Role of hormones in human behaviour

Question 1

Hormones

Manufactured in endocrine glands and secreted into the blood stream

Answer 1

Hormones are biochemical messengers transported around the body

Act much more slowly than the nervous system but have widespread and powerful effects

Each hormone only affects specific target organs or cells, e.g. adrenal glands secrete adrenaline and noradrenaline, which affect cells in the heart

Crucial role in the fight-or-flight response to perceived stressors (increasing heart rate, helping to fuel that aggressive response that may be needed to respond to a threat

Question 2

Role of testosterone

Male sex hormone may explain why males are more aggressive than females

Answer 2

Testosterone has a key role in regulating social behaviour through its influence on areas in the brain implicated in aggression

Animal studies (Giammanco et al) show that experimental increases in testosterone are related to more aggressive behaviour in the males of several species

This converse is also true- decreases in testosterone as a result of castration are related to reductions in aggression

Evidence for a similar association in humans comes from Dolan et al who found a positive correlation between testosterone levels and aggressive behaviours in a sample of 60 male offenders in UK maximum security hospitals. These men has personality disorders (psychopathy) and histories of impulsively violent behaviour

Question 3

Dual-hormone hypothesis

Testosterone and cortisol interact to cause aggression

Answer 3

Hormonal causes of aggression are more complex than the role of a single hormone implies

Cortisol is secreted by adrenal glands to protect the body against effects of stress (suggesting there is an interaction between the systems responsible for regulating aggression and the stress response)

Carre and Mehta claim high levels of testosterone lead to aggressive behaviour only when levels of cortisol are low (when cortisol is high, testosterones influence on aggression is blocked)

Pompa et al studies adolescent males and found exactly this association in relation to direct physical aggression

So, according to the dual-hormone hypothesis, the combines activity of testosterone and cortisol may be a better predictor of human aggression than either hormone alone

Question 4

Female aggression

Lower than in males but still enhanced by testosterone

Answer 4

Dabbs and Hargrove found evidence for an aggression-testosterone link in females

However, Eisenegger et al found that women given a dose of testosterone behaved more generously and sociably in a lab-based negotiating game

The aggression-testosterone link in females appears to be more complex than it is in males, suggesting that non-biological factors may be important

Question 5

A strength is research support for testosterone effects in females

Answer 5

Dabbs and Hargrove measured testosterone in female inmates of a maximum security prison - degree of criminal violence was positively correlated with testosterone levels

Testosterone also correlated with the extent of the women’s aggressive dominance within a prison

The aggression- testosterone link so often found in male prisoners was replicated in this study of females, increasing the validity of the association

Question 6

Competing argument

Answer 6

Many studies of hormonal influences on human aggression are correlational, including the one above. This is a sensible for ethical and practical reasons, but means we cannot establish a causal relationship. For instance, elevated testosterone may be the outcome of aggression, or both may be the result of changes in another hormone