Aggression
3.3.8 Aggression
● Neural and hormonal mechanisms in aggression, including the roles of the limbic system,
serotonin and testosterone. Genetic factors in aggression, including the MAOA gene.
● The ethological explanation of aggression, including reference to innate releasing mechanisms
and fixed action patterns. Evolutionary explanations of human aggression.
● Social psychological explanations of human aggression, including the frustration-aggression
hypothesis, social learning theory as applied to human aggression, and deindividuation.
● Institutional aggression in the context of prisons: dispositional and situational explanations.
● Media influences on aggression, including the effects of computer games. The role of
desensitisation, disinhibition and cognitive priming.
.
,Neural factors in aggression (Limbic system and aggression)
The limbic system is a circuit of structures involved in regulating motivated behaviours such as
feeling, fighting, and sexual behaviour. This includes the amygdala and hippocampus which is
associated with aggression.
The amygdala is responsible for evaluating the emotional importance of sensory information and
helps to coordinate an appropriate response. When the amygdala is electrically stimulated, it causes
an animal to respond with aggression e.g. snarling. Surgically removing the amygdala causes the
animal to not respond to the stimuli.
Amygdalectomy (removal of amygdala) also reduces aggression in humans.
The hippocampus is involved in the formation of long term memories and allows an animal to
compare a current threat with past experiences. For example if someone has hurt you in the past
you’re likely to respond with aggression or fear.
Impaired hippocampal functioning prevents the brain from putting things into a meaningful context, so
the amygdala might respond inappropriately to sensory stimuli, resulting in aggressive behaviour.
Serotonin is a neurotransmitter thought to inhibit aggressive responses to emotional stimuli. It typically
inhibits the firing of neurons in the amygdala. Low levels of serotonin removes this inhibitory effect
and are associated with increased influence to impulsive, aggressive, and violent behaviour.
Therefore, the amygdala becomes more active to external stimuli and increases the likelihood of
aggression.
The frontal cortex also moderates how we express aggression. Low levels of serotonin activity in the
prefrontal cortex has also been linked to reduced self control.
+ Support for serotonin using animals studies
Raleigh et al fed monkeys a diet that's high in tryptophan (which increases serotonin levels in the
brain). These monkeys showed a decrease in aggressive behaviours. When monkey’s had a diet low
in tryptophan, they were more aggressive. This suggests aggression in animals can be partly caused
by serotonin levels in the brain.
- Deterministic and reductionist
Biological explanations that say limbic system abnormality or an imbalance in biochemistry causes
aggression can be deterministic because it removes the element of free will and choice over our
behaviour. We can’t control our biology which means we can’t control our behaviour. This can then
take away personal responsibility for people’s antisocial acts, which then has implications in the
justice system.
+ Support from scans
Raine et al used PET scans to scan the brains of 41 murderers and 41 controls (non violent people).
They found that those who were murderers showed deficits in their limbic system functioning. This
supports the idea that the amygdala and hippocampus can affect aggression. However, research
linking the limbic system and aggression is often correlational, so we can't establish causation.
, Hormonal factors in aggression (Testosterone)
Testosterone is an androgen which means it’s a male hormone that produces male characteristics. It’s
thought to act on areas of the brain which control aggression from young adulthood onwards.
Levels peak in young males and then decline. When testosterone levels peak around the start of
puberty, there is a peak in aggression levels in boys suggesting a correlational link
There is a link between testosterone levels and aggression, in that men are generally more
aggressive than women. This is because men have higher levels of testosterone in comparison to
women. Young men are also more aggressive than older men.
Castration studies of animals show that removing the testes reduces aggression in the males of many
species and giving injection of testosterone to the same animal restores aggressive behaviour
(Giammanco et al).
- Deterministic and reductionist
Biological explanations that say testosterone causes aggression can be deterministic because it
removes the element of free will and choice over our behaviour. We can’t control our biology which
means we can’t control our behaviour. This can then take away personal responsibility for people’s
antisocial acts, which then has implications in the justice system.
+ Research support from prison studies
Dolan et al found a positive correlation between testosterone levels and aggression behaviours in a
sample of 60 male offenders in UK maximum security hospitals. These men mostly had personality
disorders (psychopathy) and a history of impulsively violent behaviour. This shows there is a clear
link, and so testosterone could influence aggression behaviours. Although this is correlation, we can’t
establish cause and effect.
- Gender bias
Such studies into how hormones such as testosterone affect aggression also suffer from gender bias
as they have focused mostly on men and not how women may be affected. Research into this has
produced mixed results with some suggesting the association between testosterone and aggression
is higher for female than male samples (Archer et al). Further studies have shown higher
testosterone in women is displayed through higher occupational status possibly due to them being
more assertive (Baucom et al). Therefore, research shows bias and is not consistent for both
genders. This can lead to socially sensitive issues such as the general statement that all men are
aggressive due to testosterone.
