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  • Created on: 12-06-19 02:33

Neural and Hormonal mechanisms in aggression

The limbic system - Network of structures deep inside the brain. Papez & Maclean.

  • The Amygdala, emotion processing centre, It has a basic function found in all animals. 
    • If certain areas are activated, by external stimuli or by electrodes, aggressive behaviour is shown. 
  • Serotonin inhibits aggressive impulses from the amygdala.
    • Low levels of serotonin mean we cannot inhibit/control these impulses – we show aggressive behaviour.

Hormonal mechanisms in aggression

  • Testosterone is known to control aggressive behaviour, it is produced in the testes and small sums in the ovaries. 
  • Dabbs found higher levels of testosterone to correlate with more aggressive behaviours.
  • It has a role in regulating social behaviour via influence on certain brain areas implicated in aggression.
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Neural and Hormonal Mechanisms in Aggression - Eva

P – There is research supports the role of brain structures.

E – Gospic et al. fMRI scans showed increased activity in the amygdala showed a direct association between the amygdala and aggression. 

E – The experiment also showed that benzodiazepine lowered neural activity in the amygdala for those who had taken it before the game. These individuals showed reduced levels of aggression.

L – This suggests that the regulation of aggression can possibly be explained by the limbic system.

P – One strength is that there is supporting evidence for the role of serotonin.

E – Berman et al. found that the paroxetine group gave less intense shocks than the placebo group. But findings were only true for those with a history of aggression.

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Genetic factors in aggression

  • Several twins studies have suggested heritability accounts for about 50% of the variance in aggressive behaviour. For physical aggression the concordance rate of 50% for MZ twins and 19% for DZ. For verbal aggression were 28% for MZ and 7% for DZ.
  • Similarities in aggressive behaviour with adopted parents suggest that environmental influences are operating. Rhee & Waldman found  41% genetic influences of aggression.
  • MAOA is responsible for enzyme monoamine oxidase which ‘mops up’ left over neurotransmitters e.g. Serotonin.
  • One MAOA gene variant - leads to low MAOA activity and linked with aggressive behaviour.
  • Genes are crucial influences on aggressive behaviour but they do not function in isolation.
    • MAOA gene activity is only related to adult aggression when combined with early traumatic events.
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Genetic factors in aggression - Evaluation

P – Genetic factors are difficult to isolate from environmental factors.

E – McDermott et al. – participants with low activity MAOA gene only reacted aggressively in a lab setting when provoked.

P – One limitation of the MAOA explanation is there are many genetic influences

E – Stuart et al. found Intimate partner violence was due to a combination of the MAOA gene and serotonin transporter gene (5-HTT), another that influences serotonin activity in the brain.

E – This suggests that other genes could also be involved in aggressive behaviour, implying that it is difficult to search for a single candidate gene responsible for aggression.

L – This shows uncertainty in the use of one particular gene to explain aggression and aggressive behaviour when genes interact in complex ways.

P – Another limitation is that findings depend on how aggression is measured. 

E – Rhee & Waldman’s meta-analysis showed that genetic factors seemed to have a larger influence on aggression in self-report studies. 

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The Ethological Explanation of Aggression

Ethological Explanation suggests that the main function is aggression is adaptive. Aggression is believed to be instinctive, we do not need to learn it. Adaptive function is to establish dominance hierarchies.

  • A ritual is a series of behaviors carried out in a set order. Lorenz – Most aggressive encounters consisted of a period of ritualistic signaling (e.g. bearing teeth).
  • It is adaptive because if ever an aggressive encounter ended with death, that could threaten the existence.
  • Innate releasing mechanisms (IRM) is a built-in physiological process or structure (e.g. neurones). It acts as a 'filter' to identify threatening stimuli in the environment and triggers the fixed action pattern (FAP).
  • FAP is triggered by the IRM. Lea argues that a FAP is a relatively unchanging behaviour sequence (ritualistics) found in every individual of a species (universal) and follows an inevitable course which cannot be changed (ballistic).
  • Key study: Tinbergen male sticklebackFindings –  Regardless of shape, if the model had a red spot the stickleback aggressively displays and attack it.
    • Male sticklebacks are highly territorial during the spring mating season and develop a red spot on their underbelly.
    • If another enters their territory a FAP in triggered. The red stop is the sign stimulus that triggers the IRM.
    • Tinbergenpresented sticklebacks with a series of wooden models of different shapes.
    • No red spot = no aggression. Once triggered, the FAP always ran its course.
    • Tinbergen also found that these aggressive FAPs were unchanging from one encounter to another.
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The Ethological Explanation of Aggression - Evalua

P – Research shows support for the biological basis of aggression.

E – Brunner et al. study found activity in the limbic system, particularly the amygdala, has been shown to trigger greater aggressive behaviour in humans.

L – Ethological explanation argues that aggression is genetically determined as it is an innate response, its validity is supported by studies that demonstrate the genetic basis of aggression.

P – One limitation is that there are cultural differences in aggressive behaviour.

E – Nisbett found white males both southern and northern states – those from southern states were more likely to become aggressive when they were insulted then northern states.

P – Evidence against ritualistic aggression.

E – Goodall  – Observed chimpanzees. She recorded that aggressive behaviour continued even when the chimps showed appeasement and defencelessness. 

E - This challenges the view of the ethological explanation of aggressive behaviour has evolved into self-limiting behaviour and harmless rituals. 

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Evolutionary Explanations of Aggression

Paternity uncertainty is because are at risk of cuckoldry; fathering someone else’s child - it is a waste of resources not his own. Psychological mechanisms have evolved to increase anti-cuckoldry behaviours in males, e.g. sexual jealousy. Wilson & Daly's Mate retention strategies:

  • Direct guarding – tracking apps, keeping tabs on what they are doing, who they’re talking to.
  • Negative inducements - threats/consequences for infidelity.
  • Such behaviours are linked to violence: Wilson et al. found women who reported mate retention strategies were x2 more likely to suffer physical violence. 73% required medical attention, 53% feared for their lives. 

Evolution explanation - Bullying occurs because of power imbalance.

  • Researchers traditionally viewed bullying as a maladaptive behaviour.
  • Evolutionary ancestors may have used bullying as an adaptive strategy to increase chances of survival.
  • Volk et al. suggest characteristics linked with bullying behaviour are attractive to the opposite sex. As in males, it suggests dominance, strength and resources.
  • Female bullying in relationships is seen as a means of controlling a partner’s infidelity so that they continue to devote resources to them in the future.
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Evolutionary Explanations of Aggression - Evalutat

P – Research supports evolutionary concepts such as mate retention strategies. 

E – Shackelford et al. IPV study found a strong positive correlation between reports of mate retention strategies and violence in relationships. 

L – This suggests that the risk of cuckoldry is linked with aggression, supporting the predictions from the evolutionary explanation concerning the adaptive value of aggression.

P – Evolutionary explanation helps explain the gender difference in aggression.

E – Campbell argues that aggression in females risks their offspring’s survival as well as themselves, so they use verbal aggression to retain a partner who provides resources. 

L – This increases the validity of the evolutionary explanations as it explains gender differences and can predict them in research.

P – Bullying remains despite so many anti-bullying interventions in place.

E – Volk et al. suggested one method to increase the cost of bullying at the rewards could be to encourage bullies to compete aggressively but fairly in sporting activities. 

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Social Psychological Explanations of Aggression: F

Dollard et al. Frustration-Aggression Hypothesis - frustration always leads to aggression, and aggression is always the result of frustration. Based on the psychodynamic concept of Catharsis.

Believes aggression is a psychological drive affected by biological drives like hunger. It is cathartic as aggression created by frustration is satisfied following aggressive behaviour. 3 reasons why aggression can be expressed indirectly at the frustration source: Abstract, too powerful we risk punishment, unavailable.• So, our aggression is displaced onto alternative.

There are environmental cues so even if we become angry, we still might not behave aggressively. Berkowitz suggested frustration merely creates a readiness for aggression but the presence of aggressive cues in the environment makes the expression more likely.

Key study: Geen jigsaw puzzle.

  • Their level of frustration was manipulated in one of 3 ways: the puzzle was impossible to solve, ran out of time because of an interfering student and an insulting confederate.
  • Findings: Insulted participants gave the strongest shocks, then the interfered group, then the impossible task participants.
  • All three groups gave more intense shocks than a non-frustrated, control group
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Social Psychological Explanations of Aggression: F

P – The frustration-aggression hypothesis has been used as an explanation of mass killings. 

E –Some historians (Goldhagen), have argued that Germans condoned the violence against Jews during this period, seeing them as responsible for Germany’s difficulty. 

E - Staub suggests mass killings are often caused by social and economic crises with society. These frustrations lead to scapegoating, discrimination and aggression against this group.

L - This shows that widespread frustration, particularly when skilfully manipulated by a propaganda machine, can have violent consequences for a scapegoated group. 

P – There is real-life application for the frustration-aggression hypothesis.

E - Priks that when a team performed worse than expected, the supporters threw more things onto the pitch and were more likely to fight with the opposing supporters.

P – Aggression is not found to have a cathartic effect on individuals.

E – Rushman found that participants who vented their anger by repeatedly hitting a punchbag became angrier and more aggressive.

