LAWRENCE, Kan., March 30 (UPI) -- A U.S. researcher says compulsive Facebook use may be a result of the fact that there's always something new on the social networking site.

Nancy Baym, a University of Kansas professor, said on sites such as Facebook, MySpace and Twitter, users share status updates, self-generated media, journal entries and other interpersonal communication in a continuous dribble.

"It's a continuous link of hanging out in the halls with your friends between classes or hanging around the water cooler at the office," Baym said in a statement.

Baym completed research on Last.fm, a niche site that connects fans of similar music. She found that online friendships based on common taste in music tended to be more fragile, although people also used the site to maintain closer relationships.

"What I found on Last.fm was that on average these relationships are not very strong," Baym said. "Other people have described them as on average being weak ties, which means that you don't discuss a wide range of topics. You don't do a variety of activities together. You tend to be kind of specialized in what topics you talk about."

Social networking sites are not about a person's 30 actual friends, but a lot of weak-tie relationships that give people access to a lot of resources that they wouldn't otherwise have, Baym said.

Baym is co-editor of the recently published book "Internet Inquiry: Conversations About Method."