aggression Flashcards
Outline the function of the limbic system
-involved in the regulation of emotions and emotional behaviour
-It consists of the amygdala , hypothalamus , hippocampus and thalamus as found by (Maclean 1952)
Outline the function of the amydgdala
-The amygdala is thought to be particularly important in regulation of emotional behaviour as demonstrated by Gospic et al (2011)
Outline research conducted into the amygdala
Gospic et al (2011) : Ultimatum game
researchers found:
- when participants rejected unfair monetary award (could be seen as social provocation) there was a sudden increase n amygdala activity
-as seen by fMRI scans
-spikes were less drastic when given serotonin agonist benzodiazepines (reduces arousal of ANS
-suggests : strong link between action of ANS and aggression
Outline the function of serotonin in aggression
- serotonin is an inhibitory neurotransmitter
-reduces the action potential within post synaptic membrane , therefore amygdala sends fewer nervous impulses to the hypothalamus - And is associated with the regulation of impulsive behaviour when found at normal levels in the OFC (Denson et al 2012)
(virkkunen et al) : found lower levels of a serotonin breakdown metabolite within violent impulsive prisoners compared to non violent non-impulsive prisoners
Evaluate a limitation of neural explanation for aggression (over-reliance)
P - REDUCTIONIST : over-reliance on limbic system as an explanation for aggressiion
E- (e.g) orbitofrontal cortex (OFC) : significant role, due to its link with the action of serotonin, (Denson)
E-Therefore, as suggested by Gospic et al, it may be more effective to focus on the neural connections between the OFC and the limbic system, as opposed to looking at the two in isolation.
L- therefore : neural regulation of aggression more complex than theories solely on amygdala
Evaluate one strength of the neural explanation for aggression (negative corr)
P- evidence supporting negative correlation between ++ serotonin and — levels of aggression
E- Berman et al found that participants who were given the serotonin agonist ‘paroxetine’, behaved less aggressively compared to a control group (placebo group) whilst playing a video game, delivering fewer and less intense shocks!
E-This is evidence for the causational link between serotonin and aggression
Outline the hormonal explanation for aggression
Testosterone (released by adrenal glands and sex glands) is an androgen (male sex hormone) present in significantly larger concentrations in men, compared to women,
- It is responsible for the production of male facial characteristics and reproductive organs, being secreted from the pineal gland.
There may be a link between increased testosterone levels and increased levels of aggressive behaviour, a positive correlation demonstrated by castration studies. (Dolan)
- low levels of progesterone in woman : more aggression (negative correlation) found by Anna et al 2012
Outline a research done into hormonal mechanisms for aggression
- Dolan et al (2001) provided further support for this link by showing that violent prisoners in maximum security prisons displayed higher levels of testosterone than their non-violent counterparts.
Outline a limitation in the hormonal explanation for aggression
P- Research evidence to support the over-reliance on the hormone testosterone (REDUCTIONIST)
E- Carre and Mehta (2011) suggest that, through their dual-hormone hypothesis, testosterone does not work alone in determining aggression, but rather has an antagonistic relationship with the stress hormone cortisol,
E- where increased levels of aggression are associated with increased testosterone levels but only when cortisol is low.
L-Therefore, this implies that different hormones have different predictive values for aggression and are part of a system when developing aggressive behaviour.
Outline research evidence found for twin studies in the genetic explanation of aggression [2]
- Evidence from this comes from Coccaro et al (1997), who found concordance rates of 50% for MZ twins and 19% for DZ twins in terms of physical acts of aggression. This strongly suggests a genetic basis for aggression.
adoption studies
- Rhee and Waldman (2002)
-meta-analysis of aggression adoptees suffering from aggressive behaviour and ADP
-genetic influence accounted for 41% of variance in aggression
-therefore aggressive behaviour can be accounted for by candidate genes
Outline twin studies involved in the genetic explanation for aggression
determines the genetic/biological basis of a behaviour, due to the fact that MZ twins are genetically identical, whilst DZ twins share 50% of genes with each other.
Outline a candidate gene for aggression
MAOA GENE
-regulates and breaks down serotonin within the pre-synaptic cleft after neurotransmission
can code for :
- enzyme-L
-enzyme-H
L-ENZYME
- low activity
-more aggression because there is less serotonin breakdown
Outline a research study for candidate gene for aggression (genetic explanation)
EVALUATION - CASE STUDY
Brunner et al provided evidence for the link between decreased MAOA levels and aggression
- large Dutch family
-all actively engaged in aggressive behaviour (e.g. rape, attempted murder, physical assult ) - all had unusually low MAOA levels
(brain and activity) - less serotonin is broken down within the synaptic cleft,
leading to an increased rate of stimulation of the postsynaptic membrane. - woman were not affected because MAOA gene is carried on the X chromosome therefore more likely to be dominant in males
Outline the interactionist approachh for the genetic explanation of aggression
Frazzetto et al (2007) suggests that it may be more beneficial to take an interactionist approach.
The researchers found that low MAOA levels only resulted in increased aggression when accompanied by traumatic childhood events which had occurred within the first 15 years of life.
This supports the interactionist, diathesis-stress model where the diathesis (biological vulnerability) is the genetic mutation of the MAOA gene and the stressor (environmental stressor) is childhood abuse, showing how genes and the environment interact with each other.
Outline a limitation in the interactionist genetic explanation for aggression
P- major problem with the use of the diathesis-stress model is the difficulty in distinguishing between the effects of nature (MAOA genetic mutations) and nurture (childhood trauma), as well as determining which has a larger influence.
E- For example, it was found in a study that provocation in a money-lending game was key to triggering aggressive behaviour in individuals with low MAOA activity levels,
whereas previously they displayed the same levels of aggression as the healthy, neurotypical control group.
