AGGRESSION

Question 1

Define aggression

Answer 1

An act carried out with the intention to harm another person

Question 2

What are the two types of aggression?

Answer 2

• Proactive aggression: planned method of getting what you want and so it it less emotional
• Reactive aggression: angry and impulsive, accompanied by physiological arousal

Question 3

Give a one sentence summary of neural mechanisms

Answer 3

Areas of the brain and how they communicate that may be responsible for aggression (lymbic system and serotonin)

Question 4

Give a one sentence summary of hormonal mechanisms

Answer 4

Chemical substances that circulate in the bloodstream that may be responsible for aggression

Question 5

Outline the role of the amygdala in influencing aggression

Answer 5

• Quickly evaluates the emotional importance of sensory information
• Assesses and responds to environmental threats and challenges
• More likely to interpret the sensory information as a threat
• Reactivity increases accordingly = aggression

Question 6

Outline the role of the hippocampus in influencing aggression

Answer 6

Involved in the formation of LTM, so an animal can compare the conditions of a current threat to similar past experiences. For example, if an animal had previously been attacked by another animal, the next time they encounter that animal they are likely to respond with aggression or fear.
Impaired hippo a pal function prevents the nervous system from putting things into a relevant and meaningful context, and so the amygdala may respond inappropriately to sensory stimuli, resulting in aggression

Question 7

Outline the role of serotonin as a neuronal mechanism affecting aggression

Answer 7

• Serotonin is an inhibitory neurotransmitter
• Serotonin typically inhibits the firing of the amygdala. Low levels of serotonin remove this inhibitory effect
• People are therefore less able to control impulsive and aggressive behaviour. This means that when the amygdala is stimulated by external events, it becomes more active, causing the person to act on their impulses and making aggression more likely.

Question 8

Give a weakness of both limbic system and serotonin (neural explanations)

Answer 8

The links between biological mechanisms such as serotonin and the amygdala are well established in non-human animals. However, the position in not quite so clear in humans - the complexity of human social behaviour means that a biological explanation for aggression is insufficient on its own to explain all the many different aspects of aggressive and violent behaviour because it is reductionist. For example, Bandura’s study demonstrates that humans can learn aggression through SLT (children imitated the behaviour of adults). This suggests that the neural explanations are incomplete on their own to explain all instances of aggression and so they are not completely valid explanations of all aggressive behaviour.

Question 9

Give a piece of supporting evidence for the limbic system (CW)

Answer 9

In 1966, Charles Whitman killed 13 people from an observation tower at Texas University, after killing his wife and mother. He left behind a note asking doctors to examine his brain as he was convinced that something was making him aggressive. He was found to have a tumour pressing against his amygdala. This supports that the amygdala plays an important part in aggression in humans, with the tumour potentially making his amygdala more reactive triggering aggression, supporting the validity of the theory.

Question 10

Give a piece of supporting evidence for the limbic system (Gospic)

Answer 10

Gospic et al exposed some ppts to mild provocation and their responses were recorded using an fMRI. When ppts responded aggressively, the scans showed a fast and heightened response by the amygdala. They also found that a benzodiazepine drug taken before the provocation had two effects - decreasing the activity of the amygdala and reducing the aggression. This supports that there is a causal link between the amygdala and aggression, and when provoked, the amygdala showed greater reactivity and this was linked to aggressive responses, and when the amygdala reactivity was reduced, aggressive responses also decreased. Therefore, this supports the internal validity of the limbic system as a causal factor in aggression.

Question 11

Outline how testosterone influences aggression

Answer 11

• Testosterone plays a role in regulating social behaviour
• Higher levels of testosterone are related to aggression

Question 12

Outline how progesterone influences aggression

Answer 12

• Progesterone is a female ovarian hormone that is thought to play an important role in aggression in women
• Levels of progestoerone vary during the ovulation cycle and are lowest during and just after menstruation
• Low levels of progesterone are linked to increased aggression in women

Question 13

Give a piece of supporting evidence for testosterone

Answer 13

• Dabbs et al measured salivary testosterone in violent and non-violent criminals. Those with highest testosterone levels had a history of primary violent crimes. This supports that testosterone levels are linked with aggression in humans, where higher levels are correlated with more aggressive behaviour, suggesting the explanation has some validity

Question 14

Give a piece of undermining evidence for testosterone

Answer 14

There is mixed evidence of a link between testosterone and aggression in humans. Carre and Mehta developed a dual-hormone hypothesis to explain why. They claim that high levels of testosterone lead to aggressive behaviour, but only when cortisol levels are low. When cortisol levels are high, testosterone’s influence on aggression is blocked. Therefore the combined activity of testosterone and cortisol may be a better predictor of aggression that either hormone alone and so the testosterone explanation may not be a completely valid explanation of aggression

Question 15

Give a piece of supporting evidence for progesterone

Answer 15

Ziomkiewica et al found a negative correlation between progesterone levels and self-reported aggression. This supports that progesterone levels are linked with aggressive behaviour in humans, where lower levels are correlated with more aggressive behaviour, suggesting the explanation has some validity.

Question 16

Give an overview of the genetic factors in aggression

Answer 16

• The propensity for aggressive behaviour lies in a person’s genetic make-up i.e., offspring inherit aggression from their parents via genes.

