WASHINGTON - A new study found that men have a harder time reading women's emotions than they do other men's - because they use different parts of their brain when trying to identify feelings in women versus in men.

In the study, published in the online Plos One journal - a peer-reviewed, open-access resource from the Public Library of Science - the researchers examined the brains of 22 male participants as they conducted a well-established empathy test called "Reading the Mind in the Eyes Test".

The test consists of snapshots of sets of eyes, and subjects have to guess whether the eyes belonged to a man or a woman, and then what emotional state the eyes were expressing, reported Discover magazine.

While subjects performed the test, researchers examined their brain activity via MRI scans.

The subjects did equally well at guessing the gender of the men and women's eyes, but they did much worse at recognising the emotions of the women's eyes, compared to the men's eyes, researchers said.

The subjects interpreted women's emotions correctly 76 per cent of the time, compared to 87 per cent of the time for men's eyes, and also took longer to guess them.

As to why this happens, it could be evolutionary. The researchers said that, to aid in territorial battles, for example, it may have been beneficial for men to interpret another man's facial expressions accurately and rapidly.

But, while there are differences in how men read men and women's emotions, the scientists said that men still do a decent job at understanding women, most of the time.

Prior research has found that, when compared to women, men are better at identifying facial expressions of anger, while women are better at recognising fear and sadness.