Like it or hate it, Facebook is here to stay. Increasingly, this once college-oriented media site is becoming the communication platform for everyone from political candidates to retailers. We're asked to "like" our favorite TV stations, party nominees, stores, cities, Broadway musicals, movies, books, and charities. We can reunite with former classmates, long-lost pals from our past, and (maybe unadvisedly) our exes. Even as Facebook encroaches upon the farthest reaches of our online existence, however, there are individual differences in who uses this social media tool, and how they do so. These individual differences reflect people's personalities in some surprising ways.
There's a definite upside to Facebook for psychology researchers..After years of despair regarding how to study relationships as they take place in real life, psychology researchers are finding that Facebook provides a potentially rich storehouse of useful data. It's possible to study complex social networks and communication patterns in ways that none of us ever imagined. We no longer have to rely solely on self-report to find out how people feel about each other and then act on those feelings. We don't even have to put people in artificial lab situations that don't reflect how they interact in their daily lives. With Facebook, psychologists have a naturalistic data base with almost infinite opportunities for detailed study of relationship patterns.
Psychologists are finding that they can use Facebook to study both what people say about their online behavior and, more importantly, how they actually behave (within the boundaries of the ethical principles that govern psychological research). Extrapolating from experiences that all Facebook users can relate to, psychologists are now studying such behaviors as using Facebook for such diverse needs as overcoming loneliness or gratifying narcissistic needs. Also fair game for researchers are the consequences of Facebook use, from feeling Facebook regret to procrastinating from work or school.

Facebook is also increasingly being studied as a way to gain insight into how people project their personalities onto their Facebook use. You can think of Facebook as an online Rorschach test. It's an ambiguous, open-ended stimulus that people interpret in ways consistent with their personalities. Want to let everyone know about your latest success? It just takes one "status update" and your social world can now stand up and cheer for you. Worried about what others think about you? Check out how many "likes" your comments receive from your friends.
Psychology defines personality in many ways, from Freudian-style defense mechanisms to the behaviorist's reinforced habits. Becoming more and more popular is the "Five Factor Model (FFM)" a theory that defines five underlying traits or long-standing dispositions. These traits exist within everyone, according to the theory, but to different degrees. You're not all one or the other; instead everyone is a little bit more or a little bit less of the opposite poles of the five dimensions. We're all a little bit introverted, no matter how gregarious we might seem.
Here's the brief version of each of the high (positive) scoring ends of the five factors:
Openness to Experience: Willing to entertain new ideas, to enjoy exploring fantasies and adventure, and to appreciate the arts.
Conscientiousness: Punctual, neat, and attentive to detail.
Extraversion: Outgoing, sociable, and willing to self-disclose.
Agreeableness: Calm, level-headed, and unlikely to complain.
Neuroticism: Prone to excessive worry, anxiety, and feelings of self-doubt.
Now, that you know the basics, try this thought experiment. Map people who would get high scores on these dimensions onto what you imagine to be the typical Facebook user. Extraverted? Sure! Open to experience? Probably? Conscientious? Certainly not. Hold onto these predictions and let's see how close they come to the data.
In a January 2012 publication, Iowa State University researchers Kelly Moore and James McElroy present the results of their survey of Facebook users, combined with actual Facebook data, to examine how FFM traits relate to such Facebook behaviors as amount of usage, types of wall postings and regret. All of the participants were undergraduates, and of the 219 who participated in the anonymous survey, 143 voluntarily befriended Moore's experimental site, allowing her to study their actual Facebook behavior. The survey asked respondents to report on their usage (time spent each day and frequency). To measure regret, respondents used a 5-point scale to indicate whether they regretted posting material that they felt bad about later, or were worried about being seen by potential employers or (even worse) their parents. To study the actual Facebook behavior of participants, raters placed 175 of the wall posts they accumulated into "self-focused" or "other-focused" categories. The researchers also collected data on numbers of friends and numbers of photos posted. In their analyses, they also controlled for gender and level of experience.
Overall, personality accounted for a hefty proportion of the scores in numbers of self-postings (24%) and a whopping 41% of the scores in numbers of postings about others. Even more interesting was the fact that personality was related more strongly to actual Facebook use than to the self-reports that people gave about their Facebook behaviors. A second intriguing finding was the relatively high regret score; of a maximum score of 5, the average was a shade over 3, indicating that people often feel they commit the sin of oversharing on Facebook and wish they hadn't.
The people high on extraversion truly had a wide social network; the highest 10% of the sample had an average of 484 more friends than did the lowest 10%. People high on introversion seemed to use Facebook to compensate for their lack of communication with others. They were more likely to use Facebook to find out what their friends were doing than to share their own information. The people showing the most regret were those high on agreeableness and conscientiousness. Those showing the least regret were high on neuroticism and low on extraversion (i.e. were more introverted). Openness to experience wasn't significantly related to regret.
You might wonder whether these findings, based as they were on college students, are truly representative of individuals who use Facebook. Of course, college students are heavy Facebook users and will often do so whenever possible, including in class, unless physically separated from their laptops or smartphones. What about adults? Australian researchers Tracii Ryan and Sophia Xenos (2011) examined the online behavior of over 1300 adults ages 18-44. The heavy Facebook users in their study were more likely to be both extraverted and narcissistic (i.e. self-centered). As the authors concluded, "it could be argued that Facebook specifically gratifies the narcissistic individual's need to engage in self-promoting and superficial behavior" (p. 1663). Unlike the college study, the adults in this online survey who rated themselves as shy said that they spent more time on Facebook. People high on neuroticism said that they preferred to share information using the "wall" rather than the more interactive messaging function.

Between these two studies, a picture of the personalities of Facebook users begins to emerge and the potential risks that each type of individual might face. See which profile best describes you: