aggression
neural and hormonal mechanisms
neural - limbic system is the subcortical structures in the brain that Papez and Maclean thought to be closely involved in regulating emotional behaviour including aggression, they defined the limbic system as the hypothalamus, amygdala and hippocampus
orbiofrontal cortex and serotonin - serotonin has widespread inhibitory effects in the brain, slows down and calms neuronal activity, Denson et al found normal levels of serotonin in the orbitofrontal cortex are linked with reduced firing, meaning more self control, therefore decreased serotonin (deficiency) is linked to increased impulsive behaviour and aggression
hormonal - testosterone is the male sex hormone and is an androgen responsible for development of masculine features, many researchers found males are more aggressive than females, Daly and Wilson found that males are more aggressive to other males during early 20s when their testosterone levels are highest
castration of animals (removing the testes, which is the source of testosterone) reduces aggression in the males of many species, similarly to how adding testosterone increases aggression
progesterone is the female ovarian hormone, some evidence to suggest it plays a role in aggression in females, progesterone levels vary during the menstrual cycle, low levels of progesterone are linked to higher aggression
strength - effects of drugs, drugs that increase levels of serotonin are found to decrease aggression, Berman et al gave ppts a placebo or dose of paroxetine and the ppts took part in a lab based game involving giving and receiving electric shocks - paroxetine group consistently gave fewer and less powerful shocks (could just be due to participant variables, argue some research methods shit)
weakness - also evidence that non limbic structures are also involved in aggression, limbic structures function along side the orbiofrontal cortex, which isn't part of the limbic system, the OFC is involved in impulse regulation and inhibition of aggressive behaviour, OFC is reduced in patients w psychiatric disorders, therefore neural regulation of aggression is more complex
strength - evidence support from non human animals, Giammanco et al confirmed that increased testosterone = increased aggression, castration of male rats reduced testosterone and less mouse killing behaviour, injecting female rats w testosterone increased mouse killing beh
weakness - dual hormone hypothesis, mixed evidence linking testosterone and aggression in humans, Carre and Mehta claimed that high testosterone levels leads to aggression if cortisol levels are low therefore combined activity may be a better predictor of aggression than either testosterone or cortisol alone
genetic
twin studies - heritability accounts for about 50% of variance in aggressive beh, Coccaro et al studied adult male mz and dz twins, for aggressive behaviour defined as direct physical assault they found concordance rates of 50% for mz and 19% for dz, verbal aggression was 28% and 9%
adoption studies - similarities in aggression in adopted children and their biological parents implies there are genetic influences, similarities in aggression between adoptive children and their adoptive parents implies environmental influences
MAOA gene - responsible for the activity of the enzyme monoamine oxidase in the brain, low activity variant of the gene is closely associated w aggressive behaviour, has been nicknamed the warrior gene because of research by Lea and chambers who found that the MAOA-L gene was found in 56% of male Maoris in new zealand who have a reputation for being warriors, compared to 34% of caucasians
Brunner syndrome - Brunner et al studied 28 members of a large dutch family who were repeatedly involved in impulsive aggressive violent crime such as rape/physical assault/attempted murder, these men had abnormally low levels of MAOA as well as the MAOA-L gene variant
gene-environment (GxE) interactions - genes influence aggressive beh but don't function in isolation, Frazzetto et al found links between high levels of antisocial aggression and the MAOA-L gene in males as expected, this was only the case in males who experienced some sort of trauma in the first 15 years of their life, those who didn't experience trauma and still had the MAOA-L gene had lower levels of aggression (diathesis stress, gene environment interaction)
media influences on aggression
strength - research support for MAOA, brunner, lea and chambers, etc however there's also evidence for environmental factors
weakness - biologically reductionist, ignores the environmental factors, realistically it's interactionist. precise mechanisms are unclear, MAOA-serotonin-aggression link is unclear, research linked low serotonin w high aggression, same w low MAOA and aggression, however low MAOA should in turn lead to higher serotonin meaning the relationship between the 3 is a mystery. twin studies lack validity, twins don't necessarily share the same environment, equal environments assumption, ignores how the twins are treated by others, family, friends, who they surround themselves w, they have control over that, concordance rates are inflated, could also be researcher bias where they make concordance rates for mz twins higher cos that's what they think they should do
TV - excessive tv watching can be linked to aggression regardless of if the show is violent or not, also associated with reduced social interaction and poorer educational achievement, indirect link
violent film content - violent content is the most significant media influence, Bandura et al showed the children a film of the bobo doll being hit, children replicated this behaviour, shows that social learning theory applies to both FtF and media
computer games - growing evidence to suggest video games have a stronger effect than screen based media, passive vs active involvement, game playing is more directly rewarding than watching (operant conditioning)
lab experiments have an advantage of demonstrating cause and effect but a disadvantage in directly exposing ppts to violence to encourage aggressive behaviour. a standard lab measure is the taylor competitive reaction time test (TCRTT) in which ppts blast white noise at different volumes to their non existent opponent, bartholow and anderson found that students who played a violent computer game for 10 mins were more likely to blast louder noise than those playing a non violent video game of golf
