ContextCapture: Exploring the Usage of Context-based      Awareness Cues in Informal Information Sharing          Ville An...
Oulasvirta et al. have studied how sharing context information        for situation-aware recommendations. The application...
3.1.1 Context RecognitionThe context recognition is based on different “sensors” of activity,such as the accelerometer, am...
reply with the data, should they possess it. The syntax for theexchange protocol is as follows:CCRAControlProtocol:<role_n...
in their everyday lives. This section introduces the user study andthe results from the trial.4.1 MethodologyThe aim of th...
Some of them also thought that the device information is not          status updates as additional context information. We...
the application interaction should follow the idea of “type the      [6] Endler, M., Skyrme, A., Schuster, D. & Springer, ...
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ContextCapture: Exploring the Usage of Context-based Awareness Cues in Informal Information Sharing


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In this paper, we investigate the usage of context-based awareness cues in informal information sharing, especially in social networking services. We present an experimental mobile application, which allows users to add different descriptions of context information to their Facebook status updates. The meaningfulness and the usage of different context descriptions were evaluated in a two-week user trial. The results show that the most frequently used awareness cues in the test setting were location, surroundings, friends and activity. The results also indicate that user-defined semantic abstractions of context items (e.g. “home”, “work”) were often more informative and useful than more accurate indicators (e.g. the address or the name of the place). We also found out that using shared context from friends in vicinity (e.g. identifying the people around) needs careful design to overcome the extended privacy implications.

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  1. 1. ContextCapture: Exploring the Usage of Context-based Awareness Cues in Informal Information Sharing Ville Antila*, Jussi Polet*, Ari-Heikki Sarjanoja**, Petri Saarinen***, Minna Isomursu* *VTT Technical Research Centre of **Nokia Research Centre ***Nokia Research Centre Finland Yrttipellontie 1 Visiokatu 1 Kaitoväylä 1 90230, Oulu, Finland 33720, Tampere, Finland 90570, Oulu, Finland firstname.lastname@vtt.fiABSTRACT addition, to ensure the privacy and user control there should beIn this paper, we investigate the usage of context-based awareness means for adding semantic information by abstracting thiscues in informal information sharing, especially in social information regarding the specific needs and desires of the user.networking services. We present an experimental mobile To give some examples, mobile devices can be used as sensors forapplication, which allows users to add different descriptions of adding contextual information to content or applications. Photoscontext information to their Facebook status updates. The can be tagged with GPS coordinates, or presence information canmeaningfulness and the usage of different context descriptions be shared by an instant messaging application. Furthermore,were evaluated in a two-week user trial. The results show that the location check-ins, adding sports activities and giving informalmost frequently used awareness cues in the test setting were awareness cues in status updates are increasingly usedlocation, surroundings, friends and activity. The results also functionalities in SNSs (Social Networking Services), such as theindicate that user-defined semantic abstractions of context items Facebook.(e.g. “home”, “work”) were often more informative and useful In this paper, we investigate the meaningfulness of different typesthan more accurate indicators (e.g. the address or the name of the of contextual information and the practices of abstracting thoseplace). We also found out that using shared context from friends for public (or semi-public) sharing. To facilitate this, we havein vicinity (e.g. identifying the people around) needs careful developed an experimental mobile application, which allows usersdesign to overcome the extended privacy implications. to add different types of contextual information to their Facebook status updates in a format of a story. The types of contextualCategories and Subject Descriptors information explored in this study include the current physicalH.5.2 [Information Interfaces and Presentation]: activity of the user, the currently active applications in the mobileMiscellaneous. device, information about the current device, information about the friends around, the current location as well as information about the surroundings. Through a two-week user trial weGeneral Terms explored the meaningfulness of these context types and the usageDesign, Experimentation, Human Factors. of different abstraction levels when publicly sharing this information. The goal was to shed light into the practical use ofKeywords context information in informal information sharing and theContext-awareness, computer-mediated communication, mobile generalization of these practices in designing context-awareapplications, sensing, social media. applications.1. INTRODUCTION 2. RELATED WORKContemporary mobile devices are equipped with hardware and There has been a body of research on exploring differentsoftware, which can provide