After working with social navigation for a while, my collegues Per Persson, Fredrik Espinoza and others, wanted to have a look at whether the idea would carry over to mobile settings. Would it be possible for users to leave their trails behind in some kind of mobile service so that others could see their "virtual graffitti" and be influenced by it? Per Persson, Fredrik Espinoza and a bunch of students, among them Petra Sundström (then Fagerberg) built a system named GeoNotes. In GeoNotes, users could leave virtual post-it notes at locations.

In a user study of GeoNotes, they saw the people wanted to leave these notes not only on physical locations, but also on virtual locations. Users in GeoNotes are allowed to freely name the places that they intended that their post-it note would be placed at. This was a way of dealing with the problem that the positioning system was not fine-grained enough. The place-labels system that was integrated in GeoNotes turned out to be a lucky strike. It allowed users to name places freely. Read more about this in Fagerberg et al., 2003.

In my lab we found this fascinating and therefore continued to build several other social mobile services. One is the MobiTip system. In MobiTip, the notes are not located at physical places, but are instead exchanged between mobile phones via BlueTooth when users meet. They are socially positioned. BlueTooth is a fascinating wireless technology that only has a short range of about 10 metres. This means that if we use BlueTooth to transfer information between users, then tips will be exchanged between people who can more or less see eachother. The best account of this piece of work can be found in Åsa Rudström's thesis that can be found here.

This closeness of devices equipped with BlueTooth has inspired other research ideas in the lab. Annika Waern who works with the idea of pervasive games picked up on this and created a system they named Hot Potatoe (Niemi et al., 2005). In Hot Potatoe, players leave burning potatoes on other people's mobile phones (virtually - not for real) who may not even participate in the game and then the player, in order to win, has to collect them all back. This could mean "stalking" people who are unaware of the fact that a game is being played. Annika is exploring what happens when we break "the magic circle" of a game and act it out in streets and public places.

After working with these social mobile services for a while, we found that the prevailing idea that users' should not be told about the positioning system or network coverage in all its gory details - the so-called seamlessness ideal - perhaps was not such a good idea after all. People seems to be intriguied and amused by the possibility to exploit and appropriate the seams that shine through here and there in technology. We therefore work on ways of creating more seamful designs.

Acknowledgement
This work was started by Per Persson while he was at SICS. He worked with Fredrik Espinoza, Petra Sundström (then Fagerberg), and many others. When he left, Martin Svensson and Åsa Rudström and others at SICS took over this line of research.

References
Jenny Niemi, Susanna Sawano and Annika Waern (2005) Involving Non-Players in Pervasive Games, Short paper, Conference on Critical Computing, Aarhus, August 2005.

Åsa Rudström, Kristina Höök, and Martin Svensson (2005). Social positioning: Designing the Seams between Social, Physical and Digital Space. In 1st International Conference on Online Communities and Social Computing, at HCII 2005, 24-27 July 2005, Las Vegas, USA., Lawrence Erlbaum Associates (CD-ROM). PDF.

Matthew Chalmers, Andreas Dieberger, Kristina Höök, and Åsa Rudström (2004). Social Navigation and Seamful Design. Journal of the Japanese Cognitive Science Society, September 2004. PDF.

Åsa Rudström, Rickard Cöster, Martin Svensson, and Kristina Höök (2004). MobiTip: Using Bluetooth as a Mediator of Social Context. In Ubicomp 2004 Adjunct Proceedings. PDF.

Persson, P., Espinoza, F., Fagerberg, P., Sandin, A. & Cöster, R. (2002) GeoNotes: A Location-based Information System for Public Spaces, In Kristina Höök, David Benyon and Alan Munro (eds), Readings in Social Navigation of Information Space, pp. 151-173, Springer. PDF.

Petra Fagerberg, Fredrik Espinoza, and Per Persson (2003) What is a place? Allowing users to name and define places, In Proceedings of CHI 2003, Fort Lauderdale, USA. PDF.

Per Persson and Petra Fagerberg (2002) GeoNotes: a real-use study of a public location-aware community system, Technical report, (T2002:27), Stockholm, SICS. (The full story of the GeoNotes user study - unfortunately not published elsewhere). PDF.