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What's the limbic system responsible for?
Processing emotional responses an, cortex mediates levels of aggression by moderating testosterone levels
most important part of limbic system
amygdala
what does malfunction in the amygdala lead to (eg. tumour/ atypical development)
being overly sensitive and the individual interprets situations as aggressive when they're not
what does malfunction in the amygdala cause (eg. tumour/ atypical development)
increased testosterone levels making aggression more likely
research into limbic system (1)
Raine scanned 41 murderes brains and 41 controls. Pet scans sound some had abnormalities in limbic system functioning
research into limbic system (2)
Kramer et al, 14 year old girl with tumour in the limbic system. Suffered seizures and aggressive behaviour. Tumour treated with drugs and returned to normal levels of aggression.
What's serotonin?
A neurotransmitter involved with communication of impulses between neurons.
What are normal levels of serotonin linked to
reduced levels of firing neurons and a greater degree of behavioural self control
What are decreased levels of serotonin linked to
increase in impulsive behaviour including aggression
Research into serotonin (1)
Bond, drugs that clinically raise serotonin levels (eg. antidepressants) found to lower levels of irritability and impulsive aggression
Research into serotonin (2)
Virkunnen et al, compared levels of serotonin metabolite in violent impulsive and non-impulsive offenders and found significantly lower in impulsive offenders
What's testosterone?
hormone that's responsible for development of male features and plays role in regulating social behaviour
what do levels of testosterone influence (eg. high)
activity in orbital-frontal cortex, high = heightened emotional aggressive response is likely
Research into testosterone (1)
Dabbs, found that those with high levels of testosterone had history of primarily violent crimes and low levels primarily committed non-violent crimes
Research into testosterone (2)
Dolan et al, found positive correlation between testosterone levels and aggressive behaviours in sample of 60 male offenders in UK maximum security hospitals who had histories of impulsively violent behaviour
Evaluation of the role of neural and hormone mechanisms overview
supporting evidence, evidence mixed, too simplistic, issue with cause and effect
evaluation of neural and hormonal mechanisms strength
A strength for neural and hormonal mechanisms is supporting evidence, Scerbo and Raine carried meta- analysts of 29 studies assessing levels of serotonin in anti-social children. They found that the children have low levels of serotonin, this suggests that a reduction in serotonin results in impulsive behaviour and aggression
evaluation of testosterone, weakness
A weakness of the role of testosterone is that evidence of its role is mixed. Carre & Mehta's dual hormone hypothesis claims high testosterone levels only lead to aggression when cortisol levels are low. This suggests that the combines activity of testosterone and cortisol may be a better predictor of aggression that testosterone itself.
Evaluation of limbic system weakness
A weakness for the limbic system explanation for aggression is that its too simplistic. Coccaro et al showed that the orbital frontal cortex activity is reduced in psychiatric patients that feature aggression. This shows that aggression can't be explained by the limbic system alone - its highly complex.
evaluation of neural and hormonal mechanisms weakness
A further limitation of neural and hormonal mechanisms are issues with cause and effect. Most research is correlational as alternatives are limited. This is because studies with humans would have ethical issues and animal studies raise issues with generalisability. As the research is just correlational, it could actually be that carrying out aggressive acts leads to changing levels of hormones or neurotransmitters rather than the reverse.
what's the genetic explanation of aggressive behaviour based on
the nature argument that aggression runs in families, a specific gene is inherited
what are the two types of studies used to research genetic explanations of aggression
twin studies and adoption studies
what's a twin study for genetic factors
Coccaro et al, 187 MZ adult twin pairs and 118 DZ. Measured physical and verbal aggression. Concordance rate of 50%for MZ and 19% DZ for physical aggression and 28% MZ and 7% DZ for verbal. Shows that more genes shared more similarities of aggression, shows genes have effect.
what's a negative for Coccaro et als twin study
hard to separate effect, MZ could have copied each other
Whats another twin study for genetic explanation
MuGuffin and Gottesman, Mz and DZ twins measured aggressive and antisocial behaviour. 87% for MZ vs. 72% for DZ for aggression and antisocial behaviour
what's a negative for MuGuffin and Gottesmans twin study
Wasn't 100% concordance rate so genetic factors cant be only influence
what's one of the adoption studies for biological explanation
Rhee and Waldman, meta-analysis 51 twin and adoption studies 87000 individuals for aggression and antisocial behaviour. Genetic influences accounted for 41% of aggression
whats a weakness for Rhee and Waldmans adoption study
meta-analysis hard to draw conclusions because they measure aggression differently
what's another adoption study
Hutchings and Mednick, reviewed 14000 adoptions In Denmark, significant positive correlation between number of convictions for violence among biological parents and adopted sons. Shows genes isn't only influential fact, environment plays part.
