Over the past decade, social network sites have experienced dramatic growth in popularity, reaching most demographics and providing new opportunities for interaction and socialization. Through this growth, users have been challenged to manage novel privacy concerns and balance nuanced trade-off s between disclosing and withholding personal information. To date, however, no study has documented how privacy and disclosure evolved on social network sites over an extended period of time. In this manuscript we use profile data from a longitudinal panel of 5,076 Facebook users to understand how their privacy and disclosure behavior changed between 2005 - the early days of the network - and 2011. Our analysis highlights three contrasting trends. First, over time Facebook users in our dataset exhibited increasingly privacy-seeking behavior, progressively decreasing the amount of personal data shared publicly with unconnected profiles in the same network. However, and second, changes implemented by Facebook near the end of the period of time under our observation arrested or in some cases inverted that trend. Third, the amount and scope of personal information that Facebook users revealed privately to other connected profiles actually increased over time|and because of that, so did disclosures to "silent listeners" on the network: Facebook itself, third-party apps, and (indirectly) advertisers. These findings highlight the tension between privacy choices as expressions of individual subjective preferences, and the role of the environment in shaping those choices.In discussing research limitations and conclusions the authors comment that
We have presented the results of a longitudinal analysis of 5,076 Facebook users who were members of the Carnegie Mellon Facebook network in 2005. Over the course of seven years, we captured pro file content with a goal of understanding how disclosure practices change over time. Before summarizing our results, we point out a number of limitations of the current analysis.
First, as we have observed in the introduction, one limitation of this data is that it does not originate from a random sample of Facebook users - nor could it, as the bulk of Facebook users in 2013 did not have Facebook accounts in 2005. Our trends are based on a panel of Facebook users dominated by undergraduate students, and our analysis focuses on one specifi c Facebook network - the Carnegie Mellon network - and only on those who were members of that network in 2005. Hence, our results may not extrapolate to more diverse samples of users. However, both survey data and analyses of other Facebook networks are consistent with one of the results presented here: that over time Facebook users have become less likely to share their personal information publicly. Our analysis extends that research by offering evidence that the privacy-seeking behavior started early in the life of the network, and then progressed over several years of Facebook usage - until it was partly obstructed by Facebook's policies and interface changes.
Second, in this manuscript we did not distinguish between non-disclosures due to the member actually not filling out a field, and those due to the member altering the privacy settings of that field (or of their entire profile) in order to limit public disclosures. While such distinction is of interest (and is the object of our ongoing research), it does not invalidate the main conclusions of the current analysis, which focused on the trends in public disclosures of personal information over time. It does affect, however, the discussion of how much information remains available to third-parties (such as apps providers) and to Facebook itself.
On the other hand, we also observed that, over time, the amount and scope of personal information that Facebook users have revealed to friends' profiles seems to have markedly increased - and thus, so have disclosures to Facebook itself, third-party apps, and (indirectly) advertisers. Such findings highlight the challenges users of social network sites face when trying to manage online privacy, and the power of providers of social media services to affect individuals' disclosure and privacy behavior through interfaces and default settings.