Hormones and aggression

Testosterone

Testosterone is a male sex hormone (found at lower levels in females). The explanation: higher testosterone is linked to more dominance and aggression, possibly by affecting brain areas such as the amygdala.

Dabbs et al. (1987) measured testosterone in the saliva of 89 male prison inmates: those with higher testosterone had more often been convicted of violent crimes (10 of the 11 inmates with the highest levels had committed violent crimes). However, a meta-analysis by Archer et al. (2005), cited by Carre and Mehta (2011), suggests the direct link between testosterone and human aggression is weak and inconsistent.

Cortisol and the dual-hormone hypothesis

Cortisol is a stress hormone. Low cortisol may mean a person is under-aroused and less anxious about consequences. McBurnett et al. (2000) followed 38 boys aged 7 to 12 referred to a clinic for disruptive behaviour for four years: boys with consistently low salivary cortisol showed three times as many aggressive symptoms as boys with higher levels.

The dual-hormone hypothesis (Mehta and Josephs, 2010) says testosterone is linked to aggression and dominance mainly when cortisol is low; when cortisol is high the effect of testosterone is blocked. Popma et al. (2007) found that among delinquent male adolescents with high cortisol, testosterone was unrelated to overt aggression.

Evaluation

• Strength: hormone levels can be measured objectively (for example in saliva), which gives scientific, replicable data.
• Strength: the dual-hormone idea explains why simple testosterone studies give inconsistent results.
• Weakness: much human evidence is correlational; aggression or competition might raise testosterone rather than the reverse.
• Weakness: animal studies may not generalise to human aggression, which is often social and verbal.
• Weakness: hormone explanations ignore learning; social learning theory offers an alternative explanation.

Worked example

A study finds a positive correlation between salivary testosterone and aggressive acts in prisoners. Give two reasons why this does not show testosterone causes aggression.

1. Correlation does not show direction: aggressive behaviour could raise testosterone.
2. A third variable, such as stress (cortisol) or a violent upbringing, could affect both.

Answer: Direction of cause is unknown, and other variables could explain the link.

Check yourself

1. Which hormone is most associated with dominance and aggression in males?
   • Testosterone
   • Melatonin
   • Oxytocin
   • Insulin
   Show answer

   Testosterone. Testosterone is the hormone most often linked to aggression.

2. According to the dual-hormone hypothesis, testosterone is most strongly linked to aggression when
   • cortisol is high
   • melatonin is high
   • cortisol is low
   • serotonin is high
   Show answer

   cortisol is low. High cortisol blocks testosterone's effect; low cortisol allows it.

3. Cortisol is best described as a
   • stress hormone
   • neurotransmitter made in the dendrites
   • sex hormone
   • sleep hormone made by the pineal gland
   Show answer

   stress hormone. Cortisol is released in response to stress.

4. What did the Archer et al. (2005) meta-analysis suggest about testosterone and human aggression?
   • Testosterone explains all aggression
   • There is no testosterone in women
   • Testosterone lowers aggression in every study
   • The direct relationship is weak and inconsistent
   Show answer

   The direct relationship is weak and inconsistent. Carre and Mehta cite Archer et al. as finding a weak, inconsistent direct link.

5. In a study like McBurnett et al. (2000), the low-cortisol group shows 3 times as many aggressive symptoms as the high-cortisol group. If the high-cortisol group averages 4 symptoms, how many does the low-cortisol group average?
   Show answer

   12 symptoms. 3 x 4 = 12 symptoms.

6. Explain why hormone research into aggression may lack validity.
   Show answer

   Most studies are correlational, so aggression might raise hormone levels rather than hormones causing aggression, and animal studies may not generalise to humans.. Validity is about whether the research really shows what it claims.

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Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Psychology specification, Issue 5 (February 2021)
• Pearson IAL Psychology component guide: WPS02 (Issue 2, November 2024)
• Carre and Mehta (2011), Importance of considering testosterone-cortisol interactions in predicting human aggression and dominance, Aggressive Behavior 37
• Dabbs, Frady, Carr and Besch (1987), Saliva testosterone and criminal violence in young adult prison inmates (NCJRS abstract)
• University of Chicago Medicine (January 2000): low levels of salivary cortisol associated with aggressive behavior (McBurnett et al., Archives of General Psychiatry)

Last updated 8 November 2026. Spotted a mistake? Tell us.