biological psycology

• Raine (1997) showed importance of central nervous system on decision making and murders, with low activity in prefrontal cortex
• Aggression affected by other factors, not just neurotransmitters
• Theory is reductionist
• Drugs


  Chemical substances that affect the body's function, interfere with chemical signals in the brain
• Addiction


  Drugs abuse the brain's reward system by increasing dopamine release
• Some people may be genetically inclined to addiction
• Addiction cycles


  Repeated drug use leads to addiction
• Sedatives


  Drugs that calm you down, depress the central nervous system
• Stimulants


  Drugs that make you feel more alert
• Stimulants


  • Caffeine, nicotine, amphetamines, cocaine
• PET scans show reward pathways linked to addiction, providing scientific evidence
• Drugs affect the reward system, explaining why they are addictive
• Drugs have different effects based on receptor interactions
• Theory less valid as unsure how drugs cause their effect on the brain
• Hormones


  Chemical substances produced in the body that send messages to organs
• McBurnett (2000) study of boys with behaviour problems consistently showed low cortisol levels
• Studies found low cortisol in habitual violent offenders and violent children
• Testosterone


  Male sex hormone, involved in aggression across species
• Studies show females exposed to more testosterone in the womb are more aggressive
• Supports the theory that testosterone has an organising effect on the brain, explaining gender differences in aggression
• Cortisol


  Stress hormone, inhibits aggression
• Low cortisol is due to low autonomic nervous system arousal, seen in behaviours that arouse the ANS
• Cortisol mediates aggressive acts, those with low cortisol feel less stressed when committing aggressive acts
• Brown (2001) meta-analysis showed positive correlation between testosterone and aggression, but other factors must be involved
• Amygdala


  Located deep in the temporal lobe, responsible for emotion and aggression
• Animal studies show that damaging/removing the amygdala reduces aggression
• Electrical stimulation of the amygdala causes stress and aggression
• Prefrontal cortex


  Develops from age 5, controls the amygdala and regulates social behaviour
• Reduced prefrontal cortex functioning increases aggression
• Antisocial personality disorder is linked to abnormal amygdala function and lack of recognition of negative facial expressions
• Prefrontal cortex controls the amygdala's emotion, validating the theory
• Evolution


  How inherited characteristics change over generations
• Sexual selection


  Successful males historically were bigger and stronger, providing an adaptive advantage
• Daly & Wilson (1988) meta-analysis supported the theory of the evolution of aggression through sexual selection
• Female aggression is a result of competition and male sexual jealousy, but doesn't account for female domestic abuse
• Verbal aggression and non-lethal physical violence show no gender differences, invalidating the theory
• Anderson (1999) showed that damage to the prefrontal cortex in infancy leads to increased aggression in adults
• Raine (1994) found reduced prefrontal cortex activity in murderers
• Conduct disorder and ADHD are linked to low prefrontal cortex activity and aggression/murder
• Complications at birth and high antenatal testosterone exposure can cause aggression