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.

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 ari-heikki.sarjanoja@nokia.com petri.1.saarinen@nokia.com
firstname.lastname@vtt.fi
ABSTRACT addition, to ensure the privacy and user control there should be
In this paper, we investigate the usage of context-based awareness means for adding semantic information by abstracting this
cues 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 for
application, which allows users to add different descriptions of adding contextual information to content or applications. Photos
context information to their Facebook status updates. The can be tagged with GPS coordinates, or presence information can
meaningfulness 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 informal
most frequently used awareness cues in the test setting were awareness cues in status updates are increasingly used
location, surroundings, friends and activity. The results also functionalities in SNSs (Social Networking Services), such as the
indicate 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 types
than more accurate indicators (e.g. the address or the name of the of contextual information and the practices of abstracting those
place). We also found out that using shared context from friends for public (or semi-public) sharing. To facilitate this, we have
in vicinity (e.g. identifying the people around) needs careful developed an experimental mobile application, which allows users
design 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 contextual
Categories and Subject Descriptors information explored in this study include the current physical
H.5.2 [Information Interfaces and Presentation]: activity of the user, the currently active applications in the mobile
Miscellaneous. 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 we
General Terms explored the meaningfulness of these context types and the usage
Design, Experimentation, Human Factors.
of different abstraction levels when publicly sharing this
information. The goal was to shed light into the practical use of
Keywords context information in informal information sharing and the
Context-awareness, computer-mediated communication, mobile generalization of these practices in designing context-aware
applications, sensing, social media. applications.
1. INTRODUCTION 2. RELATED WORK
Contemporary mobile devices are equipped with hardware and There has been a body of research on exploring different
software, which can provide a wide range of awareness and applications for exploiting context information with mobile
presence information about the user and the surroundings. devices. Eagle and Pentland demonstrate the ability to use mobile
Nevertheless, if not filtered or abstracted this information contains devices to recognize social patterns, infer relationships, identify
a lot of noise and has little meaning for the end user. One way to socially significant locations, and model organizational rhythms
approach this challenge is to build algorithms to mine the [5]. These life patterns can be used as input for creating narrative
different 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. Oulasvirta et al. have studied how sharing context information for situation-aware recommendations. The application concept is
could 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 different
the different design requirements for representing the context-
context types in informal information sharing.
based awareness cues [14]. We have used and adapted some of
these design requirements as the basis of the application concept, Meaningfulness – Another goal was to explore the
to explore the relevance, meaningfulness and user control in using meaningfulness of the different abstraction levels of context
context-based awareness cues. information (i.e. labeling).
The perceived privacy implications of shared presence Control – The application was designed to give full control
information are largely related to the information type as well as to the user, thus providing mechanisms to control the
the 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 contextual
downside of added richness of information is always vulnerability information to their status updates they send to Facebook. In
to misuse. For example, Brown et al. [3] discuss the possibilities addition to the selection of different context types, the user can
of extracting information from social networks to create context- also decide the desired abstraction level (e.g. coordinates, address
aware spam. We have adopted a basic setup of privacy rules and or semantic label such as “office”). Our hypothesis is that in
security measures. Nevertheless, adding security mechanisms many cases, rather than using exact parameters provided by
beyond the basic cryptography tools is outside the scope of this context recognition modules for describing the situation, people
work and is extensively researched in other works. For example, would like to add semantic meaning by using more abstract
Beach et al. has explored the implications of sharing social notions. As Benford et al. argue: “[in this context,] declaring
networking IDs locally and they also discuss the privacy one’s position is perhaps as much about deixis (pointing at and
implications of such sharing mechanisms [1]. In addition, Lee and referencing features of the environment) as it is about telling
Chandra propose a phone-to-phone based context sharing to allow someone exactly where you are” [2].
dynamic privacy control [9]. These mechanisms could be relevant
when developing the proposed approach further. In this work, we explore not only the different abstractions of
location information, but also other commonly available and used
The use of mobile devices to create context-aware content to context information types. We selected six basic information types
social networking services has grown recently. Services such as that the users could use to describe their context. The selected
Foursquare1, Gowalla2 and Facebook Places3 can be used to context types are activity, applications, device, friends, location
check-in to venues using mobile devices equipped with GPS- and surroundings. These context types are described more in the
chips. Furthermore, location-based formation of social networks next sections.
has been researched recently [10]. As the social computing is
getting more mobile and pervasive there has been an increase in 3.1 Software Design and Implementation
interest of exploring the social-side of context-awareness [6]. In The prototype consists of a mobile application and a server-side
addition to mere location or physical activity of the user, the application, which is integrated with Facebook. The overall
systems 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 from
paper, we suggest mechanisms to gather context from the nearby devices. The application presents the sensed context
surroundings to enhance both availability and relevance of context information to the user along with proposals for other semantic
information (e.g. querying the devices around). In addition, we abstractions which have been used to describe similar contexts
investigate the extended privacy implications of such sharing earlier. After selecting the context items and their abstractions, the
mechanisms from the user’s point-of-view and point out design status update is sent over HTTP to the server. The server
challenges based on the findings. application stores the received context data into a semantic model
(including the raw data from the sensors and the associated
3. APPLICATION abstraction) and creates a story-like status update, which is used to
There 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 of
collaborative context, for example, how the contextual
information can be exchanged between different devices.
Secondly, we were able to gain new information about the user
experience of context-aware systems, e.g. about the privacy
concerns related to the context sharing, understandability of the
contextually adaptive applications and the meaningfulness of
different abstractions. Furthermore, the shared and stored
information can also be used for future purposes, such as the basis
1
http://foursquare.com/ Figure 1. ContextCapture general architecture - main
2
http://gowalla.com/ components of the client and server-side applications.
3
http://www.facebook.com/places/

3. 3.1.1 Context Recognition
The 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 system
information, the nearby Bluetooth devices and the WLAN access
points. Based on this data, context descriptions are shown to the
user. 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 street
address, GPS coordinates and current temperature and weather
descriptions are shown. In the list below we describe all the
context 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 mobile
The main functionality of the mobile application is to gather application, where the user first selects the physical activity
information about the current context and show it to the user. The context to be added to the status update and then selects the
user can then use these context items to create context-aware wanted abstraction for the activity. In the Figure 2, the user selects
status updates. In addition to the sensed context abstractions, the the “Sitting” abstraction out of the five suggested abstractions
application also lists other commonly used abstractions to give the instead of the actual physical activity (which is “Still”) or writing
user control over the selection of items and abstractions to include an own abstraction.
in the message. This gives the user the opportunity to reflect any
higher-level semantics, which cannot be inferred by the system, 3.1.3 Protocol for Exchanging Collective Context
but also gives the system the possibility to learn these new The client-to-client communication is done over a Bluetooth
semantics given in specific contexts making the recommendations connection, using a specified communication protocol. The
smarter over time. When the user sends the status update, the mobile client sets up a RFCOMM service when the application
mobile application sends the selected abstractions as well as the starts and notices whether there are other devices nearby offering
sensed raw sensory data to create the association link to enable the specified service. If so, the devices exchange MD5-hashed
machine 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 ContextCapture
users. 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. reply with the data, should they possess it. The syntax for the
exchange protocol is as follows:
CCRAControlProtocol:<role_name>:<BT_name>:<command
>:<parameters>
For example, the mobile client requesting for weather data from
a nearby ContextCapture friend takes the client role and sends a
request as follows:
CCRAControlProtocol:Client:ClientBluetoothName:WTH
R:Request
And the service running on the specified device replies:
CCRAControlProtocol:Server:ServerBluetoothName:WTH
R:-3 degrees Celsius,Sunny
If the other device does not have the context data asked for, it
will simply reply:
CCRAControlProcotol:Server:ServerBluetoothName:NAC
K:WTHR
The client-to-server communication enables the mobile client to Figure 3. ContextCapture application on Facebook.
send status updates to Facebook. The ContextCapture Facebook
application is located at the server and relays the incoming status After a successful installation and registration of both the
update messages from the mobile client to the Facebook. The Facebook application and the mobile application, the user can
client-to-server communication is based on normal HTTP GET send context-enhanced status updates from the mobile device
and POST operations, where the data sent is JSON formatted. The directly to the Facebook wall (an example is presented below in
two 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 Facebook
application and the MD5-hashed IMSI string. This way, the user’s
Facebook account and the user’s mobile device are coupled
together 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, the
mobile client is able to recognize the nearby Facebook friends by
exchanging 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 JSON
formatted data package containing all the context data and the
user-given abstractions to server. The server then parses the 3.2 Used Technologies
message and creates a story-like status update string, which is sent The mobile application was implemented for Symbian devices. Qt
as a wall post to Facebook. Depending on the success, the server for Symbian with additional third-party libraries (such as
sends back a reply, which also contains the current QBluetooth and QJson) was used. The persistent storage for
ContextCapture friends, so that the mobile client can update the context data was implemented with the Qt APIs for SQLite4. The
friends 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 is
3.1.4 Server-side Application and Facebook
saved using RDF5 format with Jena Semantic Web Toolkit6 and
Integration persisted in a PostgreSQL7 database. The SNS integration was
The key functionality of ContextCapture application is the implemented using the Facebook APIs, which enables
integration to Facebook. This integration was done by functionalities such as the user authentication and status updating.
implementing a Facebook application, which handles the first
phase of registration. To install the application, the user simply
accesses the application URL
4. EVALUATION
To evaluate the ContextCapture application and to find answers to
(http://apps.facebook.com/contextcapture). After
our research questions, we arranged a trial where 12 participants
allowing the permissions, the user is redirected back to the
used ContextCapture for two weeks with their own mobile phones
ContextCapture application with access credentials (Facebook
will give the ContextCapture application an OAuth token for
accessing the Facebook API). This access token is used to query
4
the basic user information, such as the name and the profile http://www.sqlite.org/
picture. Then the user is given a unique login key, depicted in the 5
http://www.w3.org/RDF/
Figure 3, which can be used to sign in with the mobile 6
application. This creates the link between the mobile application http://jena.sourceforge.net/
and the Facebook user account. 7
http://www.postgresql.org/

5. in their everyday lives. This section introduces the user study and
the results from the trial.