a wide range of awareness and applications for exploiting context information with mobilepresence information about the user and the surroundings. devices. Eagle and Pentland demonstrate the ability to use mobileNevertheless, if not filtered or abstracted this information contains devices to recognize social patterns, infer relationships, identifya lot of noise and has little meaning for the end user. One way to socially significant locations, and model organizational rhythmsapproach this challenge is to build algorithms to mine the [5]. These life patterns can be used as input for creating narrativedifferent sensory data available from the devices [11, 12]. In events [15]. Campbell et al. discuss the rising possibilities of people-centric sensing where social ties are used to both enhance the system learning capabilities and to motivate the user to label Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are activities [4]. In the work of Miluzzo et al. they propose a system, not made or distributed for profit or commercial advantage and that which is capable of sensing various activities (location, physical copies bear this notice and the full citation on the first page. To copy activity, social and physical surroundings) and share this otherwise, or republish, to post on servers or to redistribute to lists, information on various social networking platforms [11, 12]. We requires prior specific permission and/or a fee. propose a similar approach, but give even more freedom for the user to select the message to convey (including different MindTrek’11, September 28–30, 2011, Tampere, Finland. abstractions), thus giving the system possibility to gather more nuanced data from the activities and learn more abstract Copyright 2011 ACM 978-1-4503-0816-8/11/09....$10.00. associations, which can be used for labeling the contexts.
  2. 2. Oulasvirta et al. have studied how sharing context information for situation-aware recommendations. The application concept iscould create awareness about the user’s situation and thus build around three main design goals (adapted from [14]):enhance communication and collaboration [13]. They also discuss Relevance – We wanted to explore the relevance of differentthe different design requirements for representing the context- context types in informal information sharing.based awareness cues [14]. We have used and adapted some ofthese design requirements as the basis of the application concept, Meaningfulness – Another goal was to explore theto explore the relevance, meaningfulness and user control in using meaningfulness of the different abstraction levels of contextcontext-based awareness cues. information (i.e. labeling).The perceived privacy implications of shared presence Control – The application was designed to give full controlinformation are largely related to the information type as well as to the user, thus providing mechanisms to control thethe intended audience, but people are also willing to stretch the disclosure of the overall information or message.boundaries of privacy in exchange for useful services [8]. The The developed application allows people to include contextualdownside of added richness of information is always vulnerability information to their status updates they send to Facebook. Into misuse. For example, Brown et al. [3] discuss the possibilities addition to the selection of different context types, the user canof extracting information from social networks to create context- also decide the desired abstraction level (e.g. coordinates, addressaware spam. We have adopted a basic setup of privacy rules and or semantic label such as “office”). Our hypothesis is that insecurity measures. Nevertheless, adding security mechanisms many cases, rather than using exact parameters provided bybeyond the basic cryptography tools is outside the scope of this context recognition modules for describing the situation, peoplework and is extensively researched in other works. For example, would like to add semantic meaning by using more abstractBeach et al. has explored the implications of sharing social notions. As Benford et al. argue: “[in this context,] declaringnetworking IDs locally and they also discuss the privacy one’s position is perhaps as much about deixis (pointing at andimplications of such sharing mechanisms [1]. In addition, Lee and referencing features of the environment) as it is about tellingChandra propose a phone-to-phone based context sharing to allow someone exactly where you are” [2].dynamic privacy control [9]. These mechanisms could be relevantwhen developing the proposed approach further. In this work, we explore not only the different abstractions of location information, but also other commonly available and usedThe use of mobile devices to create context-aware content to context information types. We selected six basic information typessocial networking services has grown recently. Services such as that the users could use to describe their context. The selectedFoursquare1, Gowalla2 and Facebook Places3 can be used to context types are activity, applications, device, friends, locationcheck-in to venues using mobile devices equipped with GPS- and surroundings. These context types are described more in thechips. Furthermore, location-based formation of social networks next sections.has been researched recently [10]. As the social computing isgetting more mobile and pervasive there has been an increase in 3.1 Software Design and Implementationinterest of