Just in time for International Women’s Day, the University of Buffalo has released a new study that shows that women who “base their self worth on their appearance” post more pictures of themselves online. They also tend to “maintain larger networks on online social networking sites.”

The study, released Monday in the journal Cyberpsychology, Behavior and Social Networking, included 311 participants (49.8 percent of whom were female) who filled out a survey that measured their contingencies of self-worth — whether they derive self-worth from public sources, like the Internet, or private sources, like family — and asked questions about their Facebook habits.

“Those whose self esteem is based on public-based contingencies (defined here as others’ approval, physical appearance and outdoing others in competition) were more involved in online photo sharing,” says Dr. Michael A. Stefanone, who led the study, “and those whose self-worth is most contingent on appearance have a higher intensity of online photo sharing.”

Those who derived their self esteem primarily from things like “academic competence, family love and support, and being a virtuous or moral person,” says Stefanone, “spend less time online” and seek less attention overall.

While the study seems to confirm the long-held stereotypes about image-conscious women, Stefanone says he was surprised to find that they are still true in this modern day.

“It is disappointing to me that in the year 2011 so many young women continue to assert their self-worth via their physical appearance,” says Stefanone, “in this case, by posting photos of themselves on Facebook as a form of advertisement.”

The study also found that, on average, Facebook users have never met about 12 percent of the “friends” in their social network. Women tend to have “significantly larger networks of strong ties,” and they spend more time “managing their profiles.”

View the full study here: PDF