Aggression: Hormonal

Aggression: Hormonal

1. Testosterone

   • • Testosterone increases aggression. » Thought to influence aggression from young adulthood onwards. » Acts on brain areas controlling aggression. • Correlational link – testosterone makes it more likely that a behaviour will be expressed. • Dabbs et al (1987) – compared testosterone levels in saliva samples of violent and non-violent criminals. » Violent criminals with history of violence had higher testosterone levels. » Non-violent criminals had lower testosterone levels. • Shows clear correlation between higher testosterone levels and aggression in violent criminals.
     • AO2: Supported by meta-analysis by Archer (1991). • Analysed results of 230 meals over 5 studies. • Low positive correlation between testosterone and aggression. • Shows testosterone does have an influence on aggression. » However, type of ppt and measurement of aggression differed substantially between studies.
       • AO3: • Gender bias. • Lacks population validity as only involves male ppts and cannot be generalised to include effects of testosterone on aggression in females. • Research suggests association between testosterone and aggression is higher for females than males. » Further study – women with higher testosterone levels had higher occupational status – possibly a result of being more assertive.
     • AO2: Book et al (2001) found weak mean positive correlation in a meta-analysis of 45 studies. • Mean correlation between testosterone and aggression = 0.14 » Archer claimed correlation of 0.08 was more appropriate due to methodological issues. • Suggests a weak link between testosterone having an influence on aggression.
       • AO3: • Research on correlation between testosterone and aggression is inconsistent. » Criticise small samples of men – primarily prison inmates – and use of self-report methods. » Reduces overall validity as may exhibit social desirability, demand characteristics or sabotage results. • Difficult to determine cause and effect.
     • AO2: Testosterone may have a positive influence. • Testosterone levels typically decline in older males » Depressive symptoms tend to increase in males between ages of 50-89 years old. • McNicholas et al (2003) – increases in positive mood and decreases in negative mood with testosterone replacement therapy » Study of 208 men with testosterone deficiency.
       • AO3: • Theory is reductionist. • Only focuses on biological mechanisms of testosterone causing an increase in positive mood or aggression. • Fails to consider free will – choose to feel more positive and therefore aggression is not to do with testosterone levels.

2. Cortisol

   • • Cortisol reduces aggression. • Mediating effect on testosterone. » Possibly because increases anxiety and likelihood of social withdrawal (Dabbs et al 1991). • Inverse correlation – lower levels of cortisol associated with higher levels aggression. • Higher cortisol levels inhibit testosterone and so reduce aggression. • Research reported low levels of cortisol in persistent violent offenders and in violent school children.
     • AO2: Supported by McBurnett et all (2000). • Longitudinal study over 4 years – 38 boys ages 7-12 with behavioural problems. • Consistently low cortisol levels. » Began antisocial acts at younger age. » 3 times more aggressive symptoms compared to higher/fluctuating cortisol levels. • Cortisol levels ‘strongly and inversely related to aggressive conduct disorder.
       • AO3: • Only correlational, not causal. • Difficult/unable to determine cause effect. » Unknown whether hormones cause aggression or if they’re an effect of aggression.