Biological Explanations

Biological Explanations

1. Neural Mechanisms

   • Serotonin: low levels associated with increased susceptibility to impulsive behaviour and aggression; serotonin prevents the stimulation of the amygdala, so low levels will allow it to be more active
     • Mann et al (1990) gave 35 healthy participants dexfenfluramine, which is known to deplete serotonin. Using a questionnaire to assess hostility and aggression levels found that dexfenfluramine treatment in males (but not females) associated with increase in hostility and aggression scores.
       • May be gender bias; although a link between low levels of serotonin and aggression found, this was not evident for female participants
         • Suggests role of serotonin in aggression may be different for females compared to males, therefore gender bias in human studies in this area.
     • Popova et al (1991) found that among dogs that have been selectively bred for domestication and for increasingly docile temperament; there has been corresponding increase over generations of brain serotonin.
       • Suggests link between low levels of serotonin and high levels of aggression.
         • However may not apply to humans due to differences in brain structure.
   • Dopamine: high levels associated with increased aggression; e.g. increased rates of aggressive behaviour found in the schizophrenic population believed to be due to raised levels of dopamine
     • Role of dopamine demonstrated in studies that use amphetamines.
       • Lavine (1997) found increases in dopamine via amphetamines have been associated with increases in aggressive behaviour.
     • Antipsychotics, which reduce dopamine activity in the brain have been shown to reduce aggressive behaviour in violent delinquents. (Buitelaar, 2003)
     • Evidence for the casual role of dopamine in aggression is inconclusive.
       • Couppis and Kennedy (2008) found that dopamine may be a consequence of aggressive behaviour.
         • They suggest that people may seek out aggressive encounters because dopamine is released as a positive reinforcer whenever they engage in aggressive behaviour.

2. Reductionist: the links between biological mechanisms and aggression can be described as reductionist.

   • The complexity of human behaviour means that the biological explanation for human aggression is insufficient on its own to explain the many different aspects of aggressive and violent behaviour.