However, solutions such as those above assume that people spend most of their time at a desktop workstation. If people are working from several places (using laptop computers or PDA:s), workstation-based solutions will not work very well for initiating face-to-face communication. Beepers and mobile phones are tools which can be used regardless of where the user is situated, but these do not provide continuous awareness information. A call via phone or beeper can also be disruptive, since there is no way of knowing what activity the person at the other end is engaged in, and for this reason many people are wary of using them when not absolutely necessary.
Based on these observations, we argue that there is need for solutions which combine the advantages of desktop-based awareness applications - constant, undisruptive awareness - with the freedom provided with mobile devices such as beepers and mobile phones. We propose that a new class of IT devices, Inter-Personal Awareness Devices, or IPAD:s, as a solution to the problems outlined above.
We define an IPAD as a small device, designed to be carried at all times. By some method (e.g. wireless communication) it searches the environment for other IPAD:s, and gives an indication - aural, visual, tactile, etc. - when another IPAD is in the vicinity. The search can be selective, so that it only gives indication when sensing another IPAD belonging to a member of the same group. Since an IPAD is only detectable to users of IPAD:s of the same type, it does not unnecessarily broadcast its presence to others. Following from the name, an IPAD has the following characteristics:
Apart from the practical function of facilitating communication, the use of IPAD:s can also be comforting. They can be used to convey the sense that a user is not alone or cut off from the group even when the other members can not be directly heard or seen, for instance when the user is situated alone in her room or in a crowded public place with many unfamiliar people around. Our evaluations have shown that this is a not insignificant function of our current prototype.
In the research community, there are several examples of computationally augmented badges, intended to be used in an office or in a social setting, but none of these confirm completely to our classification of an IPAD. For instance, Thinking Tags  compare a profile input by a user to that of another tag, and give a visual indication whether two users’ profiles match. They are similar to IPAD:s in that they do not rely on a local infrastructure or absolute positioning, but differ in that their primary function is to augment a communication that has already been initiated, rather than to provide continuous group awareness. Active Badges  are a system which provide continuos location information of their wearers, which may be used for awareness information, but unlike IPAD:s they rely on an infrastructure of sensors in the environment and can not be used outside this setting. A related system is PARCTABS , palm-top sized computers which provide location-specific services in a ubiquitous computing environment. Significantly, all these systems communicate with infra-red light, which means that there range is limited to sensors in direct view, making them unsuitable for extending the physical awareness range.
A commercial product which conforms to all the criteria of an IPAD is the Lovegety . These small devices are equipped with radio transceivers, and come in two colors - pink for girls and blue for boys. There are three user-selectable settings - "talk," "karaoke," and "get2" - and when two differently colored Lovegetys on the same setting are close, an indication is given in the form of a beep. Lovegetys are used to initiate contact between users of different sex who are on the same "wavelength". The huge commercial success of these devices indicates that they fulfill an important need, at least in their native country Japan where they have sold in record numbers.
Each member of a group is given his or her own Hummingbird. The user brings the Hummingbird with her at all times when she wants her presence to be detectable by the rest of the group. Whenever two or more Hummingbirds are in the vicinity of each other, they will "chirp," and the identity of other Hummingbirds in the vicinity will be shown on a display. Thus a Hummingbird will give their user continuos information of which other Hummingbird-using group members are close, whether in the place they usually meet, or somewhere else. "Close" in this case is approximately when users are in the same building when indoors, or within "shouting distance" when outdoors.
To make the prototypes useful, they needed a protective "carrying case". For our user tests we had the Hummingbirds encased in mobile phone "holsters" of a type readily available in electronics stores. The holsters were comfortably soft to the touch and provided with "carrying hooks" to make them easily wearable.
For the user tests, each Hummingbird was programmed to continuously transmit an identification code, while simultaneously listening for other Hummingbirds in the vicinity. Whenever another Hummingbird was found, an identifying letter would show up on the LCD screen and the Hummingbird would emit a "chirping" noise. Since each Hummingbird in the vicinity would give rise to a separate sound, a Hummingbird would generate noise at a level relative to how many other Hummingbirds were in its vicinity. The noise level would give a continuous indication of how "crowded" the environment was, even when the other Hummingbirds could not be heard directly.
