Biological theories of Aggression

HideShow resource information
View mindmap
  • Biological Explanations of Aggression
    • MAOA gene
      • Regulates enzyme of same name.
        • Enzyme mops up excess amounts of neurotransmitters.
          • Seratonin
            • Build up can lead to aggressive response.
          • Dopamine
          • 2 activity forms
            • High activity (H-MAOA)
              • High levels of enzyme produce
            • Low Activity (L-MAOA)
              • Less enzyme produced
                • Higher levels of aggression
      • Strengths
        • Cases et al
          • Genetically engineered mice -> lacking MAOA.
            • Mice had dramatically altered serotonin
              • Mice showed enhanced aggression esp. during mating
                • t/f MAOA deficiency = aggressive behaviour
        • Mattson
          • MAOA def. MALE mice attacked new mice
            • T/F effect may only be inherited by males
        • Brunner
          • Defective MAOA gene in Dutch family
            • Males in fam = history of DV
              • t/f defective MAOA gene does play a role in human aggression
                • The fact that these studies show MAOA affects ag. in humans + animals provides strong evidence for the role of MAOA in aggression.
                  • T/F effect may only be inherited by males
                  • t/f MAOA deficiency = aggressive behaviour
      • Weaknesses
        • Moffit et al
          • Anti Social Behaviour = 9x more likely in L-MAOA ppts who had been abused
            • Suggests that MAOA gene requires an enviromental trigger to be activated
        • Deneris et al
          • behaviour of GM mice w.out PET-1 gene = reminiscent of human psych disorders
            • GM mice = not enough seretonin. t/f PET-1 is necessary for foetal development of those neurons
    • Neural Mechanisms
      • Amygdala & PFC
        • PFC = regulation of correct social behaviour
          • Damage
            • Impulsivity
            • Immaturity
            • Altered emotionality
        • Strengths
          • Potegal et al
            • Stimulation of the corticomedial amygdala = aggressionn
              • Lesioning the area = reduces aggression
                • Supportive bc amygdala = inv. in aggressive behaviour.
                  • Research not done on humans
                    • Stimulation of the corticomedial amygdala = aggressionn
                      • Lesioning the area = reduces aggression
                        • Supportive bc amygdala = inv. in aggressive behaviour.
                          • Research not done on humans
            • Raine
              • Significant differences/ lev. brain activity
                • 41 murderers & control group
                  • Lateral + Medial PFC = murderers - less activity
                    • Areas w/abnormal activity
                      • Lowered self control
                      • Increased aggression / impulsivity
                      • problems w/ controlling / expression of emotion
                      • Lack of fear
            • Volkow
              • Reduced PFC activity in 9 psychiactric prisoners
          • IDA
            • Socially Sensetive research
              • Wider ranging implications for society b/c lack of control
                • Lack/control = issue of culpability
                  • Biology influences agg-prisoners = no blame
        • Serotonin
          • Reduces agg by inhibiting responses to emotional stimuli
            • Normal levels
              • Calming, inhibitory effect
            • Low levels
              • Reduces calming, inhibitory effect
          • Supporting Evidence
            • Mann et al
              • dexfenfluramine - 35 healthy adults
                • Dexfenflurmaine - depletes serotonin levels
                • Questionnaire: assess hostility & agg
                  • Found: male hostility + agg increased post treatment
            • HOWEVER
              • role/neurotransmitter = unclear
                • low levels of serotonin -> agg DOESN'T FIT W/WARRIOR GENE RESEARCH
                  • Cases et al
                    • W/G disabled -> S levels INCREASED
                      • t/f may not be as simple as "high"/"low" levels of seretonin
        • Dopamine
          • response to rewarding stimuli
            • aggressive behaviour produces a rush of dopamine
              • t/f pleasure
                • bc aggression = pleasure, behaviour will be repeated.
            • food
            • sex
          • Supportive Evidence
            • Lavine
              • Increased aggression
                • When AMPHETAMINES administered.
            • Buitelaar
              • Decreased aggression
                • When DOPAMINE INHIBITING APs taken
              • However
                • doesn't tell us how dopamine is linked to aggression.
      • Hormonal Mechanisms
        • Testosterone
          • Produced by the LEYDIG CELLS
            • Male testes
              • 10x more than females
              • Muscle Growth
              • Bone Growth
              • Aggression
            • Adrenal Cortex
            • Female ovaries
          • Basal Model
            • Testosterone causes change in levels of DOMINANCE
              • + testosterone = + competition &  + dominance
                • Dominance = aggression
          • Serotonogenic Synapses
            • low levels serotonin = high levels of aggression
              • T modulates certain neurotransmitters that lead to + levels of aggression
          • Supportive Evidence
            • Beeman
              • Castration decreases aggression
                • Castrating male mice reduced their aggresion
                  • Normal levels re-established when injected w/testostrne
            • Edwards
              • injections of T in F/Mice made them act like M/Mice w/increased T.
                • Behaviours compared to control mice only given T as adults
                  • T masculinizes andro/sensetive circuitrs
                    • Explains why timing of castration = crucial
          • Weaknesses
            • Simpson
              • T = implicated to only certain types of aggression
            • Albert
              • Lots of research that shows no relationship between agg & T
            • IDA
              • Nature & Nurture
                • Enviroments facilitate aggression
                  • Feilden & Lutter
                    • ppts saliva tested for T before / after World Cup match
                      • Average T levels of WINNING fans increased by 27.6%
                        • Losing fans decreased by 26%
                        • This suggests some group situations increase levels of T, therefore social factors come into play
                          • Losing fans decreased by 26%

    Comments

    No comments have yet been made

    Similar Psychology resources:

    See all Psychology resources »See all Aggression resources »