Male hormone gives women stubborn egos
Testosterone-fuelled individuals are more likely to be overconfident and stubborn, a study suggests.
Boosting levels of the male sex hormone can lead to overconfidence and poor co-operation, research has found.
Scientists demonstrated the effect in women, who have low base levels of testosterone which are easier to alter.
Researchers at University College London (UCL) conducted tests on 17 pairs of female volunteers.
Over the course of two days spaced a week apart, both participants in each pair were given a testosterone supplement and then a 'dummy' placebo.
The women performed computer-based tasks designed to assess their levels of co-operation.
When they agreed on what images were being shown, they moved on to the next trial. If they disagreed, they were asked to discuss the problem and reach a joint decision.
Having extra testosterone was associated with volunteers behaving egocentrically and favouring their own selections over their partner's.
The findings, published in the journal Proceedings of the Royal Society B, could have implications for the way dominant individuals influence group decisions.
Study leader Dr Nick Wright, from the Wellcome Trust Centre for Neuroimaging at UCL, said: "When we are making decisions in groups, we tread a fine line between co-operation and self-interest.
"Too much co-operation and we may never get our way, but if we are too self-orientated, we are likely to ignore people who have real insight."
Previous research has already shown that another hormone, oxytocin, makes people more likely to bond and co-operate.
"Our behaviour seems to be moderated by our hormones -- we already know that oxytocin can make us more co-operative, but if this were the only hormone acting on our decision-making in groups, this would make our decisions very skewed," said Dr Wright.
"We have shown that, in fact, testosterone also affects our decisions, by making us more egotistical.