Aggression P3 Flashcards
neural mechanisms
Brain structures such as neurons, neural circuits and regions of the brain. Includes by chemicals in the nervous system such as neurotransmitters.
Hormonal mechanisms
hormones are chemical messengers transmitted via the bloodstream and regulates activity of other cells/organs.
Neural explanation for aggression (Limbic System)
=The LS contains subcortical structures in the brain (inc amygdala and hypothalamus) thought to be closely involved in regulating emotional behaviour such as aggression.
Deals with…
Emotions
Memories
Psychological arousal (stimulation)
= The speed and sensitivity of the LS’s responses to stimuli are important predictors of aggression (eg the more responsive the amygdala is, the more aggressive a person is).
Made up of six structures - if one or more malfunctions -> difficulty in controlling reactive aggression (ie responses to perceived threats in an immediate situation)
Inside;
1) Amygdala : regulates emotions and responds to threats.
- Dysfunction -> someone may perceive situations as threats when they are not , leading to agg (inappropriate activation of ForF).
2) Hypothalamus: regulates the release of hormones (receives info from amygdala/part of the NS and ES)
-Dysfunction -> inappropriate activation of flight or fight.
= Amygdala and Hypothalamus are keys steps for ForF.
3) Hippocampus : formation of long-term memories.
- Dysfunction -> NS unable to put current sensory events into relevant/meaningful context (based on experience).
= therefore, amygdala responding inappropriately, leading to aggression.
Neural explanation for aggression (serotonin)
Serotonin -> an inhibitory neurotransmitter (increases neg charge to make neurons less likely to fire).
- Normal levels of serotonin in the orbitofrontal cortex are linked with greater behavioural control (due to reduction of neuronal firing).
THEREFORE, when serotonin is reduced…
THE SEROTONIN DEFICIENCY HYPOTHESIS:
=Low levels of serotonin lead to reduced self control (impulsive behaviour) and therefore increased aggression.
EG
Inside amygdala, low levels of serotonin, which means more neurons firing, which reduces impulsive control, increasing reactive aggression .
Hormonal explanation for aggression
Testosterone -> a hormone from the androgen group that is produced mainly in male testes (smaller amount in female ovaries). Associated with aggression.
-> responsible for the masculinisation of the body .
-> Has a role in regulating social beh via its influences on certain areas of the brain implicated in agg.
-> influences activity in the amygdala: high levels of testosterone linked to enhanced amygdala reactivity.
HIGH LEVELS OF TEST -> HIGH AGGRESSION
= cross cultural research shows how men are usually more aggressive than females (especially in male adolescents), this could explain why - they have more testosterone.
Neural explanation of aggression pros
1) Gospic et al (The Ultimatum Game)
- FMRI brain scans on participants in a lab base game that provoked aggression.
- Found : when responders reject an unfair offer (an aggressive reaction) scans showed fast and heightened responses by amygdala.
2) Scerbo and Raine
- meta analysis assessing 29 studies on serotonin levels in antisocial kids.
- Found : those who had low serotonin levels had a high aggression rates (especially in those who attempted suicide)
Hormonal explanation of aggression pros
1) Dolan et al
- 60 male UK offenders who had a history of impulsive behaviour
- Found: a positive correlation between testosterone levels and aggression.
2) Dabbs et al
- Tested prison inmates and found an association between high testosterone and violent crimes. COMPARED TO low testosterone levels with nonviolent crimes.
3) Can explain gender differences; boys have more testosterone, and therefore more aggressive than girls
cons of the neuronal/hormonal explanation of aggression
1) reductionist
- An explanation that only focuses on one biochemical is too simplistic. For example, it has been shown that high testosterone levels only link to aggression when cortisol levels are low. Therefore, aggression involves a complex interaction of the instructions are neurotransmitters. (also ignore nurture)
2) issues with determining cause-and-effect
- Research is largely correlational
Genetic explanation of Aggression
-Aggression is hereditary (can be passed down families in DNA). Research often includes twin studies and adoption studies.
MAOA = a gene that is responsible for the activity of the enzyme ‘monoamine oxidase A’ in the brain.
MAO-A = the enzyme responsible for breaking down important neurotransmitter’s like serotonin, dopamine and noradrenaline.
MAOA-L = the low activity variant that causes aggression (the MAO-A deficiency)
Referred to as the ‘WARRIOR GENE’ : low activity and production of MAOA leads to fewer neurotransmitters broken down in the synapse, ultimately leading to high levels of these neurotransmitters (serotonin, noradrenaline, dopamine).
The low variant MAOA gene is found in…
Xchromosome from mother
- males -> one X chromosome
- females -> two X chromosomes
= Therefore, in females have one (normal) high activity variant of the MAOA gene has a protective effect; diluting the MAOA gene
Twin studies/ Adoption studies (why used in genetic factors for agg/ limitations)
TWIN -> Help us compare the extent genetic factors play in our aggressive behaviour by comparing twins in the same environment.
-> As MZ twin share 100% of DNA if they have higher concordance rates than DZ twins, suggests a genetic basis to agg beh.
-> Suggest that heritability accounts for 50% of variance in aggressive behaviour.
X lack validity -> equal environments assumption (they assume that MZ and DZ twins share their environments to the same extent). UNTRUE as MZ are identical, parents treat them more similarly than DZ twins. Therefore, cr are inflated and genetic influences on aggression may not be as great as twin studies suggest.
ADOPTION -> Helps us examine the extent adoptees inherit aggressive behaviour from their biological parents, even when brought up by someone else.
