Study looks at why some marriages last and others don't

BOSTON -- Why do some marriages last while others don't? A new study sheds some light.

Researchers at Stanford University recruited 35 heterosexual couples living in China who had been married for at least a year. They were put through a battery of personality tests and asked to rate their marital satisfaction. 

The study found little correlation between personality traits and marital happiness. But those reporting greater marital satisfaction were more likely to have the same parts of their brains active while watching marriage-related videos.  

It's unclear whether having similar brain activity brings couples together in happier partnerships or whether being in a happy marriage causes brains to become more synchronized.