Aggression Flashcards

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1
Q

What are neural mechanisms?

A

Related to the neurone, such as large neural structures or the actions of neurotransmitters.

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2
Q

What are hormonal mechanisms?

A

How chemical messengers influence the body.

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3
Q

What are the 3 key biological influences on aggressive behaviour?

A
  • Limbic system
  • Serotonin
  • Testosterone
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4
Q

What is the difference between hot and cold blooded aggression?

A

Reactive aggression (hot blooded) - Angry and impulsive behaviour coupled with physiological arousal.

Proactive aggression (cold blooded) - A pre-meditated way of getting what you want (e.g rape, murder).

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5
Q

What is the limbic system?

A

A set of neural structures located in the centre of the brain.
The amygdala and hypothalamus are key to aggressive responses.
Speed and sensitivity of limbic responses to stimuli are important predictors of aggressive behaviour in humans.

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6
Q

What is the limbic system also known as?

A

The Papez circuit (1935).

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7
Q

What are some of the key regions of the limbic system? (x3)

A
  • Amygdala
  • Thalamus / hypothalamus
  • Hippocampus
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8
Q

What did MacLean (1990) say about the limbic system?

A

The limbic system of the mammalian brain is the centre of emotion and learning.
It is thought to be linked with aggression.

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9
Q

What is the role of the amygdala within the thalamus?

A

The amygdala has been identified as being linked to the production of aggressive behaviour; fMRIs show increased activity during aggressive responses (Gospic).

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10
Q

What is the role of the hypothalamus within the thalamus?

A

Has a role in integrating and expressing emotional responses, and it can trigger aggressive behaviour as part of the fight or flight response.

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11
Q

What is the role of the hippocampus within the thalamus?

A

Chang & Gean (2019) found that stress in socially isolated mice activates the ventral hippocampus neurones, which induces attack-like behaviour (aggression).

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12
Q

Why is the amygdala thought to be so important in aggression?

A
  • In humans and animals, it acts as a threat sensor from the environment.
  • In humans there is a positive correlation between how reactive the amygdala is and aggression levels in an individual.
  • An over-reactive amygdala can lead to increased aggression.
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13
Q

Kluver & Bucy (1937) - role of amygdala in aggression

A

Discovered the destruction of the amygdala in a monkey who was dominant in a social group caused it to lose its dominance in the group.

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14
Q

What is Kluver-Bucy syndrome? - neural and hormonal mechanisms

A

It is a rare neuropsychiatric disorder due to lesions affecting bilateral temporal lobes, especially the hippocampus and amygdala; symptoms include placidity (not easily upset or excited).

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15
Q

What happens if the amygdala is stimulated? - neural and hormonal mechanisms

A

Stimulation near the amygdala produces fear, anxiety, defensive and sometimes violent behaviour.

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16
Q

Mark & Ervin (1970) - amygdala is stimulated

A

A woman receiving painless stimulation to her amygdala became engaged and smashed her guitar against the wall.

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17
Q

King (1961) - amygdala is stimulated

A

Reported violent behaviour in a patient with schizophrenia undergoing amygdala stimulation.

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18
Q

Gospic et al (2011) - role of amygdala in aggression

A
  • Participants played ‘The Ultimatum Game’.
  • Subject A proposer, subject B responder.
  • Used fMRI to monitor brain activity.
  • When subject B rejected the offer, there was increased response in the amygdala in those subjects.
  • When participants took benzodiazepines it halved the number of rejections; it only decreased those who were previously aggressive.
  • Suggests an association between reactive aggression and the amygdala.
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19
Q

What is the role of serotonin in aggression? - neural and hormonal mechanisms

A
  • Serotonin has widespread inhibitory effects on the brain - slowing down neuronal activity.
  • Aggression in humans and animals is associated with low levels of serotonin.
  • Normal levels in the OFC reduce the firing of neurons and allow for a greater degree of behavioural self-control.
  • Decreased levels disturb this mechanism, reducing self-control and increasing compulsive behaviour (including aggression).
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20
Q