E- This suggests that although the interactionist approach may be a better explanation for aggression compared to biological determinism,
L- there is still a lack of clarity over the role of the stressor.
Outline a strength in the genetic approach of aggression
(twin study)
- This is backed up as using old Danish police records Christiansen (1977) demonstrated that levels of criminality showed a stronger correlation between identical twins (55%) – with the same genes – than between dizygotic twins (22%) .
CP: However criminality is not always the same as aggression. (Environment also plays a role)
Outline a strength in the genetic approach of aggression
(provocation )
P- evidence supporting a positive correlation between increasing MAOA activity levels and increasing levels of prosocial behaviour,
E- as demonstrated by Mertins et al (2011) who found that participants with high MAOA activity levels behaved more compassionately in a money-lending game, often with fewer provocations and refusals of offers.
E- Therefore, this suggests that the link between MAOA and aggression is valid because correlations in both directions (increasing and decreasing MAOA levels) are supported by research evidence.
Outline strength of the genetic approach to aggression (animal study
P-
strong link between MAOA activity levels and concentrations of serotonin, which has been based upon animal studies where researchers are able to ‘switch off’ or prevent the expression of the gene coding for the MAOA enzyme, thus allowing the researchers to study its effects in isolation.
E- For example, Godar et al (2014) found that when the MAOA gene was switched off in mice, these mice were ‘hyperaggressive’,
E- potentially due to the increased stimulation of postsynaptic neurons and increased amount of nerve impulses sent from amygdala to hypothalamus
L- Therefore, alongside additional evidence that the serotonin agonist ‘fluoxetine’ reverses this effect, increases the validity of the MAOA-aggression link.
Outline the ethological approach to explaining aggression& process
Ethological explanations draw links between animal and human behaviour, on the basis of studying animals in their natural habitats.
Conrad Lorenz (1950) proposed that aggression was an innate adaptive drive – evolved in humans and animals
- increasing survival : ritualistic behaviours , appeasment to the victor , making themselves vunerable & seeking new terrority
From the ethological perspective, aggression is adaptive because of two reasons:
1) aggression increases the chance of survival of a species through ritualistic beehaviours such as appeasement (trying to lessen the anger someone has towards you) :following an aggressive confrontation, the ‘loser’ will seek out new territory, increasing resources forthe species and so increasing their chances of survival.
-Secondly, aggression acts as a method of increasing one’s social status within a hierarchy, as demonstrated by Pettit et al (1988) : who found that young children use aggressive tactics in playgrounds to assert their authority, lead the others and have their way.
Outline the function of the IRM
a specific set of neurones that produces a FAP in response to specific sign stmuli
Outline the function of the FAP
innate fixed set of behaviours , occurs in response to specific sign stimuli
Outline how the IRM leads to the cascade of reactions by the FAP ( LEA)
The physiological process of an innate-releasing mechanism (IRM) is activated by a release signal, causing a cascade of the same series of behaviours, described as a fixed action pattern (FAP).
These can be characterised as being, according to Lea:
Stereotyped – behaviour follows a certain pattern each time.
Universal- all the animals in that species use the same type of threat.
Innate- all the animals in that species seem to be born with it and don’t have to learn it.
Ballistic- Once it starts it cannot simply be stopped.
Specific: only certain triggers seem to set it off
(SUIBS)
Outline research evidence for the FAP
Tinbergen (1951) who found that male sticklebacks will respond aggressively to model red spots (a releaser) which triggers the IRM , regardless of whether the model resembles a stickleback or not.
Fish showed a FAP to both a fake sickleback with a red dot and a piece of wood with a red dot
. Tinbergen’s study supports the idea that aggression is a FAP triggered by sign stimuli.
Evaluate a strength of the ethological explanation for aggression
P-evidence supporting the biological, innate basis of IRM and FAP systems.
E- there is researc to support the roe of the limbicc system in triggering aggression (E.G gospic et al Ultimatium game and Bremner study)
E- supports the suggestion that that aggression may be primitive , innate instinct therefore an adaptive trait
L- therefore role of IRM and limbic system ccan b valid explanation for aggression
eval weakness of ethological approach (chimpanz)
P- evidence to suggest that ritualistic aggression may not be displayed by all species and in all situations.
E- For example, Goodall’s (2010) observation of chimpanzees in a national park found that rival communities slaughtered each other in a systematic
fashion, despite appeasament and ritualistic signals being displayed by the victims.
E-This supports the idea that once a releaser has triggered the IRM, this will always lead to a FAP, however it is diffcult to be explained by konrad lorenz’s ritualistic idea of aggression (limiting validity)
Outline the evolutionary explanation of human aggression
- Through the process of natural selection we have evolved to display aggression as in the age of prehistoric man , aggression was an adaptive behaviour that helped us to survive and reproduce
-Sexual jealousy is stronger in males (compared to females) due paternity uncertainty, which may lead to cuckoldry i.e. a male raising a son which is not his own. This is an evolutionary disadvantage, due to the male wasting his resources which he could have otherwise used on raising his own children. Therefore, anti-cuckoldry behaviours, in the form of male retentive strategies, are adaptive because they reduce the risk of cuckoldry
- Therefore, there is a clear link between male retention strategies and aggression, the latter of which is usually used to implement such strategies.
Outline a weakness of the ethological explanation of aggression
(cultural relativism)
P- (lacks Cultural relativism) An ethological explanation assumes that behaviour is innate : should be uniform across all cultures.
E- However, Nisbett (1996) found that in a laboratory experiment when South American white males were insulted they were more likely to respond aggressively than white North American males under the same conditions.
E- This research demonstrates cultural differences that would be problematic for the ethological explanation to account for, as there was a high variation in aggressive responses.
