Aggression Flashcards
What is the most important structure in the limbic system
Amygdala
What is a simple and summarised definition of the limbic system
Subcortical structures in the brain thought to be closely involved in regulating emotional behaviour including aggression.
What components of the brain is the limbic system made out of (name the two main components)
- Fornix
- Cingulate gyrus
- Thalamus
- Hippocampus *
- Amygdala *
- Hypothalamus
What is the hippocampus and what may an impaired hippocampus prevent
- Involved with the formation of long - term memories and so allows one to compare a current threat with similar past experiences
- An impaired hippocampus prevents the nervous system from putting things into a relevant and meaningful context and so may cause the amygdala to respond innapropriately to sensory stimuli
What does the amygdala do
- Plays a key role in humans in animals and how they respons to their environment (threats and challenges)
- Fight or flight
- Heightened activity in amygdala = increased aggression
- Responsible for quickly evaluating the emotional importance of sensory information and prompting the appropriate response
What is the Ultimatum game (and who created it)
Gospic et al:
- 2 players
- The proposer offers to split the money in a certain way with the responder (often unfairly split towards the proposers advantage)
- If the responder accepts then the money is split as proposed
- If rejected both receive nothing
- Responders have their brains scanned (fMRI)
- When responders rejected offers their amygdala showed heightened response
What did results show of the ultimatum game if responders had taken benzodiazepine before
- Halved the number of rejections
- Decreased amygdala behaviour
What two hormones are associated with aggression
- Serotonin
- Testosterone
How is serotonin associated with aggression
- Serotonin = a neurotransmitter involved in communication of impulses between neurons
- Has wide spread inhibitory effects and dampens neuronal activity
- Normal levels of serotonin in the orbital frontal cortex are linked with reduced firing of neurons and is associated with self control
- Low levels of serotonin disturbs this mechanism = no self control leading to impulsive behaviour- aggression (Denson et al)
What do decreased levels of serotonin mean in a person and how may you overcome this issue
- Decreased levels of serotonin mean that neural impulses are not dampened when they start to fire more (no inhibitory effect)
- Self control is harder to maintain = aggression
- SSRIs taken - prevention of serotonin being reabsorbed by presynaptic transmission and therefore dissapearing from the bloodstream so normal levels remain
How is testosterone associated with aggression
- Men often more aggressive than women (have higher levels of testoterone)
- Testosterone has a role in regulating social behaviours via its influence on certain areas of the brain
What are 2 supporting studies for the association of testosterone and aggression
- Giammanco et al - Used animal studies to demonstrate experimental increases in testosterone are related to greater aggressive behaviour in several species
- Dolan et al - found a positive correlation between testosterone levels and aggressive behaviours in a sample of 60 male offenders in UK maximum security hospitals - these men mainly suffered from personality disorders and have histories of impulsively violent behaviours
What is one weakness on the explanation of aggression and neural mechanisms (the limbic system)
- Recent studies indictate that the amygdala does not operate in isolation - functions in tandem with the orbifrontal cortex (not part of the limbic system)
Normal levels of serotonin in orbifrontal cortex = self control
What are 2 strengths on the explanation of aggression and hormones
- Drugs that increase serotonin activity also reduce levels of aggression
Berman et al - gave participants either a placebo or a dose of paroxetine (enhances serotonin activity) - participants then took part in a lab based game in which shocks were received in response to provaction. The paroxetine participants consistently gave fewer and less intense shocks - this was only evident for those with prior aggressive history - Higher levels of testosterone found in men than women - can explain why men are generally more aggressive than women
Who first identified the XXY karyotype
Sandberg
What research evidence does Court-Brown have on the XYY karyotype
Found that of a sample of 314 patients in a high security hospital , 15 were found to have chromosomal abnormalities and 9 had an extra Y chromosome and had an increased likelihood of aggressive behaviour
Rutter et al’s Twin Study - procedure and findings
Procedure:
Carried out a meta-analysis of twin studies on criminality
Findings:
Dizygotic twins have concordance rates between 13 & 21% and monozygotic twins have concordance rates between 26 & 51%
Both types of twins grew up together - difference is as such likely to be genetic
Medrick, Gabrielli and Hutchings Adoption Study - procedure and findings
Procedure:
Studied the criminal records of all Danish children adopted between 1924 - 47
Findings:
- If criminal records of adopted children were more similar to those of their biological parents than adopted parents it suggests there is a genetic component
- Having a criminal biological father increased the risk of criminality but the highest risk was for those with a criminal biological father and criminal adoptive father
Which approach would agree and support Medrick, Gabrielli and Hutchings adoption studys conclusion
Interactionist - Diathesis - Stress model : Have genetic vulnerability but also need external stressor to trigger development of condition
Belyaev - Animal breeding study - Study and findings
- Aim was to reduce the aggressiveness of the Silver Fox to make them easier to breed for their much sought after fur
- After 18 generations the animals were tame (similar to dogs)
- Unfortunately for Belyaev the animals also now resembled dogs aswell so the fur they required no longer existed
- The programme was also able to breed extremely aggressive silver foxes - supports hypothesis genes are involved with aggression
What may be a weakness of Belyaevs animal breeding study
