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02.05.2009

Testosterone user's heart beats faster at an angry face

The heart of testosterone users beats faster if they see a person with an angry face. Researchers in Utrecht, the Netherlands, reported this in an article published eight years ago in Behavioral Neuroscience. Even a fraction of a change in expression caused a measurable reaction in women test subjects.

Biologists make a distinction between individuals with a lot of testosterone and those with a lot of cortisol. Cortisol individuals avoid conflict and show submissive behaviour. Testosterone individuals, on the other hand, seek conflicts. In a series of experiments – which we have written about before – the Dutch researchers examined whether they could observe the influence of testosterone in humans as well. In the experiment they gave young women a small quantity [0.5 mg] of testosterone and examined them soon after. The dose given was enough to raise the women's testosterone level to that of a man. The researchers repeated the experiment a few days later, but giving the women a placebo.

In this experiment the researchers measured the heart rate of sixteen women aged between 19 and 25. They also showed the women photos of human faces, with a neutral, happy or angry facial expression. Below you can see the effect of faces with a neutral expression. The dotted line represents the women who took a placebo. The solid line represents the women who took testosterone.

The photos of people with happy facial expressions had the same effect.

Angry facial expressions caused the heart rate of the women who had taken testosterone to beat faster, as the graph below shows.

Anger is a sign that an attack is imminent. The raised heartbeat indicates, according to the researchers, that the women are braced to defend their position.

From other research done in Utrecht it emerged that test subjects in similar experiments do not consciously observe anger – or other negative emotions. Testosterone, it would seem, increases aggression, but does not promote social intelligence.

Source:
Behav Neurosci. 2001 Feb;115(1):238-42.

More:
Testosterone leads to social handicap 09.04.2009
Testosterone doesn't make everyone a jerk 17.12.2008