Aggression

Aggression

1. Institutional aggression

   • Importation
     • People bring their traits and values into the institution with them
       • If enough people value aggression institutional aggression will occur
     • Harer et al
       • Black inmates had higher rates of aggression but lower rates of drug and alcohol related misconduct
         • This matches the differences in the general US population
     • Hard to control all variables
     • Social sensitivity
       • Needs to be considered when deciding what to publish in order to avoid reinforcing false negative stereotypes
   • Deprivation
     • The deprivations that prisoners are faced with cause them to behave aggressively
     • McClorke et al
       • Lack of privacy and crowding influence peer violence
     • Zimbardo
       • When psychologically normal people were put in a prison setting they became aggressive
     • Nijman et al
       • Increased space didn't increase aggression
   • Jiang Fisher-Giorlando
     • DM - better able to explain violence against staff
     • IM - Better able to explain aggression against other prisoners

2. Hormonal explanations

   • Serotonin
     • Has a calming effect on the brain
     • Low = Aggressive
     • Mann et al
       • 35 adults - given drug to deplete serotonin
         • Aggression and hostility measured by a questionnaire
         • Aggression increased in men
     • Ferrari et al
       • Made rats fight at the same time for 10 days
         • On the 11th day they didn't fight but still had low levels of serotonin
     • Increased alcohol = decreased serotonin = increased aggression
   • Serotonin receptors
     • High = aggression
     • Mann et al
       • Looked at individuals who had committed suicide and found that as methods became more violent levels of serotonin receptors increased
     • Badamy
       • Alcohol disrupts serotonin metabolism
   • Testosterone
     • Makes in more likely that an action will be expressed
     • Archer
       • Meta-analysis of 5 studies
         • low positive correlation between testosterone and aggression
     • Bain et al
       • no significant differences between men charged for murder and men charged for nonviolent crimes
     • Kreuz and rose
       • 10 out of 21 prisoners they looked at with histories of more violent crimes in adolescence showed increased levels of serotonin
     • Zitzmann
       • Link between testosterone and aggression probably only relevant in athletes who supplement their testosterone to exceedingly high levels

3. Genetic explanations

   • Twin studies
     • Mason and Frick
       • Meta analysis 12 twin studies approx. 50% of the difference between antisocial and non-antisocial behaviours could be attributed to genetic factors
     • McGuffin and Gotseman
       • concordance rate of 87% for aggressive and antisocial behaviour in MZ twins and 72% for DZ twins
     • Coccaro et al
       • 182 MZ and 118 DZ twins
         • genes accounted for more than 40% of the differences in aggression, Environment accounted for around 50% in physical aggression and about 70% of verbal aggression.
     • It is hard to find high numbers of MZ twins reared apart
       • This means most of the twins studies share genes, environment and most people treat them the same
   • Adoption studies
     • Hutchings and Mendick
       • 14000 adoptions in Denmark
         • significant positive correlation between the number of convictions for criminal violence among the biological parents and their adopted sons
     • Methodological problems
       • children given up for adoption display a higher rate of antisocial behaviour at the time of their adoption compared with the general population
   • Miles and Carey
     • 24 twin and adoption studies
       • strong genetic influence which accounted for as much as 50% of the variance in aggression.
   • Difficult to distinguish between violent and non-violent crimes
   • Many studies don't distinguish between people who are continually violent and those for whom it is a one off event
   • Findings from genetic research on antisocial and violent behaviour may have some valuable uses in offender treatment and rehabilitation.