Virkunnen et al (2014) - role of serotonin in aggression - neural and hormonal mechanisms

A
  • Compared levels of a serotonin breakdown product (5-HiAA) in the cerebrospinal fluid of violent impulsive and violent non-impulsive offenders.
  • The levels were significantly lower in the impulsive offenders, because the reduction of the 5-HiAA means there is decreased serotonin activity in the brain which has an effect on controlling impulsive (reactive) aggressive behaviour.
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21
Q

What is androgen? - hormonal mechanisms

A

Testosterone is a male sex hormone (androgen), which are hormones responsible for masculine features.

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22
Q

What are the biological effects of testosterone? - hormonal mechanisms

A
  • Brain: increased sex drive, improved mood, memory function.
  • Muscles: muscle growth, increased strength, increased endurance.
  • Bones: bone mass density maintenance.
  • Sex organs: sperm production, erectile function, prostate growth.
  • Skin: hair growth, collagen growth.
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23
Q

What is the role of testosterone in aggression? - hormonal mechanisms

A
  • Males are generally more aggressive than females.
  • Testosterone has a role for regulating social behaviour via its influence on the brain implicated in aggression.
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24
Q

Daly & Wilson (1988) - role of testosterone in aggression - hormonal mechanisms

A

Aggression is highest in males 20+ years old when testosterone peaks.

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25
Q

How do steroids work? - hormonal mechanisms

A

Steroids work by mimicking the hormone testosterone, increasing muscle mass and strength but can also make people aggressive.

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26
Q

Gimmanco et al (2005) - animal studies - hormonal mechanisms

A

Demonstrated experimental increases in testosterone are related to greater aggressive behaviour, and the removal of the testes reduced aggression in many animal species.

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27
Q

Dolan et al (2001) - prison studies - hormonal mechanisms

A

Found a positive correlation between testosterone levels and aggression in a sample of 60 male offenders in UK maximum security hospitals.
The men mostly had personality disorders and history of impulsive (reactive) violent behaviour.

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28
Q

Ziomkiewick (2012) - role of hormones in female aggresison

A
  • Levels of progesterone vary during the menstrual cycle and are lowest after menstruation.
  • Ziomkiewick (2012) found a negative correlation between progesterone levels and self-reported aggression.
  • Low levels of progesterone are linked to increased aggression in women.
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29
Q

What are some examples of proteins? - role of genetics

A
  • Receptor molecules
  • Nerve chemicals
  • Hormones
  • Enzymes
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30
Q

How is the genetic component of aggression determined? - role of genetics

A
  • To determine the genetic component of aggression (nature) vs the environmental component (nurture), each influence needs to be disentangled.
  • This can be done by looking at twin, adoption and family studies.
  • It can also be done by looking at the contribution of particular genes.
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31
Q

Value of twin studies - role of genetics

A
  • MZ twins share all their genes, so we can assume that any differences between them must be due to their environment.
  • Similarly, if both MZ twins are highly aggressive we could assume this is due to genetics.
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32
Q

Concordance rate

A

The degree of similarity on some measureable trait.
(The presence of the same trait in both members of a pair of twins).

33
Q

How are concordance rates used? - role of genetics

A
  • Usually we compare concordance rates to DZ twins.
  • Higher concordance rates in MZ twins suggest a heritable component to whatever is being measured.
  • A high degree of genetic influence is indicated when the correlation for MZ twins greatly exceeds the correlation for MZ twins.
34
Q

Coccaro et al (1997) - twin studies - role of genetics

A
  • Studied specifically aggressive behaviour (physical assault) in adult twins.
  • He found that MZ twins had concordance rates of 50% and DZ at 19%.
  • Verbal aggression was 28% in MZ twins, and 7% for DZ twins.
  • As the concordance rate is higher for MZ twins, it shows that genetics do have a role in aggression (they have a closer genetic similarity than DZ twins).
35
Q

