3.1 Aggression Flashcards

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1
Q

What is aggression?

A

An act that is intended to harm another individual physically or psychologically

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1
Q

What is the limbic system?

A

Subcortical structures in the brain thought to be closely involved in regulating emotional behaviour e.g aggression

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2
Q

Name 3 components of the limbic system

A
  • Hypothalamus
  • Amygdala
  • Parts of the hippocampus
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3
Q

What is the link between the amygdala and aggression?

A

The reactivity of the amygdala in humans and mammals is a predictor of aggressive behaviour. The more responsive the amygdala, the more aggressive a person is

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4
Q

Describe Gospic et al (2011) study on the role of the amygdala

A
  • Participants subjected to mild provocation
  • When participants acted aggressively fMRI scans showed fast and heightened response by amygdala
  • A benzodiazepine drug, which reduces arousal of ANS taken before provocation
  • Led to a decreased activity of the amygdala
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5
Q

What are the neural mechanisms in aggression?

A
  • The limbic system
  • Orbitofrontal cortex and serotonin
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6
Q

What is serotonin?

A

A neurotransmitter that has widespread inhibitory effects in the brain

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7
Q

Describe the link between serotonin and aggression?

A
  • Normal serotonin levels linked with reduced firing of neurons which is associated with greater behavioural self control
  • Serotonin deficiency in the Orbitofrontal cortex, disrupts the mechanism and leads to impulsiveness (linked with aggression)
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8
Q

What is testosterone?

A

A hormone from the androgen group that is produced mainly in the male testes (associated with aggressiveness)

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9
Q

What is the link between testosterone and aggression?

A

Testosterone has a role in regulating social behaviour via its influence on certain areas of the brain implicated in aggression

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10
Q

What did Giammanco et al (2005) find about the role of testosterone?

A
  • Through castration studies on animals, showed that removing the testes reduces the aggression in the males of many species
  • Giving injections of testosterone to the same animals restores aggressive bahviour
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11
Q

What did Dolan et al (2001) find about the role of testosterone in aggression?

A

Found a positive correlation between testosterone levels and aggressive behaviours in a sample of 60 violent offenders

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12
Q

What did Ziomkiewicz et al (2012) find about the role of progesterone in aggression?

A

Found a negative correlation between progesterone levels and self-reported aggression (suggests low progesterone levels linked to increased aggression in women)

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13
Q

When are progesterone levels lowest (leading to increased aggression)

A

Levels of progesterone are lowest during and just after menstruation

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14
Q

What are the hormonal mechanisms in aggression?

A
  • Testosterone
  • Progesterone
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15
Q

AO3 of neural mechanisms in aggression

A

1. Other brain structures: recent evidence shows non-limbic structures also involved, limbic structures function with the orbitofrontal cortex which is not part of the limbic system, OFC involved in impulse regulation and inhibition of aggressive behaviour, Coccaro (2007) OFC activity reduced in psychiatric disorders that feature aggression causing aggressive behaviour, shows neural regulation of aggression more complex than theories suggest

2. Drugs and serotonin: drugs e.g paroxetine that increase serotonin also found to reduce levels of aggressive behaviour, Berman et al (2009) gave participants placebo or dose of paroxetine then engaged in lab-based game involving giving and receiving electric shocks in response to provocation, paroxetine group consistently gave fewer and less intense shocks than placebo, evidence of casual link between serotonin and aggression

16
Q

AO3 for hormonal mechanisms in aggression

A

1. Animal research: Giammanco et al (2005) research confirms the role of testosterone, in male rhesus macaque monkeys there is an increase in testosterone levels and aggressive behaviour during mating season, in rates castration of males reduces testosterone and also mouse killing behaviour, injecting female rats with testosterone increases mouse killing

2. Dual-hormone hypothesis: Carre and Mehta (2011) developed a dual hormone hypothesis which claimed that high levels of testosterone lead to aggression but only when cortisol levels are low (responds to chronic stress), when cortisol is high testosterones influence on aggression is blocked, combined activity of testosterone and cortisol may be better predictor of aggression

17
Q

What are the 4 genetic factors in aggression?

A
  • Twin studies
  • Adoption studies
  • The MAOA gene
  • Gene-environment interactions
18
Q

What Is the MAOA gene?

A

The gene responsible for activity of the enzyme monoamine oxidase (MAO-A) in the brain

19
Q

Describe Coccaro et al’s (1997) twin studies into aggression

A
  • Studied men who were either monozygotic or dizygotic twins
  • For aggressive behaviour defined as direct physical assault, researchers found concordance rates of 50% for MZ twins and 19% DZ twins
  • The corresponding figures for verbal aggression were 28% MZ and 7% DZ
20
Q

Why would there be a difference in aggression between monozygotic and dizygotic twins?

A
  • Monozygotic twins share 100% of their genes but dizygotic only share around 50%
  • It would be expected to find greater similarities in aggression between MZ twins if aggression influenced by genetic factors
  • This is because both MZ and DZ twins raised together in the same environment, but MZ twins have greater genetic similarity
21
Q

Why are adoption studies useful for aggression?

A

Similarities in aggressive behaviour between an adopted child and their adoptive parents suggest environmental influences are operating

22
Q

Describe Rhee and Waldman (2002) adoption studies on aggression

A
  • Carried out meta-analysis of adoption studies of direct aggression and antisocial behaviour
  • Found that genetic influences accounted for 41% the variance in aggression
23
Q

What is the role of the MAO-A enzyme?

A

Regulates the neurotransmitter serotonin

24
Q

What is the link between the MAOA gene and aggression?

A
  • The gene comes in different variants. The low activity variant (MAOA-L) results in low activity of the MAO-A enzyme (deficiency)
  • This MAOA-L variant has been linked to high levels of aggressive behaviour
25
Q

What did Lea and Chamers (2007) find on the influence of the MAOA gene in aggression

A

Found research showed MAOA-L variant possessed by 56% of New Zeland Maori men (compared to 34% caucasians)

26
Q

What did Brunner et al (1993) find about the link between MAOA-L and aggression?

A
  • Studied 28 men from large Dutch family who were repeatedly involved in impulsively aggressive/violent criminal behaviors e.g rape, attempted murder
  • The men had abnormally low levels of the MAO-A enzyme and MAOA-L gene variant
27
Q

What does gene-environment interactions suggest?

A

Suggests that genes do not function in isolation. MAOA-L gene activity only related to adult aggression when combined with early traumatic life experiences

28
Q

Describe Frazzetto et al’s (2007) study into gene-environment interactions

A
  • Found association between higher levels of antisocial aggression and the MAOA-L variant in men
  • This only the case in those who had experienced significant trauma e.g sexual/physical abuse during first 15 years of life
  • Those who had not experienced childhood trauma did not have particularly high levels of aggression as adults (even if possessing MAOA-L)
29
Q

AO3 for genetic factors in aggression

A
  1. Research support
  2. Complex link
  3. Problem with twin studies