Neural and Hormonal Mechanisms in Aggression

Question 1

What do biological explanations assume?

Answer 1

The potential for aggression is located within an individuals biological makeup

Question 2

What are neurotransmitters?

Answer 2

Chemical substances that enable impulses to travel from one area to another

Question 3

How does serotonin influence aggression?

Answer 3

• Can inhibit responses to emotional stimuli so reduce aggression
• Low levels are associated with increased susceptibility to impulsive, aggressive, violent and suicidal behaviours

Question 4

What did Mann do in his study into serotonin?

Answer 4

• 35 p’s given dexfemfluramine to reduce serotonin

- Questionnaire to assess hostility and aggression given after

Question 5

What did Mann find in his serotonin study?

Answer 5

Drug was associated with an increase in hostility and aggression scores, providing support for a link between low serotonin levels and increased aggression

Question 6

What is a limitation of Mann’s study into serotonin?

Answer 6

• Self report methods may lower reliability due to SDB

- People want to paint themselves in the best light

Question 7

What is a second methodological limitation of Mann’s study?

Answer 7

• Only conducted on men - shows beta bias
• May not be valid to women
• May encourage stereotypical beliefs about female aggression and an andocentric view of human behaviour

Question 8

What can we conclude from Mann’s study after taking methodological flaws into account?

Answer 8

• While this study provides some support for the S/A link

- Lack of generalisability may limit it’s use in supporting the link as results may not be valid to wider population

Question 9

Where does further support for the serotonin and aggression link?

Answer 9

Non-human studies - Raleigh

Question 10

What did Raleigh’s study involve?

Answer 10

• Half a group of monkeys fed diet high in tryptophan to increase serotonin
• Half fed diets low in tryptophan to decrease serotonin

Question 11

What did Raleigh’s study show?

Answer 11

Low serotonin - increase aggression, providing considerable research support for the role of neurotransmitters

Question 12

However, what are 2 criticisms of Raleighs study?

Answer 12

• May lack generalisability as we cannot apply to humans. Animals have different anatomy and their behaviour is a poor predictor of human behaviour, limiting the support we can gain.
• However may offer us an expanded insight into physiological and psychological processes
• Ethical concerns - could cause pain and suffering, lacking credibility outside the study

Question 13

What did Bond find?

Answer 13

Evidence to support the idea that neurotransmitters can influence aggression from antidepressants

Question 14

What were Bond’s findings in clinical studies of antidepressants?

Answer 14

Antidepressants that increased serotonin were found to reduce irritability and impulsive aggressiveness

Question 15

How can dopamine lead to aggressive behaviour?

Answer 15

Increases in dopamine via amphetamines have been associated with increases in agg, whereas antipsychotics to reduce dopamine reduce aggressive behaviour

Question 16

Who does evidence for dopamine link come from?

Answer 16

Couppis and Kennedy

Question 17

What did Couppis and Kennedy find?

Answer 17

Mice - reward pathway in brain becomes engaged in response to aggressive event - Dopamine acts as a positive reinforcer following an aggressive act as it causes feelings of euphoria

Question 18

Why might dopamine acting as a reinforcer cause aggressive behaviour?

Answer 18

Suggests individuals may intentionally seek out an aggressive encounter for the rewarding sensation

Question 19

Why do Couppis and Kennedys findings provide conflicting evidence?

Answer 19

• Provides support for idea that dopamine is linked
• As a cause rather than a consequence as initially suggested
• Need for further research?

Question 20

What did a meta analysis of 29 studies involving antisocial children and adults find?

Answer 20

• Low serotonin found in aggressive individuals but no difference in dopamine
• Reduce serotonin found in all antisocial groups but particularly suicide attempters
• Suggests that serotonin depletion leads to impulsive behaviour which can result in aggression in various forms

Question 21

What does the meta analysis of 29 studies show?

Answer 21

• Biological, deterministic approach in explaining aggression
• Serotonin levels are a predictor of future behaviour

Question 22

What hormonal mechanism is thought to explain aggressive behaviour?

Answer 22

Male sex hormone Testosterone

Question 23

When and why does testosterone influence aggression?

Answer 23

Influence aggression from young adulthood onwards due to its action on brain areas involved in controlling aggression

Question 24

Who tested the testosterone/aggression hypotheses?

Answer 24

Dabbs in a study measuring salivary testosterone levels in violent and non violent criminals

Question 25

What did Dabbs find in his testosterone study?

Answer 25

Highest testosterone levels found in those with a history of primarily violent crimes

Question 26

However, what could be argued as a result of Dabbs findings?

Answer 26

Lack of generalisability as research was conducted only on criminals. However, this was responded to by studies of non-prison population, finding similar results and so giving credit to original findings

Question 27

What is the challenge hypothesis?

Answer 27

Monogamus species: testosterone levels should rise only in response to social challenges like threat to status, partner or male-male aggression. Humans are M so we would expect the same findings

Question 28

What approach does the challenge hypothesis link to?

Answer 28

Evolutionary approach, as it suggests we are biologically adapted so our T levels rise only to conditions of threat in order to provide defence

Question 29

Which further studies provide further evidence for the challenge hypothesis and so add credibility to hormonal explanations as they can be applied to the real world?

Answer 29

• Gun related crimes can be explained by testosterone increase by the presence of stimulus, as this is seen as a threat
• Klinesmith: Child saliva measurements for testosterone post play with gun or childs toy. Gun - significant testosterone increase

Question 30

However, Klinesmith’s study may be limited because..

Answer 30

Conducted on male students so many not be valid to the general population e.g females and different ages

Question 31

There has been inconsistent evidence from research into testosterone…

Answer 31

Archer - meta analysis of 250 males in 5 studies. Weak positive correlation was found.

• May be accredited to different measurements used over the studies (small samples, only men, etc) so show beta bias
• Concluded that due to methodological issues, a correlation of 0.8 was more appropriate providing modest support

Question 32

What is Cortisol?

Answer 32

Another hormonal mechanism that may influence aggressive behaviour

Question 33

What does cortisol do?

Answer 33

Increases anxiety and likelihood of social withdrawal, thus has a mediating effect on other aggression related hormones such as testosterone

Question 34

What do low/high levels of cortisol do?

Answer 34

High levels inhibit testosterone which leads to aggression. Low levels are found in habitual violent offenders and school children.

Question 35

What do levels of cortisol suggest?

Answer 35

• Although T is primary hormonal influence

- Low cortisol also plays a role by increasing the likelihood

Question 36

Evidence for the role of Cortisol comes from McBurnett on boys with behavioural problems..

Answer 36

Consistently low levels of cortisol boys began antisocial acts at a younger age and show 3x the number of aggressive symptoms than those with high or fluctuating levels

Question 37

The neural and hormonal mechanisms explanation follow a biological approach. What is a strength of this?

Answer 37

Such approaches allow for empirical data, easy to gather strong scientific evidence such as saliva samples, validating the theory as an explanation

Question 38

The neural and hormonal mechanisms explanation follow a biological approach. What is a limitation of this?

Answer 38

Reductionist - does not take factors such as social influencing factors into account