biological determinants of aggression
Post on 05-Jan-2016
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Biological Determinants of
Aggression
Overview of Biology/Physiology
• Evolution (we already talked about)• Genetic• Neurotransmitters• Hormonal • Structural
Biology/Physiology is probabilistic, not deterministic (so how to prevent aggression?)
Genetics• Behavioral genetic research has shown genes influences individual
differences in a wide range of human behaviors: cognition, academic achievement, personality, temperament, and so forth.
• What about aggression?
• How studied?• Heritability – proportion of variability attributable to genetic factors• Environmental – proportion of variability due to situation• Monozygotic twins – same egg• Dizygotic twins – different eggs• Adoption studies – Raised separately so test genes/situation separately• Adoptive siblings share environments but not genes• Biological siblings raised apart share genes but not environments• Confounded because imitations and co-offending in siblings
• Findings• Clear evidence of heritability of criminality• Mixed results of heritability of aggression • Possible indirect effect through personality (impulsivity, dominance)
Genetics• A chromosome is an organized structure of
DNA and protein that is found in cells.• Men – XY• Women – XX
• Y-Chromosome Hypothesis• XYY
• More criminals than non
• Not more aggressive
• More likely charged/convicted
• X-Chromosome Hypothesis• XXY
• Not more aggressive
Only have to know first line for Final
Neurotransmitters
• Dopamine• animal studies show large changes during
aggressive behavior but not conclusive and not replicated in humans
• Norepinephrine• Does control mood and arousal but no relationship
to aggression• Serotonin
• Lower levels of serotonin linked to aggression because lowers inhibitions so more impulsive
• GABA• while it can inhibit behaviors, the findings are
mixed in regard to aggression
Hormonal
• Testosterone• sex hormone and anabolic steroid that has
mixed evidence to producing aggression, more likely about status and dominance so indirect relationship to aggression
• Premenstrual Syndrome (PMS)• inconclusive evidence its associated with
aggression and criminality but see next slide for indirect relationship
Structural• Hypothalamus – located under the thalamus that
controls several body functions, including feeding, breathing, drinking, and temperature.
• Amygdala – an almond-shaped neural structure that regulates emotions.
• Prefrontal cortex – implicated in planning complex cognitive behaviors
• How to study?• Brain damage• Direct stimulation• Physiological
Reactivity
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