3.1.3 (part 2) - brain structure as an explanation of aggression Flashcards
what is aggression?
behaviour which is intended to physically or psychologically hurt others (so even if it doesn’t succeed it still counts as aggression)
what is reactive-hostile aggression?
when an individual is in a heightened emotional state and has a goal to hurt the target
what is controlled-instrumental aggression?
when an individual is pursuing another goal but hurts someone in the process of doing this
how is the midbrain involved in aggression?
contains the periaqueductal grey matter (PAG), which plays a role in modulation of pain and defensive behaviour
it coordinates and integrates behavioural responses to perceived internal and external stressors eg. heat and pain
role of midbrain - Lonstein and Stern (1998)?
showed that lesions (damage that causes area to die) to PAG in rats which have recently given birth show increased aggression when confronted with a potential threat (unfamiliar male rat)
how is the amygdala involved in aggression?
centre for emotions (particularly anger and fear), emotional behaviour and motivation
gives us instinctive reactions to the environment, including aggression - allows us to perceive and respond (though aggression) to threats
pre-frontal cortex is connected to amygdala and this connection may lead to expression of aggression
helps us recognise emotion in others
how is the hypothalamus involved in aggression?
it maintains homeostasis by regulating hormones, so it links to aggression in males because it produces testosterone
electrically stimulating the hypothalamus in cats can cause them to pounce - influences attack behaviour
how is the pre-frontal cortex involved in aggression?
it doesn’t produce emotions or the resulting behaviours but is important in regulating them
has connections to amygdala and hypothalamus
allows us to make choices about our behaviour by thinking through the options ie. can decide whether or not we act on aggressive impulses (impulse control)
explains why damage to this area can cause problems with anger management and impulsive behaviour
how is the limbic system involved in aggression?
it is where the amygdalae and hypothalamus is found, so could be where aggressive impulses originate
how do different brain areas interact to bring about aggressive behaviour?
- we receive info from the environment via the senses
- amygdala interprets info as a threat (fear) or provocation (anger)
- hippocampus influences our interpretation based on memories from previous experiences and pre-frontal cortex exercises inhibitory control
- hypothalamus activates aggressive behaviour
supporting evidence - Raine et al. (1997)?
used PET scans to compare 41 murderers (who pleaded not guilty by reason of insanity) with control group of non-offenders, found that murderers had lower levels of activity in pre-frontal cortex and differences in functioning of limbic system
supporting evidence - Raine et al. (1998)?
used PET scans to compare offenders in different types of violent crime, found lower levels of activity in pre-frontal cortices of emotional-impulsive offenders compared to planned-predatory offenders and control group
supporting evidence - Swantze et al. (2012)?
correlation study comparing volume of pp’s amygdalae with self-reported levels of aggression, found a significant strong negative correlation (individual differences in aggression linked to individual differences in brain structure)
supporting evidence - Gorka et al. (2013)?
used fMRI scans to compare how the brains of pps who had and hadn’t consumed alcohol reacted to pictures of angry and fearful faces, found that alcohol reduced the reactivity of the amygdalae and orbitofrontal cortex (alcohol changed perception of threat and fear)
supporting evidence - Downer (1961)?
surgically altered brains of monkeys to interfere with transmission of visual information to their amygdalae, found that when monkeys saw human and visual information was received by their amygdala they showed aggression (normal reaction), but when same visual stimulus wasn’t received by amygdala they were calm
strengths of brain structure as an explanation of aggression - supporting evidence?
there are lots of studies (including Phineas Gage) which show that specific brains structures are associated with aggression eg. Raine et al. (1997), differences in these structures correlate with differences in aggression eg. Swantze et al., and deliberately changing these structures can influence aggressive behaviour eg. Downer (1961)
strengths of brain structure as an explanation of aggression - consistency with genetic explanation?
genetic blueprint builds brain structures, so people with a genetic blueprint for aggression will also have brain structures which predispose them to aggressive behaviour
weaknesses of brain structure as an explanation of aggression - use of animals in research?
lots of lab research into the topic has used animals
there are problems with generalisability across species
lots of research has been done by damaging precise brain areas in cats an d rodents, but human brains are much more complex than those of small rodents
ethical issues as some say it is immoral but others say it isn’t worse than using them as pets or food - studies with animals now need cost-benefit analysis (balances suffering of animal against quality of research and medical benefit of knowledge)
weaknesses of brain structure as an explanation of aggression - evidence from unusual samples?
lots of research has been done on animals however their brain structures may not function in the same way as in humans
studies like those by Raine et al. are conducted on violent criminals, however these are cases of extreme aggression so findings can’t be generalised to the everyday population
weaknesses of brain structure as an explanation of aggression - reductionist?
theory could be seen as this because it reduces the production of aggressive behaviour down to the function of the nervous system, but ignores other possible causes like social learning (supported by fact that some cultures show higher average aggression which is likely to be due to social learning)
weaknesses of brain structure as an explanation of aggression - biological determinism?
some people may use theory to argue that your behaviour is determined by your biological makeup so individuals have no free will over how they behave - cold be harmful as people may use as defence or excuse for violent behaviour (people say they aren’t responsible), and it may limit their willingness to engage in treatments like anger-management therapy if they think their behaviour can’t be changed
weaknesses of brain structure as an explanation of aggression - incomplete explanation?
doesn’t explain why variation in the structure and functioning of some people’s brains occur, so we need other explanations alongside it
