Tools for Achieving Usable Ex Post Transparency: A Survey <s> a: MULTILAYERED <s> A number of mobile applications have emerged that allow users to locate one another. However, people have expressed concerns about the privacy implications associated with this class of software, suggesting that broad adoption may only happen to the extent that these concerns are adequately addressed. In this article, we report on our work on PeopleFinder, an application that enables cell phone and laptop users to selectively share their locations with others (e.g. friends, family, and colleagues). The objective of our work has been to better understand people's attitudes and behaviors towards privacy as they interact with such an application, and to explore technologies that empower users to more effectively and efficiently specify their privacy preferences (or "policies"). These technologies include user interfaces for specifying rules and auditing disclosures, as well as machine learning techniques to refine user policies based on their feedback. We present evaluations of these technologies in the context of one laboratory study and three field studies. <s> BIB001 </s> Tools for Achieving Usable Ex Post Transparency: A Survey <s> a: MULTILAYERED <s> Feedback is viewed as an essential element of ubiquitous computing systems in the HCI literature for helping people manage their privacy. However, the success of online social networks and existing commercial systems for mobile location sharing which do not incorporate feedback would seem to call the importance of feedback into question. We investigated this issue in the context of a mobile location sharing system. Specifically, we report on the findings of a field de-ployment of Locyoution, a mobile location sharing system. In our study of 56 users, one group was given feedback in the form of a history of location requests, and a second group was given no feedback at all. Our major contribution has been to show that feedback is an important contributing factor towards improving user comfort levels and allaying privacy concerns. Participants' privacy concerns were reduced after using the mobile location sharing system. Additionally,our study suggests that peer opinion and technical savviness contribute most to whether or not participants thought they would continue to use a mobile location technology. <s> BIB002 </s> Tools for Achieving Usable Ex Post Transparency: A Survey <s> a: MULTILAYERED <s> Location-Based Mobile Service (LBMS) is one of the most popular smartphone services. LBMS enables people to more easily connect with each other and analyze the aspects of their lives. However, sharing location data can leak people's privacy. We present PDVLoc, a controlled location data-sharing framework based on selectively sharing data through a Personal Data Vault (PDV). A PDV is a privacy architecture in which individuals retain ownership of their data. Data are routinely filtered before being shared with content-service providers, and users or data custodian services can participate in making controlled data-sharing decisions. Introducing PDVLoc gives users flexible and granular access control over their location data. We have implemented a prototype of PDVLoc and evaluated it using real location-sharing social networking applications, Google Latitude and Foursquare. Our user study of 19 participants over 20 days shows that most users find that PDVLoc is useful to manage and control their location data, and are willing to continue using PDVLoc. <s> BIB003 </s> Tools for Achieving Usable Ex Post Transparency: A Survey <s> a: MULTILAYERED <s> We present a prototype of the user interface of a transparency tool that displays an overview of a user's data disclosures to different online service providers and allows them to access data collected about them stored at the services' sides. We explore one particular type of visualization method consisting of tracing lines that connect a user's disclosed personal attributes to the service to which these attributes have been disclosed. We report on the ongoing iterative process of design of such visualization, the challenges encountered and the possibilities for future improvements. <s> BIB004
Multilayered visualisations display information in multiple levels of detail. 22 Multilayered designs usually start with an overview of generic, coarse-grained information. To be as clearly readable and as quickly digestible as possible, such data are often kept to a bare minimum. Buttons, hyperlinks or icons reveal secondary, more detailed information about the respective data item. Multilayered displays often implement a hierarchical, top-down navigation paradigm. Some visualisations support cross-references between multiple views, allowing for a sequential or contextual traversal of the available data. Mun et al. BIB003 display location sample points on a map where each additional contextual detail can be displayed. Tsai et al. BIB002 display a 'show details'-button along with reviewed log records. Sadeh et al. BIB001 provide similar functionality complemented by a real-time notification that offers general and detailed information about queries regarding the user's location. The implementations presented by 22 Multilayered (adjective): ''Having or involving several distinct layers, strata, or levels.''  Bier et al.  and Angulo et al. BIB004 work similarly in how they visualise disclosed personal data. Both provide an initial overview that shows the relationships of data subjects with whom the stakeholders they share personal data. Upon request, both TETs provide detailed information on individual data controllers, as well as on the individual data items that have been disclosed to these stakeholders.