4.1 Methodology
The aim of the evaluation was to study how people would use
context information in their status updates, what kind of feelings
and user experience automatic context recognition would invoke
and what kind of abstraction levels would be suitable for
presenting 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 the
As we wanted to ensure that all significant data would be initial web questionnaire. The users were requested to fill in the
collected, various data collection methods were used. In the initial questionnaire after they had successfully completed the
beginning of the trial we had an initial web questionnaire which installation of the application. This indicated that they had started
included questions about the Facebook usage and expectations the trial.
towards the ContextCapture application. During the trial The participants used the application for approximately two
participants could report about their experiences with the weeks. During that time, they could tell their experiences through
application through a web-based diary questionnaire. The diary the web diary. We asked them to fill in the diary at least five times
inquired, which of the context types had been most useful to the and preferably in separate days. Total of 26 diary entries were
participants lately and whether they had got any comments and made during the trial. At the end of the trial, we interviewed all
feedback from their Facebook friends related to the contextual the participants; nine of them with face-to-face interviews and
status 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’ expectations
formatted feedback about the study and tell the possible problems and meeting them, attitudes, privacy and the most pleasing and
with the application through the diary questionnaire. At the end of unpleasing experiences related to usage. Furthermore, participants
the trial all participants were interviewed for getting more in- were asked about their ideas for further development of the
depth information about the user experience. Interviews also application. Interviews lasted approximately 30 minutes each.
included a background information sheet, which was given on
paper. 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 of
4.2 Participants applications are novel to many people. It seemed that participants
As ContextCapture is currently designed to work with Facebook thought they understood well how ContextCapture application can
only, the first criterion for the trial participants was the fact that be used, as Figure 6 describes. In addition, privacy was not
they 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 of
groups of people, who could see each other’s status updates and the participants. Also, under half of the trial participants felt that
be 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 extra
have 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 most
Total of 12 users participated in the trial, six male and six female. valuable context field. Many participants seemed to think that
The age of the participants was between 30-46 years, 37.25 years added context information enlivens the status updates in a
on average. Participants used ContextCapture with their own pleasant way. Status updates with location information are also
mobile devices and personal Facebook accounts during the trial. more informative as people can use them to reference their
All participants were experienced Facebook users as 25% of them activities with the relevant location or point out features from the
had used the service 1-2 years and the rest for over two years. environment. Weather information, which was related to
Figure 5 shows how often the participants were used to send Surroundings field, was also seen highly interesting. Application
status 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. Some of them also thought that the device information is not status updates as additional context information. Weather
relevant 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 time
Privacy 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 the
while using the application. For example, the participants did not relevance and meaningfulness of the different context types as
use 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 and
by the participants. It seemed that the accurate location of these
surroundings were the most relevant context types, as by
places was too sensitive to be shared. In addition, many of the
disclosing them the current situation could be described quite
participants stated that the semantic meaning of the place is
extensively. The more virtual context types, that are the
enough. For example, saying that “I’m at home” is adequate
applications and the device, were seen as less relevant, as the
enough for the people the message is meant for, i.e. my friends
users did not want to advertise the make or the model of their
know where I live.
mobile device and the applications running were mostly seen as
Sharing friend’s location was also one thing, which invoked quite boring information to be included. Disclosing the nearby
thoughts. In many participants’ opinion sharing this kind of friends or colleagues in the status updates was seen as relevant but
information without permission is not acceptable. So there should problematic due to privacy issues.
be some way for asking a permission to share context data
The context types were seen as most meaningful when the used
including other users. Friends’ names were also often viewed as
abstraction level was high, i.e. the participants felt that the exact
private information and participants preferred to use more abstract
low-level information, such as the street address or the GPS
words, like “group of friends”, instead of giving the exact names.
coordinates, conveyed a too matter-of-fact type description
One of the key findings was the fact that participants were clearly whereas more abstract descriptions, such as “at the movie
interested in context data and in using context-aware application. theatre” or “at the botanical garden” were seen as more
Context information was seen as highly interesting, but the illustrative, interesting and meaningful. Also using the name of
participants hoped that they could have had even more control in the building or other abstract place names were preferred, as this
the 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 of
secure in many situations than the exact street addresses. There information abstraction can be thought in some way as “privacy
were 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 controls
should recognize the place, which is located in the address, like a
regarding the information disclosure were good. In fact, most of
movie theater or a shop.
the participants wished that most of the context fields should be
Participants 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

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