Aggression

Question 1

What is the hypothalamus responsible for

Answer 1

The hypothalamus is responsible for the regulation of the autonomic nervous system, which in turn regulates responses to emotional circumstances.

Question 2

What is the amygdala responsible for?

Answer 2

The amygdala is responsible for attaching emotional significance to sensory information.

Question 3

What is the limbic system?

Answer 3

The limbic system is believed to be hierarchical with signals being passed from the lower systems to the higher systems in the prefrontal cortex where feelings are monitored and interpreted, which then triggers a physical response.

Question 4

The prefrontal cortex in relation to aggression

Answer 4

The prefrontal cortex is crucial for regulating social behaviour and aggressive responses. Damage to the prefrontal cortex would reduce the inhibition of the amygdala resulting in higher levels of aggression.

Question 5

Kluver and Bucy (1939)

Answer 5

Kluver and Bucy (1939) were early researchers who, using Rhesus monkeys, removed the main areas of the limbic system including the amygdala, hippocampus and surrounding cortical areas. They found that the monkeys displayed an absence of emotional, motor and vocal reactions normally associated with stimuli or situations eliciting fear and anger. Lesioned monkeys also lost the social understanding of group hierarchies and would try to fight the more dominant and larger members of the group. This research demonstrates the importance of the limbic system in regulating aggressive responses.

One of the main criticisms of research using animals to provide evidence for aggression in humans is the differences between animal and human physiology and the question of whether we can extrapolate research findings from animals to human aggressive behaviour. Despite humans and monkeys both possessing similar neural structures, we cannot be sure that the processes involved in mediating aggression in humans are the same as those shown in animals such as the Rhesus monkey.

Question 6

Gospic et al (2011)-The Ultimatum game

Answer 6

• 2 players- the proposer; the responder
• Way, wop over pettentiesplit money in a certain
• If the responder accepts the money is split as
proposed
• If the responder rejects the offer, both receive
nothing

Question 7

There is supporting evidence which demonstrates the importance of the limbic system in the regulation of aggression….

Answer 7

There is supporting evidence which demonstrates the importance of the limbic system in the regulation of aggression. For example, Kluver and Bucky 1939 through their study which included rhesus monkeys and the removal of parts of the limbic system such as the amygdala and hippocampus in these monkeys’ established changes in these monkeys. One such example of a change in behaviour is the newly found absence of emotional, motor and vocal reactions which are normally displayed when in a fearful/angry situation. Moreover, the monkeys also lacked social understandings of the group and so attempted to fight with larger, more dominant monkeys. Therefore, through their study we are able to appreciate the limbic system and its vital role in the maintenance of normal reactions when exposed to a stimulus which would illicit a particular emotion and so action as a result, an important and innate process needed for survival.

Question 8

However, a major limitation of the study is the use of monkeys, a type of animal to illustrate human behaviours such as an aggression.…

Answer 8

However, a major limitation of the study is the use of monkeys, a type of animal to illustrate human behaviours such as an aggression. Humans and animals have significantly different physiological and so there is an issue of extrapolating such findings to explain aggression in humans. Although, both humans and monkeys have similarities between structures, the processes involved when aggression is displayed, we are unsure of and so cannot be sure that they are similar in the two species. For this reason, further implications are introduced if we were to extrapolate and incorporate these findings in the creation of laws and social practices.

Question 9

Ferrari et al. (2003)

Answer 9

♦ They allowed adult male rats to fight with another rat at a specific time for ten days. On the eleventh day, the rat wasn’t allowed to fight.
♦ However, researchers found that the rat’s dopamine levels had raised by 65%, and his serotonin levels were reduced by 35%.
♦ Despite the fact that the rat was not fighting, the experience had changed the rat’s brain chemistry.

Question 10

There is supporting evidence for the serotonin hypothesis…

Answer 10

There is supporting evidence for the serotonin hypothesis. For example, Virkkunen et al (1994) found levels of serotonin to be significantly lower in offenders. Similarly, Ferrari et al (2003) found that after a mouse displayed aggressive behaviour multiple times serotonin levels were shown to have decreased by 35% whilst dopamine levels increased by 65%. This supports the biological claims in which aggression is shown to be as a result of hormonal imbalances as illustrated by the findings of the studies. For this reason, we can place our confidence in the neural hypothesis and so confidently draw conclusions.

Question 11

However, these studies merely establish a correlation in which cause and effect cannot be distinguished.…

Answer 11

However, these studies merely establish a correlation in which cause and effect cannot be distinguished. The research raises the question of whether lower levels of serotonin cause aggression or if they are as a result of expressing aggression. For this reason, the findings are limited and so further research is required for us to fully understand the role of serotonin in aggression. Nevertheless, this research does demonstrate the complexity of the role of serotonin in aggressive behaviour.

Question 12

Moreover, the serotonin hypothesis has practical application; from the hypothesis we are able to advice those experiencing high levels of aggression…

Answer 12

Moreover, the serotonin hypothesis has practical application; from the hypothesis we are able to advice those experiencing high levels of aggression. For example, foods that increase serotonin levels such as walnuts and bananas can be advised to increase serotonin levels and thus, decrease aggression levels. Therefore, we are able to apply the hypothesis to predict and treat increased aggression in individuals. Furthermore, there are positive societal implications; if we are able to effectively treat aggression by increasing serotonin levels, violent crime rates and the number of individuals institutionalized along with the levels of institutionalised aggression would decrease. Additionally, such advice could help improve life quality Aswell as having both a direct and indirect effect on the economy.

Question 13

Hormonal Mechanisms in Aggression:

Testosterone

Answer 13

• Testosterone is an androgen (male sex hormone) present in significantly larger concentrations in men, compared to women, and is responsible for the production of male facial characteristics and reproductive organs, being secreted from the pineal gland.
• There may be a link between decreased testosterone levels and decreased levels of aggressive behaviour, a positive correlation demonstrated by castration studies.

Question 14

•Nelson (1995)

Answer 14

• Nelson (1995) found that there was a positive correlation between levels of testosterone circulating in the body and aggressive behaviour in female and male prisoners.

Question 15

• Wagner, Beuving and Hutchinson (1979)

Answer 15

• Wagner, Beuving and Hutchinson (1979) show that if a mouse is castrated, overall levels of aggression tend to reduce, as testosterone is produced in the testes. If a castrated mouse receives testosterone aggression levels increase.

Question 16

There is supporting evidence for the influence of hormonal mechanisms in aggression, particularly the hormone testosterone….

Answer 16

There is supporting evidence for the influence of hormonal mechanisms in aggression, particularly the hormone testosterone. For example, Nelson (1995) found that there was a positive correlation between levels of testosterone circulating in the body and aggressive behaviour in female and male prisoners. Similarly, Wagner, Beuving and Hutchinson (1979) show that if a mouse is castrated, overall levels of aggression tend to reduce, as testosterone is produced in the testes. If a castrated mouse receives testosterone aggression levels increase. These increase our confidence in hormonal mechanisms in influencing aggression as the findings illustrate the aggression to be of a hormonal basis.

Question 17

However, Nelson’s study suffers from methodological criticisms where gender bias, in specific beta bias has been found.

Answer 17

However, Nelson’s study suffers from methodological criticisms where gender bias, in specific beta bias has been found. Nelson ignored the qualitative differences between males and females. It has been proven that men produce testosterone in significantly larger concentrations compared to women and the study does not reflect this. For this reason, the research is limited as we cannot conclusively claim that males and females experience aggression for the same reasons.

Question 18

However, Bain et al found no significant difference between men who had been charged with violent or murder crimes compared to those who had been charged with non-violent crimes…

Answer 18

However, Bain et al found no significant difference between men who had been charged with violent or murder crimes compared to those who had been charged with non-violent crimes. This contradictory evidence is limitation of the testosterone hypothesis, making it an unreliable one and possibly invalid. It is possible that the testosterone hypothesis is too simplistic as it ignored other factors outside of biological mechanisms which may induce increased aggression levels.

Question 19

Both the neural and hormonal hypothesis are biologically reductionist; where the complexity of aggression as a common human behaviour is simplified into both neural and hormonal activity…

Answer 19

Both the neural and hormonal hypothesis are biologically reductionist; where the complexity of aggression as a common human behaviour is simplified into both neural and hormonal activity. Whilst this allows for the in-depth analysis of the exact mechanism that influences aggression it is a limited level of explanation as other factors such as environmental, social and cultural influences are ignored.

Question 20

Genetics and Aggression

Answer 20

• Twin studies are particularly important in determining the genetic/biological basis of a behaviour, due to the fact that MZ twins are genetically identical, whilst DZ twins share 50% of genes with each other.

Question 21

Coccaro et al (1997),

Answer 21

Evidence from this comes from Coccaro et al (1997), who found concordance rates of 50% for MZ twins and 19% for DZ twins in terms of physical acts of aggression. This strongly suggests a genetic basis for aggression.

