Biological Explanation

• What is aggression?

  An act carried out with the intention to harm another person physically or psychologically
• What is Proactive Aggression?

  • Cold Blooded
  • Planned method
• What is Reactive Aggression?

  • Hot Blooded
  • Angry and impulsive accompanied by psychological arousal
• What is the Limbic System?

  • Subcortical structures in the brain (Hypothalamus and Amygdala) thought to be closely involved with regulating emotional behaviour including aggression
  • Plays a key role in assessing and responding to environmental threats and challenges
• What is the Amygdala?

  • Responsible for attaching emotional significance to sensory information
  • Responsible for how we respond to threats and challenges
  • How reactive it is can be a predictor of aggressive behaviour
• Key Study: Gospic et al

  • Ps had brain activity scanned using and fMRI whilst playing the ultimatum game
  • When responders were given an unfair offer there was a fast and heightened reaction in the amygdala and offer was rejected
  • Can be seen as an aggressive act towards a social provocation
  • Also found that when Ps were given benzodiazepine (which reduces amygdala activity) rate of rejection dropped
• What is the role of the Hippocampus?

  • Formation of LTM
  • Allows individuals to compare current threat conditions with past experiences
  • If a person is attacked next time they are likely to respond with aggression
• What is the role of the Hypothalamus?

  • Responsible for the regulation of the autonomic nervous system (regulates responses to emotional circumstances)
  • Damage to or ANS not working = inappropriate response to perceived threats
• What is the role of Serotonin?

  • It is a hormone with an inhibitory effect
  • Makes neurons less likely to fire
  • reduced serotonin activity is related to reduced self control / disinhibition
  • Normal levels of serotonin inhibit activity in the orbitofrontal cortex
  • If levels are too low then this part of the brain becomes overreactive -> results in a loss of control and more impulsive behaviours including aggression
• Evidence support for the role of Serotonin - Virkkunen et al

  • Compared levels of serotonin breakdown product in the cerebrospinal fluid of violent impulsive and violent non-impulsive offender
  • Levels were significantly lower in impulsive offenders
  • They also suffered more sleep irregularities
  • This disturbance in sleep pattern strongly implies some disruption of serotonin functioning
• Evidence support for the role of Serotonin - Bearman et al

  • Lab experiment, Ps were given the choice to give electric shocks to each other in response to provocation
  • Experiment had an independent groups design - half the Ps were given paroxetine (SSRI) and half were given a placebo
  • The paroxetine group consistently gave fewer and less intense shocks than the placebo group