Testosterone gets you thinking

People often say that their performance on certain tasks differs throughout the day, and explanations for these fluctuations in mental abilities have focussed on factors such as changes in body temperature or diet. New research by psychologists suggests however that alterations in the hormone testosterone may be responsible for these mental changes.

Dr Daryl O’Connor and colleagues from the University of Leeds present their findings today, Saturday 17 April 2004, at the British Psychological Society’s Annual Conference at Imperial College, London.

They asked males and females to carry out various verbal and spatial tasks between 8am and10am when testosterone levels are high; and between 3pm and 5pm when testosterone levels have declined. Saliva samples were collected before and after both sessions to measure actual levels of the hormone.

Performance on the Mental Rotations Test (a spatial task where you have to decide quickly if geometric figures are the same or not) was much better in the morning than in the evening. Performance on the Synonyms Test (a verbal test where you have to write down a word that has a similar meaning to another word) was much better in the evening than in the morning.

The authors argue that circulating levels of testosterone may influence cognitive abilities, higher levels in the morning may lead to better performance on spatial tasks, while lower levels in the evening may lead to better performance on verbal tasks.

Dr O’Connor said: “These results are very interesting as they suggest that sex hormones may have important non-reproductive actions as well as being central to the regulation of sexual functioning in humans”.