Whats another possible explanation for aggression amongst adoption studies
Trauma from adoptions
Whats a strength for Hutchngs and Mednicks adoption study
Big sample size, strengthens research
what's the gene called linked to aggressive behaviour
the MAOA gene
what's the MAOA gene responsible for
producing the enzyme Monoamine Oxidase A
what the role of the Monoamine Oxidase A enzyme
regulate levels of serotonin in the brain
what's the warrior gene
a variant of MAOA gene
what does the warrior gene lead to
low levels of MAOA activity linked to low levels of serotonin and in turn aggressive behaviour
Research into the MAOA gene
Brunner studied 28 male members of a dutch family who repeatedly involved with criminal behaviour such as rape, attempted murder and physical assault, found these men had abnormal low levels of MAOA in their brains and lower activity version, this suggests the gene that produces MAOA may be a candidate gene for aggression
Another research into the MAOA gene
Stuart at al, studied 97 men who were part of a 'batterer' treatment programme because they've been involved in inflicting intimate partner violence. Men with low activity MAOA gene found to be most violent perpetrators.
What are the evaluations of the genetic explanation - overview
support from prosocial behaviour, support from animal studies, conc not 100%, multiple genetic influences
strength to the MAOA explanation
A strength of the MAOA explanation is support from prosocial behaviour. Matins et al found that ps with high activity MAOA were more co-operative and less aggressive than those with low activity MAOA. This finding confirms the importance of the MAOA gene in aggressive behaviour.
another strength of the MAOA explanation
Another strength of the MAOA explanation is support from animal studies, when genetic deletion techniques allow research to 'knock out' single genes in mice. Godar et al found that MAOA know out mice had significantly high serotonin levels and were more aggressive. When serotonin blocked by drug fluoxetine, mice reverted to non-aggressive again. These findings show MAOA must normally have some function in relation to serotonin, keeping it at a 'normal' level.
Limitation to genetic explanation
Limitations with some of the supporting research studies. For example, concordance rates for twin studies aren't 100% - this suggests that there must be other factors involved. Eg environmental effects. With adoption studies its difficult to know if genetic factors have resulted in higher aggression levels in the adoptees, or whether these high levels of aggression are down to the trauma of adoption
another limitation to the genetic explanation
another issue that there are probably multiple genetic influences - the sizes of genetic effects are statistically significant but quite small. This means there are probably other genes involved in aggression. Research by Vassos et al in meta-analysis shouldn't find any association between a single gene and aggression. This suggests that its likely that several genes interact in a complex way to determine aggressive behaviour and that there's unlike to be a single candidate gene for aggression.
What do ethological explanations of aggression aim to do
understand innate behaviour of animals by studying them in their natural environments and assume the aggression is adaptive for the survival of their species
whats the evidence of the ethological explanation in the animal kingdom
the 'defeated' animal is rarely killed but is forced to establish territory elsewhere. This means that members of the species will spread elsewhere and find new resources and mates (reducing competition)
whats an innate releasing mechanism
a biological process or structure which is activated by an external stimulus that triggers a fixed sequence of behaviours (FAP)
Whats a fixed action pattern
a sequence of behaviours that occurs throughout the species
what are the 6 features of a FAP
stereotypes, universal, unaffected b learning or individual experiences, ballistic, single purpose, occurs in response to a specific stimulus or signal
state Tinbergens research into ethological explanation
Tinbergen observed that male sticklebacks are highly territorial during mating season when they also develop a red spot on their underbelly. If a male enters with a red underbelly IRM and FAP take place. He presented a series of wooden models of different shapes and found that regardless of the shape if the model had a red spot the stickleback would be aggressive.
What are the 4 evaluations for the ethological explanation of aggression
Supporting evidence, cultural differences, against ritualistic aggression, evidence suggesting FAPs aren't fixed
Strength for ethological explanation
A strength of the ethological explanation is that a it has supporting evidence. Tinbergen supports the existence of IRM and FAP though his study of the male stickleback. this adds to the validity of the explanation as it demonstrates the genetic and physiological basis to aggression.
Limitation of ethological explanation (1)
One limitation is that there's cultural differences in aggressive behaviour. Nisbett at al found there was a north-south divide in homocide rates in the USA. When white males from southern US were insulted in a research situation they're were more likely to become aggressive that northern white males. He concluded aggressive behaviour was a 'learned social norm' against white males in the southern sates. This contradicts ethological theory as its difficult to explain how cultural differences can override innate influences.
