The research also uncovered a key reason for the change was that those who married also experienced significant improvements in self-control.
“Self-control is one of the strongest predictors of differences between people in terms of their involvement in crime,” said Dr Forrest.
“People who avoid taking risks, can easily defer gratification, and have little trouble controlling their impulses are much less likely to commit a variety of offenses.
“That said, very little is known about how changes in self-control relate to changes in people’s involvement in crime over time.”
This latest study indicates that the link is due in part to the effects of marriage on self-control.
“Our study shows that improvements in a person’s level of self-control are related to changes in their involvement in crime over time. It also shows that marriage is a significant source of those improvements,” said Dr Forrest.
The study was based on analyses of the 1997 National Longitudinal Survey of Youth, a nationally-representative survey of American adolescents and young adults.
Many criminologists have assumed that marriage helps reduce crime because married people feel they have more to lose by committing crime or because married people tend to think about how their spouses might react when deciding how to act in different situations.
Those who are married also spend less time in situations that might lead to crime or in the company of friends who might encourage them to commit crime.
“Most people seem to develop greater self-control as they get older, but married people seem to experience the greatest increases, independently of the age at which they married,” said Dr Forrest.
“Those increases in self-control, in part, explain why people are less likely to be involved in crime when they are married than when they are single.”
Dr Forrest said that marriage helps contribute to the development of self-control because it provides new standards of behaviour as well as a reason to maintain those standards.
“And, as any married man or women knows, couples are rarely shy about telling one another when they’ve failed to live up to those standards. We think that helps provide people with practice regulating their behaviour,” said Dr Forrest.
The article titled Life-Course Transitions, Self-Control, and Desistance from crime is due to be published in the international journal Criminology and Criminal Justice early next year. The full report is available online.