But Aryn Karpinski, a doctoral student in education at Ohio State University and coauthor of the study, cautioned against finding a cause-and-effect connection between Facebook and lower grades. "We can't say that use of Facebook leads to lower grades and less studying," Karpinski said, "but we did find a relationship there."

'Other Factors Involved'

She added that "there may be other factors involved, such as personality traits, that link Facebook use and lower grades."

At the same time, Karpinski did say the study showed a "disconnect" between students who "claim that Facebook use doesn't impact their studies and our finding." The study, coauthored by Adam Duberstein of Ohio Dominican University, will be presented later this week in San Diego at the annual meeting of the American Education Research Association.

The difference was significant, showing that Facebook users had GPAs between 3.0 and 3.5, and nonusers had 3.5 to 4.0. Also, users averaged one to five hours of studying per week, compared to 11 to 15 hours for nonusers.

However, the sample size was relatively small, 219 students at Ohio State. Of those, 148 said they had a Facebook account. About 85 percent of 102 undergrads were Facebook users, as were 52 percent of the 117 graduate students.

The study also found several other differences between users and nonusers. The more hours a student worked at a paying job, the less likely he or she was to use Facebook, but it wasn't only a factor of having more free time. The more students were involved in extracurricular activities, for example, the more likely they were to use Facebook.

'A Huge Distraction'

And students whose majors were science, technology, engineering, math or business were more often Facebook users than those concentrating on social sciences or humanities. The authors speculated that science, technology and similar majors were heavier Internet users overall.

Karpinski noted that she doesn't have a Facebook account, but Duberstein does. "For me," Karpinkski told news media, "Facebook is a huge distraction."

Brad Shimmin, an analyst at industry research firm Current Analysis, cautioned that this study should "be taken with the same grain of salt" as those showing, for instance, that people who listen to certain kinds of music had higher IQs.

Causality is a difficult thing to assign, Shimmin said, especially in a study like this that doesn't address such variables as the amount of time the lower-performing students spend at other activities, such as playing video games or visiting friends.

However, Shimmin did say he wouldn't be surprised to find that, someday, social-networking tools like Facebook could become another way for students to study together as they seek to improve their grades.