A three-year German study ending in 2012 showed that the more people disclosed about themselves on social media, the more privacy they said they desired. The lead author of the study, Sabine Trepte, a professor of media psychology at the University of Hohenheim in Stuttgart, said the paradox indicated participants’ dissatisfaction with what they got in return for giving away so much about themselves.

“It’s a bad deal because what they get is mainly informational support like maybe a tip for a restaurant or link to an article,” she said. “What they don’t get is the kind of emotional and instrumental support that leads to well-being, like a shoulder to cry on or someone who will sit by your bedside at the hospital.”

And yet, she added, they continued to participate because they were afraid of being left out or judged by others as unplugged and unengaged losers. So the cycle of disclosure followed by feelings of vulnerability and general dissatisfaction continued.

“There’s also this idea in our society that if I just embarrass myself enough I can be the next Snooki or Kardashian,” said Anita L. Allen, author of “Unpopular Privacy: What Must We Hide?” and professor of law and philosophy at the University of Pennsylvania Law School. “There’s a real financial incentive to not care and give it all up.”

The problem is that if you reveal everything about yourself or it’s discoverable with a Google search, you may be diminished in your capacity for intimacy. This goes back to social penetration theory, one of the most cited and experimentally validated explanations of human connection. Developed by Irwin Altman and Dalmas A. Taylor in the 1970s, the theory holds that relationships develop through gradual and mutual self-disclosure of increasingly private and sensitive personal information.

“Building and maintaining an enduring, intimate relationship is a process of privacy regulation,” said Dr. Altman, now an emeritus professor of psychology at the University of Utah. “It’s about opening and closing boundaries to maintain individual identity but also demonstrate unity with another, and if there are violations then the relationship is threatened.”

Thought of another way, information about yourself is like currency. The amount you spend on a person signifies how much you value the relationship. And that person compensates you in kind. That’s why it feels like theft when someone tells your secrets or data miners piece together your personal history — using your browsing habits, online purchases and social networks — and sell it. And it’s also why if you’re profligate with information about yourself, you have precious little to offer someone really special.