Aggression

Aggression

1. Neural & Hormonal mechanisms in AGG

   • BENZODIAZEPINE (reduces arousal of the ANS) was taken before a game= halved the number of aggressive activity and amygdala responses
     • The AMYGDALA plays a key role in how we repond/assess to environmental threats. GOSPIC et al carried out fMRI brain scans on pps in a lab based game that provoked AGG. Scans showed that AGG reactions were associated with a fast and heightened response from the amygdala
       • Neural mechanisms of AGG: 2 researchers identified the LIMBIC SYSTEM which included the CINGULATE GYRUS, HYPOTHALAMUS, FORNIX and AMYGDALA. Speed and sensitivity of limbic system responses to stimuli are important predictors of AGG beh in humans
         • Hormonal mechanisms in aggression: TESTOSTERONE is a hormone responsible for the development of masculine features. It helps regulate social behaviour via influence on areas of the brain involved in AGG
           • Dolan et al found a positive correlation between testosterone levels and aggressive behaviours in male offenders in a UK maximum security prison. Most had personality disorders and history of violent behvaiour
             • Animal studies show that experimental increases in testosterone are related to AGG behaviour. And vice versa
               • E: - The limbic system excludes other possibilities as it states teh amygdala functions in tandem with the orbitofrontal cortex to maintain self control and inhibit AGG. One researcher showed OFC activity is reduced in patients with disorders that feature AGG. This shows regulation in AGG cannot be explained by limbic system alone
                 • E: + Supporting evidence for the role of serotonin as research shows that drugs that increase serotonin levels also reduce AGG behaviour. - then 1 researcher literally found this in a study (basically milgrams study) compared to placebo group though
                 • E: - evidence for the role of testosterone in humans is mixed because some research does shoe that other hormones are also significantly involved in reducing AGG. For instance 2 researcher's dual hormone hypothesis claims high testosterone leads to AGG only when cortisol is low - high cortisol blocks its influence on AGG behaviour
     • Normal levels of serotonin in the ORBITOFRONTAL CORTEX = inhibitory and linked with reduced firing of neurons and associated with greater self behavioural control
       • Decreased serotonin disturbs this mechanism, reduces self control and increases impulsive beh (like AGG) 1 researcher compared levels of a serotonin metabolite (breakdown byproduct)in cerebrospinal fluid of violent and non violet offenders. F: levels lower in non violent offenders- disruption of pattern indicates disruption of serotonin fucntioning
   • evolutionary explanations of human AGG
     • Men face the threat of cuckoldry (raising another's offspring) - its a waste of resources because it contributes to survival of rivals genes which leaves little for man to invest in his own offspring. men in the past to avoided cuckoldry = more reproductively successful so psychological mechanisms have evolved for anti-cuckoldry (eg sexual jealousy more in M than F). This drives them to mate retention strategies to prevent partner from 'straying'
       • Wilson and Daly identified 2 major mate retention strategies: *DIRECT GUARDING: a mans vigilance over partners beh (eg. checking their phone/ friends).............* NEGATIVE INDUCEMENTS: (eg threats of consequences for infidelity - "i'll kill myself if you leave me!"
     • WILSON et al found women who reported mate retention strategies in partners were twice as likely to suffer violence at their hands (73% had to require medical attention) Men who used guarding (eg stalking partner) or negative inducements (eg threats to kill) were more likely to use physical violence - these retention behaviours reliably predict husbands use of AGG against their wives
       • E: + 1 strength is research support for central evolutionary concepts as many reserach studies demonstrate that male retention strategies are associated with sexual jealousy and AGG 1 researcher did a dramatic example - direct guarding and negative inducements are overwhelmingly used y males, against both females and other males. Suggests risk of infidelity, cuckoldry and AGG are linked and supports predictions from the explanation about the adaptive value of AGG
         • E: + Real life application: One researcher reviewed several established anti-bullying interventions. Despite the availability of such interventions, bullying remains prevalent. Most interventions fail to recognise that bullies bully beacuse they gain advantages - it would make no sense for them to voluntarily give up power without compensation.with this evolutionary understanding of bullying as a adaptive beh can help devise effective anti-bullying interventions to increase the costs of bullying and the rewards of prosocial alternatives
     • F bullying more often takes place within rather than outside a relationship and is a method of controlling a partner. Women use bullying behaviour to secure partners fidelity which means the partner continues to provide resources 4 future offspring - again such beh would be naturally selected as it would enhance women's reproductive success
       • in men, bullying suggests dominance, acquisition of resources, strength and also wards of potential rivals. Characteristics associated with with bullying delivers the ideal combination of access to more females and minimal threat from competing males - so AGG bullying was naturally selected because these males would have reproductive success
         • Bullying is a power imbalance in which a stronger person uses AGG repeatedly against a weaker person. Researchers have traditionally viewed bullying as a maladaptive beh (eg due to poor social skills or childhood abuse) but evolutionary ancestors may have used it as an adaptive strategy to increase chances of survival by promoting their own health and creating reproduction opportunities

2. Ethological exp of AGG

   • AGG is beneficial to survive because it: 1) REDUCES AGG because a defeated animal is rarely killed but instead forced into territory elsewhere to reduce competition pressure. 2) ESTABLISHES DOMINANCE HIERARCHIES eg a male chimps dominance gives it social status inc mating rights with females. 1 researcher observed playgrounds to see if interaction at this age had an effect on dom between children when they grow up. -this is adapted (natural selection) because dominance brings others benefits
     • LORENZ observed most intra-species AGG consisted of ritualistic signalling (displaying teeth) and rarely became physical. Intra specie AGG usually ends with an appeasement display - indicates acceptance of defeat and inhibits AGG in the winner. This is adaptive because every AGG encounter ending with a death of an individual could affect the existence of the species
       • INNATE RELEASING MECHANISM (IRM) is a built in physiological process or structure (eg network of neurons in the brain) it acts as a filter to identify threatening stimuli in the environment. An environmental stimulus (eg facial expression) activates the IRM. It triggers and releases a FAP
         • FIXED ACTION PATTERN (FAP) is a pattern of behaviours triggered by an IRM. One researcher argues that a FAP is a relatively unchanging behaviourial sequence (ritualistic) found in every individual of a species and follows an inevitable course which cannot be altered before it is completed
           • TINBERGEN : male stickleback and AGG
             • P: Another male entering a stickleback's territory in the mating season initiates a sequence of aggressive behaviours (FAP). The red on the males underbelly is the stimulus that triggers the IRM that in turn leads to the AGG FAP. TINBERGEN presented male sticklebacks with a series of wooden models of diff shapes
               • F: if the model had a red underbelly the stickle back would aggressively display and attack it - but no red meant no AGG. Tinbergen also found that AGG FAP did not change from 1 encounter to another - once triggered it always ran its course to completion without any stimulus
     • E: One strength is that there is supporting research evidence by Bruner who shows the low activity variant of teh MAOA gene is closely associated with agg behaviour in humans suggesting a biological basis. ((plus one more ))
       • E: - 1 lim is that there cultural diffs in AGG behaviour. 1 researcher found that southern US white males were more likely to be AGG if insulted than northern US white males. This only occurred during reactive aggression triggered by arguments so researchers concluded that the diff was caused by a culture of honour - impulsive AGG was a learnt social norm. Difficult for ethological theory (with its view of AGG as instinctive) to explain how culture can override innate influences
       • E: Another lim is evidence that FAPs are not 'fixed'. One researcher points out that sequences of behaviours that appear to be fixed/unchanging are greatly influenced by environmental factors and learning experiences