PAPER 3 - Aggression Flashcards
What are the two NEURAL mechanisms in aggression ?
- limbic system
- serotonin
What are the two components of the LIMBIC SYSTEM ?
- amygdala
- hippocampus
What is the role of the AMYGDALA ?
evaluating the EMOTIONAL IMPORTANCE of SENSORY INFORMATION and promoting an APPROPRIATE RESPONSE
What research was done into the amygdala ?
- Narabayashi 43 / 51 patients received operations destroying amygdala and showed more normal social behaviours after and reduced aggression
What is the STRENGTH for the amygdala ?
PARDINI- longitudinal study of male pp, received MRI scans at age 26, discovered lower amygdala volumes associated with higher levels aggression
shows amygdala plays an important role in evaluating importance of sensory information
What are the WEAKNESSES for the amygdala ?
EXACT ROLE IS UNKNOWN
- Muller = 6 male psychopaths / 6 non-psychopaths
- psychopaths = increased amygdala activity
What is the role of the HIPPOCAMPUS ?
- formation of long-term memories
- compare current situations/threat to past experiences
- impaired hippocampal functioning prevents nervous system putting things into relevant context so amygdala responds inappropriately
What research has been done in to the hippocampus ?
- boccardi = HABITUALLY VIOLENT offenders exhibited abnormalities of hippocampus functioning
What are the STRENGTHS for the hippocampus ?
RESEARCH
- raine = successful and unsuccessful psychopaths = MRI showed abnormalities/asymmetries in unsuccessful criminals as they were impulsive so got caught
- summer = 14yr old with tumour - epileptic seizures and aggressive manner
- treated with drugs - returned to normal
What are the WEAKNESSES for the hippocampus ?
NOT CLEAR CUT
- many components in limbic system - not sure which part causes what behaviour
may be interaction between the components
What is the role of SEROTONIN ?
and support for it
- communication of impulses between neurons
- normal levels have calming, inhibitory effect
- low levels in PFC remove inhibitory effect so individuals less likely to control their impulses or aggressive responses
-support from research showing major waste product of serotonin is low in people who display aggression
What research has been done in to SEROTONIN ?
mann et al - drug that depletes (use up) serotonin - questionnaire to assess hostility - those with drugs had increased hostility so lower serotonin = more aggression
strengths of neural mechanisms (serotonin)
- supportive evidence by crockett, studied pp in game playing scenario, half pp received SSRIs to increase serotonin, half had reduced serotonin through diet manipulation, those with lowered levels showed more retaliation against opponents
- practical applications= increasing serotonin levels may be beneficial for juvenile delinquents or institutionalised patients to reduce aggression
weaknesses of neural mechanisms (serotonin)
- supportive study by crockett has low validity as game playing is not a direct physical aggressive response
- deterministic, does not account for free will so problems may arise in law and order system
what are the two hormones in the hormonal mechanism
testosterone
cortisol
testosterone
hormone involved in development of masculine features, influences aggression in young adulthood
changes in testosterone levels influence aggressive behaviour by increasing amygdala reactivity in social threat
what is cortisol
hormone produced by adrenal medulla, reaction to stress
inverse correlation between cortisol and aggression
lower cortisol=higher aggression
when cortisol is high it blocks the influence of aggression
(carre and mehta suggest high testosterone only leads to aggression when cortisol levels are low)
strengths of hormonal mechanisms
TESTOSTERONE
- wagner el al
- when mouse is castrated aggression lowers
- when mouse injected with testosterone aggression increases
CORTISOL
- McBurnett
- longitudinal study on 38 boys referred to clinic because of problem behaviours
- boys with lower cortisol levels (saliva tests) were 3 times more aggressive than boys with high levels
weaknesses of hormonal mechanisms
-supportive research e.g wagner uses animals so the findings cannot be generalised to humans
- inconsistent evidence, some show positive relationship between aggression and testosterone but others don’t, e.g no correlation found between testosterone and actual violent behaviour in prisons
- correlations also do not show cause and effect, is the aggression causing high testosterone/low cortisol?
ways of studying genetic factors of aggression
twin and adoption studies
what is the gene involved in aggression
MAOA gene
twin studies and supportive study
-researchers compare degree of similarity for a particular trait for MZ and DZ twins
concordance must be higher for MZ for genetics to play a part
- coccaro: studied male MZ and DZ twins
- for physical assault 50% concordance for MZ and 19% for DZ
- for verbal assault 28% for MZ and 19% for DZ
adoption studies and supportive study
- untangle contribution of environment and genetics
- Hutchings and mednick studied 14,000 adoptions in denmark and found significant no. of boys with criminal convictions had biological parents with similar convictions, so supports genetic influence
support for twin and adoption studies
- miles and carey meta analysis of 24 twin and adoption studies showing genetic basis
weaknesses of twin and adoption studies
-supportive study by miles and carey show there may be other variables at play e.g age, assessment method may influence other factors that do influence aggression
-supportive studies use parental or self reports which can be bias e.g miles and carey used self report
these self report method studies show different findings to those of observations
- difficult to isolate genetic factors from environment e.g aggressive tendencies may only be expressed if the environmental conditions warrant it
MAOA
- Monoamine oxidase A (MAOA) is an enzyme which mops up neurotransmitters after nerve impulse has been transmitted
- breaks down neurotransmitter, specifically serotonin to be recycled or excreted
- production of enzyme controlled by MAOA gene, dysfunction of gene leads to abnormal activity of MAOA enzyme, affecting serotonin levels in brain
warrior gene and supportive study
- one variant of MAOA gene is known as the warrior gene which leads to low MAOA activity in areas of brain and has been associated with aggression
- Brunner studied 28 members of a large dutch family involved in aggressive and violent behaviors like rape murder and assault. it was found the men had abnormally low levels of MAOA(-L) in their brains and low activity version of the MAOA gene
support for MAOA and aggression
- Caspi et al studied 500 male children and found those with the low variant of MAOA were more likely to grow up and exhibit anti social behaviour
- practical applications as findings have uses in offender treatment and rehab. this info can help develop treatments
limitations of MAOA and aggression
- supportive studies show importance for genes and environment e.g Caspi found those with MAOA would only exhibit antisocial behaviours if they were maltreated as children
- problems with law and order system if genes cause aggression, people may be deemed biologically determined to commit aggressive acts, ignores freewill
what is the ethological explanation
- function of aggression is adaptive
- aggression establishes dominance hierarchies
- aims to understand innate behaviour of animals and humans by studying their natural environment
what is an innate releasing mechanism
ETHOLOGICAL
-innate releasing mechanism (IRM) is built in physiological process triggered by environmental stimulus which releases a specific sequence of behaviours called fixed action patterns (FAPs)
according to Lea, what are the 6 features of fixed action patterns
- stereotyped (unchanging sequence)
- universal (same for each individual in a species)
- unaffected by learning
- ‘ballistic’ (if triggered it follows an inevitable cause)
- single purpose
- response to specific identifiable sign/stimulus
what study demonstrated FAPs
TINBERGEN
- research stickleback fish
- male sticklebacks produce fixed sequence of aggression when another male enters territory
- the sign/stimulus is not another male but the sight of its distinctive red underbelly
ritualistic aggression (ethological)
- not all aggression involves fighting, rather threat displays
- e.g male gorillas beat their chest to intimidate an opponent without physical contact
e. g in some african cultures they jump to show who can jump the highest