Aggression Flashcards
what is aggression
Agression can be defined as actions or intentions to harm or gain advantage over someone else.
2 types of Biological explanation
1) Neural and hormonal
2) Genetics
Types of neural and hormonal (limbic system, amygdala and hippocampus)
Limbic system
serotonin
Testosterone
types of genetics
Research on genetics factors
MAOA gene
What is the limbic system
It coordinates behav that satisfies emotional and motivation urges.
Controls the basic emotions and drives.
What does the amygdala do.
It quickly evaluates the emotional importance of sensory info and promotes a response to environmental threats and/or challenge.
If these areas are stimulated, then animals respond aggressively.
Removing these areas of the amygdala eliminates the aggressive response.
Kluver and Bucy - found that destruction of the amygdala in a monkey who was dominant in a social group caused it to lose its dominant place in the group.
The hippocampus
Involves with the formation of LTM
If one animal encounters another it has previously been attacked by, it responds aggressively.
Impaired functioning stops the nervous system putting stimuli into context, this may cause inappropriate aggressive responses.
Serotonin
Serotonin inhibits the firing of the amygdala
low lvl of serotonin
removes the inhibitory effect. Indiviuals are not able to control aggressive impulses.
When serotonin levels are low the inhibitory effect is removed and aggression is more likely. Drugs which deplete (use) serotonin lvls are associated with inc in aggression in men but not in women.
Testosterone
Testosterone is linked with aggressive behav. This is due to its action on brain areas responsible for controlling aggression.
sapolsky found that the removal of testosterone source in animals lead to a reduction in aggressive behav.
Castraction leads to a dec in aggression in most animals.
Pos correlation between lvls of testosterone and aggressive behav in male prisoners.
Evaluation for neural and Hormonal expl
The amygdala role is supported by research into human aggression. For example paradini et al (2014) carried out a longitudinal study of 56 male participants with varying histories of violence. MRI scans showed that ppl with a smaller amygdala showed high lvl of aggression and violence even after controlling for confounding variables. This suggests that the amygdala plays an important role in evaluating sensory info’s importance and a smaller amygdala cant do this as well, which makes aggression more likely.
The role of the hippocampus in aggression is supported by MRI scans of hippocampal asymmetry. Raine et al (2004) found that the hippocampus in the right and left hemispheres were diff in size in convicted violent criminals but not in non violent criminals. Hippocampal asymmetry possibly arises early in brain development. These asymmetries might impair the ability of the hippocampus and amygdala to work tg, leading to faulty processing of emotional emotional stimuli and inappropriate responses, such as aggression.
There is some support for the serotonin deficiency hypothesis to explain human and non human aggression. For example Duke et al (2013) did a meta analysis of 175 students found a small, inverse rs between serotonin lvls and aggression. Raleigh et al and Rosoda found lower serotonin lvls were associated with inc aggression in monkeys and dogs.
This suggests that the low lvls of serotonin could be a casual factor in aggression.
The role of testosterone in human aggression is seemingly supported by a large number of research studies.
For example Dabbs et al measured salivary testosterone in violent and non violent criminals. Those with the highest lvl of testosterone had a history of violent whereas those with the lowest levels had only committed non violent crimes.
This suggests that testosterone does play a role in human aggression.
However, the role of testosterone has been challenged by studies failing to show a rs between it and human aggression.
For example, some research has shown no correlation between testosterone and actual violence in male prison inmates. Mazur suggests that testosterone may actually promote status-seeking behaviour, of which aggression is just one type.
This suggests that the rs between testosterone and aggression in humans might be more complex than has been suggested.
Twin studies
Monozygotic twin share 100% of their genes, therefore they shld be more alike in terms of their aggression behav compared to dizygotic twins as they only share 50% of their DNA.
Research on twin studies have shown heritability accounts for 50% of the variance in aggression behav.
Coccaro et al - studies of MZ and DZ twins who were raised in the sme environment. They found concordance rates for MZ twins were 50% and 19% for DZ twins for physical aggression. They found that concordance rates were 28% for MZ and 7% for DZ twins.
Adoption studies
If an adoptees aggressive behav correlate more with its biological parents that its adoptive parents, than this suggests this this is related to genetic influence.
If an adoptees aggressive behav correlated more with its adoptive parents, then this suggests it is due to environmental influences.
Rhee and Waldman (2002) - Carried out a meta analysis on adoption studies of aggression and anti-social behav.
They found genetic influence accounted for 41% of variance in aggression, which is in line with findings from twin studies.
Hitchings and Madnick (1975) - In a study of over 140000 adoptions in Denmark, they found that significant number of adopted boys with criminal convictions had a violent criminal convicted biological parents providing evidence for a genetic link.
MAOA Gene
No individual gene for aggression has been identified in humans. MAOA is associated with aggression.
MAO-A is an enzyme.
The MAOA gene controls the production of the MAO-A enzyme.
MAO-A regulates serotonin productions and low level of serotonin are associated with aggressive behav. MAOA-L results in low activity of MAOA which has been linked to high levls of aggression.
(MAOA = gene MAO-A = enzyme)
MAOA gene is also known as the warrior gene.
Lee and Chambers - found that the MAOA-L variant was found in 56% of new Zealand maori men in comparison with 34% of Caucasians. Historically Maori ppl have a reputation for being ferocious warriors.
Brunner et al - 28 men from a large Dutch family who were particularly aggressive, showed abnormally low MAOA lvls and a defect in this gene.
Gene environment Interactions
Frazzetto et al - found that there was an association with high levels of aggression and men who possessed the MAOA-L variant. However this was the only true for those who suffered from significant trauma during the first 15 years of their life. This supports the diatheis stress model that aggression is only developed when the individual is exposed to trauma/stressful situations and possess the MAOA-L variant.
Capsi et al (2002) - study of 500 boys. Found that those with MAOA-L variant were more likely to behave anti-socially as adults, but only after childhood maltreatment.
strength of Genetic Factors
one strength is that there is research to support for the role of MAOA gene in aggression. Reseach has found that the MAOA-L variant is associated with higher levels of aggression. Mertine et al’s reaserch has also found similar studies. They found that amle participent with the MAOA-H variant were more cooperative and made fewer aggressive moves than those with MAOA-L variant in a money distributing game.
This supports the association of the MAOA gene and aggression.
The role of MAOA gene in serious violent behav is supported by research studies.
For example Tilhonen et al found that extremely violent behav in finnish prison was associated with MAOA-L gene in combination with CDH13 gene. There was no substantial evidence for either of these genes in non violent offenders, showing that this genetic combi is specific violent behav only. This suggests that MAOA does play a role in some type of aggression.
Gender difference in aggressive behav might be explained by the MAOA gene.
For example the MAOA gene is linked to X chromosome, of which men only have one whereas women have two. in women, an unaffected second x chromosome with the normal MAOA gene may prevent the expression of an abnormal versions of it.
This could explain why males are more aggressive than females.
weakness of genetic factors
One issue of this area is that most studies have focused on ppl convicted of violent crimes.
However convicted violent criminals form only a sample of those who actually commit violent crime. Additionally, offenders designated as violent on the basis of a court conviction aren’t necessarily the most persistent or serious offenders.
This might explain why many studies have found little or no heritability for violence (genetics cause aggression).
A further critisism of this area of investigation is that there are more methodoligical issues with the measurement of aggresive behav.
For example miles are careys meta analysis found that the method assessing aggresson was a significant moderator o aggressive behav. Genetic factors explained a large proportion of the variance in aggressive behav in self report studies but in observational studies showed less genetic influence and more environmental influence.
These inconsistencies from diff methods assessing the raltive contributions of genetic and environmental infulence.
evolutionary expl of aggression
Human brain is product of evolution by natural selection. Human brain evolve various adaptations to cope with various challenge associated with grp living.
One adaptation is to be aggressive which can be effective for solving some problems. so being aggressive enhances survival and reproductive success. Aggression passed onto offspring and spreads the gene pool.
Male retention strategies and the study of phsyical violence against partner
Direct guarding - controlling behav/belief vigilant
Negative inducement - threats as consequences of infedility
wilson et al asked women to report male retention strategies in thier partner. This was measured in terms of the extend to which they agreed with statements. Women who did agree with such statements twice as likely to have experienced physical violence at the hands of their partners. Of these women 73% required medical attention and 53% said they had feared for their lives. This suports the male retention stratgies are linked to physical violence.
Bullying
is an adaptive behav as it consists of behav that would aid survival.
- dominance
- strength
- aquistion of resource
Female bullying in rs is seen as a means of controlling a partner’s infidelity so that they continue to devote resources to them in the future.
Volk et al: women see bullying behav as attractive
Male bullying
female view bullying as attractive as it shows dominance, strength etc.
It also potential rivals
Accordimg to evolutionary explaination, bullying is naturally selected.
Sapolsky (2004): Boys who have a repuatation for being bullies/tough, other boys are less likely to provoke them therefore they experience less stress and have better health.
Female bullying
Females bully thier partner as a way of controlling them.
They use it to secure their partners fidelity so they continue to provide resource for future offspring
This behav is also seen as naturally selsected for reproductive success.
Strength of evolutionary explaination
A strength of this strength explaination is that there is research for aggression and sexual jealousy.
For example studies have found that mate retentions strategies (such as direct guarding and negative inducement) are associated with sexual jealousy and aggression.
These results show a clear link with the greater risk of infidelity and cuckoldry and aggression.
Therefore this adds validity to the explanation as it supports the prediction concentric the adaptive view of aggression.
A strength of this explanation is that there are useful real world application, such as when it comes to devising effective anti-bullying interventions.
For example, research has suggested to encourage bullies to compete aggressively but fairly in sporting activities. This works because it inc the cost of bullying and the rewards of prosocial alternatives, as it allows bullies the opportunity to display prowess, strength and other attractive qualities.
Therefore compared to other strategies. assuming an evolutionary approach allow us to address the root of the issue which is to gain power over others.
A limitation of the evolutionary approach is that it cannot address cultural diff in aggression. For example the kung san ppl have negative attitudes towards
Ethological explanation
According to ethology, aggression is an instinctive behaviour that has evolved in animals (including humans) to increase their chances of survival and reproduction.
Ethologists like Konrad Lorenz proposed that aggression is a natural part of an animal’s behaviour.
Lorenz (1966) argued that aggression is an innate behaviour that serves a specific function in nature. He believed that animals have evolved aggressive tendencies to protect themselves, defend their territory, and ensure survival.
Aggression is not always lethal. Instead, animals often engage in ritualized aggression, which allows them to resolve conflicts without causing serious harm to each other.
FAPs are stereotyped, instinctive behaviours that occur in response to specific stimuli. They are considered hard-wired and typically involve aggression, such as attacking an intruder or defending young.
These behaviours are often triggered by specific cues or “releasers” that provoke aggressive responses, ensuring that the aggression serves its evolutionary purpose