Pers Ubiquit Comput (2007) 11: 45–58 DOI 10.1007/s00779-006-0068-5 ORIGINAL ARTICLE Yanna Vogiazou Æ Bas Raijmakers Æ Erik Geelhoed Josephine Reid Æ Marc Eisenstadt Design for emergence: experiments with a mixed reality urban playground game Received: 13 March 2005 / Accepted: 20 September 2005 / Published online: 8 June 2006 Ó Springer-Verlag London Limited 2006 Abstract In this paper we present our work in the design integrating virtual presence with physical presence of ubiquitous social experiences, aiming to foster group through location and proximity information. We focus participation and spontaneous playful behaviours in a on the possible social implications of these technologies city environment. We outline our approach of design for such as the feeling of being part of a group, based pri- emergence: to provide just enough of a game context marily on the sense of others being present in virtual or and challenge for people to be creative, to extend and mixed reality (both physical and virtual) spaces. enrich the experience of play through their interaction in Recent studies Paulos and Goodman [16] have ex- the real world. CitiTag is our mixed reality testbed, a plored ways to represent and communicate our rela- wireless location-based multiplayer game based on the tionships with people we encounter regularly in our concept of playground ‘tag’. We describe the design and everyday lives, yet hardly ever get to interact with, our implementation of CitiTag and discuss results from two encounters with ‘familiar strangers’ [10]. These studies user studies. have illustrated that our perception of who else is around us is a significant factor for feelings of comfort Keywords Social computing Æ Wireless location based and reassurance in public spaces. Rheingold’s discussion games Æ Mixed reality Æ Emergence Æ Group behaviour of Smart Mobs [20] highlights the overwhelming power of social cohesiveness that can be brought about by knowledge of the presence and location of others in both 1 Introduction real and virtual spaces. We know that messaging tech- nologies (IM, SMS) have been used extensively for The uptake of mobile technologies has undoubtedly purposeless communication, just for the sense of being been changing our communication practices and affect- in touch with other people. For example, the exchange ing our everyday life patterns. One of our key interests is of ‘goodnight’ text messages creates connectedness [21]. presence, as knowing or being aware of other people’s Similarly, Nardi and Whittaker [13] report that people in existence, for example whether one’s friends and col- their study of IM use in the workplace found value in leagues are online or somewhere in a nearby location. simply knowing who else was ‘around’ as they checked With the advent of mobile technologies, presence has their buddy list, without necessarily wanting to interact become a rich concept as well as more ubiquitous, with buddies. These examples show that a sense of presence can be communicated in symbolic ways, via the Y. Vogiazou Æ M. Eisenstadt display of meaningful state information (e.g. availabil- Knowledge Media Institute, The Open University, ity, activity, location, identity etc). MK7 6AA Milton Keynes, UK New opportunities have also emerged for individuals B. Raijmakers (&) and groups to communicate and coordinate their Interaction Design Department, Royal College of Art, activities spontaneously in urban environments. We Kensington Gore, London SW7 2EU, UK know that wirelessly inter-networked groups of humans E-mail: [email protected] can exhibit emergent prediction capabilities [20] and thus demonstrate self-organizing dynamics. In this E. Geelhoed Æ J. Reid Hewlett-Packard Laboratories, Filton Road, context, we have been exploring how spontaneous Bristol BS34 8QZ, UK individual and group behaviours can emerge in the real world through playful collective experiences. Previous Y. Vogiazou online studies [27] have shown that spontaneous Design Department, Goldsmiths College, University of London, London SE14 6NW, UK social behaviours can ‘emerge’ among groups present in 46 multi-user environments, even without explicit and ver- them in the actual design, but encouraging team play at bal communication. The recent Flash Mobs phenome- the same time, we expect to see spontaneous individual non [8] illustrated that people do not hesitate to perform and collective behaviours to emerge. certain acts in public together with many others, which Why design for emergence? Johnson [7] in his book otherwise would have been quite embarrassing. In fact, Emergence has described how artificial intelligence sci- people participating in those events seemed very engaged entists and game designers like Will Right who designed and amused. These acts of spontaneous play have been SimCity have understood and recreated emergent sys- thought-provoking within the context of our research. tems based on simple rules that have a complexity and Play has been inherently social, before the advent of life of their own. In fact, emergence is a particularly communication