exploring the social-side of context-awareness [6]. In The prototype consists of a mobile application and a server-sideaddition to mere location or physical activity of the user, the application, which is integrated with Facebook. The overallsystems could benefit from the knowledge of the social prototype architecture is depicted in the Figure 1 below.surroundings. For example, there has been research to explore the The mobile application gathers context data from the device itself,social use of ubiquitous computing in urban areas [7]. In this available sensors and by using Bluetooth to collect data frompaper, we suggest mechanisms to gather context from the nearby devices. The application presents the sensed contextsurroundings to enhance both availability and relevance of context information to the user along with proposals for other semanticinformation (e.g. querying the devices around). In addition, we abstractions which have been used to describe similar contextsinvestigate the extended privacy implications of such sharing earlier. After selecting the context items and their abstractions, themechanisms from the user’s point-of-view and point out design status update is sent over HTTP to the server. The serverchallenges based on the findings. application stores the received context data into a semantic model (including the raw data from the sensors and the associated3. APPLICATION abstraction) and creates a story-like status update, which is used toThere are two main goals we addressed with the developed create a new status update in Facebook.application. First, we wanted to study the technical aspects ofcollaborative context, for example, how the contextualinformation can be exchanged between different devices.Secondly, we were able to gain new information about the userexperience of context-aware systems, e.g. about the privacyconcerns related to the context sharing, understandability of thecontextually adaptive applications and the meaningfulness ofdifferent abstractions. Furthermore, the shared and storedinformation can also be used for future purposes, such as the basis1 Figure 1. ContextCapture general architecture - main2 components of the client and server-side applications.3
  3. 3. 3.1.1 Context RecognitionThe context recognition is based on different “sensors” of activity,such as the accelerometer, ambient light detector and GPS data,the open applications on the mobile device, the device systeminformation, the nearby Bluetooth devices and the WLAN accesspoints. Based on this data, context descriptions are shown to theuser. For example, based on the ambient light detector data,information about the current lighting is shown to user, such as“Dark lighting” or based on the GPS data, the current streetaddress, GPS coordinates and current temperature and weatherdescriptions are shown. In the list below we describe all thecontext information items supported by the application: Activity – Based on the accelerometer data, a decision is made whether the user is running, walking or still by using movement detection algorithms. This is then shown to the user as a description of the current physical activity abstraction. Applications – Based on the data gathered from the mobile device, the currently open applications are shown to the user as a description of the current virtual activity abstraction. Device – Some of the data gathered about the mobile device itself, such as the device type, is shown to the user. Friends – Based on the Bluetooth device and service scan data, the current nearby Bluetooth devices and ContextCapture friends are shown to the user as the current social context. The current ContextCapture friends’ detection is based on the Facebook friends and ContextCapture use, i.e. if the users are friends in the Facebook and both are using ContextCapture and are nearby, they are shown in the current social context abstractions. Location – Based on the GPS, network and WLAN scan data, the current street address, GPS coordinates, network cell ID and nearby WLAN access points are shown as the possible current location abstractions. Surroundings – Based on the ambient light detector and GPS data, the current ambient lighting and the temperature and weather (which are downloaded based on the GPS coordinates) are shown as the current physical surroundings Figure 2. An example use sequence of the ContextCapture abstractions. mobile application.3.1.2 Mobile Application In the Figure 2 we present an example use sequence of the mobileThe main functionality of the mobile application is to gather application, where the user first selects the physical activityinformation about the current context and show it to the user. The context to be added to the status update and then selects theuser can then use these context items to create context-aware wanted abstraction for the activity. In the Figure 2, the user selectsstatus updates. In addition to the sensed context abstractions, the the “Sitting” abstraction out of the five suggested abstractionsapplication also lists other commonly used abstractions to give the instead of the actual physical activity (which is “Still”) or writinguser control over the selection of items and abstractions to include an own the message. This gives the user the opportunity to reflect anyhigher-level semantics, which cannot be inferred by the system, 3.1.3 Protocol for Exchanging Collective Contextbut also gives the system the possibility to learn these new The client-to-client communication is