Male sex hormone makes people less cooperative and more egocentric

London, Feb 1 (ANI): Too much testosterone can make us overvalue our own opinions and blind us to other people's views, researchers have revealed.

The findings from the Wellcome Trust Centre for Neuroimaging at UCL (University College London) may have implications for how group decisions are affected by dominant individuals.

Previous research had shown that people given a boost of the hormone oxytocin tend to be cooperative.

Now, a new study has found that the hormone testosterone has the opposite effect - in other words, it makes people act less cooperatively and more egocentrically.r Nick Wright and colleagues at the Wellcome Trust Centre for Neuroimaging at UCL carried out a series of tests using seventeen pairs of female volunteers who had previously never met. The test took place over two days, spaced a week apart. On one of the days, both volunteers in each pair were given a testosterone supplement; on the other day, they were given a placebo.

The researchers found that, as expected, cooperation enabled the group to perform much better than the individuals alone when individuals had received only the placebo.

But, when given a testosterone supplement, the benefit of cooperation was markedly reduced. In fact, higher levels of testosterone were associated with individuals behaving egocentrically and deciding in favour of their own selection over their partner's.

"When we are making decisions in groups, we tread a fine line between cooperation and self-interest: too much cooperation and we may never get our way, but if we are too self-orientated, we are likely to ignore people who have real insight," explained Dr Wright.

"Our behaviour seems to be moderated by our hormones - we already know that oxytocin can make us more cooperative, but if this were the only hormone acting on our decision-making in groups, this would make our decisions very skewed.

"We have shown that in fact testosterone also affects our decisions, by making us more egotistical. Most of the time, this allows us to seek the best solution to a problem, but sometimes, too much testosterone can help blind us to other people's views. This can be very significant when we are talking about a dominant individual trying to assert his or her opinion in, say, a jury," Dr Wright added.

The finding has been published in the journal Proceedings of the Royal Society B. (ANI)