Eva C. Klohnen and Shanhong Luo of the University of Iowa analyzed data collected from nearly 300 couples that participated in the Iowa Marital Assessment Project. The questionnaires covered personality characteristics and attitudes as well as a number of indicators of marriage quality, including how couples approach conflict and how satisfied they feel with their union. The findings, published today in the Journal of Personality and Social Psychology, show that people marry mates with highly similar attitudes and values. The authors suggest that the attraction arises "because attitudes are highly visible and salient characteristics and they are fundamental to the way people live their lives."
The findings also suggest that once in a committed relationship, similarities in personality become more important for a happy marriage. Only resemblances in partners' personality traits were related to marital satisfaction, the researchers discovered. They posit that this is because being in a long-term relationship "entails regular interaction and requires extensive coordination in dealing with tasks, issues and problems of daily living. Whereas personality similarity is likely to facilitate this process, personality differences may result in more friction and conflict in daily life."