1 - Neural + Hormonal Mechanisms In Aggression Flashcards
What are the 3 main neural + hormonal factors that must be learnt?
1) Limbic system
2) Serotonin
3) Testosterone
Define aggression
An act carried out with the intention to harm another person physically or psychologically
What is hostile aggression?
‘Affective aggression’ - driven by anger + emotion (e.g. murder)
What is instrumental aggression?
‘Pre-meditated aggression’ - calmer, more emotionally detached aggression (e.g. in sport)
What are the 2 neural factors related to aggression?
1) Limbic system
2) Serotonin
What is the limbic system?
A subcortical structure in the brain, thought to be involved with the regulation of primitive functions, including emotions + aggressive
List the components that make up the limbic system
- Cingulate gyrus
- Septal area
- Hypothalamus
- Fornix
- Amygdala
- Parts of hippocampus + thalamus
What is the main part of the limbic system we look at in relation to aggression?
Amygdala
Which 2 people linked the limbic system to emotional behaviours including aggression?
Papez + Maclean
What is the role of the amygdala?
Responds to threats + challenges in the environment
How does the limbic system impact aggression?
The more reactive the amygdala (part of the limbic system), the more aggressive a person is
Name + outline the research done to support the role of the limbic system (amygdala) in aggression?
Gospic et al
- Ultimatum Game
- Ppts’ brain activity scanned using an fMRI
- fMRI showed a fast, heightened reaction in the amygdala when ppts given an unfair offer (provoked) + respond aggressively by rejecting it
- When given benzodiazepine drugs (reduce amygdala activity) rate of rejection dropped (less aggressive)
- Supports role of amygdala in aggression
What is serotonin?
A neurotransmitter with widespread inhibitory effects throughout the brain
What does it mean for a neurotransmitter to have ‘inhibitory effects’?
Neurones fire less
How do normal serotonin levels lead to behavioural self-control?
Normal serotonin levels -> Inhibitory effects in the orbitofrontal cortex -> Good self-control
How does serotonin impact aggression?
Low levels of serotonin lead to more aggressive + impulsive behaviour
How does low serotonin lead to more aggression?
Decreased serotonin disrupts the inhibitory effects in the orbitofrontal cortex -> less behavioural self-control -> more aggressive, impulsive behaviour
Name + outline the research done to support the role of serotonin in aggression?
Berman et al
- Lab study
- Group 1: given SSRI paroxetine (higher serotonin)
- Group 2: given placebo (lower serotonin)
- Groups provoked + able to shock each other
- Group 1 gave fewer, less intense shocks (high serotonin - less aggressive)
Give 3 evaluation points for the role of neural mechanisms in aggression
GOOD
Drugs (SSRIs) support
- Berman’s research using SSRIs supports role of serotonin
- Using SSRIs has a practical application as a cheap + effective treatment for high aggression
BAD
Other brain structures may also be important
- Limbic system isn’t only important brain structure
- Orbitofrontal cortex is also involved in impulse regulation + inhibiting aggression
- Coccaro et al found less activity here led to greater aggression
- So, the neural explanation may be too simplistic currently
Deterministic
- Suggests aggression is pre-determined by neural factors
- Pessimistic view + acts as an alibi for aggressive crimes (negative implications for the legal system)
What is the main hormonal factor we learn in relation to aggression?
Testosterone
What is the extra hormonal factor that we learn in relation to aggression?
Progesterone
What is testosterone?
A hormone from the androgen group produced 10-40x more in men (in testes) than in women (in ovaries)
How does testosterone impact aggression?
High testosterone leads to high aggression
Name + outline the human research done to support the role of testosterone in aggression?
Dolan et al
- Correlational study
- Looked at 60 male offenders + their testosterone levels
- Found positive correlation between testosterone + aggression
Name + outline the animal research done to support the role of testosterone in aggression?
Wagner
- Lab
- Castrated mice (stopping testosterone production)
- Castrated mice were less aggressive (less biting)
- If testosterone was re-injected, aggression (biting) increased, showing cause + effect of the impact of testosterone on aggression
What is progesterone?
Female ovarian hormone
When is progesterone lowest?
During + just after menstruation
How does progesterone impact aggression?
Low levels of progesterone lead to high aggression
Does testosterone vary throughout the month?
No - some men just have higher testosterone
Does progesterone vary throughout the month?
Yes - varies in relation to the menstrual cycle
Name + outline the research done to support the role of progesterone in aggression?
Ziomkiewicz et al
- Self report data on levels of aggression across menstrual cycle
- Found negative correlation between levels of progesterone + aggressive behaviour
Give 3 evaluation points for the hormonal mechanisms in aggression
GOOD
Animal research support
- Research support from multiple animal studies on role of hormones
- E.g. Wagner (mice - testosterone) + Giammanco (meta analysis)
- BUT: Issues - may be unethical (no consent + potentially harmful)
BAD
Alternative theory
- Dual hormone hypothesis
- Carre + Mehta said high testosterone only leads to aggression if cortisol levels are simultaneously low (because cortisol can block testosterone’s influence on aggression)
- Testosterone’s current role may be too simplistic, as cortisol must also be considered
Deterministic
- Suggests aggression is pre-determine by hormonal factors
- Pessimistic view + acts as an alibi for aggressive crimes (negative implications for the legal system)
What is the dual hormone theory?
Idea that high testosterone only causes aggression if cortisol levels are low - because high cortisol has a blocking effect on testosterone
What impact does cortisol have on testosterone?
A ‘blocking effect’ (blocking its ability to increase aggression)