How do adoption studies disentangle the role of genetics and the environment? - role of genetics

A
  • If a positive correlation is found between aggressive behaviour in adopted children and aggressive behaviour in their adoptive parents, then an environmental effect is implied.
  • If the correlation is between the adopted child and their biological parents, then a genetic effect is implied.
36
Q

Rhee & Waldman (2002) - adoption studies - role of genetics

A
  • Carried out a meta-analysis of adoption studies of direct aggression and anti-social behaviour (a prominent feature being aggression).
  • They found genetic influences accounted for 41% of the variance in aggression - the same finding as in twin studies.
37
Q

Hutchings & Mednick (1975) - adoption studies - role of genetics

A

A study on 14,000 adoptions in Denmark found that a significant number of adopted boys with criminal convictions had biological parents (especially fathers) with criminal convictions.

38
Q

Brennan & Mednick (1993) - adoption studies - role of genetics

A

Found that genetic influences were significant only in cases of property crime and not violent crime.

39
Q

Monoamine Oxidase A - role of genetics

A
  • The MAOA gene controls the production of the MAOA-A enzyme.
  • The MAO-A enzyme regulates the metabolism of monoamines (dopamine, noradrenaline and serotonin).
  • Low levels of serotonin are associated with high levels of aggression.
40
Q

MAOA-L - role of genetics

A
  • Genes can come in high or low variants.
  • The MAOA-L (low variant) result in low activity of the MAOA-A enzyme (MAO-A deficiency).
  • This gene has been linked to high levels of aggression.
41
Q

The warrior gene - role of aggression

A

MAOA has been dubbed the ‘warrior gene’ because the low activity variant (MAOA-L) is seen much more frequently in populations with a history of warfare, with 2/3s of these populations having low activity version.

42
Q

Lee & Chambers (2007) - role of genetics

A
  • Showed that the MAOA-L variant was possessed by 56% of New Zealand Māori men, compared to 34% Caucasians.
  • Māori people have a reputation for being warriors.
43
Q

Brunner et al (1983) - MAOA research - role of genetics

A
  • Studied a Dutch family in which 28 of the males behaved very aggressively and violently (e.g rape, attempted murder and assault).
  • These men were found to have abnormally low levels of MAO-A enzyme and the MAOA-L gene variant (sometimes referred to as Brunner Syndrome).
44
Q

Stuart et al (2014) - MAOA research - role of genetics

A

Found that of 97 men convicted of intimate partner violent (IPV), those with the MAOA-L variant gene were the most violent perpetrators, and this resulted in the worst injuries on their partners.

45
Q

Gene-environment interaction (GXE)

A
  • Genes do not appear to have a crucial role in aggression, but they do not function in isolation.
  • It appears the MAOA-L gene activity is only correlated with adult aggression when combined with traumatic life experiences.
  • This can also be explained using the diathesis-stress model.
46
Q

Caspi et al (2002) - GXE

A
  • Studied 500 male children.
  • They found those with the MAOA-L gene are more likely to grow up and behave antisocially, but only if they had also been mistreated as children.
  • Children with MAOA-H who were also maltreated, and those with MAOA-L who had not been maltreated did not display antisocial behaviour.
47
Q

What is ethology?

A

The study of animal behaviour in a natural setting.

48
Q

What is Lorenz’s definition of aggression? - ethology

A
  • Konrad Lorenz is the founder of ethology.
  • He defined aggression as ‘the fighting instinct in beasts and man that is directed against members of the same species’.
49
Q

What assumptions does Lorenz make that the study of aggression in animals is relevant to that in humans? - ethology

A
  • Aggression is an instinct. It occurs in all members of a species without the need for learning. It is innate, and mostly genetically determined.
  • We can study non-human animals and extrapolate to humans because we are all subject to the same levels of natural selection.
50
Q

What is meant by an adaptive behaviour? - ethology

A

Behaviour that enables a person to get along in his / her environment with greatest success and least conflict with others.
Ethological explanations suggest that the main function of aggression is adaptive.

