Neural & Hormonal Mechanisms in Aggression

Neural & Hormonal Mechanisms in Aggression

1. There are 2 neurotransmitters (Serotonin & Dopamine) that are linked to aggressive behaviour.

   • Serotonin
     • Low levels of Serotonin in the brain has been associated with an increase in aggression.
       • Serotonin usually reduces aggression by inhibiting the firing of the amygdala in response to external events.
     • A02:
       • (Popova et al) found research evidence to support the importance of serotonin in aggressive behaviour, from a study of non-animal humans.
         • They found that animals that have been selectively bred for reduced aggressiveness, appear to have higher serotonin levels.
           • Thus suggests that there is a link between low levels of serotonin and high levels of aggression.
             • However, these results may not apply to humans due to the differences between our brain structures and those of animals.
       • Further evidence comes from the use of "drugs" that raise serotonin levels in the brain.
         • (Bond) found that in clinical studies, "antidepressants" drug which tend to increase serotonin levels, tend to reduce aggressive behaviour.
   • Dopamine
     • Increases in dopamine can also produce increase in levels of aggression.
       • Research suggests that some individuals seek out aggressive encounters because of the rewarding sensations caused by the increases in dopamine.
         • A02:
           • Evidence for the role of dopamine in aggression is "inconclusive".
             • A study by (Couppis et al) found that dopamine may be a "consequence" of aggressive behaviour rather than a "cause".
               • Thus suggests that some people may seek out aggressive encounters because dopamine is released as a "positive reinforcer" whenever they engage in aggressive behaviour.

2. Testosterone

   • The male sex hormone testosterone is thought to influence aggression.
     • Research suggests that violent criminals who had higher levels of testosterone committed more violent crimes than those who had lower testosterone levels.
       • Cortisol
         • Low levels of Cortisol has also been linked to aggressive behaviour.
           • A02:
             • (McBurnett et al) supports the importance of cortisol on aggressive behaviour
               • They studied 4 year old boys with behavioural problems, and they found that those boy who had lower cortisol levels were 3 times more likely to be aggressive sooner than those boys who had high cortisol levels.
                 • Thus suggests a possible link between Cortisol & aggression.

3. IDA: Gender Bias

   • Most research into neural & hormonal aggression has been based on male participants.
     • Therefore, findings cannot be generalised to females.
       • The lack of research with women in this area highlights the limitation of such theories, as similar findings should also be evident in women.
         • However, very few comparison studies have been done, suggesting gender bias as well as gender differences, as women have been found to be less prone to violence.

4. IDA: Reductionist

   • The link between neurotransmitters, such as dopamine & Serotonin can be argued to be reductionist, as they ignore the role of cognitive & psychological factors.
     • Biological explanations are not enough on their own to explain aggressive behaviour.
       • For example, (Bandura) has shown that "Social Learning" can be a powerful influence on the aggressive behaviour of children.