison had this pattern suggested link between chromosomal abnormality and aggressive behaviour
Challenging evidence, a researcher compared personality traits of XYY men with XY men and examined levels of aggressiveness. He found increase in height but not in aggression. XYY may only have a slight impact on aggression and more height. Lacks validity (not measure what meant to)
Gender bias = not explain for women
Explain the MAOA gene theory of aggression
MAOA is an enzyme which mops up neurotransmitters such as serotonin after transmission across the synapse.
Production of this enzyme is determined by the MAOA gene.
A variant of this gene is called MAOA-L gene creates low levels of MAOA and a build up of serotonin and this is linked to aggression
MAOA-L gene means low MAOA means higher serotonin.
Studies call this ‘warrior gene’
Evaluate the MAOA gene
Supporting evidence from case studies - Bruner et al assessed 8 male and 3 female from family. Males had been repeatedly involved in impulsively aggressive behaviour such as rape, attempted murder and assault - aggressive. Males had abnormally low levels of MAOA in brains and possessed MAOA-L gene. Study supports role of MAOA-L gene, however case study is not generalisable.
Supporting evidence - using mice and ‘knock out’ technique to knock out MAOA gene completely = very high levels serotonin. Mice hyper aggressive. Confidence in MAOA and aggression. Also problematic - can’t extrapolate to human aggression - more complex
Challenging of MAOA hypothesis. Vassos used meta analysis - found no association for one single gene and aggression. Thousands of genes together contribute to aggression - its polygenic. Doubt simplicity of theory.
Ignores other influences eg environment. Capsi found association between MAOA-al in males who where treated badly as children. Suggests MAOA gene is a contributing factor paired with significant stressor. Suggests role for diathesis stress. Biologically reductionist
What are hormonal mechanisms in aggression
Testosterone
Corrisol
Explain how testosterone affects aggression
High levels testosterone associated with increased physical aggression.
Males have higher testosterone and are found to have more aggression than females.
Makes between 15-25 show highest level of violence as testosterone levels are highest.
Testosterone may alter the way males react to stimulus, as when females where injected with testosterone they showed higher hate rate when reacting to photos of angry faces.
Testosterone also reduces the amount of serotonin that is available for transmission across the synapse of nerves in the brain - low serotonin related to aggression
Evaluate testosterone as a hormonal mechanism to aggression
Supporting evidence - salivary testosterone was measured in violent and non violent criminals. Similar results found in non-prison populations. Other research shows those who behave aggressively when drunk have higher testosterone than those who arent. Suggests positive correlation between testosterone levels and aggression.
Challenging evidence - link is more complex. Research shows females with high occupational status have higher testosterone levels. Related perhaps to the increased assertiveness that comes from high testosterone levels. Another study shows females kinder who have more testosterone. It could be testosterone that promotes status seeking behaviour which aggression may be. Testosterone could be leading to status seeking not aggression.
Practical applications - aggression is anti social behaviour. If linked to high testosterone a biological treatment could be developed to reduce testosterone levels and aggression levels. Positive implications for the economy reduce demand placed on NHS for victims of violence and reduce pressure of judicial system in dealing with fewer arrests from violent people
Explain cortisol as a hormonal mechanism for aggression
Cortisol - hormone produced by adrenal glands in response to stress. Research shows high levels of cortisol associated with lower levels of aggression (negative correlation)
Could be because cortisol increases anxiety and withdrawal - individual less likely to engage
Cortisol may inhibit testosterone levels - lower aggression
Evaluate cortisol as a hormonal mechanism for aggression
Challenging evidence to a negative correlation.
