Tools for Achieving Usable Ex Post Transparency: A Survey <s> 4) FEEDBACK <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> BIB001 </s> Tools for Achieving Usable Ex Post Transparency: A Survey <s> 4) FEEDBACK <s> A large body of research has focused on disclosure policies for controlling information release in social sharing (e.g., location-based) applications. However, less work has considered how exposed these policies actually leave users; i.e., to what extent are disclosures in compliance with these policies actually being made? For instance, consider a disclosure policy granting Alice's coworkers access to her location during work hours. Alice might feel that this policy appropriately controls her exposure, but may feel differently if she learned that her boss was accessing her location every 5 minutes. In addition to specifying who has access to personal information, users need a way to quantify, interpret, and control the extent to which this data is shared. We propose and evaluate an intuitive mechanism for summarizing and controlling a user's exposure on smartphone-based platforms. Our approach uses the visual metaphor of eyes appearing and growing in size on the home screen; the rate at which these eyes grow depends on the number of accesses granted for a user's location, and the type of person (e.g., family vs. friend) making these accesses. This approach gives users an accurate and ambient sense of their exposure and helps them take actions to limit their exposure, all without explicitly identifying the social contacts making requests. Through two systematic user studies (N = 43,41) we show that our interface is indeed effective at summarizing complex exposure information and provides comparable information to a more cumbersome interface presenting more detailed information. <s> BIB002 </s> Tools for Achieving Usable Ex Post Transparency: A Survey <s> 4) FEEDBACK <s> The work presented in this paper introduces the concept of On-line Interactive (OI) privacy feature which is defined as any on-line interactive tool, component or user-interface that creates privacy awareness and supports users in understanding their on-line privacy risks. These features have been developed as an interactive social translucence map that discloses the flow of personal information, a privacy enquiry for a direct chat about users' privacy concerns and a discussion forum presenting users' privacy concerns using their language in an interactive FAQ format. The paper presents an evaluation of a prototype of this set of embedded OI privacy features. The field study presented evaluates the prototype's usability and its effect on users' privacy awareness, understanding and attitude. 100 participants took part in the study and were drawn from groups of experienced and less experienced users. Both quantitative and qualitative data collection methods were used. Findings suggest that OI privacy features increase users' privacy awareness and encourage users to find out more about the uses of their personal data. However, users' ICT skills and Internet experience significantly influence whether a feature is favoured or otherwise. In general, it is concluded that privacy features are very much welcomed and necessary to empower users to manage their privacy concerns but some groups need to be further supported by social and institutional privacy management processes. <s> BIB003 </s> Tools for Achieving Usable Ex Post Transparency: A Survey <s> 4) FEEDBACK <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> BIB004 </s> Tools for Achieving Usable Ex Post Transparency: A Survey <s> 4) FEEDBACK <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> BIB005
The 'visibility of the system status' as a core usability heuristic  merits particular attention. The availability of meaningful information about the status of a system is a necessary condition for rational decision-making on the part of a user. Without feedback BIB005 from a TET, a user might be unable to assess the current status of her personal data  . Consequently, such a user might be unable to make a rational decision as to how to interact with and exercise control over the TET. Multiple user studies examine the impact of system feedback on the users of a TET. The findings of Schlegel et al. BIB002 show that system feedback makes users more comfortable in sharing their location data. Along similar lines, Tsai et al. BIB001 state that the users' level of comfort in terms of sharing their location data differs depending on whether they receive meaningful feedback from the system about the queriers of their data. In contrast to a control group that had not received feedback, test subjects who had received system feedback were more comfortable sharing their location. The user study conducted by Hsieh et al.  shows that users particularly value immediate system feedback on queries to their location, and also appreciate the ability to audit disclosed personal data in general. Mun et al. BIB004 write that their user study shows that users appreciated system feedback in that it helped them to better understand whether their respective settings matched their actual preferences, as well as what kind of data were actually disclosed to whom. BIB005 Feedback (noun): ''The modification or control of a process or system by its results or effects''  Kani-Zabihi et al. BIB003 concede that the online chat implemented for their TET proved to be the least favourable of the feedback controls evaluated. According to the test subjects, chat as a medium was considered inappropriate in terms of serving as a means to convey privacy concerns to a data controller.