strength - paik and comstock meta analysis of ~200 studies, significant positive correlation between viewing tv violence and antisocial beh - however tv violence only accounts for between 1-10% of the variance in children's aggressive behaviour. bartholow and anderson's computer game study
weakness - relatively small influence compared to other source's of aggression. lab experiments are artificial, only measures short term aggression, unethical. przybylski looked at two often used video games and found a difference in complexity, implying aggression could simply be caused by temporary frustration if the game is too difficult rather than the level of violence they're exposed to
ethological explanation - an explanation that seeks to understand the innate behaviour of animals by studying them in their natural environments
the ethological explanation suggests that the main function of aggression is adaptive and beneficial to survive as well as to establish dominance hierarchies, natural selection
ritualistic aggression - Lorenz (1966) observed that fights between animals of the same species often caused very little physical damage and most the aggressive encounters consisted more so of ritualistic signalling (eg showing claws or teeth, facial expression, threat)
innate releasing mechanisms and fixed action patterns - an innate releasing mechanisms (IRM) is is an automatic biological process response in the brain, an environmental sign stimulus (eg a certain facial expression) may trigger the IRM which causes a 'release' of automatic behaviour patterns (known as the fixed action patterns, FAP)
Tinbergen (1951) found that male sticklebacks will release a fixed sequence of aggressive behaviours when another male comes into its territory, however, the sign stimulus is not the male stickleback but in fact the sight of the red underbelly of the fish, if it's covered up then there is no aggressive behaviours
Lea (1984) found that FAPs have 6 main features:
- stereotypes/unchanging sequence of behaviours
- universal, as the same sequence is found in every individual in a certain species
- unaffected by learning, same for every individual, regardless of learning
- ballistic, once one behaviour is triggered it cannot be stopped until it ends naturally
- single purpose, behaviour only occurs in a specific situation and none other
- a response to an identifiable sign stimulus (if it's a communication between two individuals of the same species it's known as a releaser)
strength - research support, Brunner et al found the MAOA-L gene was closely associated with aggressive behaviours in twin and adoption studies as well as showing that there's a significant link between genetics and aggression in humans which supports the claim that aggression is both adaptive and inheritable
weakness - however, aggression differs from one culture to another, Nisbett et al found that one form of homocide was much more common among white men in the southern US than in the northern US, therefore culture can override innate predispositions which the ethological theory does not explain
evolutionary explanation - any behaviour that enhances survival and successful reproduction is perpetuated (continued)
sexual jealousy is a major motivator of aggression in males which is an evolutionary explanation
paternity uncertainty - men can never know that they are definitely the father of their child which causes jealously, helping bring up this offspring is a waste of resources, contributes to the survival of a rival's genes and leaves them with fewer resources for the future
men adapted aggressive strategies in order to keep their partner from 'straying'
male retention strategies - Wilson and Daly (1996) found several male retention strategies, including:
direct guarding - male vigilance over partner, eg checking who they've been messaging, tracking them
negative inducements - threats, 'ill kill myself if you leave'
physical violence against partner - Wilson et al (1995) asked women to report their males retention strategies, 'how far do you agree with this statement..', women who did agree with these statements were twice as likely to have experienced physical violence, 73% of these women required medical attention, 53% said they feared for their lives
bullying occurs because of a power imbalance, evolutionary explanation views bullying as an adaptive strategy to increase their chances of survival by promoting themselves for reproduction
male bullying - volk et al (2012) argued that characteristics associated w bullying (dominance, strength etc) are attractive to women, therefore the bullying is just a form of natural selection, those at the top of this hierarchy experience less stress (sapolsky)
female bullying - bullying more often takes place within a relationship in order to control their partner, enhances reproductive success, also seen as natural selection
strength - gender differences in how aggression is shown, campbell argued it's not adaptive for women to be physically violent as it puts their survival at risk, hence why women display verbal aggression instead. real life application, can be used to reduce bullying, address the bully's deficiencies (assuming they bully as they feel inferior), may lead to more adaptive bullying prevention interventions
weakness - however, bullying is still prevalent. cultural differences, people from western botswana in africa were seen to be completely harmless people (thomas, 1958) as aggressive behaviour is discouraged in both boys and girls during childhood, making it rare, this means that aggressive behaviours may not actually be adaptive as it's not universal - however, controversy over 'harmless people', richard et al found that homocide rates are surprisingly high for such peaceful people, argument lacks validity
social psychological explanations - any theory that argues aggression is the result of an interaction between biology and environment
frustration aggression hypothesis - dollard et al(1939), idea that frustration always leads to aggression, anger, hostility and violence are always the outcome when we are prevented from achieving our goals (frustration), aggression is displaced onto an alternative
weapon effect - berkowitz (1989), even if we're angry we don't necessarily behave aggressively, frustration creates a readiness for aggression, we need environmental cues to feel frustration. ppts given fake electric shock by confederates in lab experiment, creates frustration and anger, ppts later had opportunities to give fake shocks to the confederates - the number of shocks were greater if there were two guns on the table therefore presence of environmental cues = aggression
