UNIT 3 AGGRESSION (PART B)

UNIT 3 AGGRESSION (PART B)

1. Genetic Factors

   • Twin Studies
     • Identical twins compared to non identical for levels of aggression. Identical twins share the exact genetics, non identical 50%
       • If identical twins have similar aggression levels, due to genetics
     • McGuffin et al. Identical twins correlated more at 87%, non identical 72%
       • On first glance supports the basis of genetics behind similarities.
         • However, non identical also had high correlation, this could be down to environmental factors. Therefore family environment may play a big factor.
     • Finding large number of identical twins which are reared apart if rare, most studies rely con comparing non to identical twins.
       • Non identical twins seen as individuals. Identical twins may be treated the exactly the same way, making behaviour in turn similar due to same exposure.
         • Argument that similar behaviour may be due to learnt behaviour and not genetics.
   • Adoption Studies
     • Examines correlation of aggression between adopted children and that of biological parents.
       • Correlation between biological then genetics
         • Correlation between rearing family then environmental
     • Hutchings et al conducted study of 14,000 adopted Danish children.
       • Significant positive correlation between no. of convictions for biological parents and that children who been adopted.
         • Have to take into account environmental factors, adopted children may have harder time adapting to environment.
           • Learnt behaviour from biological parents or even stigma that is attached with being adopted affect how they are treated by friends, family and even how they view themselves.
       • Cultural bias, based in Denmark, cannot generalise to other cultures.
   • MAOA Gene
     • Brunner et al - Breakthrough study on Dutch family, males had history of serious violent crimes. Low levels of MAOA found, and later defective gene found.
       • Adds weight to argument genetics could be at work to lead people more prone to violence.
       • However, behaviour could be explained due to similar exposure and learning from role models from within family - Social Learning Theory
         • Only males were tested, no females checked nor were they commonly found to have aggressive dependancies, despite 50% chance of carrying gene.
           • Results are inconclusive.
     • Gene that regulates metabolism on Serotonin. Low levels associated with aggression.
       • A faulty variant of gene could result in lower levels of Serotonin.
     • Caspi et al offered alternative view how genes interact with the environment.
       • Studied 500 children, half high levels of MAOA, other half had low MAOA
         • Low levels were associated with higher aggression, but only if they were maltreated as children
           • High levels and were mistreated and low levels and where not mistreated did not exhibit any anti social behaviour
             • Suggests that faulty genes may increase possibility of aggression, but need to be psychological stressors
   • Effectively asking the question of Nature vs Nurture.
   • IDA
     • REDUCTIONIST
       • Proposes genes alone as response for aggression, little control over. Ignores cognitive, psychological or cultural factors.
     • DETERMINISTIC
       • People have ability of free well and making their own decisions, those found with aggressive gene not always found to be aggressive.
     • ETHICAL CONCERNS
       • Genes identified may lead to stigmatisation of people or even chemical castration, or even push people towards genetic engineering.
     • METHODOLOGICAL PROBLEMS
       • Most research based on correlational data
         • Cannot infer cause and effect, as many unknown variables may exist in between that contribute to results.

2. Neural & Hormonal Mechanisms

   • Dopamine
     • Higher levels believed to cause aggression. Support comes from Amphetamines - show increase aggression in normal people.
       • Antipsychotics found to reduce aggressive behaviour in schizophrenics.
     • Other research suggests different role, it is known Dopamine is produced as a response to rewarding stimuli.
       • Some individuals may intentionally seek aggressive encounters because of the dopamine release rewarded.
         • Couppis et al
   • Serotonin
     • Believed to reduce aggression by inhibiting responses to emotional stimuli that might led to aggression.
       • Low levels of serotonin in brain, particularly prefrontal cortex has been linked with higher chances of aggression.
         • Mann et al - 35 healthy subjects given drug depleted serotonin levels
           • Judged aggression based on hostility scores on questionnaire; found lower levels serotonin with higher levels of aggression.
             • Found link in males, not females.
     • Raleigh et al - increased/decreased serotonin in vervet monkeys
       • Monkeys on diets that increased serotonin levels, less aggression.
       • Monkeys in diets that lowered serotonin levels, exhibited more aggression.
     • Ferrari et al - Support for both Serotonin & Dopamine. Allowed rats to fight period of 10 days.
       • 11th day didn't fight, measured levels of serotonin and dopamine.
         • Elevated dopamine levels and reduced serotonin, even though rats had not fought.
           • Claim this hows experience had changed brain chemistry by altering serotonin & dopamine levels
             • Allow us to draw conclusions, as experimentation on humans unethical
               • Animal research still unethical and morally wrong, potential suffering.
                 • Findings cannot be generalised, humans have difference biology and anatomy
   • Hormones
     • Testosterone
       • Male sex hormone, link with aggression not clearly cut.
         • Testosterone level peak around start of puberty, also peak in aagression levels in boys
           • Cause and effect, some theories suggest aggression produces testosterone and not vice versa.
       • Mixed results from studies.
         • Bain et al - found no significant difference in testosterone levels between violent offenders charged with murder and non violent with burglary
           • Albert et al claimed despite possible correlation, most studies small samples of only men, usually within prisons & self reports.
             • Lack internal validity
         • Kreuz & Rose also found no difference in testosterone levels comparing prisoners with records for fighting and non fighting.
           • However, those with higher violent crimes in adolescent had higher testosterone than those with no history.
             • Researchers believe when you place individuals in social environments at risk of developing aggression, testosterone may be an important additional factor.
     • Cortisol
       • Believed to have mediating effect on hormones such as testosterone, higher levels increase anxiety and inhibits testosterone.
         • Habitually violent offenders have lower levels of cortisol.
       • Low cortisol levels is unpleasant, thus seeking aggression as a means to promote cortisol release.
       • Studied young children over period of 4 years, those with low cortisol levels 3 times more likely to be more aggressive.
         • Suggests possible link, but cannot be certain of cause and effect. Other unknown variables may lay in between
         • Mcburnett et al
   • IDA
     • REDUCTIONIST
       • Ignores the role of cognitive and psychological factors
         • Not everyone with neural/hormonal imbalance is aggressive, all research based on correlational, unreliable and oversimplifying.
     • DETERMINISTIC
       • Assumes people always act aggressively, ignores the role of free will and ability of conscious.
     • GENDER BIAS
       • Most research based on males, cannot generalise to women.
         • Very few comparison studies, suggesting gender bias and gender differences.
           • Women found to be less prone to violence, however no research done to find links with cortisol, serotonin or dopamine.
     • METHODOLOGICAL PROBLEMS
       • Mann et al study used questionnaires
         • Participants may have shown demand characteristics expecting themselves to behave more aggressively due to taking drugs, results may be inaccurate.