51
Q

Give 2 reasons why aggression may be adaptive - ethology

A
  1. After an aggressive encounter, the ‘losing’ animal is rarely killed. Instead, the loser is forced into another area. This is adaptive because it spreads animals out over an area which reduces competition for resources.
  2. It allows for the formation of a dominance hierarchy. This is adaptive because to establish dominance brings benefits such as mating rights. Also, once the dominance hierarchy is established it reduces the incidences of aggression between individuals.
52
Q

What is a dominance hierarchy, and why might it be adaptive? - ethology

A

A dominance hierarchy is the organisation of individuals in a group that occurs when competition for resources leads to aggression.
The prevalence of this (all based on aggressive interactions, many ritualised) suggests that it must be adaptive.

53
Q

Dominance hierarchies in doves - ethology

A
  • Doves are non-hunters and so haven’t developed this inhibition but can simply fly away in a fight.
  • Lorenz feels humans are more like doves but can now develop weapons of mass destruction and don’t have instinctive inhibitions.
54
Q

What evidence is there of dominance hierarchies in humans? - ethology

A

Pettit et al (1988) studied play groups of young children and observed that aggressive interactions were an important aspect of how some children gain dominance over others.

55
Q

What is a ritual? - ethology

A

A series of behaviours carried out in a set order.

56
Q

What does ritualistic aggression typically comprise in humans? - ethology

A

Most aggressive interactions consist of ritualistic signalling (e.g snarling, displaying claws, pushing contests) and rarely becomes physical.

57
Q

What did Lorenz (1966) note about aggression in animals? - ethology

A

Lorenz (1966) observed that in fights between animals, actual injury is rare.
He suggested that intra-species (within species) aggressive confrontations end with a ritual appeasement display.

58
Q

What is an appeasement display, and what is their purpose? - ethology

A
  • Defeated animals show signs of appeasement, which indicates acceptance of defeat.
  • These are thought to indicate acceptance of defeat and his inhibit any further aggression from the victor (thus preventing actual injury).
  • Lorenz suggested that a wolf showing its jugular vein is an appeasement signal.
59
Q

Why are appeasement displays adaptive? - ethology

A

They are adaptive because if aggressive encounters ended with injury or death it could threaten the existence of the species.

60
Q

What was Schenkel (1967)’s opposing view to appeasement displays? - ethology

A

Argues again this view and suggests that this ‘submissive’ pose is actually a challenge that leads to further fighting.

61
Q

What is an innate releasing mechanism (IRM)? - ethology

A

An IRM is a biological structure or process (e.g in the brain) which is activated by an external stimulus that in turn triggers a fixed action pattern.

62
Q

What is a fixed action pattern (FAP)? - ethology

A

These are a sequence of stereotyped, pre-programmed behaviours triggered by an innate releasing mechanism.

63
Q

Example of an IRM / FAP in dogs - ethology

A
  • When a dog sees a cat running away from them, they have an instinctive response to chase the cat.
  • When the cat is still, the innate releasing mechanism is not activated.
  • When the cat runs, the IRM is activated and the chasing behaviour of the dog is an FAP.
  • The dog’s desire to chase the cat is automatic and instinctual in response to a cat or any other small animal running away from it.
64
Q

What are the 6 main features of FAPs according to Lea (1984)? - ethology

A
  • Stereotyped (unchanging sequence).
  • Universal within the species.
  • Unaffected by learning.
  • ‘Ballistic’ (once started they must continue).
  • Single purpose, only occurring in one type of situation.
  • A response to an identifiable and specific stimulus called a releaser (if intra-specific).
65
Q

