Unit 3: Aggression: Bio exp.

Unit 3: Aggression: Bio exp.

1. NEURAL MECHANISMS:

   • SEROTONIN(ST): Neurotransmitter-over past 50 years, studies on effect of ST on agg using animals. ST influences agg+vio beh. vST levels=impulsive beh, alcohol abuse, violent suicide, overeating, depression, agg.
     • Eval: I-Evid. to supp. ST influence. E-DAVIDSON-suggested that ST may provide inhibitory func. When comparing vio crim/non-vio crim, levels of ST were lower in vio. E-Deterministic, not allow for free will, important implications that crims. not to blame. L-TF while there is supporting research, it does not consider other factors, therefore reductionist.
   • AMYGDALA: Plays significant role in emo. resp. Careful lesioning of AMY in animals has a taming effect. POTEGAL-showed that hamsters have more active neurons in AMY during acts of agg. No other inc. in other areas.
     • Eval: I-Evid. to support AMY. E-ZAGRODSKA-damage to cats AMY was a sig. contributor to pred. like attacks. E-Animal research-lacks generalisability. BATESON emphasised need to limit anim. suff. while advancing of psych understanding. L-TF appears to be good support for NEu exp of agg.
   • FRONTAL CORTEX (FC): controlling agg. resp. Evid. of this in indivs. with damage-impulsiveness,irritability+easily provoked. HARLOW-Phineas Gage-frontal cortex damage, noticeable changes, agressive
     • Eval:I-Evid to supp. theory of brain damage. E-HARLOW-Phineas Gage-otherwise hardworking, quiet-turned negative, aggressive after accident. E-Case study-one indiv, cannot generalise, also element of bias bc wanting to support previous claims. L-TF despite compelling nature, low valid. limits use for FC

2. HORMONAL MECHANISMS

   • ANDROGENS- M sex Hormones, Testosterone (T)-Produced by Leydig cells, release of this hormone and can affect agg.
     • Eval:I-Further research to strengthen the argument that AND plays role in agg beh. E-WAGNER-castrated M mouse=(-)agg, if cast mouse receives (T)=(+)agg. E-Anim. generaliseability. POTEGAL-argue humans=non-humans, so should be able to gen. with confidence. L-TF this evid. can be used to exp. agg. beh. in humans
   • NELSON- +correlation, in level of androgens=agg beh. in M+F prisoners
     • Eval:I-And levels play imp. role in agg, supp. res. E-Bc it shows that prisoners with ^levels of and=^agg. E-Cannot establish C+E, also ethnocentric, financial incentives to study, culturally specific. L-Can TF be argued that while Nelson's research supports agg=and., methodological issues.
   • DURING PUBERTY- agg^ when andr. lev. are ^
     • Eval: I:- of AND is Individual Differences(ID) E-HARRISON: after giving 56 men (T)+frustration inducing game=+agg. resp., not the same for all participants, largely psychological. E-If agg behaviour was purely det. by horm. indivs. would respond in same way, add. causes must be known. L-TF more complex exp. of agg. required.
   • YOUNG: Injected pregnant monkeys with testosterone->if offspring born F=more masc. Also KREUZ+ ROSE-^(T) in crim with history of vio behaviour rather than non-vio.

3. GENETIC FACTORS:

   • TWIN STUDIES: MZ twins reared apart were found to have similarities in agg. Bc MZ are genetically identical, but if reared apart would have diff. exp. in diff. environ., would suggest gen. Findings have been largely variable. PLOMIN-average concordance rate(CR) for MZ=0.32, DZ=0.14, across all studies, suggests genetic contribution
     • Eval: I-Twin studies prov. supp. ot gen. exp. of agg. E-Sig. diff. in CR between MZ-DZ. E-Diff. stud. diff est. RHEE+WALDMAN-variability may be partly due to the methods used to assess agg. behaviour. Meta-analysis of 51 stud. heritability diff. accord. to assessment. 39% for self-reported agg.+53% by others, problems may aff. internal valid. L-Despite issues, clear there is gen. influence of research findings.
   • XYY
     • This extra Chromosome (CMS) suggests males=^agg. THIELGAARD:suggests 1-1,000 M are XYY
     • JACOBS: Incidence of XYY among inmates-3% compared to 0.1% of normal pop. Further studies indicated that these M were taller, ^(T)+vintellegence
     • COURT-BROWN: 314 patients, best hospitalised due to increased likelihood of agg. beh. Media depictions of XYY, contributed to held belief that they are more agg.
       • Eval: I-Research into XYY=(+)agg inconclusive. E-Earlier studies sugg. strong links, but more recent show that XYY, no more likely than normal males to exp. agg. E-THEILGAARD-compared agg of XYY-XY, no single diff. except height, very complex as many influences on behaviours. L-Although there is some evid. for role of genetics, research are conflicting, diff. to draw solid conc.
     • WITKEN: found no link between XYY=(+)agg, therefore challenged
     • Eval: I-Nature V Nurture E-Psych's with bio background see agg influenced by gen. In reality both bio+enviro factors are important. E-Important not to downplay role of social factors I.e. SLT+institution such as prison can create agg. due to lack of freedom+resources. L-Any view that simply focusess on gen. as the cause for agg, reductionist, no scope to appre. other influences, agg is complex with many different factors