Aggression Flashcards
What is the limbic system?
A central area of the brain which has many functions including the processing of emotion. One theory behind aggression is that the limbic system is malfunctioning and as it is in charge of emotions, it can lead to an increase in aggression
What is the amygdala?
The brain’s quick response to stimuli. E.g responding to being hit in the face
What is the hippocampus?
Part of the brain primarily responsible for memory. Allows an animal to compare the conditions of a current threat with similar past experiences. For example, if an animal had previously been attacked by another animal, the next time they encounter that animal ,they are likely to respond with aggression or fear
Raine (1997)- Limbic system
- Scanned the brains of 41 murderers using PET scanning
- Found reduced activity in the pre frontal cortex of the murderers compared to controls
- This abnormal limbic system functioning could have led to their aggressive behaviour
Explain the role of testosterone in aggression
- The limbic system should regulate testosterone but if it is malfunctioning, this can lead to too much testosterone and aggression
- Testosterone levels peak in young men and decline in adult hood
- Te chromosomal differences between males and females influence the difference in levels of testosterone. Levels are up to 10 times higher in men than women
Dabbs et al (1995)- Testosterone
- Measured testosterone from saliva of 692 male prisoners
- Those with higher testosterone were more likely to have committed crimes involving sex and violence and more likely to have broken prison rules
Explain the role of serotonin in aggression (neural mechanism)
- Serotonin is an inhibitory neurotransmitter
- Low levels of serotonin leads to aggression
- it is thought that when serotonin levels are low, communication is weakened between the pre frontal cortex and the amygdala
- Normal levels of serotonin are linked with reduced firing of neurons and this is associated with a greater degree of behavioural self control
- if a person has too little serotonin, they are unable to control their rage as easily
Mann (1990)- Serotonin
- Serotonin levels were artificially depleted using dexenfluramine in 35 healthy volunteers
- Found increased self report feelings of aggression in the men
What is the MAOA gene?
The gene responsible for the activity of the MAOA enzyme
Explain the role of the MAOA gene in aggression
- A dysfunction in the operation of these gene may lead to abnormal activity of the MAOA enzyme which affects levels of serotonin in the brain
- One variant of the MAOA gene (warrior gene( leads to low MAOA activity in the brain and this has been associated with various forms of aggression
Brunner (1993)- Genes
- Found a family in Holland which had very high rates of extreme violence in many of the males
- Those males who were violent had abnormally low levels of the MAOA enzyme
- This supports the idea that abnormal levels of MAOA leads to low levels of serotonin and aggressive behaviour
What is concordance rate?
The percentage given to the person’s likelihood of developing a characteristic based on the presence o it in their family
Why are twin studies used?
MZ twins share 100% genes where as DZ share 50%. It is presumed that all twins share a similar environment so therefore the influence of genetic factors can be assessed with the IV as the degree of genetic similarity
McGuffin and Gottesman (1995)- twin study
Found the concordance rate for MZ twins was 85% compared to 72% for DZ
What are adoption studies?
Studies of genetically related individuals who have been spared and allows researchers to overcome the problem of genetic and environmental influences becoming mixed up