3.3.8 Aggression
● Neural and hormonal mechanisms in aggression, including the roles of the limbic system,
serotonin and testosterone. Genetic factors in aggression, including the MAOA gene.
● The ethological explanation of aggression, including reference to innate releasing mechanisms
and fixed action patterns. Evolutionary explanations of human aggression.
● Social psychological explanations of human aggression, including the frustration-aggression
hypothesis, social learning theory as applied to human aggression, and deindividuation.
● Institutional aggression in the context of prisons: dispositional and situational explanations.
● Media influences on aggression, including the effects of computer games. The role of
desensitisation, disinhibition and cognitive priming.
.
,Neural factors in aggression (Limbic system and aggression)
The limbic system is a circuit of structures involved in regulating motivated behaviours such as
feeling, fighting, and sexual behaviour. This includes the amygdala and hippocampus which is
associated with aggression.
The amygdala is responsible for evaluating the emotional importance of sensory information and
helps to coordinate an appropriate response. When the amygdala is electrically stimulated, it causes
an animal to respond with aggression e.g. snarling. Surgically removing the amygdala causes the
animal to not respond to the stimuli.
Amygdalectomy (removal of amygdala) also reduces aggression in humans.
The hippocampus is involved in the formation of long term memories and allows an animal to
compare a current threat with past experiences. For example if someone has hurt you in the past
you’re likely to respond with aggression or fear.
Impaired hippocampal functioning prevents the brain from putting things into a meaningful context, so
the amygdala might respond inappropriately to sensory stimuli, resulting in aggressive behaviour.
Serotonin is a neurotransmitter thought to inhibit aggressive responses to emotional stimuli. It typically
inhibits the firing of neurons in the amygdala. Low levels of serotonin removes this inhibitory effect
and are associated with increased influence to impulsive, aggressive, and violent behaviour.
Therefore, the amygdala becomes more active to external stimuli and increases the likelihood of
aggression.
The frontal cortex also moderates how we express aggression. Low levels of serotonin activity in the
prefrontal cortex has also been linked to reduced self control.
+ Support for serotonin using animals studies
Raleigh et al fed monkeys a diet that's high in tryptophan (which increases serotonin levels in the
brain). These monkeys showed a decrease in aggressive behaviours. When monkey’s had a diet low
in tryptophan, they were more aggressive. This suggests aggression in animals can be partly caused
by serotonin levels in the brain.
- Deterministic and reductionist
Biological explanations that say limbic system abnormality or an imbalance in biochemistry causes
aggression can be deterministic because it removes the element of free will and choice over our
behaviour. We can’t control our biology which means we can’t control our behaviour. This can then
take away personal responsibility for people’s antisocial acts, which then has implications in the
justice system.
+ Support from scans
Raine et al used PET scans to scan the brains of 41 murderers and 41 controls (non violent people).
They found that those who were murderers showed deficits in their limbic system functioning. This
supports the idea that the amygdala and hippocampus can affect aggression. However, research
linking the limbic system and aggression is often correlational, so we can't establish causation.
, Hormonal factors in aggression (Testosterone)
Testosterone is an androgen which means it’s a male hormone that produces male characteristics. It’s
thought to act on areas of the brain which control aggression from young adulthood onwards.
Levels peak in young males and then decline. When testosterone levels peak around the start of
puberty, there is a peak in aggression levels in boys suggesting a correlational link
There is a link between testosterone levels and aggression, in that men are generally more
aggressive than women. This is because men have higher levels of testosterone in comparison to
women. Young men are also more aggressive than older men.
Castration studies of animals show that removing the testes reduces aggression in the males of many
species and giving injection of testosterone to the same animal restores aggressive behaviour
(Giammanco et al).
- Deterministic and reductionist
Biological explanations that say testosterone causes aggression can be deterministic because it
removes the element of free will and choice over our behaviour. We can’t control our biology which
means we can’t control our behaviour. This can then take away personal responsibility for people’s
antisocial acts, which then has implications in the justice system.
+ Research support from prison studies
Dolan et al found a positive correlation between testosterone levels and aggression behaviours in a
sample of 60 male offenders in UK maximum security hospitals. These men mostly had personality
disorders (psychopathy) and a history of impulsively violent behaviour. This shows there is a clear
link, and so testosterone could influence aggression behaviours. Although this is correlation, we can’t
establish cause and effect.
- Gender bias
Such studies into how hormones such as testosterone affect aggression also suffer from gender bias
as they have focused mostly on men and not how women may be affected. Research into this has
produced mixed results with some suggesting the association between testosterone and aggression
is higher for female than male samples (Archer et al). Further studies have shown higher
testosterone in women is displayed through higher occupational status possibly due to them being
more assertive (Baucom et al). Therefore, research shows bias and is not consistent for both
genders. This can lead to socially sensitive issues such as the general statement that all men are
aggressive due to testosterone.
