Aggression - Biological Explanations of Aggression Flashcards
What does MZ and DZ twins stand for?
Monozygotic (identical)
Dizygotic (non-identical)
In which type of twin is aggressive behaviour highly correlated?
MZ twins
What are the study associated with twin studies of aggression?
McGuffin and Gottesman (1985)
What happened in McGuffin and Gottesman (1985)?
Concordance rate of 87% for juvenile aggressive and antisocial behaviour in MZ twins, compared to 72% for DZ twins.
What do the results of McGuffin and Gottesman (1985) suggest?
There is a significant genetic contribution to aggressive behaviour.
What is the Warrior Gene?
Gene responsible for producing enzyme monoamine oxidase A (MAOA) may be associated with aggressive behaviour (Warrior Gene). MAOA’s job to break down neurotransmitters in brain. When gene not functioning correctly, excess levels of neurotransmitters may lead to aggression.
What is the case study associated with the Warrior Gene?
Jim Fallon
What happened with Jim Fallon?
Has same brain and genetics of serial killer but not a killer, however lacks empathy.
What brain damage do serial killers sometimes have?
Orbital cortex, temporal lobe, amygdala.
What are two problems to do with twin studies?
Assume MZ and DZ twins experience the same upbringing, may not as parents/teachers make an effort to differentiate twins depending upon personalities.
Concordance rates are below 100%, means genetic influence is only part of the explanation.
What are two studies associated with the influence of genes on aggression?
Lagerspetz (1979)
Brunner et al (1993)
What happened in Lagerspetz (1979)?
Bred 25 gens of mice, 2 most aggressive and 2 least aggressive. Lead to one groups being super-aggressive and the other very docile.
What do the results of Lagerspetz (1979) show?
There is, at least in animals, a genetic component to aggressive behaviour.
What is a positive and negative of animal research in relation to Lagerspetz (1979) study?
Positive - Quality of Research, bred 25 generations of mice, large participant size. Clear variables and ruled out social differences.
Negative - Degree of animal suffering, do not show outward signs of suffering. Being aggressive may reduce chances to mate and pass on their genes.
What happened in Brunner et al (1993)?
Family with men having history of violence. Violent men suffer a genetic defect on X chromosome, cripples enzyme regulating aggressive behaviour. Not found in non-violent men of family. Tested urine, found excess levels of neurotransmitters, may have predisposed men to violence.
What positive implications does research into aggressive have?
Offender treatment and rehabilitation - Can predict if a person will be aggressive then they can get help or anger management before they murder or hurt people.
Why is the role of genes in relation to aggression socially sensitive?
Blames parents for child’s aggressive behaviour, stating 2 aggressive individuals are likely to have an aggressive child.
Why is the role of genes in relation to aggression Deterministic?
People still have a moral sense of what is right and wrong, free will. Labelling people as aggressive means they have an excuse for their aggressive behaviour.
What are neurotransmitters?
Chemicals that allow impulses to travel between neurons.
What neurotransmitters play a part in aggression? High or low levels?
Low levels of serotonin
High levels of dopamine
How is serotonin associated with aggression?
Normal levels - calming effect on brain. Low levels - inhibitory effect removed, leading to less control of behaviour.
What study is associated with serotonin and aggression?
Mann et al (1990)
What happened in Mann et al (1990)?
Gave dexfenfluramine to 35 P’s, depletes serotonin levels, used questionnaires to access hostitli8ty and aggression levels, found hostility and aggression levels to increase in males.
Evaluate the study of Mann et al (1990).
Aggression didn’t increase in woman, socially desirable answers, less likely to admit to undesirable behaviour. Questionnaires only gather info P’s are willing to share, may not be same as actual behaviour. Leads to lack of validity in data.