Have a Facebook account? Laura Buffardi, doctoral student in psychology, and associate professor W. Keith Campbell from the University of Georgia says it may tell them you are a narcissist.

Narcissism is not just attention-seeking or wanting to be liked. Clearly everyone who signs up for a social media site wants to interact with others. It is more severe and characterized by an inability to form healthy, long-term relationships.

The tremendous growth of social networking sites (Facebook now has 100 million users, for example) has led psychologists to explore how personality traits are expressed online. Buffardi and Campbell chose Facebook because it's the most popular networking site among college students and because it has a fixed format that makes it easier for researchers to compare user pages.

Not everyone who uses Facebook is a narcissist. "We found that people who are narcissistic use Facebook in a self-promoting way that can be identified by others," said Buffardi.

They gave personality questionnaires to nearly 130 Facebook users, analyzed the content of the pages and had untrained strangers view the pages and rate their impression of the owner's narcissism.

The researchers found that the number of Facebook friends and wallposts that individuals have on their profile pages correlates with narcissism. Buffardi said this is consistent with how narcissists behave in the real-world, with numerous yet shallow relationships. Narcissists are also more likely to choose glamorous, self-promoting pictures for their main profile photos, she said, while others are more likely to use snapshots.

Untrained observers were able to detect the narcissists also. Observers used three characteristics – quantity of social interaction, attractiveness of the individual and the degree of self promotion in the main photo – to form an impression of the individual's personality. "People aren't perfect in their assessments," Buffardi said, "but our results show they're somewhat accurate in their judgments."

Some researchers in the past have found that personal Web pages are more popular among narcissists, but Campbell said there's no evidence that Facebook users are more narcissistic than others.

"Nearly all of our students use Facebook, and it seems to be a normal part of people's social interactions," Campbell said. "It just turns out that narcissists are using Facebook the same way they use their other relationships – for self promotion with an emphasis on quantity of over quality."

Still, he points out that because narcissists tend to have more contacts on Facebook, any given Facebook user is likely to have an online friend population with a higher proportion of narcissists than in the real world. Right now it's too early to predict if or how the norms of online self-promotion will change, Campbell said, since the study of social networking sites is still in its infancy.

"We've undergone a social change in the last four or five years and now almost every student manages their relationships through Facebook – something that few older people do," Campbell said. "It's a completely new social world that we're just beginning to understand."

Their work appears in the October issue of Personality and Social Psychology Bulletin,.