Most people make friends with others online who have common interests, but it's rare for people's interests to rub off on others, according to new research out of Harvard University based on an examination of four years’ worth of Facebook data.

The National Science Foundation-funded research, detailed in a study called "Social selection and peer influence in an online social network," has been published this week in the Proceedings of the National Academy of Sciences by three Harvard University sociologists (Kevin Lewis, Marco Gonzalez and Jason Kaufman).

One ulterior motive of the research is to get insight into the role friendships play in deeper societal issues, such as social segregation and behavioral control."We have to ask ourselves how much of online interaction--and friendship formation in general--really is about reaching out to new people and learning about totally new ideas and perspectives that don't really interest us," said Ph.D. candidate  Lewis, in a statement, "as opposed to seeking out those perspectives and ideas we already like?"

Using the Facebook data from a group of more than a thousand college students at one college, the researchers found that students whose music and movie tastes were similar were more likely to become friends or influence the formation of new friends, though book tastes were less of a factor in either case (maybe it would be different for older people, once the book club years kick in?).  The fact that music and movies tend to be more social activities probably has a bearing on their influence on friendships, the researchers write.  They found tastes in classical and jazz music were more likely to get passed along through friendships than tastes in indie/alternative music, where the aficionado of such music might be the sort to be the token indie/alt music lover in a group.

"Given the prior research on social epidemics, we found the nearly complete absence of peer influence effects to be rather striking," said Lewis, a fellow at the Berkman Center for Internet and Society at Harvard.