How did Tinbergen (1951) demonstrate FAPs in male sticklebacks? - ethology

A
  • Male stickleback fish are very territorial in mating season. During this season, males develop a red underbelly.
  • If another male enters their territory, a FAP is released in response to the releaser / sign stimulus of the colour red.
  • Tinbergen presented sticklebacks with a series of wooden models of different shapes. He found that, regardless of the shape (even if the shape was not realistic of a fish), if there was a red spot the stickleback would attack it (no red sport = no attack).
  • The FAP always ran its course to completion without any other stimulus.
66
Q

What is the evolutionary explanation of aggression?

A

Explains aggression through natural selection: if genes give a survival advantage, then the individual is more likely to reproduce, passing on these genes to the next generation.

The central idea is that for aggression to be an adaptive feature, it has to serve a purpose.

67
Q

Environment of Evolutionary Adaptiveness (EEA) - evolution

A

Refers to a group of selection pressures occurring during an adaptation’s period of evolution responsible for producing the adaptation (Tooby & Cosmides, 1992).

68
Q

Survival of the fittest - evolution

A
  • Genes can mutate, and some mutators would increase these aggressive behaviours.
  • Increased reproductive success would lead to mutated genes that promote aggression being selected for, so people with these genes are more likely to have a large number of viable children passing on aggressive genes.
69
Q

How has aggressive behaviour been beneficial to our ancestors? - evolution

A

Aggressive behaviour can help survive predators, compete for resources and mates see an aggressive mate as being able to protect them and their offspring.

70
Q

Evolutionary explanation - cuckoldry

A
  • Cuckoldry (being the husband of a cheating wife) creates a threat of paternity uncertainty.
  • It is an evolutionary waste of resources to raise children who are not a male’s own as it is contributing to the survival of competitor’s genes.
71
Q

Anti-cuckoldry behaviours - evolution

A
  • Men in our evolutionary past who could avoid cuckoldry were more reproductively successful.
  • Psychological mechanisms have evolved to increase anti-cuckoldry behaviours in males.
  • This drives the often aggressive strategies men employ to retain their partners and prevent them from straying, which were once adaptive.
  • In the past, males could not be sure of paternity; sexual jealousy reflects the evolutionary attempt to avoid cuckoldry.
72
Q

Mate retention strategies (researchers) - evolution

A

Wilson & Daly (1996) identified several mate retention strategies which involve aggression and physical violence.

73
Q

Mate retention strategies - direct guarding - evolution

A

Male vigilance over a partner’s behaviour (e.g checking who they’ve been seeing, coming home early, keeping tabs on their whereabouts, tracking them).

74
Q

Mate retention strategies - negative inducements - evolution

A

Issuing threats of dire consequences (e.g threatening to kill themselves if a partner leaves).

75
Q

Wilson et al (1995) - evolution

A
  • Found women who reported mate retention strategies in their partners were twice as likely to have suffered physical violence at the hands of their partners.
  • Of these women, 73% required medical attention and 53% said they feared for their lives.
76
Q

Evolutionary explanation - bullying

A
  • Bullying is a power imbalance where a more powerful individual uses aggression against a weaker person.
  • Researchers have traditionally viewed bullying as a maladaptive behaviour as a result of poor social skills for example.
  • But the evolutionary explanation suggests that ancestors may have used bullying as an adaptive strategy to increase chances of survival by creating reproduction opportunities.
77
Q

Bullying - reproductive advantage - evolution

A
  • Volk (2012) - Characteristics associated with bullying behaviour are attractive to females as it suggests dominance, acquisition of resources and strength and can ward off potential rivals.
  • Bullying-associated characteristics therefore deliver access to more females and minimal threat from competing males which would be naturally selected because males can reproduce more.
78
Q

Bullying - health benefits - evolution

A

Sapolsky (2004) - Bullying may even benefit the bully’s health, due to less stress and being at the top of the hierarchy.