done over a Bluetoothsemantics given in specific contexts making the recommendations connection, using a specified communication protocol. Thesmarter over time. When the user sends the status update, the mobile client sets up a RFCOMM service when the applicationmobile application sends the selected abstractions as well as the starts and notices whether there are other devices nearby offeringsensed raw sensory data to create the association link to enable the specified service. If so, the devices exchange MD5-hashedmachine learning. This will create a database of collectively IMSI strings, which are coupled with the Facebook accounts.created database of context semantics that can be shared between Thus, the mobile client will recognize the nearby ContextCaptureusers. Facebook friends. If the mobile client is lacking some context information, for example the GPS coordinates, it will request that information from the nearby ContextCapture friends, which will
  4. 4. reply with the data, should they possess it. The syntax for theexchange protocol is as follows:CCRAControlProtocol:<role_name>:<BT_name>:<command>:<parameters> For example, the mobile client requesting for weather data froma nearby ContextCapture friend takes the client role and sends arequest as follows:CCRAControlProtocol:Client:ClientBluetoothName:WTHR:Request And the service running on the specified device replies:CCRAControlProtocol:Server:ServerBluetoothName:WTHR:-3 degrees Celsius,Sunny If the other device does not have the context data asked for, itwill simply reply:CCRAControlProcotol:Server:ServerBluetoothName:NACK:WTHRThe client-to-server communication enables the mobile client to Figure 3. ContextCapture application on Facebook.send status updates to Facebook. The ContextCapture Facebookapplication is located at the server and relays the incoming status After a successful installation and registration of both theupdate messages from the mobile client to the Facebook. The Facebook application and the mobile application, the user canclient-to-server communication is based on normal HTTP GET send context-enhanced status updates from the mobile deviceand POST operations, where the data sent is JSON formatted. The directly to the Facebook wall (an example is presented below intwo main communication sequences between the mobile client the Figure 4).and the server are the login and status update.In the login sequence, the mobile client sends the login key,which the user has got from the ContextCapture Facebookapplication and the MD5-hashed IMSI string. This way, the user’sFacebook account and the user’s mobile device are coupledtogether at the server by using the Facebook user ID,ContextCapture login key and the MD5-hashed IMSI string.Depending on the login success, the server sends back a reply,which also contains the user’s Facebook friends. This way, themobile client is able to recognize the nearby Facebook friends byexchanging the MD5-hashed IMSI strings acting as identifiers. Figure 4. A context-enhanced status update shown in the Facebook profile.In the status update sequence, the mobile client sends a JSONformatted data package containing all the context data and theuser-given abstractions to server. The server then parses the 3.2 Used Technologiesmessage and creates a story-like status update string, which is sent The mobile application was implemented for Symbian devices. Qtas a wall post to Facebook. Depending on the success, the server for Symbian with additional third-party libraries (such assends back a reply, which also contains the current QBluetooth and QJson) was used. The persistent storage forContextCapture friends, so that the mobile client can update the context data was implemented with the Qt APIs for SQLite4. Thefriends list if there have been changes. mobile application is also developed for Android devices, but they were not used in the trial. The server-side implementation was developed using J2EE web framework. The contextual data is3.1.4 Server-side Application and Facebook saved using RDF5 format with Jena Semantic Web Toolkit6 andIntegration persisted in a PostgreSQL7 database. The SNS integration wasThe key functionality of ContextCapture application is the implemented using the Facebook APIs, which enablesintegration to Facebook. This integration was done by functionalities such as the user authentication and status updating.implementing a Facebook application, which handles the firstphase of registration. To install the application, the user simplyaccesses the application URL 4. EVALUATION To evaluate the ContextCapture application and to find answers to( After our research questions, we arranged a trial where 12 participantsallowing the permissions, the user is redirected back to the used ContextCapture for two weeks with their own mobile phonesContextCapture application with access credentials (Facebookwill give the ContextCapture application an OAuth token foraccessing the Facebook API). This access token is used to query 4the basic user information, such as the name and the profile Then the user is given a unique login key, depicted in the 5 3, which can be used to sign in with the mobile 6application. This creates the link between the mobile application the Facebook user account. 7
