Unit 3 – A2 Psychology - Aggression
Aggression Pack 3
Social psychological approaches to explaining aggression
• Social psychological theories of aggression, for example, social learning theory, deindividuation
• Explanations of institutional aggression
Biological explanations of aggression
• Neural and hormonal mechanisms in aggression
• Genetic factors in aggressive behaviour
Evolution and human aggression
• Evolutionary explanations of human aggression, including infidelity and jealousy
• Evolutionary explanations of group display in humans, for example sport and warfare
Task: What is meant by… (place the definitions below in the correct order)
Neural mechanisms
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Hormonal mechanisms
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Genetic factors
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Aggression may be inherited; aggressive people inherit genes that lead them to be aggressive for example, in some cases, people
inherit a genetic mutation that causes a deficiency in monoamine oxidase A (MAO-A – the so-called ‘warrior gene’)
The role of neurotransmitters in causing aggressive acts, such as low levels of serotonin or high levels of dopamine, or both!
The role of the endocrine system which regulates the secretion of hormones; in aggression, testosterone and cortisol are implicated.
TASK: Which explanation best explains these cases?
Simon has just received a prison term for 3 years for GBH. This was after a road-rage incident which lead him to attack
another driver who had apparently stolen his parking space. Simon’s family history showed repeated acts of aggression,
with both his father and grandfather serving time in prison for acts of violence. Which explanation above would best
explain Simon’s aggression? ________________________
Luz-Marina has a reputation of acting violently at work (shouting, throwing objects, slamming doors etc.) when she does
not get her way; she once threw a laptop computer at a wall when one important business deal fell through. Luz-Marina
likes to be in power and has a dominant personality. Recent medical tests have revealed that she has unusually high levels
of testosterone. Which explanation above would best explain Luz-Marina’s aggression? ________________________
In the late 1980s, Wayne had been a participant in a medical trial for a weight-loss drug called dexfenfluramine, the team of
researchers were especially looking for side-effects of the drug. After a few weeks, Wayne reported having increased
feelings of hostility, and acted more aggressively than before. Analysis of his cerebrospinal fluid found significantly lower
levels of metabolite (waste-product) of serotonin. After he was removed from the trial, his aggression subsided and his
levels of serotonin metabolite increased to within normal parameters. Which explanation above would best explain
Wayne’s aggression __________________________
Neural Mechanisms in Aggression
TASK: Read the theory (AO1) below, then answer the questions.
Neural mechanisms refer to the role of neurotransmitters,
Psychologists have suggested low levels of serotonin in the brain can be
linked with impulsive aggression. Impulsive aggression is the tendency
to respond with hostility or aggression when faced with serious
frustration.
Normal levels of serotonin will have a calm, inhibitory effect on an
individual. If serotonin levels are low this inhibitory effect is gone.
Therefore, people will be less able to control impulsive and aggressive
tendencies. As Cleare & Bond (1997) put it, ‘Serotonin depletion tends
to ruffle people’s feathers!’
Under normal circumstances, serotonin works in the prefrontal cortex
to inhibit the firing of the amygdala, the almond-shaped structure that
controls fear, anger and other emotional responses.
If there is less serotonin in the prefrontal cortex, there will be less
inhibition of the amygdala, so the amygdala will not be under control.
When the amygdala is stimulated by outside novel and potentially
threatening events, it will become more active, driving the person to
act on their impulses.
Individuals have different levels of serotonin on a day to day, hour by
hour basis. However, there may also be people whom, for whatever
reason, have lower levels of serotonin all the time. This theory would
state that such individuals are predisposed to aggression.
1)
What do neural mechanisms refer to?
2)
What is impulsive aggression?
3)
What is linked with impulsive aggression?
4)
What effect do normal levels of serotonin have?
5)
What are people less able to control when serotonin levels are low?
6)
What does serotonin depletion tend to do, according to Cleare and Bond (1997)?
7)
Where does serotonin work in normal circumstances?
8)
What is the function of the amygdala?
9)
What does serotonin do to the firing of neurons in the amygdala?
10)
If there is less serotonin in the prefrontal cortex, how does this affect the amygdala?
11)
Is there less or more control of the firing of the amygdala when there are low levels of serotonin in the
prefrontal cortex?
12)
What happens when the amygdala is stimulated by novel and threatening experiences?
13)
Do serotonin levels fluctuate throughout the day?
14)
It is suggested that some individuals have permanently lower levels of serotonin than others. What
happens with these people with permanently low levels of serotonin?
ASSESSMENT 1 – Complete in your own words
Outline at least one neural mechanism in aggression (4 marks)
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Evaluation of Explaining the Causes of Aggression Through Low Serotonin
IDA – a Reductionist explanation.
TASK: discuss and answer the questions below
1) What is meant by reductionism?