Question 22

• The differences between MZ and DZ twins in terms of rates of aggression was further supported by Rhee and Waldman (2002)…

Answer 22

• The differences between MZ and DZ twins in terms of rates of aggression was further supported by • The differences between MZ and DZ twins in terms of rates of aggression was further supported by Rhee and Waldman (2002) who came to the conclusion that, based on their meta-analysis of aggression. adoptees suffering from aggressive behaviour and APD (antisocial personality disorder) that a further 41% variance in rates of aggressive behaviour can be accounted for by candidate genes. and Waldman (2002) who came to the conclusion that, based on their meta-analysis of aggression. adoptees suffering from aggressive behaviour and APD (antisocial personality disorder) that a further 41% variance in rates of aggressive behaviour can be accounted for by candidate genes.

Question 23

MAOA Gene

Answer 23

• enzyme that breaks down serotonin within the synaptic cleft after neurotransmission

e.g. leading to increased levels of the metabolite 5-HIAA.

Question 24

MAOA and a Brunner et al

Answer 24

Brunner et al provided evidence for the link between decreased MAOA levels and aggression through studying a large Dutch family who were all actively engaged in aggressive behaviour (e.g. rape) and who all had unusually low MAOA levels. This would mean that as less serotonin is broken down within the synaptic cleft, there is a higher rate of serotonin binding to complementary receptors on the postsynaptic membrane, leading to an increased rate of stimulation of the postsynaptic membrane.

Question 25

Explain the institutional aggression models

Answer 25

• Irwin and Cressey (1962) proposed a dispositional explanation for aggression in the form of the ‘importation model’.
• This model suggests that aggression is caused by individual differences between offenders, rather than the prison context.
• This is because, as suggested by Thomas and McManimon (2005), prison offenders will behave in the same way within prison as in the ‘real-world’ due to their dispositions e.g. drug abuse, childhood trauma, economic poverty etc.
• These characteristics will pre-dispose them to use aggression to navigate their way around the prison social hierarchy, and not be challenged for doing so because aggression is part of the ‘prison subculture’.

Question 26

Steiner (2009)

Answer 26

Steiner (2009)
♦ who, in his meta-analysis of 512 prisons in the US,
♦ found that ‘prison-level’ factors could be used as indicators for the likelihood of aggressive behaviour.
♦ e.g., the presence of female officers and Hispanic inmates.
♦ This further supports situational explanations for aggression within prisons.

Question 27

DeLisi et al (2011)

Answer 27

DeLisi et al (2011)
♦ who found that certain dispositional traits, such as childhood trauma and irritability,
♦ coincided with an increased risk of violent behaviour and suicides,
♦ in a group of 813 juvenile offenders when compared to a control group. T
♦ Therefore, this suggests that dispositional traits, as opposed to the prison environment, may be a more important predictor of aggression.

Question 28

Kane and Janus 1981-

Answer 28

Kane and Janus 1981-
♦	Greater periods of unemployment
♦	Lower levels of education
♦	A more serious criminal record
♦	All were correlated with a greater likelihood of aggression whilst imprisoned.

Question 29

Podle and negoli 1983

Answer 29

Podle and negoli 1983
♦ Studied juvenile institutions
♦ Pre-institutional violence emerges as the best prediction of inmate aggression.

Question 30

A strength of the importation model of describing institutional aggression is that it has supporting evidence.

Answer 30

For example, Haver and S found through their study in 1986 that black inmates displayed higher levels of violent behaviour and lower levels of alcohol and drug misuse. It was also found that this correlation was also present outside of prison, thus, illustrating how behaviours such as aggression is imported in prisons. Furthermore, Kane and Janus 1981 found that variables outside of prison also correlated with increased likelihood of aggression whilst imprisoned. Examples of these variables are greater periods of unemployment, Lower levels of education and a more serious criminal record. The supporting evidence validates the importation model theory and so we are able to place our confidence in both the theory and any conclusions drawn.

Question 31

However, a weakness of the importation model is a failure to consider situational factors which contribute to the quality of the prison, and therefore the associated prison factors, as proposed by Dilulio (1991)

Answer 31

He suggests that the ‘administrative control model’ (ACM) is a more valid and accurate explanation of aggressive behaviour within prisons, because it emphasises the consequences of poor prison management. These can include irregular implementation of rules and officers maintaining psychological distances with the inmates. Such factors may create ‘triggers’ for aggression which increases the influence of dispositional factors.