Wednesday, 16 September 2015

Biological Causes of Aggression

Neurotransmitters

Dopamine

High levels of dopamine are linked to high levels of aggression. Dopamine is often released in response to rewarding stimuli such as food, sex and recreational drugs. 

Studies
• Couppis et al (2008)
• Couppis & Kennedy (2008)
• Ferrari (2003) 

Evaluation
- Use of animals
- Nature/Nurture
- Free will/Determinism

Serotonin 

Low serotonin can result in impulsive behaviour, aggression, overeating, depression, alcohol abuse and violent suicide. e.g. Silver foxes tamed by humans for more than 30 years - found high levels of serotonin. 

Studies
• Linnolia & Virkkunen (1992) 
• Cleare & Band (1997) 
• Summers et al (2005)
• Davidson (2000)

Evaluation
- Nature/Nurture
- Free will/determinism
- Ethics



Brain Structure 

Amygdala:  Direct stimulation of an area of the amygdala in can make people more aggressive. It is more active during 'red alert' - when an animal attacks another. People are also armed to be more aggressive for 5-20 minutes after being provoked. Research: Protegal (1996).
Charles Whitman.

Hypothalamus: The hypothalamus has been shown to cause aggressive behaviour when electrically stimulated, but more importantly, has receptors that help determine aggression levels based on their interactions with serotonin. Research: Siegel & Pott (1988).

Cortex: The cortex seems to inhibit emotion and aggression. Research: Bard (1930s).




Hormonal Mechanisms

Testosterone: The male sex hormone testosterone is thought to influence aggression from young adulthood. Males produce testosterone in the testes and women also produce testosterone but in smaller amounts. Testosterone is an androgen hormone and peaks in males between 15 and 25. 
Research: Dabbs et al (1987); Lindman (1987); The Challenge Hypothesis

Cortisol: Cortisol is produced by the adrenal medulla and is an important part of the body's response to stress. Lower cortisol levels are related to higher levels of aggression. 
Research: Van Goozen et al (2007); Virkkunen (1985); Tennes and Kreve (1985)








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