Studies found no significant correlation between cortisol and aggression. One study found higher cortisol in higher aggressive people. The role of cortisol in relation to aggressive behaviour is not clear
Evaluate the limbic system
Supporting evidence for the role of amygdala in aggression. One case study documented adult who suffered brain damage had frequent outbursts of unprovoked violent behaviour. Surgery destroyed part of his amygdala and he had no further violent episodes. In another study a PET scan of murderers abnormalities were found in the limbic system of murderers suggesting this part of the brain could be linked to aggressive behaviour. Although case study unique can’t generalise
Describe the evolutionary explanation of aggression
Focus on adaptive nature. Aggression is seen as an adaptive strategy that solved a number of challenges such as finding a mate.
Two examples - male aggression in response to sexual competition
( male ancestors had to compete with each other for female mates. Males successfully used aggression to eliminate competition, would have been more successful in acquiring mates and therefore reproduced, passing on their genes. This is why males aggressive on males. Research suggests traits present in males today due to competition that took place such as men having 75% more muscle mass than women)
Male aggression in response to sexual jealousy ( infidelity has serious implications for men. If a women had another sexual partner, her partner can not be sure any children are biologically his own. Men risk being ‘cuckolded’ - putting effort into raising a child who does not carry their genes. Researchers have suggested it would be adaptive for males who are jealous to use buss mate retention strategies which includes coming home early, checking who the female is with, suicide threats
Explain an evolutionary explenation for male aggression in response to sexual competition
( male ancestors had to compete with each other for female mates. Males successfully used aggression to eliminate competition, would have been more successful in acquiring mates and therefore reproduced, passing on their genes. This is why males aggressive on males. Research suggests traits present in males today due to competition that took place such as men having 75% more muscle mass than women)
Explain an evolutionary eplenation for male aggression in response to sexual jealousy
infidelity has serious implications for men. If a women had another sexual partner, her partner can not be sure any children are biologically his own. Men risk being ‘cuckolded’ - putting effort into raising a child who does not carry their genes. Researchers have suggested it would be adaptive for males who are jealous to use buss mate retention strategies which includes coming home early, checking who the female is with, suicide threats
Evaluate the evolutionary theory of aggression
Supportive evidence - for sexual jealousy. Shackelford used questionnaires to investigate mate retention strategies. They used 461 men and 560 women. All were in heterosexual relationships. The findings showed positive correlation between men’s use of mate retention strategies and their violence scores. Results from women’s scores agreed with men. Shackelfords result support evolutionary explanation jealousy is associated with use of aggression towards partner. (Problem correlation - no cause and effect. People change answers to be more socially desirable)
Challenging evidence - fail to explain high levels of cruelty that are often found in human conflict yet are not evident among non-human species. Does not explain wide-scale cruelty such as genocide. Do not explain why humans torture opponents when they have already defeated and no longer pose a threat. Other evidence suggests this can be explained by social psychological theories such as a lack of loss of personal identity. Aggression is different in culture, wouldn’t happen if all same species. Hard determinism
Weakness - socially sensitive. Legitimates domestic violence as states it’s in men’s genes to act violent - very controversial. Aggression is socially unacceptable. This explanation says it’s ‘natural’ and we must accept natural masculine behaviour. Ideas are ethically questionable, representing women in subordinate role in society and seriously damaging the campaign for men and women to have equal rights. Theory provides man with ready made excuse - not morals (free will)
Weakness - theory based on male aggression, suffer from gender bias (alpha bias). However men also engage in mate retention strategies and carry out aggressive acts towards partners. A review of 2060 murders in the US found women were twice as likely to murder their partner out of jealousy. Research has neglected to examine the behaviour of women in this area and it’s sole focus on male behaviour means it’s gender bias
What is the supportive evidence for evolutionary theory of aggression
Supportive evidence - for sexual jealousy. Shackelford used questionnaires to investigate mate retention strategies. They used 461 men and 560 women. All were in heterosexual relationships. The findings showed positive correlation between men’s use of mate retention strategies and their violence scores. Results from women’s scores agreed with men. Shackelfords result support evolutionary explanation jealousy is associated with use of aggression towards partner. (Problem correlation - no cause and effect. People change answers to be more socially desirable)
What are ethologists
They study animals in their natural environment