Aggression

• what are the neural (brain) mechanisms in aggression

  - the limbic system

  - serotonin
• what is the limbic system?


  - structure in brain linked to instictive behaviours essential to survival (eg. feeding, drinking, defence)

  - includes hypothalamus, hippocampus + AMYGDALA

  
• what is the amygdala?

  - sub-section of limbic system

  - important in our emotions + instinctive drives

  - important predictor of aggression

  - HIGH LEVELS OF ACTIVITY IN AMYGDALA = POSITIVELY CORRELATE W/ HIGH LEVELS OF AGGRESSION

  
• what study shows the limbic system is linked to aggression?

  GOSPIC ET AL.

  - ultimatum game where Ps potentially provoke other Ps w/ unfair monetary offers

  - if Ps r provoked + respond w/ aggressive reaction (ie. rejecting monetary offer from spite) = amygdala - fast + heightened response

  - amygdala actvity measured w/ fMRI scanner

  - when given drugs which calm amygdala actvity (eg. benzodiazepines - reduces ANS activity) = fewer aggressive acts (after unfair offer)

  - HEIGHTENED ACTIVITY IN AMYGDALA = CORRELATE W/ AGGRESSIONS OF OFFER (IE. AGGRESSION)
• what drug was given to Ps in gospic et al study?

  - benodiazepines - reduces ANS activity
• what is serotonin + what does it do?

  - MOOD REGULATING neurotransmitter

  - has INHIBITORY EFFECT on several brain structures

  - suggested that ABNORMAL serotonin levels in the ORBITOFRONTAL CORTEX = linked to POOR SELF-CONTROL + IMPULSIVE BEHAVIOUR (ie. aggression)
• what correlation does serotonin have w/ aggression?

  NEGATIVE CORRELATION - low levels of serotonin lead to higher levels of aggression
• what studies show that serotonin is linked to aggressive behaviour?

  VIRKKUNEN = (natural exp) - compared violent, impulse PRISONERS w/ non-violent prisoners + measured CONC. OF SEROTONIN in CEREBROSPINAL FLUIDS - VIOLENT OFFENDERS = SIG. LOWER LEVEL OF SEROTONIN

  
  

  RALEIGH = manipulated MONKEYS DIETS (using TRYPTOPHAN - chemical which inc. serotonin) - those given diet HIGH in chemical = LOWER LEVELS OF AGGRESSION (ie. inc. serotonin = dec. aggression)
• what is the hormonal mechanism in aggression?

  - testosterone
• what is testosterone + what does it do?

  - androgen (male hormone)

  - primarily produced by testes

  - largely responsible for development of male features (+ possibly brain structure)

  - SUGGESTED TO PLAY ROLE IN REGULATING AGGRESSION (= face validity - males 20x more likely to go to prison)
• what studies show that testosterone is linked to aggression?

  GIAMMANCO = MANIPULATED test. level is various ANIMALS (dogs/ monkeys/ cats) + it led to CHANGES IN AGGRESSION

  
  

  DOLAN = MEASURED test. levels of PRISONERS + found POSITIVE CORRELATION - more violent criminals = higher levels of test.
• what are the strengths of neural/hormonal factors in aggression?

  - METHODOLOGICALLY STRONG EVIDENCE = highly scientific, controlled procedures, quantitve + objective measures, precise tech. equipmemt (eg. fMRI), replicable, strong internal validity (manipulated IVs)

  - CONCURRENT VALIDITY = countless other peices of research agreeing w/ findings - inc. validity - eg. genetics + MAOA research highlight role of serotonin (but testosterone explanation less well supported)

  - IMPORTANT IMPLCATIONS + APPLICATIONS = theories leada to effective treatments - if know whats causing aggression - eg. Gospics study - showed benzodiazepines were effective/ Bond - gave ps w/ anger management issues SSRIs + boosted serotonin activity - were effective
• what are the weaknesses of neural/hormonal factors in aggression?

  - AGGRESSION MORE COMPLEX THN SINGLE CHEMICAL/ STRUCTURE = cant reduce explanation to 1 variable, its a complex interaction of several structures + chemicals = interaction between amygdala + orbitofrontal cortex/ dopamine believed to be linked w aggression/ cortisol has mediating effect on testosterone - suggests other hormones linked to aggression (high cortisol, test. has little-no effect)

  - ETHICAL ISSUES W/ TESTING = cant test effects of neural/hormonal chemicals experimentally as causing aggression = serious consequences - so only correlational studies, apart from ANIMAL studies - but animals not comparable to humans

  - REDUCTIONIST = full explanation of aggression involves nature + nurture (interactionist) - eg. FRAZZETTO et al

  - LEGAL IMPLICATIONS = if bio. causes aggression, raises q on responsibility for blame - ie. ppl don't choose to be aggressive (its their bio) - so lack free-will = serious implications on legal systems + conviction for crime
• what is the frazzetto et al study?