Question 17

Outline the procedure of Coccaro et al’s study

Answer 17

They studied adult male MZ and DZ twins. For aggressive behaviour, the researchers found concordance rates of 50% for MZ twins and 19% for DZs. The corresponding figures for verbal aggression were 28% for MZ twins and 7% for DZ twins

Question 18

Outline the conclusions of Coccaro et al’s study

Answer 18

The results suggest that aggression is at least partly genetic, because the concerdance rates are higher for MZ twins (who share more of their genes - 100%) than DZ twin (50%). Therefore, the greater similarity in aggression between MZ twins is likely to be due to their greater number of shared genes. However, the concordance rates for MZ twins is not 100% - and should be is aggression is entirely genetic as MZ twins share 100% of their genes.

Question 19

Outline the procedure of Hutchings and Mednick’s study

Answer 19

They conducted one of the largest-ever adoption studies when they review over 14 000 adoptions in Denmark. They found a positive correlation between the number of convictions for criminal violence among the biological parents, and the number of convictions for criminal violence among their sons who were adopted into other families

Question 20

Outline the conclusions of Hutching’s and Mednick’s study

Answer 20

This suggests that aggression is partly genetic, as there is a positive correlation between the number of convictions among biological parents, and the number of convictions for violence among their sons who were adopted. Therefore - aggression must be partly genetic, as the criminals and their biological parents only share their genes, and not the environment - so the shared genes are responsible for aggression. However, this was only a correlation so it is not possible to see the cause and effect between genes and aggression. This means that we can’t tell that genes caused aggression.

Question 21

Outline the procedure of Miles and Carey’s study

Answer 21

They carried out a meta-analysis of 24 twin and adoption studies that supported the genetic basis of aggression. Most of the studies relied on parental or ppts self reports of aggressive tendencies, but some involved observation of aggression. The results suggested a strong genetic influence that could account for as much as 50% of the variance in aggression. They also found that as people got older, the influence of the environment decreased and the influence of genetics increased

Question 22

Outline the conclusions of Miles and Carey’s study

Answer 22

The results suggest that aggression plays a significant role in aggression (any concordance rate above 40% of considered a strong genetic influence). Most of the studies were based on subjective data (self-report techniques). These may be unreliable and so may not reflect the true influence of genes on aggression.

Question 23

Outline the role of the MAOA gene in influencing aggression

Answer 23

• MAOA is an enzyme which regulates the metabolism of serotonin in the brain.
• There is a gene responsible for producing this enzyme that has been associated with aggression
• One low activity variant of the MAOA gene leads to low MAOA activity of areas of the brain, and has been associated with various forms of aggression.

Question 24

Outline Brunner et al’s study

Answer 24

• Studied 28 members of a large Dutch family who were repeatedly involved in impulsively aggressive criminal behaviours such as rape, attempted murder and physical assault.
• They found that these men had abnormally low levels of MAOA in their brains and the low-activity version of the MAOA gene

Question 25

Outline a weakness of the supporting evidence for the genetic factors in aggression

Answer 25

Many twin and adoption studies have focussed on individuals who have been convicted of violent crime. This leads to difficulties when trying to draw meaningful conclusions from the studies. Convictions for violent crime are relatively few compared to the number of violent attacks that never result in a conviction. Additionally, those classified as ‘violent’ on the basis of a court conviction are not necessarily the most serious, persistent offenders. For example, a convicted murderer may only have otherwise had a lifetime free of crime and only committed one violent incident. This might go some way to explain why so many studies have found little or no evidence of heritability for violence, but it also suggests that the results from such studies may not be externally valid as the samples are not representative of the majority of people who are regularly involved in aggressive behaviour. Therefore, from the studies, it is difficult to strongly support the role of genetic factors in aggression. It may even be that the studies underestimate the contribution of genetics to aggression.

Question 26

Outline a piece of supporting evidence for the MAOA gene

Answer 26

Mertins et al studied ppts with low-activity and high-activity variants of the MAOA gene in a money distributing game. Ppts had to make decisions about whether or not to contribute money for the good of the group. The researchers found that males with the high-activity variant were more cooperative and made fewer aggressive moves than the low-activity participants. This supports the importance of the MAOA gene in aggressive behaviour. It suggests that possession of the high activity variant leads to the exact opposite behaviour to that associated with the low activity variant. The two predictions of the MAOA explanation are opposite sides of the same coin. As both are confirmed by research evidence, this increases out the confidence that the genetic explanation is a valid account of how genes influence aggressive behaviour.

Question 27

Give a piece of supporting and undermining evidence for the MAOA gene

Answer 27

Caspi et al. studied 500 children. They discovered a variant of a gene associated with high levels of MAOA and a variant associated with low levels of MAOA were significantly more likely to exhibit antisocial behaviour, but only if they had been maltreated as children. Children with high levels of MAOA were maltreated, and those with low levels of MAOA who were not maltreated did not exhibit antisocial behaviour. This suggests that whilst genes are crucial influences on aggressive behaviour, they do not act in isolation. It appears that neither the genes nor the environment have a significant impact in isolation. This suggests that it is the interaction between genes and the environment that determines behaviours such as aggression (diathesis-stress).