2612611
Neural + hormonal mechanisms in aggression
- Neurotransmitters - Serotonin
- A01
- Thought to reduce aggression by inhibiting responses to emotional stimuli
that might otherwise lead to aggressive response
- Low levels in brain have been associated w/ increased susceptibility to impulsive behaviour, aggression + even violent suicide
- Some drugs thought to alter S levels + thus increase aggressive behaviour
- Some drugs thought to alter S levels + thus increase aggressive behaviour
- Low levels in brain have been associated w/ increased susceptibility to impulsive behaviour, aggression + even violent suicide
- Thought to reduce aggression by inhibiting responses to emotional stimuli
that might otherwise lead to aggressive response
- A02
- Evidence from non-human studies
- Raleigh et al
- Study of vervet monkeys
- Found indivi. fed on experimental diets high in tryptophan
exhibited decreased levels of aggression
- Indivi. fed on diets that were low in tryptophan exhibited increased aggressive
behaviour, suggesting differences in aggression could be attributed to S levels
- Indivi. fed on diets that were low in tryptophan exhibited increased aggressive
behaviour, suggesting differences in aggression could be attributed to S levels
- Study of vervet monkeys
- Raleigh et al
- Evidence from antidepressants
- If low levels are associated w/ low impulse control + aggressive behaviour, drugs
clinically raising S levels should produce concurrent lowering in aggression
- Bond
- Established this is exactly what happens in clinical studies of
antidepressant drugs that elevate S levels
- Established such drugs do tend to reduce irritability +
impulsive aggression
- Established such drugs do tend to reduce irritability +
impulsive aggression
- Established this is exactly what happens in clinical studies of
antidepressant drugs that elevate S levels
- Bond
- If low levels are associated w/ low impulse control + aggressive behaviour, drugs
clinically raising S levels should produce concurrent lowering in aggression
- Evidence from non-human studies
- A01
- Hormonal mechanisms - Testosterone
- A01
- M sex hormone T thought to influence aggression from young adulthood
onwards due to its action on brain areas involved in controlling aggression
- Evidence for this association comes from no. of sources
- Evidence for this association comes from no. of sources
- Challenge hypothesis - Wingfield et al
- In monogamous species, T levels should only rise above baseline breeding level in
response to social challenges
- M-M aggression or threats to status
- M-M aggression or threats to status
- Human species is considered to be monogamous, would predict M T
levels would rise sharply in response to such challenges
- T surge is to be expected, w/ consequent increase in aggression,
provided threat is deemed relevant to reproductive competition
- T surge is to be expected, w/ consequent increase in aggression,
provided threat is deemed relevant to reproductive competition
- In monogamous species, T levels should only rise above baseline breeding level in
response to social challenges
- M sex hormone T thought to influence aggression from young adulthood
onwards due to its action on brain areas involved in controlling aggression
- A02
- Inconsistent evidence
- Albert et al
- Claim despite many studies showing +ve correlation between T +
aggression, other studies find no such relationship, particularly those
which compared T levels of aggressive + less aggressive indivi.
- Most studies showing +ve correlation have involved small samples
of men within prisons, using either self-report measures or
judgements based solely on severity of crime committed
- Most studies showing +ve correlation have involved small samples
of men within prisons, using either self-report measures or
judgements based solely on severity of crime committed
- Claim despite many studies showing +ve correlation between T +
aggression, other studies find no such relationship, particularly those
which compared T levels of aggressive + less aggressive indivi.
- Albert et al
- IDA - Real-world application
- Statistics suggest sharp increase in gun-related crime in UK, why does
presence of guns in environment lead to increased aggression?
- Perhaps presence of stimulus triggers increases in T levels, which in turn increases
aggressive behaviour - chain of events which would be predicted by challenge hypothesis
- Klinesmith et al
- Had M college students provide saliva sample, interact either
w/ a gun or child's toy for 15 mins + provide another sample
- M who interacted w/ gun showed significantly greater
increases in T + behaved more aggressively toward another
ppt compared to those who played w/ child's toy
- M who interacted w/ gun showed significantly greater
increases in T + behaved more aggressively toward another
ppt compared to those who played w/ child's toy
- Had M college students provide saliva sample, interact either
w/ a gun or child's toy for 15 mins + provide another sample
- Klinesmith et al
- Perhaps presence of stimulus triggers increases in T levels, which in turn increases
aggressive behaviour - chain of events which would be predicted by challenge hypothesis
- Statistics suggest sharp increase in gun-related crime in UK, why does
presence of guns in environment lead to increased aggression?
