The document discusses neural and hormonal factors that influence aggression. Testosterone is the main hormone associated with aggression, though its effects are complex and depend on social and cultural factors. Low levels of the neurotransmitter serotonin have also been linked to increased aggression. While testosterone and serotonin seem to play a role, establishing clear causal relationships is difficult given individual differences and the interaction of biological and environmental influences on behavior.

1. The Role of Neural and
Hormonal Factors in Aggression

2. Hormonal Factors
What is the main hormone associated with aggression?
Testosterone
AO1 Hormonal Factors
The ‘Basal model
•Testosterone – androgen (produced by Leydig cells of testosterone’
in the make testes and adrenal cortex). suggests that the
hormone causes a
•Release hormone follows a natural circadian rhythm. change in a
person’s
•Levels of hormones reach a peak in young males and dominance.
typically will gradually decline. Therefore, it
follows that a
•Relationship between aggression and testosterone man with high
is not a simple biological ‘cause and effect’ levels of
mechanism. testosterone will
engage in anti-
•Presence of testosterone simply increases the social behaviour
chances of aggressive behaviour. such as fighting.

3. Evaluating Hormonal Factors
AO2 Dabbs et al (1987) measured salivary testosterone in violent
and non-violent crimes. Those with high levels of testosterone
had a history of committing violent crimes, whereas those with
lower levels had a history of non-violent crimes.
This supports the role of increased testosterone being
related to aggression.
Deterministic
Socially Sensitive
Research

4. Evaluating Hormonal Factors
AO2
An alternative approach...socialisiation. Parents
can encourage specific behaviours in their children.
IDEA’s – Cultural Differences
Difficulty separating nature and
nurture influences further
illustrated in Aronson’s (1992)
research on non-violent societies
such as the Pygmies, Central Africa.

5. Evaluating Hormonal Factors
AO2
Inconclusive Evidence:
Harrison et al (2000) gave testosterone to 56 men (20-50 years
old), when given a frustration-inducing computer game, aggressive
responses were significantly increased.
But this effect was not the same for the entire sample. If
anything the changes were largely psychological and few had any
noticeable physical effects on behaviour
This suggests that there are large individual differences in the
effects of testosterone on a person’s level of aggression. Rather
we should view testosterone as one factor affecting aggression
IDEA’s? AO3?

6. Neural Factors
Neurotransmitters are chemicals that enable impulses to be transmitted
from one area of the brain to another.
AO1
Low Levels of Serotonin
•Reduces aggression by inhibiting responses to emotional stimuli that
might otherwise lead to an aggressive response.
•Low levels of serotonin have been associated with increased
susceptibility to impulsive behaviour, aggression and even violent
suicide.
•Some recreational drugs are thought to alter serotonin levels and thus
increase aggressive behaviour.
•Studies of pets that have been bread for low levels of aggression
seem to have higher levels of serotonin.

7. AO2
Evaluating Neural Factors
Evidence from non-human animal
Mann et al (1990) gave 35 healthy
studies
adults dexfenfluramine, which is
Raleigh at al (1991) have added
known to deplete levels of
support for the role of serotonin
serotonin. Using a questionnaire to
in aggression through carrying out
assess hostility and aggression
research on vervet monkeys. They
levels, they found that
found that individuals fed on a
dexfenfluramine treatment in males
diet high in trytophan (increases
(but not females) was associated
serotonin levels in the brain)
with an increase in hostility and
exhibited decreased levels of
aggression scores.
aggression.
IDEA’s? AO3?

8. Neural Factors
Neurotransmitters are chemicals that enable impulses to be transmitted
from one area of the brain to another.
AO1 High Levels of Dopamine
•There is some evidence to suggest that a link between high
levels of dopamine and aggression exist (although this link is not
as well established as the link between serotonin and
aggression).
•Increases in dopamine activity through the use of
amphetamines have also been associated with increases in
aggressive behaviour.
•Buitelaar (2003) suggested that antipsychotics which reduce
dopamine activity in the brain have been shown to reduce
aggressive behaviour.

9. AO2
Evaluating Neural Factors
AO3? Problems establishing cause and effect
•Recent research has suggested that
elevated levels of dopamine maybe a
consequence of aggressive behaviour.
•Dopamine is involved with feelings of
rewards
IDEA’s?
Reductionist....