2) Explain how this theory is reductionist
3) What are the positive consequences of this reductionist approach? (think about intervention)
4) What are the negative consequences of this reductionist approach? (what issues arise?)
Evidence supporting the theory
TASK: Read the article on Crockett’s research by Scott P. Edwards (2008) and consider the questions below
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Is it a repeated measures experiment?
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What are the two conditions?
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What control was introduced? (for serotonin levels)
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How was aggression was measured?
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What was the conclusion of the study with regard to serotonin and aggression
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Does this study support the theory about serotonin and aggression?
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What new information does it add about aggression, serotonin and hunger?
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Is the methodology of the study sound enough for us to view the findings as valid?
The theory is further supported by other research.
TASK: Turn to page 140 in the A2 textbook and find the research by Mann et al (1990) write details of the study below
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Validity: Using a questionnaire to rate Ps feelings of hostility and aggression lacks validity, in that what people say and what
people do are often not the same, so one can question the validity in using this evidence to support the role of Serotonin
and aggression.
Davidson et al (2000) found that violent criminals had markedly lower levels of serotonin to non-violent criminals.
What are the positive and negative consequences of the finding by Davidson et al (2000)
Alternative Explanations as Evaluation
It might not be only low levels of serotonin, an increase in dopamine may also be attributed to higher levels of aggression,
although the evidence is not as well established as it is for the role of serotonin. Still, the role of dopamine may be a path
for further enquiry in the future.
TASK – Complete the questions below…
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How much reliable evidence do you think there is to support the serotonin theory?
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Comment on the validity of the supporting evidence
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Is the evidence strong enough for us to agree with the reductionism of this explanation?
Overall evaluation
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How is this theory useful in countering aggression?
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How convincing and/or important do you think this theory is as a reason for aggression?
Hormonal Mechanisms in Aggression
The Hormone most researched in relation to aggression is ______________________________
The explanation
Testosterone is a hormone. It is present in both men and women, although men have around eight times as
much of it as women. The picture for how testosterone links to aggression is less clear than for the role of
genetics or the role of neural mechanisms in aggression, but it is equally controversial.
Early theories simply state that high testosterone causes aggression, so people who have higher levels of
testosterone – whether permanently or temporarily – will be more aggressive. More recently, high testosterone
has been linked to the need for dominance rather than aggression. For instance, successful businessmen and
athletes have higher testosterone than their less successful counterparts, but are not necessarily more aggressive
– they simply want to dominate.
So, how does testosterone link to aggression? It may come into play when the individual has high testosterone
but low serotonin. The high testosterone makes them seek dominance and they are therefore put in situations
where frustration of dominance may occur. If frustrated, the low levels of serotonin in the prefrontal cortex
mean that the impulsive behaviour caused by the amygdala is not under control, with aggression as the result.
An alternative theory is the mismatch effect. This effect also reflects the view that testosterone links to
dominance, so the higher the testosterone you have, the more dominance or status you also want. According to
the mismatch effect, testosterone only becomes important when there is a mismatch between the level of
testosterone in the body and the status of the individual. If an individual has high status and high testosterone, no
aggression will result, but high testosterone and low status, or low testosterone and high status, will result in
aggression.
TASK: Answer the questions below linking to the theory of testosterone and aggression
1) Is testosterone present in both sexes?
2) What is eight times greater in men than in women?
3) What was the early thinking about levels of testosterone and aggression?
4) How has recent thoughts about testosterone changed?
5) How might the role of testosterone link with low levels of serotonin?
6) The alternative theory is the mismatch effect, what are the conditions for:
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i)
Aggression to occur?
ii)
Aggression not to occur?
Can you think of a real life example where these explanations are demonstrated?
ASSESSMENT 2 – Complete in your own words
Outline at least one hormonal mechanism in aggression (4 marks)
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IDA – a Determinist explanation.
TASK: discuss and answer the questions below
7) What is meant by determinism?
8) Explain how this theory is deterministic
9) What are the positive consequences of this deterministic approach? (think about intervention)
10) What are the negative consequences of this reductionist approach? (what issues arise?)
NB: it is vital that you chose appropriate IDA in unit 3. If we compare the two theories of
serotonin and testosterone, it is easy to discuss the role of serotonin as a reductionist approach,
whereas recent theories about testosterone stress the importance of the environmental pressures
interacting with the levels of hormone, which is a wider explanation and less reductionist. Both
theories (serotonin and testosterone) are determinist in-so-far as a person’s behaviour is heavily
influenced by their levels of bio-chemicals, suggesting that, under certain biological and
environmental conditions, a person will have little control over their behaviour. You need to
consider whether it is useful to have determinist theories such as these.