- IDA - Gender bias
- Most studies concerned w/ T + aggression have involved
M ppts, but does T also increase aggression in F?
- Research suggests association between T + aggression is
higher for F than M samples
- Eisenegger et al
- Found T could make women act 'nicer' rather than more aggressively, depending on situation
- Lends support to idea that, rather than directly increasing aggression, T promotes
status-seeking behaviour of which aggression is one type
- Lends support to idea that, rather than directly increasing aggression, T promotes
status-seeking behaviour of which aggression is one type
- Found T could make women act 'nicer' rather than more aggressively, depending on situation
- Eisenegger et al
- Research suggests association between T + aggression is
higher for F than M samples
- Most studies concerned w/ T + aggression have involved
M ppts, but does T also increase aggression in F?
- Inconsistent evidence
- A01
- Neurotransmitters - Dopamine
- A01
- Link between high levels of D + aggressive
behaviour is not as well established as w/ S, some
evidence suggest such link exists
- Increases in D activity via amphetamines have been
associated w/ increases in aggressive behaviour
- Lavine
- Lavine
- Link between high levels of D + aggressive
behaviour is not as well established as w/ S, some
evidence suggest such link exists
- A02
- Research support
- A meta-analysis of 29 studies published before 1992
- Scerbo + Raine
- Examined neurotransmitter
levels in antisocial children +
adults
- Studies consistently found lower levels of S in indivi. described as
being aggressive, found no significant rise or fall in D levels
- Indications of reduced levels of S were found
in all antisocial groups, particularly marked
in those who had attempted suicide
- Suggests S depletion leads to impulsive behaviour, in turn may lead to aggressive behaviour in various forms
- Suggests S depletion leads to impulsive behaviour, in turn may lead to aggressive behaviour in various forms
- Indications of reduced levels of S were found
in all antisocial groups, particularly marked
in those who had attempted suicide
- Examined neurotransmitter
levels in antisocial children +
adults
- Scerbo + Raine
- A meta-analysis of 29 studies published before 1992
- Research support
- A01
- Hormonal mechanisms - Cortisol
- A01
- Appears to have mediating effect on other aggression-related hormones
(T), poss. because it increases anxiety + likelihood of social withdrawal
- High levels of C inhibit T levels + so inhibit aggression
- Studies reported low levels of C in habitual violent
offenders + in violent schoolchildren
- Suggests although relatively high T is primary biochemical influence on aggression, low C also plays an important role by increasing likelihood of aggressive behaviour
- Suggests although relatively high T is primary biochemical influence on aggression, low C also plays an important role by increasing likelihood of aggressive behaviour
- Studies reported low levels of C in habitual violent
offenders + in violent schoolchildren
- High levels of C inhibit T levels + so inhibit aggression
- Appears to have mediating effect on other aggression-related hormones
(T), poss. because it increases anxiety + likelihood of social withdrawal
- A02
- Moderating effect of C on aggressive behaviour is supported in 4 year
study of boys w/ behavioural probs.
- McBurnett et al
- Boys w/ consistently low C levels began antisocial acts at younger age + exhibited 3 times no. of aggressive
symptoms compared to boys w/ higher or fluctuating C levels
- Concluded C levels were 'strongly + inversely related to aggressive conduct disorder'
- Concluded C levels were 'strongly + inversely related to aggressive conduct disorder'
- Boys w/ consistently low C levels began antisocial acts at younger age + exhibited 3 times no. of aggressive
symptoms compared to boys w/ higher or fluctuating C levels
- McBurnett et al
- Moderating effect of C on aggressive behaviour is supported in 4 year
study of boys w/ behavioural probs.
- A01
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