A03

• What are the strengths of neural mechanisms?

  1. Effects of drugs on serotonin
  2. Animal evidence for influence of serotonin
• What are the limitations of neural mechanisms?

  1. Role of other brain structures
• Strength (neural) = effects of drugs on serotonin

  • Research has found that drugs which increase serotonin activity reduce levels of aggressive behaviour
  • Berman et al. (2009) gave 80 male and female participants either a placebo or 40mg of paroxetine (an SSRI)
  • Aggression was assessed during a competitive reaction time game
  • They found that the drugged participants‘ aggressive responding after provocation was reduced when compared with the placebo condition
• Strength (neural) = animal evidence for influence of serotonin

  • Raleigh et al. (1991) used vervet monkeys that fed on experimental diets high in tryptophan, which increases serotonin levels in the brain
  • This diet change resulted in decreased levels of aggression, compared with monkeys that fed on diets low in tryptophan, who showed increased aggression and dominance
• Limitation (neural) = role of other brain structures

  • Studies have revealed that the amygdala does not operate in isolation in determining aggression
  • It functions in tandem with the OFC, which is a nonlimbic brain structure
  • Coccaro et al. (2007) found that patients with psychiatric disorders which feature aggressive behaviours had reduced OFC activity
  • This reduction disrupts the OFC’s impulsive-control function, leading to increased aggression
  • Additionally , Gospic et al. (2011) also supports this
• What are the strengths of hormonal mechanisms?

  1. Supporting evidence
• What are the limitations of hormonal mechanisms?

  1. Other hormones involved
• Strength (hormonal) = supporting evidence

  • Research conducted by Dolan et al. (2001) and Dabbs et al. (1987) provide significant evidence for the role testosterone plays in aggression responses
  • Dolan et al. (2001) found a positive correlation between testosterone levels and aggressive behaviour in a sample of 60 offenders in the UK
  • Dabbs et al. (1987) measured salivary testosterone in violent and non-violent criminals and found those with the highest levels had a history of primarily violent crimes
• Limitation (hormonal) = other hormones involved

  • Mehta and Josephs (2010) proposed a dual-hormone hypothesis whereby testosterone is positively associated with status-seeking tendencies such as aggression and dominance, particularly in individuals with low levels of cortisol
  • Popma et al. (2007) studied aggression and criminal violence in male delinquent adolescents and found basal testosterone correlated positively with aggression and violence amongst low-cortisol individuals but not among high-cortisol individuals