Evidence supporting the theory
Kreuz & Rose (1972) studied testosterone levels in a group of 21 young adult male prisoners. Their testosterone
levels did not relate to whether they fought with others whilst in prison, but it did relate to the nature of the
crimes they had committed. The 10 prisoners with histories of more violent crime such as assault and armed
robbery did have statistically higher levels of testosterone than the 11 prisoners who had committed non-violent
crimes.
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How does this support the testosterone theory?
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Is the evidence strong enough to conclude that testosterone is the causal element of aggression? Explain
Josephs et al (2006) found that men and women high in testosterone levels reacted negatively after a loss of high
status, becoming stressed, confused, and anxious which is a state of mind that could lead to aggression. However,
men and women with low levels of testosterone who were put into a position of high status showed the same
pattern of upset which could also lead to aggression.
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How does this support the testosterone theory?
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Is the evidence strong enough to conclude that testosterone is the causal element of aggression? Explain.
TASK: Discuss and answer the questions below
Overall evaluation
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This theory is socially sensitive, what does this mean?
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How is the theory social sensitive?
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Since the explanation is socially sensitive, is the evidence strong enough in support of any explanation to
take action against those with very high levels of testosterone? Explain
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How convinced are you that testosterone plays a role in aggression? Because…
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What needs to happen next?
Genetic Factors in Aggressive Behaviour
There are two explanations linking genetics with aggression
Explanation 1
This genetic explanation for aggression says that aggression is inherited; aggressive people inherit genes that lead
them to be aggressive. The closer the relationship to the aggressive person, the stronger will be the inherited
tendency. For instance, if the father is aggressive because of his genes, the son will show more inherited
aggression than the grandson (providing the grandson has no additional forebears who were aggressive for
genetic reasons). Likewise, the more forebears you have who are aggressive for genetic reasons, the more likely
you are to have inherited genes for aggression.
Evaluation
IDA:
Point:
Explanation of point:
So what?
Supporting Evidence:
McGuffin & Gottesman (1985)
Ground this evidence to the explanation, paying particular attention to the concordance rates
Hutchings & Mednick (1973)
Ground this evidence to the explanation
Comment on the quality of the evidence – are there any major problems with it that make us unable to see
whether genes really do cause aggression?
Judging from the evidence, how much of a role do genes seem to play in aggression?
Genetic Explanation 2: the role a specific gene defect
A so called “warrior gene” has been linked to brain chemistry and increased
aggression; in some cases, people inherit a genetic mutation that causes a
deficiency in monoamine oxidase A (MAO-A) – so they inherit the “warrior
gene”. MAO-A is an enzyme that causes the breakdown of excess
monoamine neurotransmitters in the brain, such as noradrenaline and
dopamine.
The warrior gene is found on the X chromosome, which is why the gene is more prevalent in men; women are
protected from the faulty gene by their other X chromosome. The warrior gene is simply a shorter, less active
version of a gene allele (an alternative form of a gene caused by a mutation) on the X chromosome known as the
MAO-A gene.
If people inherit the warrior gene they will have an excess amount of some neurotransmitters in the brain
because not enough MAO-A has been released. This excess amount of neurotransmitters predisposes the
individual to become aggressive when under stress including when angry, fearful or frustrated.
Evaluation
Supporting evidence
Four generations of males in a Dutch family inherited a defect with regard to their MAO-A gene, specifically a
mutation was identified in the eighth exon (section) of their MAO-A gene. This means they had the warrior
gene. The men with the defective gene (and not all men in the family inherited it) showed aggressive, sometimes
violent behaviour including arson and attempted rape. The men seemed unable to regulate impulsive aggression,
which was particularly marked when provoked.
Brunner tested the urine of the men in the family: the 5 men tested with the defective gene had higher levels of
chemicals that result from neurotransmitters. This indicates that the men’s MAO-A was deficient because they
had not released enough of it to break down the neurotransmitters, hence the excess levels of the chemicals
resulting from neurotransmitters in their urine.
Ground this to the explanation
Vishnivetskaya et al (2007) studied mice that lacked an MAO-A gene (these
were called the Tg8 mice) and compared them to a control group of mice
who had the gene. The Tg8 mice showed increased aggression towards
intruder m ice and increased territorial aggression, predatory aggression,
and isolation induced aggression. However, the Tg8 mice did not show an
increase in all types of aggression; for instance, they were not more
aggressive to anesthetized or juvenile male mice.
Ground this to the explanation
Comment on the quantity of evidence available here. Is there anything that makes it difficult for us to pinpoint
the warrior gene as a cause of human aggression? Consider both pieces of evidence:
Further Evaluation
Returning to the point of biological reductionism, is the evidence persuasive enough to support the argument
that genetic factors cause aggression?
How should people with the warrior gene be treated?
Consider one of the other theories of aggression we have looked at and compare it with the genetic explanation.
Can you come up with:
One way in which they are similar
One way in which they are different
Overall conclusion: how persuasive are the genetic explanations for aggression?