  5. 5. in their everyday lives. This section introduces the user study andthe results from the trial.4.1 MethodologyThe aim of the evaluation was to study how people would usecontext information in their status updates, what kind of feelingsand user experience automatic context recognition would invokeand what kind of abstraction levels would be suitable forpresenting the context information. To discover these matters,three research questions were set (Table 1). Table 1. Research questions RQ1 Do users perceive the context data as useful in manual status updates? Figure 5. Frequency of sending status updates (generally and RQ2 Do users perceive an application supporting manual via mobile phone). status update through automatic context recognition and collective context as useful or valuable? 4.3 Trial Setup RQ3 What kind of abstraction levels (regarding the First we sent email instructions to the participants on how to semantics) is understandable for the user? download and install the application. The email included a short description of the study and its purpose, a short manual, the link and instructions on how to install the application and a link to theAs we wanted to ensure that all significant data would be initial web questionnaire. The users were requested to fill in thecollected, various data collection methods were used. In the initial questionnaire after they had successfully completed thebeginning of the trial we had an initial web questionnaire which installation of the application. This indicated that they had startedincluded questions about the Facebook usage and expectations the trial.towards the ContextCapture application. During the trial The participants used the application for approximately twoparticipants could report about their experiences with the weeks. During that time, they could tell their experiences throughapplication through a web-based diary questionnaire. The diary the web diary. We asked them to fill in the diary at least five timesinquired, which of the context types had been most useful to the and preferably in separate days. Total of 26 diary entries wereparticipants lately and whether they had got any comments and made during the trial. At the end of the trial, we interviewed allfeedback from their Facebook friends related to the contextual the participants; nine of them with face-to-face interviews andstatus updates. It also included questions about the experiences three of them via telephone interviews. Interviews were semi-related to privacy. The participants could also give general free- structured, including questions dealing with users’ expectationsformatted feedback about the study and tell the possible problems and meeting them, attitudes, privacy and the most pleasing andwith the application through the diary questionnaire. At the end of unpleasing experiences related to usage. Furthermore, participantsthe trial all participants were interviewed for getting more in- were asked about their ideas for further development of thedepth information about the user experience. Interviews also application. Interviews lasted approximately 30 minutes each.included a background information sheet, which was given onpaper. It contained demographical and closed scale questions,which were easier to ask in written form. 4.4 Findings At the beginning of the trial participants did not have much expectations, which is understandable since these kinds of4.2 Participants applications are novel to many people. It seemed that participantsAs ContextCapture is currently designed to work with Facebook thought they understood well how ContextCapture application canonly, the first criterion for the trial participants was the fact that be used, as Figure 6 describes. In addition, privacy was notthey had to be active Facebook users. Some of the participants viewed as an issue at the beginning of the trial and context-had to be connected through Facebook, as we wanted to have awareness and context-aware applications were known to most ofgroups of people, who could see each other’s status updates and the participants. Also, under half of the trial participants felt thatbe able to use friends related context information via “Facebook the application was going to be useful for them before the trial,friends nearby” –functionality. In addition, the participants had to but argued afterwards that the application does provide some extrahave suitable mobile phones supported by the application. Due to value for the status updates and overall was fun to use.this, we decided to invite only Nokia and VTT employees. As Figure 7 shows, participants viewed Location as the mostTotal of 12 users participated in the trial, six male and six female. valuable context field. Many participants seemed to think thatThe age of the participants was between 30-46 years, 37.25 years added context information enlivens the status updates in aon average. Participants used ContextCapture with their own pleasant way. Status updates with location information are alsomobile devices and personal Facebook accounts during the trial. more informative as people can use them to reference theirAll participants were experienced Facebook users as 25% of them activities with the relevant location or point out features from thehad used the service 1-2 years and the rest for over two years. environment. Weather information, which was related toFigure 5 shows how often the participants were used to send Surroundings field, was also seen highly interesting. Applicationstatus updates before the study. and Device were considered as the least useful fields. It seemed that many participants did not want to advertise the device they were using, so they considered the device field as unnecessary.