  - ps w/ gene causing low serotonin activity, only those who experienced sexual/physical abuse (by 15yrs) showed aggressive behaviours

  - aggression requires vulnerability factors (genetics) + triggers (abuse) to emerge

  (- interactionist approach)

  (limitation of neural/hormonal + gentic factors in aggression)
• what methods of research test the genetic factors in aggression?

  - twin research

  - adoption research

  (tries to minimise impact of nature/environment + isolate effect of genetics)
• what is the twin research for the genetic factors in aggression?

  COCCARO - compared concordance rates in MZs + DZs

  - PHYSICAL aggression = MZs - 50%/ DZs - 19%

  - VERBAL aggression = MZs - 28%/ DZs - 7%

  (diffs. argued to be results of genetic diffs)
• what is the limitations of the findings from coccaro's twin study?

  - highest concordance rate = 50% - therefore the other 50% isnt due to genetics/ is due to environment)
• what is the adoption research for the genetic factors in aggression?

  RHEE + WALDMAN = meta-analysis of adoption studies

  - found the ppl who were aggressive, 41% of that aggression was due to genetics

  - if seperated at birth from aggressive parents + raised in good environments, those that became aggressive normally those w/ bio. aggressive parents
• what is MAOA + the MAOA gene?

  MAOA = mono amine oxidase-A

  MAOA = enzyme that regulates serotonin

  MAOA GENE = responsible for producing the enzyme (has several variants/mutations - eg. low activity MAOA gene)
• how is MAOA linked to aggression?

  (1st researched/proposed by BRUNNER)

  - gene variant/ mutation producing LOW LEVELS OF MAOA = relates to DISRUPTED SEROTONIN ACTIVITY + AGGRESSIVE BEHAVIOUR

  (- vice versa w/ high levels of MAOA)

  - having low levels of MAOA = makes u more VULNERABLE TO AGGRESSION
• what is the nickname for the low acitivity MAOA gene?

  - 'warrior gene'

  (+ disorder labelled as 'brunner syndrome')
• what was Brunner's research into the MAOA gene?

  - studied violent + aggressive DUTCH FAMILY

  - common denominator in violent members = low-activity MAOA gene variant

  - labelled w/ 'brunner syndrome
• what is other research into the MAOA gene/

  STUART

  - group fo 97 males convicted of partner violence

  - those most violent + abusive had the low-activity MAOA gene
• what are the strengths of genetic factors in aggression?

  - ROBUST, RELIABLE FINDINGS = large body of concurring data (fam/adopt/twin studies), inc. concurrent validity + meta-analyses show statistically sig. link between genetics + aggression (not questioned whether genetics contribute - cause proven they do, its how much they contribute?)

  - POSSIBLE USES + APPLICATIONS = developments in genomic medicine, new technique = CRISPR (cutting out undesirable genes in foetus + replacing w/desirable ones) - not been tested on humans yet, but in mice, results on aggressive behaviour was observed (ie. cut out MAOA - reduces aggression)
• what are the weaknesses of genetic factors in aggression?

  - ASSUMPTIONS OF GENETIC RESEARCH = assumptions of twin/adoption studies questioned - 'equal environments'/ 'random placements' - so genetics might play less sig. role in aggression than found in studies

  - MULTIPLE GENES PROBLEMS = no single gene explanation = META-ANALYSIS RESEARCH - VASSOS no evidence for single gene being sig. related to agg. (contradicts MAOA) - suggests 100/1000s interacting genes (+ environment) linked/ SEROTONIN GENES - several other genes regulate serotonin, may negate/dilute effects of MAOA/ INTERACTIONIST APPROACH - diathesis-stress model - shows genes on their own don't do much, have to see interaction w/ environment to fully understand aggression

  - MEASURING AGGRESSION = 'aggression' somewhat subjective some research = high security violent criminals, others = social rejection (ie. gospic). diff types of aggression + lots of research is self-report = social desireblity - dificult to compare + make diffinitive conclusion about aggression

  - GENE-ENVIRONMENT INTERACTION = reductionist. gene expression affected by environment, full explanation must be interactionist (nature + nurture). seen in twin studies - only 50% c. rates - other 50% must be environment. + FRAZZETO ET AL STUDY

  - LEGAL IMPLICATIONS = if genes 'cause' aggression, raises issues of free will + being blamed for crimes, as don't chose to be aggressive. Impacts how ppl punished/ sentenced
• what is ethology?


  the study of animal behaviour / animals in their natural habitats
• what insights have been found about aggression with ethological studies?

