Aggression 3 Flashcards
Neural mechanism of aggression
Limbic system: Papez and Maclean linked to emotional to hypothalamus, amygdala (key) , hippocampus
Gospic: fMRI to measure amygdala, benzodiazepine decreased activity and halved rejections
Orbitofrontal cortex and serotonin: low levels disrupt OFC, Denson: reduce self control more impulsive behaviour
Virkkunen: compared 5-HIAA, violent impulsive offenders = low levels of serotonin
Hormonal
Testosterone: Giammanco: castrated animals, removed testosterone and gave injection to restore aggression
Dolan found positive correlation between testosterone and aggression in 60 offenders in max security, these had personality disorders & impulsively violent
Progesterone: Ziomkiewicz found negative correlation between progesterone and self reported aggression, low progesterone linked to increased aggression
Neural mechanism in Aggression A03
*Limitation- non limbic brain structures also involved, function with orbito frontal cortex (impulse regulation and inhibition of aggression), Coccaro found OFC activity is reduced in those with psychiatric disorders with aggression= aggressive behaviour, neural is more complex than just amygdala
*Strength- serotonin explains research into effects of drugs, Berman gave ppt placebo or paroxetine (reduces aggression by increasing serotonin) and took part in lab game on giving and receiving electric shocks in response to provocation, paroxetine group gave less intense shocks, casual link
*Direct or indirect? May be directly linked in gosspic but denson also suggests it may be indirect as other factors eg social and psychological may influence aggression
Hormonal mechanisms in aggression A03
*Strength- animal research, Giammanco eg in rhesus monkeys there is an increase in testosterone and aggression during mating, in rats castration of males reduce testerone and mouse killing and injecting women increase mouse killings, show role of testosterone in range of animals
*Limitation- dual-hormone hypothesis, mixed evidence between testosterone and aggression in humans, Carre and Mehta said high levels of testosterone lead to aggressive behaviour but only when cortisol are low, when cortisol is high testosterone influence on aggression is blocked, hormone cortisol play important role in response to chronic stress, combined activity of cortisol and testosterone may be better predictor
*Animal research- very similar in mammals but humans are more complex eg cortisol and cognitive factors in cold blooded proactive aggression
Genetic factors in aggression: twin and adoption studies
*twin: Coccaro found concordance rates of 50% for MZ and 19% for DZ for non verbal aggression and 28% MZ and 7% DZ for vernal aggression
*adoption: Rhee and Waldman carried meta analysis of adoption studies of direct aggression and anti social behaviour, found genetic influences = 41% of variance in aggression , in line with twin studies
Genetic factors of aggression: MAOA gene and environment
*MAOA gene: MAOA controls enzyme MAO-A which regulates serotonin, MAOA-L (warrior gene) variant causes low activity of MAO-A enzyme = high aggression, Lea and Chambers showed MAOA-L variant possessed by 56% of New Zealand maori men (34% Caucasian) who have reputation of aggression
Brunner: studied 28 Dutch family involved in impulsively aggressive behaviour eg rape, attempted murder, assault = had low levels of MAO-A enzyme and had variant MAOA-L
*MAOA-L gene related to adult aggression when paired with traumatic experience, Frazzetto found association of aggression and MAOA-L gene only on those with significant trauma during first 15 yrs of life, evidence for gene-environment (diathesis stress) interaction
Genetic factors AO3
*Research support: Mertins found high activity variant were more cooperative in money distributing game so low activity causes aggression but converse is also true
Counter: Mertins showed non genetic factors are crucial, people behaved when they knew others were behaving cooperatively, knowledge of social norm determined low activity ppts behaviour
*complex link: low activity variant does not deactivate serotonin leaving more serotonin in synaptic transmission, MAOA-L variant disrupts serotonin not higher or lower, link not fully understood
*problems with twin studies, equal environment assumption but extent of shared environment with DZ and MZ twins is different, DZ treated less similar, concordares rates are inflated
Ethological explanations of aggression adaptive and ritualistic
*aggression is adaptive, beneficial to survival as defeated animal is not killed but has to establish territory elsewhere reducing competition pressure and starvation, establishes dominance hierarchy in social groups Pettit found aggression important to achieve benefits eg access to resources
*ritualistic aggression, Lorenz says produces little physical damage, consisted of prolonged ritualistic signalling and end with appeasement displays to show acceptance of defeat and inhibit further aggression eg wolf expose neck, if every encontre ended with death = threat to species
Ethnological explanations of aggression IRM and FAP, Tinbergen
*IRM is inbuilt physiological process eg network of neuron in brain which an environmental stimulus triggers specific sequence of behaviour (FAP): stereotyped, universal, unaffected by learning, ballistic, single purposes and response to specific sign stimulus
