Neural, hormonal and genetic explanations of aggression Flashcards
What is the limbic system?
A set of brain structures including the amygdala and hippocampus thought to be associated with the control of emotions like fear and aggression.
How is the amygdala implicates in aggression?
The amygdala is responsible for rapidly interpreting sensory information (scanning for danger) and providing an appropriate emotional response. Poorly functioning amygdala = aggression. Electrically stimulating parts of the amygdala caused hamsters to be aggressive, and removing it made no aggressive response to things that should’ve caused one.
How is the hypothalamus implicated in aggression?
Deals with the formation of long term memories. If an animal is attacked a long term memory will form. The next time an animal experiences this, the memory will be triggered and they will respond with fear or aggression, whichever is appropriate. Abnormalities here appear to prevent the amygdala processing sensory info properly which can result in aggression.
How is the pre-frontal cortex implicated in aggression?
The limbic system communicates with other areas of the brain such as the pre-frontal cortex which is important in controlling impulsive behaviour such as aggression. This part of the brain may decide whether aggression is actually demonstrated when the limbic system is stimulated. Damaged pre-frontal cortex = no inhibition on final decision to be aggressive.
Evaluate the limbic system as a neural mechanism in aggression.
S - case study documented adult suffering brain damage who had frequent outbursts of unprovoked violent behaviour after surgery destroying the amygdala he had no violent episodes. Abnormalities have been found in the limbic system and PFC of murderers. Face validity.
C - can’t definitely say it was the amygdala damaged (lesion method), case study, most research correlational bc not ethical to do on humans, lacks population validity, some people with limbic abnormalities aren’t aggressive.
How is serotonin implicated in aggression?
Serotonin is an inhibitory neurotransmitter. Most studies show low serotonin = aggression. Serotonin mediated an individuals emotional response. It had a calming effect on neurons firing particularly in the PFC, which is responsible for resisting the urge to behave aggressively when the limbic system is stimulated. Low levels disrupt the calming effect so inc agg.
Evaluate serotonin as a neural explanation of aggression.
S - aggression lowers serotonin and increases aggression. Researchers found lower levels of waste product of serotonin breakdown in cerebrospinal fluid of aggressive people.
C - beta bias. 35 healthy pps given dexfenfluramine which reduces serotonin. They completed a questionnaire on hostility and aggression was seen to increase in males but not females. Evidence suggests females don’t act in the same way but this exp doesn’t show this.
How is testosterone implicated in aggression?
High levels of testosterone associated w increased aggression. Believed that testosterone affects neural circuits before birth and these neural circuits are influenced by T in later life. Males have higher levels and show more physical aggression. Highest agg found in males 15-25 when T is highest. The link is complex. Rather than making a person aggressive it alters the way we react to a stimulus. Also T reduces Serotonin available for transmission across synapse.
Evaluate testosterone as a hormonal explanation of aggression.
S - correlational studied. Salivary T measured in violent and Non-violent criminals and levels higher in violent. Similar results found in non- prison populations. Those who behave aggressively when drunk have higher testosterone
C - research shown females with high occupational status have higher testosterone related to increased assertiveness. Another study found T made women nicer rather than aggressive depending on situation. It could promote status seeking behaviour (aggression being a type of this behaviour).
P - potential biological treatments to reduce testosterone.
How is cortisol implicated in aggression?
Cortisol is produced by the adrenal glands in response to stress. Higher cortisol is related to lower levels of aggression. This could be because cortisol increases anxiety and withdrawal so individuals less likely to engage in aggressive interactions. Alternatively it could be that big levels inhibit testosterone so lower agg.
Evaluate cortisol as a hormonal explanation of aggression.
C - no face validity as when we’re stressed we become more aggressive. Some studies found no significant correlation between cortisol and aggression. One study found higher levels of cortisol in aggressive pps.
I - reductionist as explanations don’t account for research suggesting aggression is social
What is the main genetic explanation for aggression?
The MAOA gene. A gene involved in breakdown of enzyme MAOA has been linked. It breaks down neurotransmitters like dopamine, noradrenaline and serotonin in the synapse. A defect is capable of influencing feelings mood and behaviour. Different variations identified: MAOA-L is associated with low levels of MAOA + aggression. It is termed the warrior gene as it is commonly found in pops w history of warfare. Individuals w MAOA-L don’t necessarily show agg behaviour.
Evaluate MAOA as a genetic explanation of aggression.
S - study of 500 boys w MAOA-L gene more likely to show aggression but only if treated badly. Case study of a Dutch family where males had been repeatedly involved in agg behaviour like rape attempted murder and assault. Males had abnormally low levels of MAOA in brains. Also lab study showed when pps w MAOA-L gene we’re provoked they displayed higher agg than pps without the gene. ‘Aggression’ = forcing individual to eat unpleasant hot spicy sauce.
C - acts in conjugation w experience. Can be considered a predisposition. Important of nature and nurture.
What is the secondary genetic factor in aggression?
Chromosomal abnormalities. Basic difference in males and females is genotype - XX/XY. Early psychologists believed the genetic cause could be in the Y chromosome. They were interested in looking at people with XYY. Based on idea that males more aggressive than females so extra Y = more aggression.
Evaluate chromosomal abnormalities as a factor in aggression.
S - found genotype XYY occured in 1/1000 makes. 3% of men in prison had this. 50% MZ and 19% DZ concordance found in direct physical aggression. Meta-analysis showed genetics influence 41% of variation in aggression
C - compared XYY men with XY men and looked at levels of agg. Research found XYY increases height but not aggression.