green (1968) investigated how frustration affects aggression, male university students completed a jigsaw puzzle and their frustration was manipulated in one of 3 ways: the puzzle was impossible to solve, ran out of time cos another person in the room kept interfering, confederate insulted the ppt as they couldn't solve the puzzle - the ppts later had an opportunity to give the confederate electric shocks, the insulted ppts gave the highest shocks, then the run out of time group and then the impossible puzzle group, all 3 groups did higher shocks than the control group of no interruptions
strength - marcus-newhall et all conducted meta analysis of 49 studies of displaced aggression, found that frustrated ppts were likely to displace their aggression onto an innocent person rather than the source, supports concept that aggression is displaced onto weaker or available target
weakness - aggression may not be cathartic (relieved by venting), bushman found that people who vented their anger by punching a punch bag got more angry, contradicts general idea of hypothesis. link between frustration and aggression is complex, events aren't independent, can occur without the other, only explains how aggression occurs in certain situations but not all - however, frustration can be caused by negative feelings (loneliness, jealously, pain), aggressive behaviour can be triggered by these negative emotions, therefore frustration is a broad category
social learning theory - bandura found that aggression can be learnt via positive and negative reinforcement and punishment, observational learning accounts for social learning of most aggressive behaviours, SLT can make a child more or less likely to do something, vicarious reinforcement means they see someone else get rewarded by doing something aggressive, vicarious punishment is where they see someone get punished for doing something aggressive - they will learn from both
4 cognitive conditions for social learning (attention, retention, reproduction, motivation)
self efficacy - extent to which we believe we can reach our desired goal, self efficacy develops with each successful outcome (eg constantly stealing toys from other kids)
bandura et al - bobo doll study, young children observed adult being aggressive to a bobo doll, physical assault accompanied by verbal assault - they found that the children often imitated the behaviour despite not being asked to do so, including the exact behaviours and phrases the adults said - boys imitated physical aggression more than girls, verbal aggression was equal in both, boys were more likely to follow same sex model, control group of kids who watched adults be non aggressive with bobo doll
strength - real world application, SLT can help reduce aggression, provide rewards to non aggressive models so the children imitate them, bob doll study is research support
weakness - lacks ecological validity, study was conducted in the 60s, parenting styles may have changed since then. underestimates influence of biological factors, bandura addressed that there is a natural instinct to be aggressive but that it's also likely that it's the outcome of nurture, therefore SLT is an incomplete explanation as there are also powerful genetic influences including evolutionary, hormonal and neural factors
de-individuation - individual loses their personal identity and takes on the identity of a social group, reduces feeling of responsibility
zimbardo (1969) distinguished between individuated and deindividuated behaviour:
individuated state - behaviour is rational and normative
deindividuated state - behaviours are emotional, impulsive, irrational, disinhibited. deindividuation promotes aggression including drugs, alcohol, masks, disguises - key factor is anonymity, 'anonymity shapes crowd behaviour', less fear of retribution as we're a small and unidentifiable part of a crowd
Dunn and Rogers (1982) found that deindividuation as a result of being part of a crowd makes aggression more likely due to the lack of consequences rather than anonymity
reduced self awareness - Dunn and Rogers (1982) found that deindividuation as a result of being part of a crowd makes aggression more likely due to the lack of consequences rather than anonymity
private self awareness - how we pay attention to our own feelings/behaviour, reduced when in a crowd, less self critical
public self awareness - how much we care about what other people think of our behaviour, also reduced in crowds, anonymous therefore less judged and less accountable
strength - Dodd (1985) developed a classroom exercise to illustrate deindividuation, 229 undergraduate psych students in 13 classes were asked 'if you could do anything humanly possible without consequences what would it be', the students knew their answers were completely anonymous, 3 independent raters didn't know the hypothesis and decided on the categories of antisocial beh, 36% of responses involved some form of antisocial behaviour, 26% were criminal offenses, most common was rob a bank, a few students said murder, rape, 9% were prosocial behaviours that help others. Mann investigated suicidal jumpers and how they baited a crowd who would encourage them to jump, tended to occur in darkness, large crowds, when the person is very high up, validity that faceless crowd becomes aggressive
weakness - deindividuated behaviour argues that we act differently to social norms, spears and lea argue that deindividuation leads to conforming to a group, could equally be either antisocial or prosocial
institutional aggression - violent behaviours that occur within a prison or other formal organisation
dispositional explanation - irwin and cressey's (1962) importation model argues that prisons aren't completely isolated from the real world, inmates come from the outside world and bring their own values, beliefs, gender, ethnicity
the dispositional explanation is based on individual nature and nurture, inmates who use violence inside prison reflects their character before prison, therefore aggression in prisons is the product of disposition (individual characteristics) and not the prison environment
DeLisi et al (2011) studied juvenile offenders in california institutions who had a negative background of trauma/anger/substance abuse, these individuals carried these characteristics into prison and were more likely to engage in suicidal activity, physical aggression, sexual misconduct than a control group of ppl w out negative backgrounds
situational explanation