  - aggression is adaptive (for territory/ resources + status/ + access to mates)

  - aggression is often ritualistic (aggression rituals + appeasement rituals)

  - aggression is innate + triggered by certain stimuli (innate releasing mechanism (IRMs) + fixed action patterns (FAPs)
• what is meant by 'adaptive behaviour'?

  - behaviour is considered 'adaptive' if it's BENEFICIAL to an organism GENETIC SURVIVAL, whether that be through living longer or passing on genes via offspring

  - ie. aim to SURVIVE + REPRODUCE (is adaptive)
• how is aggression adaptive?

  - argues aggression is innate + genetically programmed response to environmental triggers (ie. threat to survival/ offspring/status)

  - so aggression is an evolved ADAPTIVE BEHAVIOUR that links to certain survival + mating advantages

  - eg. animals fight - not to kill competitors but to increases status - which inc. POSSESSION OF TERRITORY/ ACCESS TO RESOURCES/ ACCESS TO MATES
• what are examples of adaptive aggression towards territory/ resources + status/ + access to mates?


  FIGHT FOR:

  - TERRITORY = area that belongs to them/ environments they live in

  - RESOURCES/ STATUS = eg. food resources/ nests/ water/ etc status - their level of importance within their group (ie. king lion) (- highest status often 1st access to mates, food, etc)

  - ACCESS TO MATES = fight w/ others to secure a mate + inc. chance of reproduction + passing on genes
• what is a ritual?


  a sequence of activities including gestures, words + actions
• what does it mean by aggression often being 'ritualistic'

  - actual physical combat = very costly to all parties (even victor)

  - so if possible, disagreements + disputes r settled before resulting to physical combat w/ 'RITUATIALS' = THREAT DISPLAYS

  - if successful, won't try to initiate aggressive move

  (threat displays + appeasment displays)
• what are threat displays?

  - used to convince would-be competitors of their superior speed + strength

  - many of the ritualistic aggression displaces involves THREATS OF VIOLENCE

  - eg. snarling, showing teeth/claws, displays of physical size
• what is an example of a threat display?

  western gorillas

  - vocal + gestural communications when threatened. Silverbacks (alpha male) = hooting, throwing, chest pounding, leg kicks, + sideways running when approached

  (- intimidates opponent + shows physical strength)
• what are appeasement displays?

  - like threat displays, these r evolved behaviours used to minimise costs if defeat is likely

  (acceptance of defeat + subservience so damage is avoided)
• what is an example of an appeasement display/ritual?

  bearded dragon

  - waving = rests on 3 legs + lifts 1 front leg + slowly waves it in circular motion

  Dogs

  - rolling on its back - sign of submission
• what is meant by innate releasing mechanisms (IRMs)?

  - biologically evolved, inbuilt + automatic/instictive response or process in the brain which is triggered by specific stimuli in environment

  (stimuli provoke a reflex-like response + this triggers IRMs which in turn 'releases' a set of predetermined behaviour patterns = FAPs)
• what is meant by Fixed action patterns (FAPs)?

  - instinctive behavioural sequence within species that is triggered by specific stimuli

  - FAPs r the BEHAVIOURAL CONSEQUENCES of IRMs. (its an unconscious, immediate reflex)
• what are the characteristics of FAPs?

  - STEREOTYPED = always the same (don't change)

  - UNIVERSAL = they r displayed by all members of the species

  - BALLISTIC = once behaviour is initiated, it can't be stopped

  - SPECIFIC = response to a specific sign stimulus/trigger

  - INNATE = don't need to be learned + r unaffected by learning
• what is supporting research for IRMs + FAPs?

  TINGBERGEN'S STICKLEBACK STUDIES

  (- male sticklebacks get aggressive during mating season = evolved IRM to deal w/ other males

  - trigger for IRM = RED SPOT on underside of stickleback

  - when sees red spot = releases FAP = darting towards + ATTACKING object)

  
  

  - presented sticklebacks w/ VARIETY OF STIMULI that clearly WEREN'T sticklebacks BUT had a RED SPOT painted on

  - this causes the FAP + stickleback attacked it as tho it was male competitor

  - BUT when models LOOKED IDENTICAL to sticklebacks but had NO RED SPOT = they weren't attacked

  - therefore = RED SPOT WAS SPECIFIC SIGN STIMULUS