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Discuss the role of neural and hormonal mechanisms in aggression. (24 marks)
Testosterone is a hormone produced in the male testes and in female ovaries however males
produce 10 times more than females. Testosterone has been linked to aggression and as it plays a
part in increased muscle and bone mass, this suggests that it plays a structural role in influencing
Testosterone has been shown to correlate with the level of aggression displayed by humans and
animals. For example when levels of testosterone peak around the start of puberty there is also a
corresponding level of aggression displayed in young males during this time.
Testosterone modulates levels of various neurotransmitters that mediate effects on aggression.
There seems to be a critical period early in life, where exposure to testosterone is essential to elicit
aggression in adulthood. It is though testosterone helps sensitise androgen responsive system.
There have been many experiments done to see the effects of adding and removing testosterone.
All of which have been performed on animals due to methodological and ethical issues with testing
on humans. It was found that male mice that are castrated at birth showed a decreased level of
aggression. These findings were also supported by similar studies involving different species fo
animals and so it is not solely specific to mice. Although castration research can be useful, castration
disrupts other hormone systems as well as testosterone and os these may be playing a part in the
However as these findings come from animal studies, we cannot apply it to humans and so we cannot
learn much about human behaviour from this specific experiment. This is because humans have a
more complex physiology, for example, and so may respond quite differently. Instead, we have to
do a cost-benefit analysis, in that is the potential harm done to the animals worth the benefit to
humans of increased knowledge. We cannot rely solely on findings from these studies or other
similar research, but at the very least we need to verify these animals' findings with findings from
human studies. Also, another problem with using animals to research testosterone affects is that
certain brain structures are involved with different types of aggression in different species. For
example, cingulated gyrus is linked to fear-induced aggression in monkeys, but to irritability in cats
and dogs, creating problems in trying to generalise in humans and to identify aggression.
Research on humans has however, provided support for this theory. Dabbs measured salivary
testosterone in violent and non-violent criminals and found that those with the highest levels of
testosterone tended to have committed the most violent crimes. Likewise, Lindman found young
males who behaved aggressively whilst drunk had higher testosterone levels than those who did not
A disadvantage of the theory of hormonal mechanisms as an explanation of aggression is that as all
the research is Correlational, we cannot prove causality. Also, studies have failed to identify whether
aggression was caused by testosterone or whether testosterone was secreted due to increased
Also there are inconsistent findings which is a disadvantage of this explanation. Book carried out a
meta-analysis of 45 studies and established a mean correlation of 0.14 between testosterone and
aggression. It could be argued that although a positive correlation was found, it was extremely weak
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and so we cannot draw any conclusions from it. Likewise, a meta-analysis by Archer also found low
positive correlation between the two variables. However, the type of participant and the form and
measurement of aggression differed substantially between studies and so may not be completely
valid. Archer also criticised Book's meta-analysis, claiming that methodological problems in the study
meant that a correlation of only 0.08 was more appropriate which is barely a correlation.
Mazur also suggested distinguishing aggression from dominance.…read more
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increased serotonin levels, the monkeys displayed reduced aggression. It is hard to generalise these
findings to humans however, as many animals do not have the same capacity for cognitive processing
and self-awareness and animal behaviour tends to rely more on biological factors.
Both neural and hormonal mechanisms in aggression are the biological approach and so both are