Supporting designers in modeling privacy for social network sites

This paper addresses privacy related to individual's personal information disclosure in the context of Social Network Sites (SNSs). We present the Privacy Design Model (PDM) - built upon Altman's theory of privacy and Semiotic Engineering theory - as a descriptive model that takes into account dimensions corresponding to aspects upon which designers should reflect at design time, regarding personal information disclosure within these systems. PDM considers as personal information disclosure not only pieces of information about the individual, but also the individual's speech and activities that express his/her identity within the system. Thus, we hope to provide designers with a better understanding of how privacy can be treated in SNS by structuring the design space of personal information disclosure through such dimensions. We also analyze the applicability of the model, through the deconstruction of a real SNS in terms of the privacy dimensions proposed in PDM and discuss the implications of our findings.