1. Outline and evaluate genetic factors in aggression
AO1:
Inheritance of low-variant MAOA gene (MAOA-L)
Decreases production of MAO-A enzyme – breaks down serotonin
Imbalanced levels of serotonin – affects mood regulation
People born w extra Y chromosome – super males
More aggressive as possess extra male chromosome
Increased likelihood of aggression
AO2:
A strength is that there is support from prosocial behaviour
Low-activity variant of MAOA associated w greater aggression
People w high-activity should be more prosocial
Mertins et al: males w high-activity MAOA more cooperative –
made fewer aggressive moves than other ppts
Confirms importance of MAOA gene in agg behaviour
However his study also showed non-genetic factors are crucial
Even ppts w low-activity MAOA variant behaved cooperatively when
made aware others were
Genes influenced by environmental factors – at least as important
Support from twin studies
Researchers compare degree of similarity for aggression between
MZ and compare similarity w DZ
If MZ more alike in terms of aggressive behaviour should be due to
genes than environment
Coccaro: studied aggressive behaviour using adult twins
Found nearly 50% of variance in aggressive behaviour could be
attributed to genetic factors
Problem is genetic explanation ignores role of environmental factors
Men in Brunner’s study all share the same environment
Potentially could have learned aggressive behaviour by observing
family members
Focussing only on genetic factors ignores role of nurture in
aggression
Research is biologically reductionist
2. Outline and evaluate neural/hormonal mechanisms in aggression
AO1:
Limbic system – amygdala + hippocampus – coordinate behaviour
that satisfy emotional urges
, Amygdala: responsible for evaluating emotional importance of
sensory info + appropriate response
Hippocampus: formation of long-term memories, allows animal to
compare current threat w past experiences
OFC + serotonin – low levels remove inhibitory effect -> impulsive
behaviours
When amygdala is stimulated, becomes more active – person acts
on impulses, aggression = more likely
Testosterone brings out aggressive behaviour – castrated rates
reduces testosterone + mouse killing behaviour
AO3:
Research support with animals
In male rhesus monkeys there’s an increase in testosterone +
aggression during mating season
In rats castration = reduces testosterone + mouse killing behaviour
Injecting female rats w testosterone increases mouse killing
Shows the role of testosterone in aggression in a range of species
Other brain structures are involved with aggression
Limbic structures function together w OFC – not part of limbic
system
OFC involved in impulse regulation + inhibition of aggression
behaviours
OFC is reduced in disorders that cause aggressive behaviour
Shows that neural explanations are more complex
Mixed link between testosterone + aggression levels in humans
Dual-hormone hypothesis claims high levels of testosterone lead to
aggression when cortisol is low
When cortisol is high testosterone influence on aggression is
blocked
Argued that combined activity of testosterone + cortisol may be
better predictor of aggression than either hormone alone
3. Outline and evaluate ethological explanations for aggression
AO1:
Aggression has an adaptive purpose – beneficial to survival,
establishes dominance hierarchies (status to victor)
Ritualistic aggression – behaviour in set order – threat +
appeasement
AO1:
Inheritance of low-variant MAOA gene (MAOA-L)
Decreases production of MAO-A enzyme – breaks down serotonin
Imbalanced levels of serotonin – affects mood regulation
People born w extra Y chromosome – super males
More aggressive as possess extra male chromosome
Increased likelihood of aggression
AO2:
A strength is that there is support from prosocial behaviour
Low-activity variant of MAOA associated w greater aggression
People w high-activity should be more prosocial
Mertins et al: males w high-activity MAOA more cooperative –
made fewer aggressive moves than other ppts
Confirms importance of MAOA gene in agg behaviour
However his study also showed non-genetic factors are crucial
Even ppts w low-activity MAOA variant behaved cooperatively when
made aware others were
Genes influenced by environmental factors – at least as important
Support from twin studies
Researchers compare degree of similarity for aggression between
MZ and compare similarity w DZ
If MZ more alike in terms of aggressive behaviour should be due to
genes than environment
Coccaro: studied aggressive behaviour using adult twins
Found nearly 50% of variance in aggressive behaviour could be
attributed to genetic factors
Problem is genetic explanation ignores role of environmental factors
Men in Brunner’s study all share the same environment
Potentially could have learned aggressive behaviour by observing
family members
Focussing only on genetic factors ignores role of nurture in
aggression
Research is biologically reductionist
2. Outline and evaluate neural/hormonal mechanisms in aggression
AO1:
Limbic system – amygdala + hippocampus – coordinate behaviour
that satisfy emotional urges
, Amygdala: responsible for evaluating emotional importance of
sensory info + appropriate response
Hippocampus: formation of long-term memories, allows animal to
compare current threat w past experiences
OFC + serotonin – low levels remove inhibitory effect -> impulsive
behaviours
When amygdala is stimulated, becomes more active – person acts
on impulses, aggression = more likely
Testosterone brings out aggressive behaviour – castrated rates
reduces testosterone + mouse killing behaviour
AO3:
Research support with animals
In male rhesus monkeys there’s an increase in testosterone +
aggression during mating season
In rats castration = reduces testosterone + mouse killing behaviour
Injecting female rats w testosterone increases mouse killing
Shows the role of testosterone in aggression in a range of species
Other brain structures are involved with aggression
Limbic structures function together w OFC – not part of limbic
system
OFC involved in impulse regulation + inhibition of aggression
behaviours
OFC is reduced in disorders that cause aggressive behaviour
Shows that neural explanations are more complex
Mixed link between testosterone + aggression levels in humans
Dual-hormone hypothesis claims high levels of testosterone lead to
aggression when cortisol is low
When cortisol is high testosterone influence on aggression is
blocked
Argued that combined activity of testosterone + cortisol may be
better predictor of aggression than either hormone alone
3. Outline and evaluate ethological explanations for aggression
AO1:
Aggression has an adaptive purpose – beneficial to survival,
establishes dominance hierarchies (status to victor)
Ritualistic aggression – behaviour in set order – threat +
appeasement