technologies, as we see everyday on intriguing buzzword for game designers [3] as they try to school playgrounds. Presence enabled technologies cre- incorporate emergent properties in their games to en- ate new prospects for play, for adults as well. In our hance the user experience. Emergent interaction based research these are the boundaries we explore: what kind on simple, high level rules can vary result in a different of engaging social experiences can emerge in the real experience every time, a game that is interesting to play world based on the awareness of individuals participat- more than once. ing in a parallel virtual experience? Does virtual presence Emergence is not only valued in game design, but penetrate physical presence in any way? other design disciplines too, such as computer-aided design. A property of a design that is not represented explicitly at the time of creation is said to be an emergent 2 Design principles property if it can be made explicit [4, 22, 11]. Protocol studies of designers while sketching have shown that We believe in the concept of ‘complexity growing out of unexpected discoveries of emergent shapes can have a simplicity’, as being crucial for the success of mixed significant impact on the course of further design activity reality experiences where the main focus should be on [23, 26]. While the above studies focus on emergence the surrounding environment and people rather than on during the design process itself, we are specifically the technology itself. This concept is summarized in our interested in emergence occurring from the unintended design principles for creating engaging social experiences uses of technology. We have many examples of unin- through the use of mobile technologies below: tended uses of technology, such as, SMS, hijacking Bluetooth phones, radio broadcasts from iPods. Often these unintended uses of technology repurpose the de- 2.1 Lightweight design: keep it as simple as possible sign towards a new direction, incorporating ludic values. Unintended use as a design ‘approach’, can also be seen The goal is to enhance our interaction with the social as a way to open up for the public to take part in the and physical world around us by adding an additional shaping of a public sphere, the cyberspace [24]. While experiential layer. So the game we describe below is there is an economic interest in designing for the unex- designed as a prompt for the real world, real people pected (e.g. SMS revenue, killer apps), it is also benefi- being physically close. cial for the design process as well, as users can become part of the process by pointing out new design directions and providing inspiration for designers. 2.2 Scalability Following from the aforementioned design principles, our research focuses on how play, based on very simple We know that certain collective behaviours, such as for game rules, can lead to more complex interaction in the example the Mexican Wave in the real world [2], can physical world, emergent cooperation and collective only emerge once a critical mass of participants has been behaviour. Experimental studies can provide useful les- achieved. By designing scalable applications, aiming to sons for the design process of future ubiquitous com- involve as many users as possible, we want to explore puting social applications and we describe our testbed what kind of spontaneous interactions could emerge at game next. large scale. 3 The game design 2.3 Design for emergence Our project has been inspired by playground games, This principle summarizes our overall approach. By particularly the simplicity, spontaneity and instant fun employing the right affordances [14], such as using of ‘playground tag’ [15]. In this well-known children’s simple metaphors, related to people’s past experiences game, play emerges at often unpredictable moments, that can be re-interpreted or subverted, we acknowledge when, for example, a group of children walk along the creative aspects of playing, game tactics and bending the street together and one touches another saying the rules. By allowing people to explore strategies and ‘you’re it’ and they then start chasing each other. Tag or cooperation practices themselves, without incorporating tig illustrates, like other playground games, that highly 47 engaging playful interaction is possible even without the specific principles and goals of structured games. As Opie and Opie [15] mention in their book on playground games, play is unrestricted, while games have rules; in the playground there is no need for an umpire, little significance is attached to who wins or loses and it doesn’t even seem to matter if a game is not finished. Mobile technologies enable short, spontaneous and intermitted interactions while on the move [18] and it is precisely these playful interactions we aim for. More- over, we know that mixed reality, location-based expe- riences are characterized by a transition between immersive and non-immersive states [19] caused by either planned events or occurring interruptions such as a happening in the physical world or a system fault.