  6. 6. Some of them also thought that the device information is not status updates as additional context information. Weatherrelevant context information since it rarely changes. information was seen as valuable, but a more informative way to show weather conditions could be by using more visual information, like a specific icon. Most participants thought that it is critical to integrate the application to Facebook, when a stand- alone application would not be needed anymore and the features could be used straight from the Facebook UI. 5. DISCUSSION AND CONCLUSIONS The motivation for the research described in this paper was to explore the usage of different types and abstractions of context information in informal information sharing. We approached this challenge by developing an experimental application that allows users to add different context information types and abstractions to their Facebook status updates. Our hypothesis was that in many cases, rather than using exact terms for describing the situation, people would like to use more abstract notions. The findings Figure 6. Statements about the application. support this hypothesis. In many cases, the participants reported that the usage of semantic labels rather than exact terms to describe the situation seemed more appropriate and meaningful. In addition, the participants brought up privacy concerns regarding the use of collective context, such as identifying friends around. We conclude that introduction of such functionalities needs careful design for mechanisms to give permissions for publication. Even though the participants felt that the service as such was not so much useful as it was fun, they argued that if developed further and integrated better with the mobile devices and the SNSs, the service could prove to be useful when one wants to share the Figure 7. The usefulness of different context fields. current situation without having to spend too much timePrivacy matters did not raise major issues during the trial, though illustrating the surrounding context.participants were clearly aware of their privacy and had thought it Based on the findings from the user study we analyzed thewhile using the application. For example, the participants did not relevance and meaningfulness of the different context types asuse the addresses of their homes or kindergarten their children well as the control of the information disclosure.were, although the audience consisted of Facebook friends known The participants felt that the current location, activity andby the participants. It seemed that the accurate location of these surroundings were the most relevant context types, as byplaces was too sensitive to be shared. In addition, many of the disclosing them the current situation could be described quiteparticipants stated that the semantic meaning of the place is extensively. The more virtual context types, that are theenough. For example, saying that “I’m at home” is adequate applications and the device, were seen as less relevant, as theenough for the people the message is meant for, i.e. my friends users did not want to advertise the make or the model of theirknow where I live. mobile device and the applications running were mostly seen asSharing friend’s location was also one thing, which invoked quite boring information to be included. Disclosing the nearbythoughts. In many participants’ opinion sharing this kind of friends or colleagues in the status updates was seen as relevant butinformation without permission is not acceptable. So there should problematic due to privacy some way for asking a permission to share context data The context types were seen as most meaningful when the usedincluding other users. Friends’ names were also often viewed as abstraction level was high, i.e. the participants felt that the exactprivate information and participants preferred to use more abstract low-level information, such as the street address or the GPSwords, like “group of friends”, instead of giving the exact names. coordinates, conveyed a too matter-of-fact type descriptionOne of the key findings was the fact that participants were clearly whereas more abstract descriptions, such as “at the movieinterested in context data and in using context-aware application. theatre” or “at the botanical garden” were seen as moreContext information was seen as highly interesting, but the illustrative, interesting and meaningful. Also using the name ofparticipants hoped that they could have had even more control in the building or other abstract place names were preferred, as thisthe level of abstraction. In addition, more abstract names like way the users can protect their privacy but in the same time it can“home”, “work”, “kindergarten” were seen as more useful and be more expressive for the people who know the area. This type ofsecure in many situations than the exact street addresses. There information abstraction can be thought in some way as “privacywere interest towards getting more specific location information, through obscurity”.bare street addresses were seen as not useful, but the application The trial participants reported that the application controlsshould recognize the place, which is located in the address, like a regarding the information disclosure were good. In fact, most ofmovie theater or a shop. the participants wished that most of the context fields should beParticipants gave some ideas for further development. For included automatically in order to avoid too much selecting, i.e.example, many were interested in using also photos with the