*Tinbergen says male stickleback highly territorial during mating with red spot underbelly (sign stimulus), presented sticklebacks with series of wooden models of different shapes but found that shape didn’t matter even if realistic, red spot triggered FAP to completion
Ethological explanations A03
*Research support: genetics and evolution, Brunner Dutch family MAOA-L, twin& adoption studies, Wilson and daly show aggression as genetically based pointing to innate basis, ethological correct in claiming it’s genetically determined, heritable and adaptive
Counter: Nisbet found homicide common amongst white men in southern USA caused by reactive culture of honour aggression which is less prevalent in north, learnt by social norms, culture overrides genetic
*ritualistic, Goodall observed 4 year war where chimpanzees killed all members of another group in systematic way eg victim held down while other hit lasting many mins even continued with appeasement signals which did not inhibit aggression, not harmless ritual
*FAP is outed & aren’t fixed, Hung said FAP greatly influenced by environmental and learning factors, made up of several behaviour in series, duration varies with individual and encounters bc modifiable by experience so it’s a model behaviour pattern, FAP more flexible than Lorenz thought
Evolutionary explanations of human aggression A01 sexual jealousy
*sexual jealousy: paternity uncertainty result of threat of cuckoldry to avoid investment in another’s offspring helping survival of rival gene and less resources for one’s own so greater in men to avoid straying
*mate retention: Wilson and Daly identified direct guarding involving male vigilance and negative inducement involving threats of dire consequences for infidelity
*physical violence against partner, Wilson found women who reported agreeing with Mate retention strategies were twice as likely to experience violence, 73% required medical attention, 53% feared for lives
Evolutionary explanation of human aggression A01 bullying
*occurs because of power imbalance, powerful individual uses aggression deliberately and repeatedly against weaker, maladaptive as result of poor social skills, ancestors used to increase survival promoting own health and creating opportunity for reproduction
*male bullying: Volk argued bullying characteristics= attractive to females and wards off potential rivals so bullying naturally selected, may benefit health bc aggressive adolescent with tough reputation experience less aggression and become top of hierarchy so less stress
*female bullying: within relationship to control partner and secure fidelity to continue to provide resource for future offspring, behaviour naturally selected bc enhances reproductive success (Campbell)
Evolutionary explanations of human aggression A03
*Gender differences, Campbell suggests not adaptive for females to be physically aggressive as it puts offspring’s and own life at risk so more adaptive to use verbal aggression to retain partner with resources
*cultural differences, Thomas investigated Kung San people of western Botswan in Africa who have negative attitudes to aggression and is discouraged in childhood so it’s rare, aggressive people diminish reputation
Counter: Lee says homocide rates high in peacefull communities, contradiction because observer is bias by expectations and sample chosen, methodological issues with outside observers lacks validity
*Real world application, reduce bullying, Ellis says bullying is advantageous for bully so meaningful roles approach increases costs and rewards of prosocial alternatives eg giving bullies roles in school as alternative source of status, effective anti bullying interventions
Social psychological explanation: Frustration-aggression hypothesis A01
*Dollard: frustration always leads to aggression, aggression always result of frustration, experience when our attempts to reach a goal are blocked by external factors creating violent fantasies to remove negative emotion (catharsis), aggression by frustration is satisfied reducing drive as it’s cathartic and makes us feel better
Cannot always express to source of frustration because frustration may be abstract, too powerful and risk punishment, or unavailable at the time so aggression is deflected on alternative
*weapon effect: Berkowitz says frustration merely creates readiness for aggression but aggressive cues make it more likely, he found ppt gave more electric shocks to confederates was greater with 2 guns
Social psychological explanation: Frustration-aggression hypothesis A03
*Geens puzzle experiment found that insulted ppts gave confederates more shocks then the interfered and run out of time group then impossible task, all three were more than control group
*research support, meta analysis by Marcus-Newhall of 49 studies of displaced aggression found that aggression that could not be retaliated were likely to aggression innocent party than those not provoked
*role of catharsis, Bushman found ppl repeatedly hitting punching bag became more aggressive, doing nothing was more effective than venting eg petrol, better feel at venting more aggressive the person
*complex link, frustration does always lead to aggression and can cause other behaviours, no automatic
Counter: Berkowitz reformulated negative affect theory, outcome of frustration ranges eg jealously, pain
