aggression Flashcards
what’s the limbic system?
subcortical systems in the brain such as the hypothalamus and amygdala thought to be closely involved in regulating emotional behaviour including agression
neural mechanisms in aggression- limbic system
Papez and Maclean linked limbic system to emotional behaviours, e.g. aggression. Defined as hypothalamus and amygdala, and part of hippocampus. Reactivity of amygdala in humans and other mammals is an important predictor of aggressive behaviour, so ir has a key role in how mammals assess and respond to environmental threats
amygdala activity research
Gospic- Ps we’re subject to mild provocation, when Ps reacted aggressively FMRI showed heightened and fast response with amygdala. Benzodiazepine drug reduces arousal of autonomic NS was taken before and this lead to two affects- decreased aggression and activity in amygdala
orbital cortex and serotonin
serotonin calms neural activity. Normal levels of serotonin in the orbitofrontal cortex are linked with reducing firing neurons, which is associated with greater self control. Serotonin deficiency disrupts this mechanism, leading to reduced self control and increased aggression.
orbitofrontal cortex and serotonin- small study
Virkkunen compared levels of a serotonin breakdown product in violent impulsive and violent non impulsive offenders. The levels were significantly lower in violent impulsive offenders
hormonal mechanisms in aggression- testosterone
a hormone from androgen, produced by male testes. People have observed that men are typically more aggressive than woman. They become more aggressive towards men at the time when testosterone is the highest.
Castration studies in animals showed decrease in aggression when testes were removed, and an increase when the animals were then given a shot of testosterone .
hormonal mechanisms in aggression- testosterone studies
Castration studies in animals showed decrease in aggression when testes were removed, and an increase when the animals were then given a shot of testosterone .
humans- prison populations- Dolan found a positive correlation between testosterone levels and aggressive behaviors in a sample of 60 male offenders. These men mostly had personality disorders and histories with violent and impulsive behavior.
hormonal mechanisms in aggression- progesterone
comes from ovaries, and there is evidence that it plays a role of aggression in woman. Progesterone levels vary over the cycle and are lowest during and just after menstruation.
Ziomkiewicz found a negative correlation between progesterone levels and self reported aggression. This suggests low levels of progesterone are linked to increased aggression in women.
Neural mechanisms in aggression- evaluation
-research showing non limbic brain structures are also involved in aggression, they work together with the orbitofrontal cortex which is not part of the limbic system. According to Coccaro, OFC activity is reduced in those with psychiatric disorders that feature aggression. The reduced activity disrupts the OFC’s impulse control causing aggressive behavior. This shows that neural regulation of aggression is more complex than theories focusing on the amydala suggest.
+research into effects of drugs. (serotonin explanation) Drugs that increase serotonin have been found to also reduce levels of aggressive behavior. P’s were given placebo drug or real drug and gave electric shocks are being insulted. those who took the serotonin increaser (non placebo) gave less intense shocks, this is evidence of a casual link between serotonin function and aggression
hormonal mechanisms in aggression- evaluation
+ research support from animals. Giammanco’s review of studies confirms the role of testosterone. E.g., increase in aggressive behavior and testosterone levels in male monkey specie in mating season. In rats, castration study. these show the role of testosterone in a range of animal species
-mixed evidence between the link of testosterone and aggression. Carre and Mehta developed a dual hormone hypothesis to explain why- claim that high levels of testosterone leads to aggressive behavior but only when levels of cortisol are low. When it is high, the influence is blocked. Cortisol plays a role in bodies response to chronic stress. So combined activity of both may be a better predictor than one hormone alone.
SLT- aggression
A way of explaining aggression that includes both direct and indirect reinforcement, combines learning theory with cognitive factors
direct and indirect learning
-direct: operant conditioning- involving positive and negative reinforcement and punishment
-indirect: vicarious reinforcement: through observing
cognitive conditions for learning aggression (4)
Attention , retention, reproduction, motivation
what is self efficacy?
