Hormones: What is Testosterone? (DP IB Psychology)

Revision Note

Hormones & Their Effect on Behaviour – Testosterone

What is a hormone?

  • A hormone is a chemical that is secreted by the endocrine glands into the blood stream which then distributes it around the body

  • Hormones act slowly (unlike neurotransmitters which are fast) and may take years to fully have an effect e.g. puberty occurs over several years

  • The major gland which regulates hormones is the pituitary gland, located at the base of the hypothalamus

  • Hormones will have different effects on the body and on behaviour, depending on the nature of the hormone itself e.g. cortisol regulates the stress response; melatonin regulates the sleep-wake cycle

What is testosterone?

  • Testosterone is the key male sex hormone that regulates fertility, muscle mass, fat distribution and red blood cell production

  • Testosterone levels rise during puberty when males begin to show secondary sexual characteristics e.g. bodily hair, deepening of the voice

  • Females produce testosterone but in much smaller volumes than males

  • Testosterone has been linked to behaviours such as aggression and competitiveness 

  • Some research shows that males in prison for violent offences have higher levels of testosterone than male prisoners convicted of non-violent crimes

Which studies investigate the effect of testosterone on behaviour?

  • Zak et al. (2009) – a lab experiment to investigate whether testosterone makes people less generous and less prosocial towards strangers 

  • Armstrong et al. (2022) – increased testosterone levels may lead to impulsive and violent criminal behaviour

The study by Zak et al. (2009) can be found in Two Key Studies of Hormones on this site: just navigate the Hormones & Pheromones topic to find it.

Examiner Tips and Tricks

An exam question on this topic is likely to be worded in a way that gives you some choice over how to answer i.e. ‘Describe/Discuss the effect of hormones and/or pheromones on behaviour’. So you do not necessarily need to have two studies per hormone, you could choose one study of a hormone and one study of a pheromone if you prefer.

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