Laugh and the world laughs with you, the saying goes, and this is especially true for couples and roommates, the results of a new study suggest.

It seems that couples and roommates tend to have similar emotional reactions as time goes by. So if your roommate or lover laughs out loud at movies or gets weepy over hurt puppies, you may too -- given time.

This so-called emotional convergence seems to be beneficial to friendships and romantic relationships, making them stronger and longer lasting.

Everyday experience suggests that people are capable of "catching" the mood of a spouse or friend, said lead author Dr. Cameron Anderson. But he said that he was surprised by the extent to which peoples' emotions converged in his study, which is reported in the Journal of Personality and Social Psychology.

"The romantic partners and roommates were virtually becoming the same emotional person over time," said Anderson.

In the first part of the study, 60 heterosexual couples at the University of Wisconsin in Madison answered questions about their personality, their satisfaction with their relationship and the balance of power within it.

To test emotional convergence, partners discussed positive and negative situations -- such as a recent success or an ongoing worry. Then each partner privately reported his or her feelings regarding the issue.

Six months later, the 38 couples that were still together repeated the experiment. The couples maintained distinct personalities, but they were more closely attuned emotionally than they had been at the start of the study, the researchers found.

Although couples' emotions converged over time, similar emotions might have drawn them together in the first place. Couples that stayed together during the study were more emotionally similar than couples that broke up, the researchers point out.

Anderson's team also found that the partner who had less power in the relationship did most of the changing in terms of emotions.

In other experiments, which involved college students who lived together in dormitories, the researchers found that roommates tended to have more similar emotional responses toward the end of the school year. The researchers gauged emotion by having students watch film clips that tend to elicit laughs or tears.

Roommates whose emotions converged the most during the school year tended to become closer friends than roommates whose emotions did not become as similar, according to the report.

The study also found that the roommate who had a lower social status in the dormitory tended to change more than popular roommates.

Anderson said these results show that "people's emotional responses to events are not completely fixed and rigid."

According to researcher, emotional similarity could be helpful in assembling the most productive corporate team, and might be an important consideration when searching for love or friendships.

(Agencies)