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Social Psychological Explanations of Aggression: S

Aggression can be learned directly by operant conditioning with positive, negative reinforcement and punishment. Bandura argued that observational learning accounts for social leaning of most aggressive behaviour.

  • The child works out how aggressive behaviour is performed, they can also observe the consequences of their behaviour.
  • Vicarious reinforcement - if the model is rewarded, the child learns aggression is an effective way to get what they want.
  • Vicarious punishment – if a model’s use of aggression is punished – the child is less likely to imitate that behaviour.
  • Bandura points out that 4 cognitive conditions are needed for observational learning to happen: Attention – observer notices the model's aggressive actions. Retention – Remembering the behaviour that has been observed. Reproduction – Copying the behaviour that has been observed. Motivation – observer imitates behaviour if they are expected to be rewarded.
  • Self-efficacy is the extent to which we believe our actions will achieve the desired goal. It develops with each successful outcome.
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Social Psychological Explanations of Aggression: S

P - A key strength of the SLT as an explanation of aggression is supporting research.

E - Poulin & Boivin found aggressive boys formed friendships with other aggressive boys, which was described as a ‘training ground’ for antisocial behaviour.

E – This meant that they were frequently exposed to aggressive behaviour and the consequences/ rewards obtained for that behaviour, and approval of the group as a reward.

L – This increases the validity of SLT as an explanation of aggression as it supports the central assumptions identified by SLT for the development and maintenance of aggressive behaviour. 

P – Cannot explain all forms of aggression.

E – Proactive can be explained by SLT but not reactive. Proactive using aggression as a way of achieving their goals, whereas reactive is using aggression for retribution.

P – One strength of SLT as an explanation of aggression is the practical applications of SLT.

E – People are not passive receivers and choose their surroundings which shapes aggression (reciprocal determinism).

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Social Psychological Explanations of Aggression: D

Le Bon used de-individuation to explain the behaviour of individuals in crowds.• We lose our sense of both individual self-identity and responsibility for our behaviour, greater disregard for norms and even laws, there is share responsibility thus experience less guilt when harm is at others.

Zimbardo argues that there are two possible reasons for deindividuation leading to aggression:

  • People feel less accountable because being in a crowd reduces the likelihood of being identified - that lower self-awareness makes people more likely to follow others.

Diener goes on to say that as aggression is often an impulsive act. Being part of a group reduces inhibition and the usual self-monitoring which prevents anti-social behaviour. 

Dunn & Rogers - the consequences of anonymity, de-individuation creates a greater likelihood of aggression. Explained in two types of self-awareness:

  • Reduced private self-awareness, how we pay attention to our own feelings and behaviour, focusing on others so we think less of our own beliefs and are less self-critical and evaluative.
  • Reduced public awareness as we anonymous our behaviour is less likely to be judged, so we no longer care.
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Social Psychological Explanations of Aggression: D

P – There is research support for de-individuation.

E – Douglas & McGarty found a strong correlation between anonymity and sending threatening messages. The most aggressive messages were sent by those who hid their real identities. 

P – Some research studies show de-individuation does not always lead to aggression.

E – Gergen et al. dark room study with strangers reported participants topped talking and began kissing and touching intimately. Even when told they could do anything.

E – Of all the behaviours de-individuation could have caused in the study, aggression was not one of them. This means there are other factors in producing aggression from de-individuation.

L – This limits the explanation as it suggests aggression is the only response to de-individuation reducing its validity.

P – There are other outcomes to de-individuation.

E – Johnson & Downing study found confederates dressed as ‘nurses’ gave received shocks at lower levels and were also more compassionate in line with the Prosocial role of a nurse.

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Institutional Aggression in the Context of Prisons

The importation model - Irwin & Cressey model that prisons are not completely covered from the happenings of everyday life.

  • Inmates import such behaviours to negotiate their way through the unfamiliar and frightening prison environment using aggression to establish power, status, influence, and access to resources – convict subculture. Therefore, aggression is the product of individual characteristics of inmates and not of the prison environment.

DeLisi et al. studied juvenile delinquents confined in institutions with negative dispositional features. Findings - These inmates were more likely to engage in suicidal activity and sexual misconducts and physical violence than to a control group.

Situational explanations - Clemmer's deprivation model suggests causes of institutional aggression within the prison environment itself. •These conditions include being deprived of freedom, independence, goods, safety, and intimacy. Violence, which becomes an adaptive solution to the problem of depravity.

Steiner found Inmate-on-inmate violence was more common in prions with higher proportions of female staff, African-American inmates, Hispanic inmates, and inmates in protective custody. These are all prison-level factors because they are independent of individual characteristics.

