Retrospective privacy: managing longitudinal privacy in online social networks

Online social networks provide access to the user's information for long periods of time after the information's initial publication. In this paper, we investigate the relation between information aging and its sharing preferences on Facebook. Our findings are based on a survey of 193 Facebook users, in which we asked users to specify their sharing preferences and intentions towards posts that were published in different periods of time (from the time of the survey and up to 24 months prior to the time of the survey.) Our results show that willingness to share significantly drops with the time passed since publishing the post. The occurrence of life changes, such as graduating from college or moving to a new town, is correlated with a further decrease in the willingness to share. We discuss our findings by relating it to information aging theories and privacy theories. Finally, we use our results to reflect on privacy mechanisms for long-term usage of online social networks, such as expiry date for content and historical information reviewing processes.