extent to which we believe are actions will achieve a desired goal. A child’s confidence to their ability to be aggressive grows as they learn that aggression can bring rewards. For example, child who hits to get toy
Banderas research- procedure:
young children observed and adult model assaulting a Bobo doll. Frustration promotion followed as children were not allowed to play with toys after. They were then taken to another room where there was a Bobo doll, plus some tools that the adult had used
Banduras research- findings
Many children imitated the behavior they saw performed. Boy imitated physical aggression more than girls but there was no difference in verbal aggression. Boys were also more likely to imitate a model of the same sex. There was also a group with non violent adults and the results were non aggressive
SLT for aggression evaluation: strengths
+research support found boys aged 9-12 formed friendships with other aggressive boys. Their aggressive behaviour was reinforced through watching each others actions and also through support in the group. (rewardal) This follows what the SLT states
+help reduce aggression as we know how it occurs. One way to reduce aggression is to provide non aggressive rewarded models. This shows SLT offers practical steps to reduction of development
SLT for aggression evaluation: weaknesses
-COUNTERPOINT: study did not find similarity for reactive aggression- instant retaliation. Results showed boys were much more likely to reduce sudden reactive outbursts. They observed them but did not imitate them. This could be due to unpredictablilty of reactive aggression consequences
-underestimates biological factors. Bandura recognized the role of biology. As we have seen on previous studies and observations there are clearly powerful genetic, evolutionary etc reasons for aggression. Therefore SLT is an incomplete explanation as it underplays these factors
twin studies: genetic factors of aggression
-studies have suggested heritability accounts for 50% of the variance in aggressive behavior.
-Coccaro studies monozygotic (share 100% of genes) and dizygotic twins (50%). Although both are raised in the same environment, we would expect MZ twins to have more similarities in aggressive behavior. For direct physical assault rates, researcher found concordance rates of 5-% for MZ and 19 for DZ. Verbal aggression- 28% mz and 7% dz.
adoptions studies: genetic factors of aggression
similarities between adopted child and biological parents in aggression suggests genetic factors are operating. The same goes for adopted children and adoptive parents, but this would mean its environmental.
-Meta analysis of adoption studies of anti social behavior and aggression. they found 41% of variance in aggression accounted for genetic influences, much like twin studies.
what is the MAOA gene responsible for?
for the activity of the enzyme monoamine oxidase (MAO-A) in the brain. The low activity variant of the gene is closely associated with aggressive behavior.
The MAOA gene linking to aggression
the low activity variant (MAOA-L)
MAOA regualtes the neurotransmitter serotonin.
this gene has been named the warrior gene and research has showed the L version has been possessed by 56% of NZ maori men, and historically they have a reputation of being ferocious warriors. The link between this gene and aggression has been furthered with a study of 28 men from a large Dutch family who were involved in violent criminal behaviors such as rape. these men had significantly low levels of the enzyme MAO-A as well as the L variant.
gene- environment interactions
-appears to be the case that MAOA-L gene is only related to aggression when the adult has had experiences of trauma in early life.
-a study found an association between the link between the gene and aggression but only when they had experienced significant trauma before 15 years. Those who did not have trauma did not have particularly high levels of aggression as adults even as they possessed the variant. This is strong indication of GxE interaction.
strengths of genetic factors in aggression: (1) research support and counter point
+research support (twin studies, adoption studies) shows that low activity variant of MAOA is associated with aggression. Another study also found this to be true, as men took part in a money game. Men with the H variant were more co-operative and made less aggressive moves that men with the L variant. This finding supports the relationship between them.
-however: Money study also showed non genetic factors are crucial. They found that P’s even with the L variant reacted co-cooperatively and non aggressively when they were made aware others were behaving that way. Knowledge of a social norm partially determined how aggressive the L participants were. Therefore genes are influenced by environmental factors that are at least important in aggression
limits of genetic factors in aggression: (2) complex link)
-precise mechanism is unclear. research linked aggression and low levels of serotonin. But L gene leads to low activity of MAO-A enzyme which should lead to higher serotonin. Because the low activity variant does not deactivate serotonin, leading to more serotonin for synaptic transmission. It may be more accurate to say that people with the L variant that their serotonin levels are disrupted rather than too high or low. This shows the relationships is not fully understood
limits of genetic factors in aggression: (3) problems with twin studies
twin studies may lack validity
In every pair of twins, they share the same environment. However DZ may not share the same environment to an extent that MZ twins do. We assume they do- equal assumption. This may be wrong as they may be treated differently by others. MZ Twins are treated very similarly, especially by parents, (e.g. equal appraisal) and DZ’s are treated in less similar ways. This means concordance rates are inflated and genetic influences may not be as great as the twin studies suggest
what is the ethological explanation for aggression?
an explanation that seeks to understand the innate behavior of animals by studying them in their natural environment. It suggests the main function for aggression is adaptive. It is beneficial to survival- the defeated animal is rarely killed but is only forced to establish territory elsewhere. Spreading elsewhere reduces competition and possibility of starvation.
-also to establish dominance hierarchies. For example monkeys, and higher dominance allows for better chances to mate.
-Study was conducted on young children and aggression played an important role in these hierarchies This would be adaptive because it bring benefit for things such as access to resources.