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Institutional Aggression in the Context of Prisons

P – There is support from research for the importation model.

E – Camp & Gaes studies 561 male inmates with similar criminal histories and aggression predispositions .33% of the low-security prisoners and 36% in the high category prisoners were involved in aggressive misconduct. 

P - There is an Alternative explanation than the importation model.

E - Diulio claims that the importation model is an inadequate explanation of aggressive behaviour because it ignores the roles of prison officials and factors relating to the running of prisons.

E – He proposes an administrative control (ACM) stating that poorly managed prisons are more likely to experience the most serious forms of inmate violence, including homicides and rioting.

L - According to the ACM, these factors are most influential in determining aggression than inmate characteristics. This limits the importation model because ignoring those factors means it is not cohesive and cannot explain the other factors within institutionalised aggression and so has decreased validity.

P – Individual-level factors are reliable predictors of aggression independent of the prison environment, but research shows that some situational variables are also influential.

E – Cunningham et al. analysed 35 inmate homicides and found that motivations for those behaviours were linked to some of the deprivation identified by Clemmer. 

L – As these factors are predicted by the model to make aggression more likely, these findings support its validity.

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Media Influences on Aggression: The Effects of Com

Experimental studies. Lab study – Bartholow & Anderson had students play either a violent game or nonviolent game for 10 minutes. They then carried out the TCRTT and delivered blasts of white noise at chosen volumes to punish an opponent. Violent game players selected a significantly higher noise level than the nonviolent players.

Correlational studies. DeLisi et al. studied Juvenile offenders, with histories of serious aggressive behaviours.•Offenders’ aggressive behaviour was correlated with how often they played violent computer games and how much they enjoyed them.

Longitudinal studies - Robertson et al. a link between ‘excessive’ TV viewing in childhood and aggressive behaviour in adulthood. •They found time spent watching TV was a reliable predictor of aggressive behaviour in adulthood. It was measured in terms of convictions for aggressive and violent crimes.

Meta-analyses - Anderson et al. found exposure to violent computer games was associated with an increase in aggressive behaviours, thoughts, and feelings. This was also true for both males and females and across collectivist and individualist cultures.

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Media Influences on Aggression: The Effects of Com

P – A weakness of experimental studies is the use of artificial materials in lab settings.  

E – for example the TCRTT which measures how loud noise.

P – A limitation pf correlation research is the inability to draw cause-and-effect conclusions.

E – What if, there was a positive correlation between viewing or playing of violent media and aggressive behaviour. This outcome does not help us choose between competing hypotheses of media effects.

P – One limitation of longitudinal studies is confounding variables.

E – This approach also views people as active consumers which is a more realistic view of how people interact with media.

E – However, studying change over time leaves longitudinal studies vulnerable to the effects of confounding variables. Many other sources of aggression interact with the media influences over a period of time.

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Media Influences on Aggression: Desensitisation, D

Desensitisation - when children view aggression on TV or play violent computer games, they become habituated to its effects. So, a stimulus that is usually aversive has a diminishing impact. This results in reduced anxiety and phycological arousal because of repeated viewing or playing.

Disinhibition - Most people generally view violence and aggression as antisocial - so there are powerful social and psychological restraints against using aggression as a solution. Violent media gives aggressive behaviour social approval especially when effects on victims are minimised or appears justified. Thus restraints loosen - disinhibited.

Cognitive priming - repeated viewing of aggressive media can provide us with a ‘script’ about how violent situations happen. Huesmann argues this script is stored in memory, and so we become primed to be aggressive. The process is mostly automatic and the script is triggered when we encounter cues in a situation that we perceive aggressive.

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Media Influences on Aggression: Desensitisation, D

P – There is research support for desensitisation.

E – Krahé et al. showed participants violent and nonviolent media while measuring physiological arousal. Participants who were habitual viewers showed lower arousal levels, higher pleasant arousal levels and lower anxious levels.

P – There is research support for disinhibition.

E – Berkowitz & Alito found that participants who saw a film depicting aggression vengeance gave more fake electric shocks of longer duration to a confederate.

E– This suggests that media violence may disinhibit aggressive behaviour when it is presented as justified. This is because vengeance is a powerful reason for justified violence is likely to be seen as socially acceptable.

P – One strength of cognitive priming is useful application.

E – Bushman & Anderson suggested that someone who habitually watches violent media access stored aggressive scripts more readily.

E – This explanation provides a means by which violent media could trigger aggressive behaviour by priming of cognitive scripts.

L – Effective intervention could potentially reduce aggressively behaviour by challenging hostile biases and encouraging habitual violent media users to consider alternatives to aggression like humour.

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