Carnegie Mellon University
March 05, 2013

Press Release: Despite Efforts To Protect Privacy, Users Increase Amount of Personal Information Available Online, Carnegie Mellon Study Finds

First Long-term Study of Facebook Users Finds Network Environment Influencing Privacy Outcomes

Contact: Ken Walters / 412-268-1151 /

PITTSBURGH-A seven-year Carnegie Mellon University study of Facebook has found evidence of three contrasting trends in the amount of information Facebook users disclosed over time: decreasing public disclosures; abrupt changes in disclosure due to interface and policy changes;  and increasing private disclosures.

The 2005-2011 study, which appears in The Journal of Privacy and Confidentiality and can be found at, is the first longitudinal study to document how privacy and disclosure evolve on social network sites over an extended period of time. Researchers found that from 2005-2009, Facebook users displayed more privacy-seeking behavior, progressively decreasing the amount of personal data shared with the public.  

This trend abruptly reversed between 2009 and 2010, when changes implemented by Facebook, such as modifications to its user interface and default settings, led to a significant increase in the public sharing of various types of personal information. The study also found that, over time, the amount and scope of personal information that Facebook users revealed to their Facebook "friends" actually increased. As a result, users ended up increasing their personal disclosures to other entities on the network, sometimes unknowingly, including to "silent listeners" such as Facebook itself, third-party apps and advertisers.

"These findings highlight the tension between privacy choices as expressions of individual subjective preferences, and the role of the network environment in shaping those choices," said CMU Associate Professor of Information Technology and Public Policy Alessandro Acquisti, who co-authored the study with CMU researchers Ralph Gross and Fred Stutzman. "While people try to take control of their personal information, the network keeps changing, affecting their decisions and changing their privacy outcomes."

Titled "Silent Listeners: The Evolution of Privacy and Disclosure on Facebook," the study profiles data from a panel of 5,076 Facebook users and is the first study to use data from Facebook's early days in 2005.

"These findings illustrate the challenges social network users face when trying to manage online privacy, the power of social media providers to affect their disclosure and privacy behavior, and the potential limits of notice and consent mechanisms in addressing consumers' on-line privacy concerns," Stutzman said.

"Access to settings which help individuals determine which profile data other users get to see may increase members' feeling of control, but perceptions of control over personal data and the misdirection of users' attention have been linked to increases in disclosures of sensitive information to strangers," Gross said.