-> Suggest that heritability accounts for 41% in aggressive behaviour.
Evaluation of genetic factors in aggression
1) Brunner
= 28 male Dutch family members
- involved in aggressive behaviour and violent criminal acts (ie rape/murder)
- found abnormally low levels of MAOA and the low activity MAOA gene.
X all had the same environment. env>genes + cultural variation
2) Coccaro et al
= 187 MZ adult twin pairs vs 118 DZ
- found concordance rates of 50% for MZ in phy agg
- found concordance rates of 19% for DZ in phy agg
X not 100% -> other contributing (social factors)
3) Hutchings and Mednick
= reviewed 14,000 adoptions in Denmark
- pos correlation of no. of convictions for criminal violence among biological fathers and their adopted sons.
4) Can explain gender differences
- low activity MAOA variant found X chromosome of mother
- females have xx so one x dilutes the other
- males have xy and so more inclined to be aggressive
5) Gene x Environment interaction
- CASPI -> children with low MAOA were more likely to exhibit anti-social behaviour when older BUT ONLY IF they had been maltreated.
Ethological exp
= Seeks to understand the innate behaviour of animals (inc humans) by studying them in their natural environment.
Lorenz: Ritualistic aggression
- A ritual -> a series of behaviours carried out in set order.
- very little physical damage fighting between same species (often not often killed but forced to ‘concede’ + move territory).-> - Meaning members of a species spread out reducing competition and possibility of starvation. + dominance hierarchies (mating opportunities)
- Instead, agg beh shown via ritualistic signaling (eg displaying clause and teeth, facial expressions of threat).
- Fighting ends by ritualistic appeasement displays -> behaviours signaling defeat , preventing further agg beh, making sure loser is not killed. EG wolf exposed neck as a submissive act.
= Adaptive as if every aggressive encounter ended in death, would threaten existence of species.
Innate releasing mechanisms + fixed action patterns + Leas 6 features
Innate releasing mechanism -> An inbuilt biological structure/proces that respond to external stimuli and trigger FAP.
An external stimulus (ie red belly sticklebacks) triggers the IRM which the releases a specific sequence of behaviours known as FAPs.
Fixed action pattern -> A sequence of stereotyped behaviours triggered by an innate releasing mechanism.
( = IRM interprets the external stimulus that in turn triggers the fixed action pattern).
1) External stimuli
2) Innate releasing mechanism
3) Fixed action pattern
Lea
1) Universal -> all members of the species behave the same way
2) Stereotyped-> unchanging sequence of beh
3) Unaffected by learning or individual experiences
4) Ballistic -> once beh is triggered it follows a predicted course and cannot be altered before completion
5) Single purpose -> the beh only occurs in a specific situation
6) Occurs in response to a specific stimulus or signal
UnderSomeUnderwearBallsSwungO
Eval of the ethological explanation of aggression
Pros
1) Tinbergen
- male sticklebacks (highly territorial during mating season, when they develop a red underbelly)
- if another male enters their territory they will display aggressive behaviours (FAPs)
- presented stickleback with a series of wooden sticklebacks with different shapes (some having red belly)
findings:
- regardless of shape, if had a red belly -> stickleback would attack (displaying FAPs)
- no red spot -> FAPs were unchanging from one encounter to another.
- once triggered, the FAP always ran its course to completion without stimulus.
= Shows support for ethological explanation (link to leo, idea that FAPS are innate)
2) Brunner -> Found low activity variation of MAOA gene could cause heightened aggression in humans(Dutch family members) Showing how we have a biological basis to our aggression as it was a biological gene that triggered this behavior> env. (same as what etho sugg)
3) Sackett -> Reared monkeys in isolation and showed them pictures of monkeys playing, exploring and in threatening poses. When they matured they reacted to pictures of threatening stimuli. Shows how agg = innate as monkeys were unable to learn via other monkeys.
Cons
1) Cultural diff in aggression
= Nisbett -> Found North Self Divide in homicide rates in the US. Southern US found higher homicide rates. Linked to agg, S = more agg> northen US. NOT INNATE
2) Research against ritualistic aggression
= Goodall -> chimpanzees behaved agg even if their same-species victims were showing appeasement signals.
3) FAP’s not fixed
= Hunt -> FAP’s influenced by environmental factors and learning experiences, so are actually quite flexible (ie if someon squared up to be in a bar, ik not to stoop to their level due to be my learning exp, but other human may react agg). FAPS AFFECTED BY LEARNING
Evolution explanation of aggression
=Some behaviours (aggression) more likely ancestors survived and passed on genes. So adaptive as facilitates survival.
1) SEXUAL JEALOUSY
- adaptive avoids cuckoldry (man been betrayed by wife ->ie raising a child to whom the father is not genetically related to). This compromises the chance of passing on his genes.
- Male sexual jealousy -> aggressive mate retention strategies like:
A) direct guarding = behaviours which restrict access of other males (ie checking her phone)
B) negative inducements = verbal threats or direct violence which induces fear to reduce female infidelity (cheating)
2) BULLYING
= where a more powerful individual attacks a weaker person deliberately and repeatedly
- adaptive; increases survival by promoting own health and creating reproductive opportunities.
-men bullying : involves controlling a partner
-female bullying : involves securing their partners fidelity so they can continue to provide resources for future offspring
Volk (2012)
-> characteristics of bullying in men are attractive to opposite sex.
-> suggests dominance, resources and strength which has the benefit of warding off potential competitors + attracting females.
-> meaning : this beh is naturally selected, giving more reproductive potential to these males