Neural and hormonal mechanisms in aggression

Question 1

Define the term aggression.

Answer 1

Is an act carried out with the intention to harm another person- this harm can be physical or psychological. There are different types of aggression.

Question 2

What are the two types of aggression?

Answer 2

Reactive aggression

Proactive Aggression

Question 3

Define the term reactive aggression.

Answer 3

Driven by anger and hurt, where the goal is to harm another for the sake of getting even with them. Characterised by displays of rage and impulsivity (screaming, shouting, etc)

Question 4

Define the term proactive aggression.

Answer 4

It’s when aggression is carried out to solve a problem. This is cool, emotionally detached and often pre-mediated.

Question 5

Define the term limbic system.

Answer 5

Is a network of subcortical structures (deep inside the brain) linked with more primitive, emotional behaviours. Structures include the hypothalamus, hippocampus, the thalamus, and the amygdala.

Question 6

Describe the amydala.

Answer 6

This is the key structure in aggression. Increased amygdala activity is associated with aggression, as it has a role in the assessment of threats and challenges.

Question 7

Give evidence supporting the association between reactive aggression and amygdala activity.

Answer 7

Gospic et al (2011) discovered that amygdala activity increased in response to an aggressive game where participants have to decide to split money with a confederate. If both agree to share money, it is split between them. If the participant refuses the offer, both leave with nothing. Participants in the study had their brains scanned by fMRI. More activity was seen in the amygdala when the confederate made an unfair offer, which the participant then rejected. Taking drugs to lower this activity also lowered aggression- the participant was less likely to reject the offer.

Question 8

State the drug participants took in the Ultimatum Game.

Answer 8

Benzodiazepine (which reduces the arousal of the autonomic nervous system).

Question 9

Define the term serotonin

Answer 9

It’s a neurotransmitter involved in the communication of impulses between neurons.
Has a calming influence.
Low levels of serotonin = increased susceptibility to impulsive behaviour, aggression

Question 10

Give evidence supporting low levels of serotonin

Answer 10

Mann et al (1990) found that dexfenfluramine- a drug that reduces serotonin- increased measures of hostility and aggression in males (but not females), as assessed through questionnaires.
Virkkunen et al (1994) found lower levels of a serotonin breakdown product, and increased sleep disruption, in impulsive offenders compared to non-impulsive offenders, suggesting a low level of serotonin is linked with aggression.

Question 11

Define the term testosterone.

Answer 11

An androgen responsible for masculine features. It has a role in regulating social behaviour through its influence on certain areas in the brain involved in aggression.
It lowers the amount of serotonin.

Question 12

Give evidence supporting that testosterone is associated with aggression.

Answer 12

Mairead Dolan et al. (2001) found a positive correlation between testosterone levels and aggressive behaviours in a sample of 60 male offenders in UK maximum security hospitals. These men mostly suffered from personality disorders and had histories of impulsively violent behaviour.

Question 13

What are the strengths of neural mechanisms in aggression theory?

Answer 13

Effects of drugs on serotonin - Mitchell Berman et al. (2009)
Drugs that increase serotonin activity also reduce levels of aggressive behaviour.

Question 14

What did Mitchell Berman et al. (2009)?

Answer 14

He gave participants a placebo or a dose of paroxetine drug. Participants then took part in a laboratory-based game where electric shocks were given and received in response to provocation. The paroxetine participant
gave less intense shocks than those in the placebo group. This was only true for the participants with prior history of aggressive behaviour. Useful evidence for link between serotonin function and aggression.

Question 15

What does paroxetine do?

Answer 15

Enhances serotonin activity.

Question 16

What are the limitations of neural mechanisms in aggression theory?

Answer 16

Role of other brain structures aren’t accounted for.

Question 17

Give evidence of this limitation.

Answer 17

Coccaro et al. (2007) says that people with psychiatric disorders that feature aggression have activity in the OFC is reduced disrupting impulsive-control function leading to increased aggression.
Gospic et al. (2011) findings indicates the regulation of aggression involves three neural structures in the brain: the amygdala, the OFC and the connection between the two.

Question 18

What is the strength of hormonal mechanisms in aggression theory?

Answer 18

Alan Mazur (1985) & Mehta and Joseph (2006) findings confirm the role of testosterone increasing validity.

Question 19

Explain Alan Mazur’s experiment.

Answer 19

He formulated the biosocial model status (BMoS) to explain the link between testosterone and aggression in humans. Testosterone levels change rapidly during the day, especially in response to social interactions related to statues (e.g competition).

Question 20

Explain Mehta and Joseph method.

Answer 20

Measured changes in their male participants’ testosterone levels before and after a competitive game (which they all lost). Once the sample was taken the participants were given a choice to either challenge opponent to another competition (aggressive) or complete an unrelated task (non-aggressive).

Question 21

State the findings of Mehta and Joseph experiment.

Answer 21

Losers whose testosterone rose after loss, 73% rechallenged
Losers whose testosterone dropped, only 22 rechallenged.
High amount of rechallenge = aggression.

Question 22

Describe cortisol.

Answer 22

Is a hormone secreted by the brain in response to stressful situations.
Boys with low cortisol exhibited three times the number of aggressive symptoms.
Low levels of cortisol = high levels of aggression