Aggression (Paper 3) ✓ Flashcards
Monday 9th June - 9:15 → 11:15
Limbic system
A set of sub cortical brain structures which are thought to be associated with the control of emotions such as fear and aggression
What does the limbic system include
amygdala and hippocampus
What is the amygdala responsible for
rapidly interpreting sensory information and providing an appropriate emotional response
What is the hippocampus responsible for
dealing with the formation of l;ong term memories
2x supporting evidence/ 1x weakness of the limbic system
+Hamster research found that when the amygdala is electrically stimulated, the hamster will prepare to attack, when the amygdala is destroyed they will not attack
+ Man who had surgery to destroy part of the amygdala no longer had any outbursts of unprovoked violent behaviour
- Most of the research is correlational so no cause and effect
Explanation for low levels of serotonin and aggression
- Serotonin mediates an individuals emotional response to a situation.
- Has a calming effect on neurons firing in the brain.
- Low levels disrupt this calming affect resulting in aggression being more likely.
Explanation for high levels of serotonin and aggression
- During development in the womb, the brain can become flooded with serotonin.
- This makes it less sensitive to the calming effect of serotonin.
- When the limbic system is stimulated, the individual may behave aggressively because the pre frontal cortex isn’t acting as a ‘brake’ as it usually would.
2x supporting evidence / 1x weakness of serotonin
+ Correlation found lower levels of waste product of serotonin in the cerebrospinal fluid of people with aggressive behaviour
+ Low serotonin levels are associated with impulsive aggression in monkeys, and assaults, and violent suicide in humans. High levels of alcohol reduces serotonin which explains the link between alcohol and aggression
- Taking a drug increased aggression scores in males but not females which shows that it suffers from gender bias
Role of testosterone in aggression
- Testosterone affects neural circuits before birth and these neural circuits are influenced by testosterone later in life.
- Testosterone alters the way people react to a stimulus. - -= -
- Testosterone reduces the amount of serotonin that is available for synaptic transmission.
2x strengths/ 2x weaknesses of testosterone in aggression
+ Higher levels of salivary testosterone in violent criminals than non violent criminals
+ Prac app for biological treatment that reduces testosterone levels
- Albert et al: many studies into testosterone and aggression show no correlation
- Testosterone could promote status seeking behaviour as women with high occupational status have higher testosterone levels
What is cortisol
A hormone produced by the adrenal glands in response to stress
Role of cortisol in aggression
- High levels of cortisol increase anxiety and withdrawal - resulting in individuals being less likely to engage in aggressive interactions
- High levels inhibit testosterone levels - resulting in lower aggression
evaluation of cortisol in aggression
+ Low levels of cortisol found in violent criminals and violent school children
- A study found higher levels of cortisol in participants with higher levels of aggression
- Dual hormone hypothesis may be more useful as testosterone and cortisol interact to produce aggression
Chromosomal abnormalities as an explanation for aggresion
- Aggression could lie in the Y chromosome so they examined individuals with XYY chromosomes
- Based on the idea that males are more aggressive than females
+/- chromosomal abnormalities in aggression
+ Jacobs et al: 3% of men in prison had XYY chromosome pattern
- Theilgaard: found that XYY can increase height but not aggression
What is the MAOA gene
- MAOA is a gene that produces an enzyme called MAOA
- This enzyme is responsible for breaking down a number of neurotransmitters including serotonin
- Once neurotransmission is complete, MAOA sweeps up any serotonin left in the synaptic gap
Role of MAOA gene in aggression
1.MAOA-L is associated with the production of low levels of the MAOA enzyme
2.This means that the enzyme is less effective than it should be
3.Leading to a build-up of serotonin in the synapse
MAOA-L = ↓MAOA + ↑Serotonin = Aggression
2x strengths/ 2x weaknesses of MAOA in aggression
+ Research on mice: gene deletion technique was used to knock out the MAOA gene. Knock out mice were hyper aggressive
+ Brunner et al: studied male members of a notoriously violent Dutch family. Found they had low levels of MAOA and possessed the MAOA-L gene
- Vassos: meta analysis found that no single gene is associated with aggression. Claimed hundreds of thousands of genes interact in complex ways to determine aggression (polygenic)
- Diathesis stress: genes act in conjunction with experiences
Ethological explanation of aggression
Lorenz: aggression is ritualistic and more adaptive than killing as it deters an opponent without physical harm being caused
What is an innate releasing mechanism
A built in neural structure which, when exposed to specific stimuli, will cause the release of an automatic behavioural response
What is a fixed action pattern
The aggressive behavioural response that results from the IRM
What are the features of a fixed action pattern
- Behaviour is stereotyped (always occurs in the same way)
- Behaviour is universal (all members of a species respond the same)
- Behaviour is innate and not affected by learning or experience
- Once triggered, behaviour will follow an inevitable path
- Each behaviour has a specific environmental trigger
1x Strength/ 2x weaknesses of Ethological explanation
+ Tinbergen: presented male sticklebacks with wooden models designed to resemble male (red spot on underbelly) or female (swollen bellies) sticklebacks. All male sticklebacks showed aggression towards ‘male’ sticklebacks
- Nisbett: when south American white males were more likely to respond aggressively after being insulted than white north American males under the same conditions
- Ethological approach underestimates the role of nurture in aggression. Environmental factors interact with innate factors
Two evolutionary explanations for male aggression
- Sexual competition (sexual success)
- Sexual jealousy (Reducing paternal uncertainty)