  7. 7. the application interaction should follow the idea of “type the [6] Endler, M., Skyrme, A., Schuster, D. & Springer, T.status update, choose the context abstractions and deselect what Defining Situated Social Context for Pervasive Socialyou do not want to include” instead of the current idea of “type Computing. Second IEEE Workshop on Pervasivethe status update, choose the context abstractions and select Collaboration and Social Networking, in Proceedings ofwhich ones you want to include”. The participants agreed that PerCom, Vol. 1. 2011. pp. 3, 2011.when designing and implementing these kind of applications, the [7] Hosio, S., Kukka, H. & Riekki, J. Social Surroundings:information disclosure and privacy should be able to be fully Bridging the Virtual and Physical Divide. IEEE MultiMediacontrolled by the user. Magazine, Vol. 17, No. 2, pp. 26-33, 2010.We argue that the proposed approach was meaningful and [8] Khalil, A. & Connelly, K. Context-aware Telephony: Privacymotivating for the users and in the same time allows the system to Preferences and Sharing Patterns. Proceedings of the 2006gather an extensive set of user-defined context labels. This 20th Anniversary Conference on Computer Supportedextensive set of labels can be used as inputs for machine learning Cooperative Work, pp. 469, ACM, 2006.mechanisms to allow smarter recommendations and evenpredictions based on higher level context abstractions, which [9] Lee, J.S. & Chandra, U. Mobile Phone-to-phone Personalcould otherwise be impossible to infer from the data only. Context Sharing. 9th International Symposium on Communications and Information Technology (ISCIT), 2009, pp. 1034, IEEE, 2009.6. ACKNOWLEDGMENTSThis work has been supported by the SMARCOS Artemis project. [10] Lübke, R., Schuster, D. & Schill, A. MobilisGroups: Location-based Group Formation in Mobile Social Networks. Second IEEE Workshop on Pervasive7. REFERENCES Collaboration and Social Networking, in Proceedings of[1] Beach, A., Gartrell, M., Akkala, S., Elston, J., Kelley, J., PerCom, 2011. Nishimoto, K., Ray, B., Razgulin, S., Sundaresan, K. & Surendar, B. Whozthat? Evolving an Ecosystem for Context- [11] Miluzzo, E., Lane, N., Eisenman, S. & Campbell, A. aware Mobile Social Networks, Vol. 22, No. 4, pp. 50-55, CenceMe – Injecting Sensing Presence Into Social Network, IEEE, 2008. Networking Applications. Smart Sensing and Context, pp. 1- 28, 2007.[2] Benford, S., Seager, W., Flintham, M., Anastasi, R., Rowland, D., Humble, J., Stanton, D., Bowers, J., [12] Miluzzo, E., Lane, N.D., Fodor, K., Peterson, R., Lu, H., Tandavanitj, N. & Adams, M. The Error of Our Ways: The Musolesi, M., Eisenman, S.B., Zheng, X. & Campbell, A.T. Experience of Self-reported Position in a Location-based Sensing Meets Mobile Social Networks: The Design, Game, pp. 70-87, UbiComp 2004: Ubiquitous Computing, Implementation and Evaluation of the CenceMe Application. 2004. Proceedings of the 6th ACM Conference on Embedded Network Sensor Systems, pp. 337, ACM, 2008.[3] Brown, G., Howe, T., Ihbe, M., Prakash, A. & Borders, K. Social Networks and Context-aware Spam. Proceedings of [13] Oulasvirta, A. Designing Mobile Awareness Cues. the 2008 ACM Conference on Computer Supported Proceedings of the 10th International Conference on Human Cooperative Work, pp. 403, ACM, 2008. Computer Interaction with Mobile Devices and Services, pp. 43, ACM, 2008.[4] Campbell, A.T., Eisenman, S.B., Lane, N.D., Miluzzo, E., Peterson, R.A., Lu, H., Zheng, X., Musolesi, M., Fodor, K. [14] Oulasvirta, A., Raento, M. & Tiitta, S. ContextContacts: Re- & Ahn, G.S. The Rise of People-centric Sensing, pp. 12-21, designing SmartPhones Contact Book to Support Mobile IEEE Internet Computing, IEEE, 2008. Awareness and Collaboration. Proceedings of the 7th International Conference on Human Computer Interaction[5] Eagle, N. & Pentland, A. Reality Mining: Sensing Complex with Mobile Devices & Services, pp. 167, ACM, 2005. Social Systems, Vol. 10, No. 4, pp. 255-268, Personal and Ubiquitous Computing, 2006. [15] Reddington, J. & Tintarev, N. Automatically Generating Stories from Sensor Data. Proceedings of the 15th International Conference on Intelligent User Interfaces, pp. 407, ACM, 2011.