What is the dark side of relationships?

Nov. 1, 2000 -- She's bad for me. He's good for me. A new study shows there may be something to those relational statements.

In the latest issue of the Journal of Personality and Social Psychology, British and American researchers find that individual personality has a lot to do with couple happiness, but in surprising, complex, and gender-specific ways.

"Our basic finding, which seems to replicate across a wide range of studies, is that the tendency to experience and express negative emotions is more important in relationships than any other personality trait," says study author Richard W. Robins, PhD, of the University of California, Davis.

After looking at 360 couples in various states of union -- dating, living together, and married -- Robins and the other researchers make one overall conclusion: Negative personality traits are among the most toxic pieces of baggage partners drag in to a relationship.

Women tend to be poisoned most by negatively aggressive men, and men by hostile or unfriendly women -- or those who get emotional when stressed. That said, however, the authors' suggest negative people are their own worst enemies, in that their grim personalities color their view of the relationship more than they affect their partners'.

The news is a bit different when it comes to positive personality traits. The researchers find, as might be expected, that two positive people make for a harmonious union. But women get more out of having a positive partner than men do. Put another way, a man with a happy partner doesn't necessarily become happy (nor necessarily does a woman). But the researchers conclude that the happiness of women in relationships is more likely to be affected by the man's personality -- no matter what it is -- than vice versa. Only when women are negative does it significantly rub off on the male partners.

"It seems intuitive that other traits such as positive emotionality and self-control would matter a great deal as well, but they don't seem to predict relationship outcomes nearly as well as negative emotionality. So it seems surprising that, for example, how happy and cheerful your partner tends to be is only weakly related to your relationship satisfaction," Robins says.

And if all that isn't surprising enough, Robins says the research also found no basis for the widely held belief that two 'bad' people thrown together -- creating something called synergy -- make an even worse marriage.

"We didn't find any evidence that particular combinations of personality traits -- for example, high negativity combined with low self-control -- had a synergistic effect," he says. "In other words, it is not the case that people who are particularly angry and impulsive are exponentially more likely to be dissatisfied with their relationship. ... Of course, these people are less satisfied, but the combination of these two characteristics does not make them even less satisfied than you might expect."

There is a hitch to all these conclusions: Very few of the couples studied were hitched. In fact, just 7% were married. The rest were almost evenly split between daters and cohabitators.

Plus, the couples were young. The mean age of the women was less than 21. The men, on average, were about 22.

"This is not really a study which can draw conclusions about marriages between people in their 30s, 40s, and 50s," says Dennis Shulman, PhD, a clinical psychologist and director of the National Training Program in Contemporary Psychoanalysis in New York. "You ask a 20-year-old something and a 40-year-old the same thing and you're going to get a very different answer."

Still, Shulman agrees with the idea that individual personalities can shape a relationship -- and that women see things differently than men: "Women do tend to come into relationships with different kinds of strengths and interests than men. As a rule, women tend to look for more issues having to do with care, community, and connection. Men tend to have more of a wish for [independence]. In good marriages men become more relational. Women become more [independent]."

"I definitely agree that a limitation [of the study] is the age of the participants," Robins says. "For a number of reasons, the effects of personality may change as people get older, and therefore it would be best not to generalize the findings from our study to all couples."

Still, he says other studies do confirm that negativity is the most damaging personality trait in married couples. "It is also possible that being in a particular type of relationship might alter your personality," he says. "So, for example, being in an unsatisfying relationship over time might increase the amount of anger, sadness, and anxiety you feel."