In the first test, four subjects used the Hummingbirds for a few hours during the Roskilde festival, a major outdoor rock festival which attracts approximately 80,000 visitors. The subjects were instructed to wander around the festival area and use the information provided by the Hummingbirds in any way they wanted to. We found that the participants enjoyed using the Hummingbirds in this setting and that they found it comforting to be able to know when other group members where nearby. It was however sometimes frustrating to know that someone was near without being able to see them. This test showed that the Hummingbirds worked as intended in that they strengthened the awareness between group members and made the users more likely to keep in contact.
The second user test was performed in an office setting, where the test subjects rooms were spread out over several floors. Four co-workers, who were all associated with the same project, were equipped with Hummingbirds. For one day, the subjects carried their Hummingbirds with them at all times. The results on the work situation were pronounced, although not dramatic. The Hummingbirds gave users a much higher awareness of when other members of the group arrived or left the building, and the subjects started to rely on and use this information almost immediately. This test made it obvious that devices such as the Hummingbirds have very high potential for use in an office environment.
Our experiences with the Hummingbird prototype show that IPAD:s are immediately useful in a variety of situations, especially when combined with other means of communication, such as mobile phones and e-mail. We believe that Hummingbirds and other IPAD:s will prove to be a useful tool for supporting group collaboration, and that they therefore may play an important part in the future development of handheld CSCW.
Since an IPAD should be carried at all times, the form factor is very important, and the current prototypes are severely lacking in that area. Design experiments should be made, where the physical form of the IPAD is integrated with the functionality. Ethnographic-type studies of specific work situations could be made to find the requirements for new form and functionality.
In a broader perspective, it will be important to examine how the use of IPAD:s change the way we work and communicate. Will constant awareness information lead to techno-stress, or will people learn to turn their IPAD:s off? If IPAD:s become popular, the development of their usage will most probably mirror that of the mobile phone, which is still in the stage of becoming naturally integrated in the daily life. A convergence of PDA:s, mobile phones and IPAD:s may be a likely future for mobile computing.
2. Dourish, P. and Bly, S. Portholes: Supporting Awareness in a Distributed Work Group. In Proceedings of CHI 92, ACM Press, 1992.
3. Harter, A. and Hopper, A. A Distributed Location System for the Active Office. IEEE Network, Vol. 8, No. 1, January 1994.
4. Ishii, H. and Ullmer, B. Tangible Bits: Towards Seamless Interfaces between People, Bits and Atoms. In Proceedings of CHI 97, ACM Press, 1997.
5. Iwatani, Y. Love: Japanese Style. In Wired News, 11 June 1998. URL: http://www.wired.com/news/culture/story/12899.html
6. Mann, S. Wearable Computing: A First Step Toward Personal Imaging. In IEEE Computer, February, 1997.
7. Roseman, M and Greenberg, S. TeamRooms: Network Places for Collaboration. In Proceedings of CSCW 96, ACM Press, 1996.
8. Tollmar, K., Sandor, O and Shömer, A. Supporting Social Awareness @Work, Design and Experience. In Proceedings of CSCW 96, ACM Press, 1996.
9. Want, R., Schilit, B.N., Adams, N.I., Gold, R., Petersen, K., Goldberg, D., Ellis, J.R. and Weiser, M. The PARCTAB Ubiquitous Computing Experiment. Technical Report CSL-95-1, Xerox Palo Alto Research Centre, March 1995.
10. Weisser, M. and Brown, J. Designing Calm Technology. In Powergrid Journal 1.01. URL: http://www.powergrid.com/1.01/calmtech.html
11. Whittaker, S., Frohlich, D. and Daly-Jones, O. Informal Workplace Communication: What Is It Like and How Can We Support It? In Proceedings of CHI 94, ACM Press, 1994.