Hormones

• Hormones

  Endocrine glands manufacture a variety of hormones and secrete them directly into the bloodstream. They are biological messengers. Act slower than nervous system but have more widespread and powerful effects. Each hormone affects certain target organs or cells.

  Eg adrenal glands secrete adrenaline which affect organs throughout body - crucial role in fight or flight
• Testosterone

  Has role in regulating social behaviour through its influence on areas of brain implicated in aggression. Animal studies demonstrate that increases in testosterone are related to agg behaviour in males of several species

  Converse also true - reduction in test reduces aggression as a result of castration

  Dolan found this correlation in sample of 60 male offenders in UK maximum security hospitals
• Dual-hormone hypothesis

  Cortisol secreted by adrenal glands to help body deal with effects of stress - suggests an interaction between systems regulating aggression and stress response

  Carre and Mehta claim high levels of testosterone lead to aggressive behaviour only when cortisol levels are low

  So, combined activity of both is a greater predictor of human aggression then either one alone
• Female Aggression !

  Testosterone levels in females (on average) are lower than in men but their aggressive behaviour can still be enhanced by it (evidence in eval bit)
• Strength 1

  Research support - Dabbs and Hargrove measured test levels in saliva of 87 female inmates of a maximum security prison - found degree of criminal violence positively correlated w test levels - also correlated w women's aggressive dominance in prison
• Strength 2

  Application to controlling aggression - if aggression chemically controlled then possible to produce a drug that influences hormones to reduce aggression behaviours - without widespread affects on bodily systems.

  Eg Maletzky et al found that a testosterone lowering drug (Depo-Provera) reduced sexually aggressive behaviour in some offenders
• Weakness 1

  Difficult to measure test levels - have to distinguish between baseline and fluctuating testosterone. Baseline is persons usual level and is relatively stable but this can also fluctuate from one social encounter to another.

  Carre et al argue that baseline has less of a role in aggression in humans than animals but this is what is often used in human research. So, baseline measure used in many studies may not be valid indicator of test levels related to agg
• Weakness 2

  Many studies of hormonal influences on human aggression are correlational and we cannot establish a causal relationship

  Eg elevated testosterone may be outcome of aggression but both may be outcome of changes in another hormone