Digital social interactions in the city: reflecting on location- based social media

1.Introduction In this paper we discuss how digital interactions are increasingly interwoven with spaces and places in urban settings and how such interactions are mediated by and in turn shape the technologies that facilitate them. We will focus on the understanding of interactions using location based social media (particularly Foursquare) as a way to reflect on issues of technological support to human activities, and on the relationship between code, digital agency and the physical world. Whether purposely built for mobile devices and with a focus on location (e.g. Foursquare; Swarm), or simply features of other social media platforms that rely on location data such as Facebook Places, various location based social networks (LBSN) increasingly mediate social and interpersonal interactions in urban settings. Essential technological infrastructure that enables such interaction is the possibility of linking data to particular places by means of devices capable of detecting their own location by means of Global Positioning System (GPS) or other mechanisms. On the basis of such infrastructure, however, location based social media user activities take different forms: from "checking-in" (e.g. users register their presence at a particular venue), to linking location data to digital content to be then shared on social media, to gameplay associated with occupying a location and performing certain activities there. The form of sharing these activities socially with contacts and other fellow users is also constrained by the platform: e.g. for example a photograph with location information; or presence at a location with associated content; or a map of movements and check-ins, etc. Such practices become coded into the system, representing both the log and content of social interactions, as well as the location to which they relate. Therefore a digital "cloud" of social interactions becomes embedded into the physical reality of a city, of its neighbourhoods, public places, cafés, transportation hubs and any other locations identified by social media users (by user-initiated "check-ins" or by the content that generated, such as photographs or textual recommendations and tips), and by the tools they use (for example, through automatic geo-tagging). Conversely, the code determining a platform's interaction and functionality is continuously changed to reflect user activities and feedback, and to implement design decisions on how location based social media services work. Among others, two sets of issues surrounding this topic are emerging that we wish to investigate further: firstly, examining how such localised interactions in physical spaces are triggering and feeding back into the algorithms and infrastructures provided by the software-how are various location-based social media platforms framing people's perceptions and identifications of locations? How is code both facilitating and scaffolding a set of social interactions relating to various spatial configurations in physical spaces? Secondly, we are interested in the rematerialisation of such cloud of interactions in the physical world: how are physical spaces and places affected by their digital counterparts and by the activities that people conduct on LBSN? There are already occurrences of the rematerialisation of digital presence and interactions in the physical world: for example, venue owners displaying badges on the premises that tell