Aggression Flashcards
What are the two neural mechanisms in aggression?
The Limbic System
Role of Serotonin
Talk about the limbic system
This is the key structure in the brain that is involved in regulating emotional behaviour involved in aggression. Specific structures in the limbic system include the hypothalamus, the amygdala and parts of the hippocampus.
What is the amygdala
his regulates emotions such s fear and aggression. It is also involved in tying emotional meaning to our memories, reward processing and decision making.
Talk about animal evidence for the role of the amygdala
Animal Studies, research on hamsters have found that stimulation of the amygdala increases aggression and lesioning of this area reduces aggression.
Talk about human evidence of the role of the amygdala
in humans, an amygdalotomy reduces aggression in previously violent individuals. However, a side effect of this type of surgery is the loss of emotion and enthusiasm. This shows that while the amygdala may play a role in aggression it is more the processing of associated emotions.
Talk about the frontal lobe
the frontal lobes are involved in many activities requiring decision-making like social behavior, motor functions, and impulse control. Reduced function of the frontal lobes has been associated with the aggression- violence tendencies.
Talk about support for the role of the frontal lobe
Phineas Gage- Accident where an iron pole was propelled through the skull causing damage to the frontal lobe changing his personality to more aggressive.
Talk about the role of serotonin
Serotonin has a calming influence on people, so low levels may mean people cannot control their impulsive, aggressive behavior. It also regulates the prefrontal cortex, lower levels affect our response to external stimuli meaning the person becomes aggressive easily and finds it harder to control
Talk about animal evidence for the role of serotonin
allowed male rats to fight with another rat at a specific time for 10 days, on the eleventh, they weren’t allowed to fight. Despite the fact that the rat wasn’t fighting the experience had changed the rats brain chemistry with serotonin levels reducing by 35%
Talk about human evidence supporting the role of serotonin
- administored a drug which depleates seretonin to 25 adults and were given a questionnaire to determine aggression levels- rise in males but not in females.
Talk about the role of Testosterone
Hormone directly implicated in aggression with variations in testosterone levels beeing used to explain both individual and gender differences. Testosterone is produced in spurts rising and falling suddenly.
Talk about evidence supporting the role of testosterone in aggression
Gotez et al.- hypothesised that testosterone may influence the activity of the amygdala, like how seretonin does in other studies. used 16 healthy men over 2 days, the researchers made sure all pp’s had the same baseline testosterone level before the experiment began. There was two conditions- 1. treatment, condition- given 1 shot of testosterone. 2. placebo. Put in MRI scanner and shown pictures of different facial expressions.
Results show that in the increased testosterone condition had higher amygdala activity higher when shown angry faces.
Talk about the XYY gene and aggression
Early psychologists believed that the Y chromosome could be an aggressive cause. They were interested in individuals with a genotype XYY which occurs in every 1000.
What is some research supporting the role of the XYY gene
Price et al.- studied males in hospitals for the clinically insane and found 28% had the extra Y chromosome compared with 0.1% of the general population suggesting a link.
Talk about the role of the MAOA gene
warrior gene’, responsible for the production of the protein monoamine oxidase which allows the metabolism of noradrenaline, seretonin and dopamine. A dysfunction in these can result in the neurotransmitter not being broken down
If adrenaline isnt metabolised, there is too much causing hypersensitivity and an overeaction in the fight or flight and they may percieve a threat where one doesnt exist.
If dopamine isnt broken down, excessive levels aren’t linked with aggressive behaviour.
Talk about twin study research into the MAOA gene
Coccaro et al.- twin studies, found that the concordance of criminal behavior for both MZ ( 50% ) and DZ ( 19% ) show the role of genetics.
→ Not 100%
Talk about the dutch family and the MAOA gene
Brunner et al- Dutch Family- 5 male members with shortened versions of the MAOA gene so consequentlly had high levels of neurotransmitters. They were aggressive- some have neen in prison as attempted rage and assult. Females were unaffected. This shows the MAOA gene affects behaviour and that the condition is sex-linked and carried on the Y chromosome.
Talk about MAOA gene and abuse in childhood
Caspi et al- interaction of the MAOA gene and abusive childhood lead to aggression i.e.boys with the gene who also suffered aggression in childhood were 3 times more likely to be aggressive in adulthood
Talk about the issues and debates associated with biological explanations
Deterministic- determined by biological makeup with no free- will- this can have serious implications on the justice system- people may not take responsibility for their actions and blame it on their biology
What is ethology?
is the study of animal behaviour and by extension, human behavior in terms of traits, characteristics and rituals which have adapted to become useful for survival
What does the ethological approach believe?
As aggression is seen in all animals, it’s believed to be innate
So the ethological explanation looks at this innate bahviour of animals by studying them in their natural environment.
The focus of the approach is to try to explain and account for behaviour in terms of it’s adaptive value to the species. Aggression is seen as helping survival as aggression can protect their resources and help establish dominance hierarchies.
Talk about ritualistic aggression
Ritualistic Aggression- This is designed to show competitors who is the leader and deter them from encroaching on the chosen territory. It’s more adaptive than direct aggression to ensure no harm (which would impar their ability to reproduce) but still gives out a threat. This includes: teeth baring, growling and snarling.
Talk about innate releasing mechanisms
certain innate behaviours are produced in all individuals of the same species. Usually, these behaviours are triggered by the key stimulus which triggers an innate releasing mechanism which produces a fixed action pattern, a constant response. The IRM can be visual, hormonal or muscular resulting in a FAP- once started, can’t stop until finished
Talk about features of fixed action potentials
- stereotyped behaviour- follows certain pattern each time
- Universal- all the animals of the same species
- Innate- all the animals in that species seem to be born with it
- Once starts cant stop
- Specific trigger sets it off.
