This insecurity is particularly marked if the woman succeeded at a task or in a situation in which their male partner had failed, the study of 896 heterosexuals found. Yet the same feelings of insecurity could be seen even where the couple were not in directly competing professions.

But women's self-esteem was not affected in the same way. In fact, in total contrast to men, women felt more satisfied with their relationship when they thought about a situation in which their partner succeeded.

According to Kate Ratliff of the University of Florida, lead author of the study, "It makes sense that a man might feel threatened if his girlfriend outperforms him in something they're doing together, such as trying to lose weight.

"But this research found evidence that men automatically interpret a partner's success as their own failure, even when they're not in direct competition.

"There is an idea that women are allowed to bask in the reflected glory of her male partner, and to be the 'woman behind the successful man', but the reverse is not true for men," she added.

The research was based on experiments carried out among groups of couples in both in The US and the Netherlands â€" the latter chosen because of its high rankings for gender equality. Yet in cases where a woman outperformed her male partner, both American and Dutch men registered a subconscious dip in self-esteem.

In other words, the study argues, it seems that men to equate their partner's successes with their own failures.

"A partner's success could lead to a decrease in self-esteem (the 'zero-sum game hypothesis') if we interpret 'my partner is successful' as 'my partner is more successful than me'."

The study, Gender Differences in Implicit Self-Esteem Following a Romantic Partner's Success or Failure, is published in the Journal of Personality and Social Psychology.