Difficult to generalise results to humans (extrapolation)
How does the MAO- A gene work
- Gene produces Monoamine Oxidase (an enzyme) - role is to ‘mop up’ / break down neurotransmitters (dopamine,norepinephrine and serotonin) in the brain after a nerve impulse has been transmitted from one neuron to another
- It does this by breaking down the neurotransmitter into constituent chemicals to be excreted or recyled
What might having too little of MAO-A mean for a person
Too little of the gene leads to the brain being flooded with too much serotonin, norepinephrine and dopamine which eventually leads to a lowered sensitivity to these neurotransmitters
How did Brunner et al study the MAO-A gene
- Studied 28 male members of a large Dutch family who were repeatedly involved in impulsively aggressive violent criminal behaviours
- Had abnormally low levels of MAO-A gene in their brains and the low activity version of the MAO-A gene
What is one variant of the MAO-A gene referred to as which leads to MAO-A low activity in areas of the brain
‘The warrior gene’
what does GxE interactions stand for
Genes x Environment
What is low MAO-A gene activity only related to aggression when combined with…
… early traumatic events
What are 3 weaknesses of the genetic factors of aggression
- Difficult to isolate genes - Not easy to seperate genetic and environmental factors - GxE interactions
- The sizes of genetic effects are statistically significant but also small - probably other genes involved
Vassos et al - in a meta-analysis could find no evidence of an association between any single gene and aggression
Hundreds or thousands of genes interact in complex ways to determine aggressive behaviour
Shows there is no single candidate gene (SUPPORTS MODERN DAY IDEA OF THE DIATHESIS-STRESS MODEL) - Methods of measuring aggression differ between studies and include self-reports, parent and teacher reports and direct observations
Findings as such vary - difficult to draw valid conclusions
Who developed the ethological approach
Lorenz
What do ethologists believe in terms of aggression
Whilst the potential for aggression may be innate, actual aggressive behaviour is triggered by environmental stimuli known as releasers
- Aggression is adaptive and promotes survival
What does FAPs and IRM stand for
FAP = fixed action pattern
IRM = Innate releasing mechanism
What is the process of an IRM and FAP
An IRM is a built-in physiological process or structure (e.g a network of neurons in the brain). An environmental stimulus (e.g a certain facial expression) triggers the IRM which then triggers a specific sequence of behaviours (FAP).
What are Leas 6 main features of a FAP
- Stereotyped/ Relatively unchanging sequences of behaviour
- Universal - same behaviour is found in every individual of that species
- Unaffected by learning - same for all regardless of experience
- ‘Ballistic’ - once the behaviour is trigerred it follows a predicted cource and cannot be altered before it is completed
- Single purpose - behaviour only occurs in a specific situation
- A response to an identifiable sign stimulus
Timbergen procedure and findings of FAPs and IRMs (male sticklebacks)
Procedure:
- Male sticklebacks = highly territorial during the spring mating season, when they also develop a red spot on their underbelly
- If another male enters their territory, a sequence of highly-stereotyped aggressive behaviour is initiated
- The sign stimulus that trigger the IRM - red spot
- Timbergen presented sticklebacks with a series of wooden models (of ‘fish’) of different shapes
Findings:
- Regardless of shape, if the model had a red spot the stickleback would aggressively display and even attack it
- No red spot = no aggression (despite shape)
- FAPs = unchanging
What does ritualistic aggression mean
Fights between the same species often use little physical aggression (maintains survival of species)
Aggressive encounters consisted mainly of a period ritualistic signalling (e.g displaying claws and teeth and facial expressions)
How do ritualistic aggressive confrontations end
Ritual appeasement - acceptance of defeat (e.g laying on belly or exposing neck)
What animal does Lorenz compare humans too and why
Doves - Humans are non-hunters so haven’t developed the same fearsome weapons other animals have (sharp teeth or claws)
What are 2 (+) weaknesses of the ethological explanation of aggression
- Lehrman - Lorenz underestimated the role of enviornmental factors - FAPs tends to not be used in ethology now and is rather referred to as behaviour patterns to acknowledge the role of experience : subtle variations between aggressive behaviours of the same species suggesting it isn’t fixed
- Cultural differences - aggressive behaviour is more common in some human cultures than others
- The view that aggression has evolved into a self-limiting and relatively physically harmless ritual has been challenged by observations made from Jane Goodall - Chimpanzees had ‘four-year war’ where male chimps from one community set about systematically slaughtering all members from another group
- Eibl-Eibesfelt - humans have FAPs such as smiling and the ‘eyebrow flash’ but believes that FAPs such as aggression are not adaptive in modern times
What is one strength of the ethological explanation of aggression
Brunner et al - Low activity variant of MAO-A gene is closely associated with aggressive behaviour - showing that aggression is innate (similar to IRM) + limbic system has shown to trigger aggressive behaviour
ethology = genetically determine + heritable
validity is supported by evidence that demonstrates the genetic and physiological basis of aggression
In the evolutionary explanation for aggression what is aggression the result of
Sexual competition (sexual jealousy) to ensure reproductive success
What does paternity uncertainty stand for
Men can not be 100% sure if they have fathered a child
Paternity Uncertainty is the result of the very real threat for the male cuckoldry
What are the two male retention strategies and what do they mean (Wilson & Daly)
- Direct guarding:
Male vigilance over a partners behaviour - e,g checking who they’ve been with and where, coming home early and going through personal belongings - Negative inducement:
Such as issuing threats of dire consequences for infidelity
