Honeymoon long over? Hang in there. A new University of California, Berkeley, study shows those prickly disagreements that can mark the early and middle years of marriage mellow with age as conflicts give way to humor and acceptance.

Researchers analyzed videotaped conversations between 87 middle-aged and older husbands and wives who had been married for 15 to 35 years, and tracked their emotional interactions over the course of 13 years. They found that as couples aged, they showed more humor and tenderness towards another.

Overall, the findings, just published in the journal Emotion, showed an increase in such positive behaviors as humor and affection and a decrease in negative behaviors such as defensiveness and criticism. The results challenge long-held theories that emotions flatten or deteriorate in old age and point instead to an emotionally positive trajectory for long-term marrried couples.

"Our findings shed light on one of the great paradoxes of late life," said study senior author Robert Levenson, a UC Berkeley psychology professor. "Despite experiencing the loss of friends and family, older people in stable marriages are relatively happy and experience low rates of depression and anxiety. Marriage has been good for their mental health."

Consistent with previous findings from Levenson's Berkeley Psychophysiology Laboratory, the longitudinal study found that wives were more emotionally expressive than their husbands, and as they grew older they tended toward more domineering behavior and less affection. But generally, across all the study's age and gender cohorts, negative behaviors decreased with age.

"Given the links between positive emotion and health, these findings underscore the importance of intimate relationships as people age, and the potential health benefits associated with marriage," said co-lead author Alice Verstaen, who conducted the study as a Ph.D. student at UC Berkeley and is currently a postdoctoral fellow at the VA Puget Sound Health Care System.

The results are the latest to emerge from a 25-year UC Berkeley study headed by Levenson of more than 150 long-term marriages. The participants, now mostly in their 70s, 80s and 90s, are heterosexual couples from the San Francisco Bay Area whose relationships Levenson and fellow researchers began tracking in 1989.

In their investigation of marital relationships, researchers viewed 15-minute interactions between spouses in a laboratory setting as they discussed shared experiences and areas of conflict. They tracked the emotional changes every few years.

The spouses' listening and speaking behaviors were coded and rated according to their facial expressions, body language, verbal content and tone of voice. Emotions were coded into the categories of anger, contempt, disgust, domineering behavior, defensiveness, fear, tension, sadness, whining, interest, affection, humor, enthusiasm and validation.

Researchers found that both middle-aged and older couples, regardless of their satisfaction with their relationship, experienced increases in overall positive emotional behaviors with age, while experiencing a decrease in overall negative emotional behaviors.

"These results provide behavioral evidence that is consistent with research suggesting that, as we age, we become more focused on the positives in our lives," Verstaen said.