Another limitation to ethological explanation (2)
Another limitation is that there's evidence against ritualistic aggression. Goodall studied chimpanzees in Tanzania and found that they continued to behave aggressively even if the victims were showing appeasement signals and were defenceless. This therefore challenges the ethological theories assumption that aggression has evolved into a self-limiting and relatively physical harmless rituals
Another weakness to the ethological explanation (3)
Theres evidence to suggest that FAPs aren't fixed. Hunt argued that they're influenced by environmental factors and learning experiences and are therefore in fact quite flexible. Some ethologists now prefer to use the term 'modal action pattern'.
what are evolutionary explanations of aggression based on
the animal kingdom and then applied to humans
what do evolutionary explanations of aggression claim humans have
an innate drive to pass on their genes
why is aggression seen as an adaptive behaviour
because its a trait which increases the chances of passing on genes which would be continued via natural selection
what are the 2 parts of the evolutionary explanation which demonstrate behaviours an individual shows that increases the chances of keeping a mate so their genes survive
sexual jealousy and bullying
whats infidelity
occurs when one partner seeks out another mate with whom to reproduce
why is infidelity evolutionary advantageous for males
increases chance of his genes being passed onto successive generations
why is infidelity evolutionary advantageous for females
ensures 'fittest' sperm fertilises the egg
what are the 2 types of sexual jealousy
direct guarding and negative inducements
whats direct guarding
involves behaviours which restrict access of other males (eg checking phone/ turning up unexpectedly)
whats negative inducement
use of verbal threats or direct violence which induce fear
why does female sexual jealousy occur
due to female ancestors needing a mate to provide for her and her offspring - sexual jealousy reduced the change of the male leaving to be with another partner
Whats one piece of research that shows that jealousy leads to aggressive behaviour
Wilson, found women who reported male retention strategies in partners were twice as likely to have suffered physical violence from their partners. 73% required medical attention and 53% feared for their lives.
whats another piece of research that shows that jealousy leads to aggressive behaviour
Shackleford, survey 461 males and 560 females in long term relationships about mate retention strategies. Found positive correlation between mens reports of their mate retention strategies and women reports of their partners physical violence. This also suggests sexual jealousy leads to aggressive behaviour
whats bullying
where a more powerful individual attacks a weaker person deliberately and repeatedly
why is bullying adaptive according to the evolutionary theory
promoting their own health and creating reproductive opportunities.
why did Volk suggest bullying was attractive to the other sex
in males it suggests dominance, resources and strength. In females tends to occur within relationships and involves controlling a partner, secures partners fidelity so continue to provide for offspring
whats the evaluations for the evolutionary explanation
gender differences, useful practical application, doesn't explain cultural differences
whats a strength for the evolutionary explanation
A strength for the evolutionary explanation is that they're able to explain gender differences in behaviour. Males engage more in aggression than females. Campbell argues aggression in females risks survival of their offspring so they use other more adaptive strategies eg. verbal aggression to retain a partner who provides resources. This ability to explain such gender differences increases the validity of the explanation.
A further strength to the evolutionary explanation
A further strength to the evolutionary explanation is the useful application. For example Clares Law gives any member of the public the right to ask the police if their partner may pose a risk to them. AN evolutionary understanding of bullying can help us devise effective anti-bullying interventions to increase the cost of bullying. Rigby found that most anti-bullying programmes fail because they fail to recognise the evolutionary assumption that bullying occurs for the individual to gain dominance
On limitation of the evolutionary explanation
one limitation is that evolutionary theory doesn't explain cultural differences in aggression eg. the Kung San people of the Kalahari discourage aggression and anyone who's aggressive loses status, whereas the Yanomamo in Venezuela use aggression to gain status in society. This suggests aggression isn't universal as evolutionary theory would suggest.
Who came u with frustration-aggression hypothesis
Dollard et al
what approach is the frustration-aggression hypothesis based on
psychodynamic
whats catharsis
process of realising pent up anger
explain the process of how frustration leads to aggression
goals blocked by external forces, frustration is experienced, an aggressive drive to release this pent up energy is experienced and then anger, hostility or violence is experienced
when is aggression more likely (in terms of frustration aggression hypothesis)
if individual is close to achieving their goal
what are 3 reasons aggression can't be directly expressed towards the source of frustration
the source may be abstract, more powerful or unavailable
what happens to the expression of aggression when the source is unavailable
aggression is displaced onto another viable source
Research that supports claim that all types of frustration leads to aggression
Buss, examined whether different types of frustration would affect the likely hood of aggression occurring (eg. falling to win money, failure on a task or failure to get expected grade), found all types of frustration led to aggression, compared to control group
Another piece of research which supports that frustration leads to aggression
Geen, male students task of completing jigsaw puzzle. Group 1 impossible puzzle, Group 2 ran out of time because one person kept interfering, 3 insulted at every mistake. Then another study where they have to give electric shocks to confederate. 3 gave strongest shocks then 2 and 1. All 3 stronger than control group
what's the 'weapons effect' in terms of aggression
shows that cues make aggression more likely