Kenton O’Hara, a senior researcher in the Socio-Digital-Systems group at Microsoft Research in Cambridge, presented the keynote at the pervasive displays symposium in Porto on the topic “Social context and interaction proxemics in pervasive displays“. He highlighted the importance of the spatial relationship between the users and the interactive displays and the different opportunities for interaction that are available when looking at the interaction context.
Using examples from the medical field (operating theater) he showed the issues that arise from the need of sterile interaction and hence avoiding touch interaction and moving towards a touchless interaction mode. A prototype, that uses a Microsoft Kinect sensor, allows the surgeon to interact with information (e.g. an x-ray image) while working on the patient. It was interesting to see that gestural interaction in this context is not straightforward, as surgeons use tools (and hence have their hands not free) or gesture as a part of the communication in the team.
Another example is a public space game; there are many balls on a screen and a camera looking at the audience. Users can move the balls by body movement based on a simple edge detection video tracking mechanism and when two balls touch they form a bigger ball. Kenten argues that “body-based interaction becomes a public spectacle” and interactions of an individum are clearly visible to others. This visibilility can lead to inhibition and may reduce the motivation of user to interact. For the success of this game the designing of the simplistic tracking algorithms is one major factor. By tracking edges/blobs the users can play together (e.g. holding hands, parents with the kids in their arm) and hence a wide range of interaction proxemics are supported. He presented some further examples of public display games on BBC large screens, also showing that the concept of interaction proxemics can be use to explain interaction .
Interested in more? Kenton published a book on public displays in 2003  and has a set of relevant publications in the space of the symposium.
 Martijn ten Bhömer, John Helmes, Kenton O'Hara, and Elise van den Hoven. 2010. 4Photos: a collaborative photo sharing experience. In Proceedings of the 6th Nordic Conference on Human-Computer Interaction: Extending Boundaries (NordiCHI '10). ACM, New York, NY, USA, 52-61. DOI=10.1145/1868914.1868925 http://doi.acm.org/10.1145/1868914.1868925
 Kenton O’Hara, Mark Perry, Elizabeth Churchill, Dan Russell. Public and Situated Displays: Social and Interactional Aspects of Shared Display Technologies. Kluwer Academic, 2003