DO you bite your nails? Have you pierced your tongue? Is your tote bag emblazoned with the words ''I'm not a plastic bag''?
People look and act the way they do for reasons too numerous to fit into any therapist's notebook. Yet we commonly shape our behavior or tweak our appearance in an attempt to control how others perceive us.
Some call it common sense. Social scientists call it ''impression management'' and attribute much of their understanding of the process to the sociologist Erving Goffman, who in a 1959 book, ''The Presentation of Self in Everyday Life,'' likened human interactions to a theatrical performance.
Now that first impressions are often made in cyberspace, not face-to-face, people are not only strategizing about how to virtually convey who they are, but also grappling with how to craft an e-version of themselves that appeals to multiple audiences -- co-workers, fraternity brothers, Mom and Dad.
''Which image do you present?'' asked Mark R. Leary, a professor of psychology and neuroscience at Duke, who has been studying impression management in the real world for more than 20 years. Like other scholars, he is now examining the online world through the lens of impression management -- studies that sometimes put an academic gloss on insights that seem obvious, and at other times yield surprising results.
''We've been struck by the dilemma people are in,'' Mr. Leary said of a study he began last month about how people edit their online personas. ''Some people seem to pick an audience. Other people pick and choose the best parts of themselves. As a professor, my Facebook page is just watered down. I can't have pictures of me playing beer pong.''
People, of course, have been electronically styling themselves for as long as there has been a Web to surf. But scholars say the mainstreaming of massive social networking and dating sites -- which make it easy to publicly share one's likes, dislikes, dreams and losses in a modern mutation of the Proust Questionnaire -- is prompting more people to ''perform'' for one another in increasingly sophisticated ways.
Indeed, today's social networking and dating sites are ''like impression management on steroids'' said Joseph B. Walther, a professor of communication and telecommunication at Michigan State University. But because they are still new forms of communication, ''people don't have a very strong sense yet of what they're doing or what the best practices are,'' he said.
Among Mr. Walther's findings is that the attractiveness of the friends on your Facebook profile affects the way people perceive you. In a study to be published this year in Human Communication Research, a journal, Mr. Walther and colleagues found that Facebook users who had public postings on their wall (an online bulletin board) from attractive friends were considered to be significantly better looking than people who had postings from unattractive friends.
''We disproved the Paris Hilton hypothesis,'' said Mr. Walther, explaining that this traces to a quote attributed to Ms. Hilton: ''All you have to do in life is go out with your friends, party hard and look twice as good'' as the woman next to you.
''That's not true,'' Mr. Walther said.
Many of the self-presentation strategies observed by scholars will seem obvious to experienced Internet users: improving one's standing by linking to high status friends; using a screen name like ''Batman'' or ''007'' when in reality one is more like Austin Powers; referring to one's gleaming head as ''shaved'' not ''bald''; using cutesy emoticons to charm the demographic that forwards inspirational chain mail; demonstrating leadership by being the first to adopt and turn others onto the latest Facebook applications; listing one's almost-career as a D.J. or model rather than the one that pays the bills; making calculated decisions about what to list as interests or favorite books.
''If someone lists some obscure Romanian title, is that person really smart or are they pretentious?'' said Judith Donath, an associate professor of media arts and sciences at the Media Lab at the Massachusetts Institute of Technology, who studies social aspects of computing.
In one study of online dating, professors at Rutgers, Georgetown and Michigan State found that in the absence of visual and oral cues, single people develop their own presentational tactics: monitoring the length of their e-mail messages (too wordy equals too desperate); limiting the times during which they send messages (a male subject learned that writing to women in the wee hours makes them uncomfortable); and noting the day they last logged on (users who visit the site too infrequently may be deemed unavailable or, worse, undesirable).
The scholars found it common for online daters to fudge their age or weight, or to post photographs that were five years old. Also, the world is round and the chemical symbol for water is H2O.
In general, scholars do not think of impression management as an intentionally deceptive or nefarious practice. It is more like social lubrication without a drink in your hand. Those studying it online have found that when people misrepresent themselves, it is often because they are attempting to express an idealized or future version of themselves -- someone who is thinner or has actually finished Dante's ''Inferno.''
''Everyone felt pretty strongly that they tried to be honest,'' said Jennifer Gibbs, one of the authors of the online dating study and an assistant professor of communication at Rutgers. (N.B.: Ms. Gibbs met her husband on Match.com.) ''They justified slight misrepresentations or distortions on trying to stand out,'' she said, adding that online and offline, people experience tension between telling the truth and showcasing themselves in the most flattering light.
Some misrepresentation stems from the actual structure of networking sites. For instance, people who decide to grow younger on dating Web sites often do so by a couple of years because they would otherwise be filtered out of search results that use age brackets. Ms. Gibbs said most people had ''no qualms'' about forgetting a few birthdays as long as they came clean upon meeting someone.
Coming clean about misrepresentations is less of an issue on social networking sites, where people are not as likely to deviate too far from the truth because their network of friends will simply call them on it. Scholars do suggest, though, that the photographs people post on the sites are about more than showing what individuals look like. Rather, members carefully choose photos to display aspects of their personalities.
Catherine Dwyer, a lecturer at Pace University who studies online behavior, said young men on MySpace commonly do this by posing with their cars.
''I use photos that describe me,'' said Leonard Alonge, 44, a chef and actor in Delray Beach, Fla., who is a member of Facebook. ''Photos of me in the kitchen, photos of me with friends. I use it to describe my personality: friendly, outgoing, nothing very explicit. I'm a pretty conservative person. I was raised in a Roman Catholic family.''
Clare Richardson, 17, of Los Angeles, is applying to colleges and is therefore mindful of what she posts on Facebook, but she knows teenagers who ''want to appear to be the partying type,'' she said. They post pictures that seem to prove it even if it is not true. ''It's clear they're trying to impress everyone out there,'' Ms. Richardson said.
Keith N. Hampton, an assistant professor at the Annenberg School for Communication at the University of Pennsylvania, said the notion of impressing ''everyone out there'' is the fundamental problem of networking sites. They are designed so that millions see the same image of a member.
For online impression management to be effective, Mr. Hampton said, the sites should be redesigned to allow people to reveal different aspects of their identity to different users. You should be able to present one face to your boss, and another to your poker buddies. ''We have very real reasons for wanting to segment our social network,'' he said.
But what of that breed of users who, despite all the warnings, could care less who sees what? They continue to post salacious photographs of themselves. They reveal deeply personal information. They inspire parental tsk-ing. They open themselves up to identity theft, hurt feelings and job loss.
And that may be the point.
''Today, posting revealing or culpable material online arguably has become another forum for signaling imperviousness to danger and repercussions,'' Ms. Donath wrote in a paper published in October in The Journal of Computer-Mediated Communication. ''They may be indicating that their future is so secure that no social network site indiscretion would jeopardize it, or they may be showing their alienation from the sort of future where discretion is needed. For such users, the risk itself is the benefit.''
