aggression

• the role of the limbic system in aggression

  the limbic system consists of a network of structures in the brain including the hypothalamus and the amygdala. It is thought to be involved in regulating emotional bvr such as agg.

  the reactivity of the amygdala is a predictor of aggressive behavior
• support for the role of the amygdala

  • Gospic et al 2011 - the ultimate game
  • proposer offered to split money with Ps who could accept or reject the offer so none gets any money
  • fMRI scans - when Ps rejected there was a heightened amygdala response
  • H/ the drug benzodiazepine (which reduces the reactivity of ANS) halved the no. of rejections
• neural mechanisms of aggression - the role of the OFC

  the hypothalamus has a role in integrating and expressing emotional responses, communicating with the OFC to control executive function (decision making) controlling agg. bvr

  serotonin has an inhibitory effect on the OFC - low serotonin means more firing of neurons reducing self control and increasing impulsivity and agg. bvr
• the limbic system AO3

  • supporting evidence - Pardini 2004 - a longitudinal study of 56M w/ history of violence, MRI found lower amygdala volumes
  • partial explanation - the role of other brain structures OFC not part of the limbic system yet distinct role - Cocarro et al - lower OFC activity in psychiatric patients displaying agg, bvr - reduces the validity of the neural explanation
  • r. into effects of drugs - Passamonti 2012 tryptophan needed for serotonin, tryptophan deficient die, Ps shown angry/neural faces fMRI - reduced communication of OFC and amygdala
• the role of testosterone in aggression

  male sex androgen - linked to agg bvr - men generally have more agg

  testosterone has a role in regulating social bvr, high levels of testosterone in the OFC reduces activity so less able to regulate agg impulses and increases amygdala activity - castration studied have shown that removing the testes reduces agg. bvr in animal
• testosterone AO3


  • animal R. castration studies - e.g Wagner 1980 agg in mice measured biting patterns, castration of male mice meant diff in males and females agg disappeared - h/ animal studies - risk of anthropomorphism
  • dual hormone hypothesis - when testosterone high agg bvr only takes place if cortisol is low as cortisol when high blocks testosterone influence - may be better combined as predictor, a partial explanation
  • biologically deterministic - application to court/ legal system
• genetic factors in aggression - twin and adoption studies


  twin - suggests heritability, accounts for 50% variance in genetic bvr

  e.g Cocarro et al - concordance rates for direct physical assult 50% MZ , 19% DZ - suggests a genetic influence

  adoption - similarities in adopted child and bio parents suggests genetic basis - Mednick 1975, 40000 danish adoptees, boys w/ criminal convictions had bio fathers also w/ criminal violence
• genetic factors - MAOA gene

  controls the production of enzyme MAO-A which regulates serotonin levels - lower serotonin levels leads to impulse and agg bvr as removes inhibitory effect, mutations of the MAOA gene have been linked to agg bvr - warrior gene

  • Brunner et al, 28 men w/a history of violence from a Dutch family found to have MAO -L gene and low levels of MAO-A enzyme - agg bvr
• genetic factors - AO3

  • twin studies, twins rarely separated so same envt, furthermore MZ not 100% suggests an environmental explanation - lacks validity
  • MAOA gene may explain diff in gender - the gene is X linked - only inherited by males as no second healthy X chromosome - may explain gender differences
  • reductionist - single gene e.g warrior gene - oversimplification - interactionist approach more ideal - e.g childhood trauma stressor, more holistic view more beneficial
• ethological explanation for aggression AO1

  • suggests agg adaptive, beneficial to survival
  • ritualistic agg - species will respond with the same set of bvrs to threats - Lorenz
  • innate releasing mechanisms - in buiilt process triggered by stimuli - predictable
  • results in fixed action patterns - stereotypes, unchanging, universal, unaffected by learning, ballistic agg response to identifiable stimuli
• ethological explanation AO3 - Tinbergens research


  male sticklebacks have red spot on their belly - sign stimulus

  when shown model fishes regardless of how life like if red spot set of FAP's stimulated as IRM triggered - agg attack, unchanging always ran course
• ethological explanation further AO3

  • In humans FAPs are not fixed - Lorenz original view is outdated, Hunt found the environment influences FAPs and are modifiable, therefore more flexible than thought
  • animal studies able to separate biological and socio-cultural influences when studying agg bvr - provides insight h/ hard to generalise to humans
• evolutionary explanation for aggression

  suggests survival advantage - aggression provides reproductive success - sexual jealousy in males due to paternal uncertainty means adaptive bvrs such as male retention strategies used to ensure genes are passed on and resources are not wasted

  • male retentive strategies - direct guarding - over vigilance of partner, negative inducements
  • lowers risk of infidelity and ensures resources spent on own children

  Bullying due to power imbalance - naturally selected for greater reproductive success by warding off rivals
• evolutionary explanation AO3


  • can explain gender diff - fear of cuckoldry unique to men, furthermore campbell - not adaptive for females to be agg as puts her survival and child at risk, therefore higher verbal agg to retain partner for resources
  • cultural differences - same evolution yet some cultures diff, e.g !Kung San known to be harmless people, negative attitudes towards agg bvr, therefore not necessarily adaptive h/ potential observer bias - homicide rates high for seemingly 'harmless' people
  • real world app - reduce bullying, reward prosocial bvr as an alternative source of status
• the frustration-aggression hypothesis AO1

  Dollard and Miller 1939 - psychodynamic theory, agg always caused by frustration, frustration happens when prevented from achieving a goal by external factors

  aggression relieves frustration through catharsis - reducing agg drive

  agg often displaced, when the cause of agg can be directed at - agg displaced onto weaker, non abstract available alternative e.g family member
• frustration-agg hypothesis AO3 Russel Geen

  • r. support - Russel Geen 1968 - Uni students given jigsaw puzzle, frustration level manipulated - 1. impossible puzzle, 2. ran out of time due to interrupting cofed, 3. confed insulting Ps - all ps opportunity to give electric shock to confed - all frustrated groups gave higher shock that control not frustrated, insulted gave highest and more shocks - h/ lab ex demand characteristics
• frustration - agg hypothesis further AO3

  • role of catharsis - may not be cathartic, Bushman - ps whop vented anger by hitting punchbag more agg that those who did nothing - central assumption not valid
  • cant explain why some resist - frustration not always lead to agg and takes place without, therefore inadequate explanation - Berkowitz explained frustration merely creates readiness for agg, presence of agg cues e.g weapon effect, shock higher when gun on the table - suggests envt factor
• SLT as applied to aggression

  acknowledges agg can be learned directly through operant conditioning and reinforcement h/ agg can also be explained through observational learning and imitation of role models

  • observing agg RM, when role model rewarded imitation of agg bvr due to vicarious reinforcement
  • for children to learn must display mediational processes, pay attention, and retain actions to reproduce - motivation id rewarded
  • role models more likely to be imitated of agg bvr if can be identified with, after internalising agg bvr - self efficacy
• SLT in aggression AO3

  • Bandura bobo doll
  • real world application - reduce agg by rewarding non agg role models - antibullying
  • research methods - Bandura lab ex high int validity h/ demand characteristics
  • underestimated biological influences
• deindividuation AO1


  LeBon 1895 - bvr constrained by social norms yet when part of a crowd able to lose restraint - loss of self awareness and personal control leads to agg bvr

  deindividuated bvrs are emotional, impulsive, irrational and disinhibited

  conditions of deindividuation that promote agg bvr - drugs alcohol anonymity

  in crowd reduction is public and private self awareness resulting in less accountability of actions

  anonymity lowers inhibitions by uniform and dark glasses
• deindividuation AO3


  • R support Dodds - 229 psych students if they could do anything and would not be detected or held responisble what would they do - 3 independent raters , 36% antisocial bvr, 26% criminal 9% prosocial - link of anonymity, deindividuation, and agg
  • real world app - can explain agg bvr of crowds - Mann 1981 - suicidal jumpers often bated by crowds - validity to idea of a faceless crowd - application in terms of well lit areas, CCTV
  • nature/nurture - not full explanation
• institutional aggression 


  • dispositional explanation - importation model, Irwin and Cressy - prison inmates bring w/ them a subculture of criminality including personal beliefs, norms, attitudes as well as gender and ethnicity - the willingness of agg bvr reflects lives before institutionalisation - inmates use agg to gain power and status
  • situational explanation - deprivation model, agg due to prison envt, harsh conditions stressful for inmates so cop w/ agg bvr - deprived of freedom, sexual intimacy, goods and services leads to competition between inmates
• dispositional explanation AO3


  • R support - Mears et al - compared street code beliefs of inmates and prison experience - found the code of the street influenced inmate violence, particularly with those lacking family support and in prison gangs
  • H/ DeLisi challenges the claim of prior gang membership resulting in prison violence - found no more likely of agg bvr than other inmates
  • deterministic
• situational explanation AO3


  • R. support - Mercocke et al - 371 US prisons, found situational factors such as overcrowding and lack of privacy significant influencer of inmate violence
  • real world application - HMP Woodhill designed to be less 'prison-like' reduced temp and noise - assaults on staff and inmates almost eradicated - benefits government
  • contradictory evidence - Haver and Steffernmeir - 84000 inmates - concluded race, age and criminal history more important predictors
• media influences - effects of computer games

  • games active role and reward system promotes operational conditioning - correlational studies e.g DeLisi - found time spent playing video games and agg correlated - should be considered a public health issue
  • excessive tv viewing - linked to agg bvr regardless of whether violent or not, Robertson et al - 100 NZ longitudinal studies, found time spent viewing Tv in adolescence predictor of agg bvr
• media influences AO3


  much of R correlational, not causation

  lab ex - demand characteristics

  findings can be explained by SLT
• desensitisation, disinhibition and cognitive priming

  • desensitisation - repeated exposure to violent media results in the normal reaction of discomfort, increased heart rate, bp, being reduced, less empathy for the victim felt and injuries minimised
  • disinhibition - generally not agg due to antisocial and harmful h/ these usual restraints are loosened after violent media, repeated exposure to justified agg in media results in new social norms
  • cognitive priming - repeated agg media creates new schema for how to respond in certain situations, process automatic and stimuli results in agg
• desensitisation AO3


  Weisz and earls - straw dogs w/ prolonged rape seen, Ps shown rape trial - compared to non sexually violent film, male straw dogs viewers showed increased acceptance of rape myths and sexual agg, less sympathy for trial victim, less likely to find guilty

  • alternative explanation of catharsis
• disinhibition AO3


  Berkowits and Alioto - Ps who saw revenge film gave more electric shocks of longer duration - media violence may disinhibit agg if presented as socially acceptable and justified
• cognitive priming AO3

  Murray 2006 - scanned brains of 8 children watching violent and non violent videos - found violent media activated area of brain associated with LTM - suggesting cognitive priming and schema formation

  • confounding variable of complexity - violent video games more complex - complexity causing priming not violence - Zendle et al - when complexity removed priming effects of violent games disappeared
• cognitive priming AO3

  Murray 2006 - scanned brains of 8 children watching violent and non violent videos - found violent media activated area of brain associated with LTM - suggesting cognitive priming and schema formation

  • confounding variable of complexity - violent video games more complex - complexity causing priming not violence - Zendle et al - when complexity removed priming effects of violent games disappeared