Saul Greenberg presented the opening keynote at PerDis2013, the second international symposium on pervasive displays, held at Google in Mountain View, US.
Saul gave a brief history motivating the challenges that arise from the move to interactive ubiquitous computing environments. The degrees of freedom for interaction, when moving from graphical user interfaces to ubiquitous computing environments, are massively increased and the social context becomes central.
The other line of motivation Saul used is the notion of proxemics as studied in social science. The primary element is the distance between people. By physical proximity a lot in the interaction between people is determined. Interpersonal relationships are at the heart of the theory by Edward Hall, who explored this already in the 1960ties (, for a short overview and introduction see the Wiki-Pages on Edward Hall and on Proxemics). It is interesting (and not undisputed) to see that people in computer science have moved the notion of proxemics beyond human-to-human interaction to include technologies.
Saul outlined the dimensions for proximic interactions:
In a paper in ACM Interactions Saul provides a really good and easy to read introductory text to proximic interactions – which is also well suitable for teaching . There is more on the dimensions, the overall concept of proximic interactions, and potential applications in a 2010 paper they presented at ITS . One of the aspects they have looked into in their work is at supporting proxemic interactions through a toolkit . For more details we can be looking forward to the PhD thesis of Nicolai Marquardt, who worked in Saul’s group and who will defend in a few weeks.
Proxiemic interaction is a hot topic and several researchers have started to explore this space. There is also a Dagstuhl Seminar on the topic later this year (http://www.dagstuhl.de/13452) orgamized by Saul Greenberg, Kasper Hornbæk, Aaron Quigley, and Harald Reiterer.
 Hall, E. T., & Hall, E. T. (1969). The hidden dimension (p. 119). New York: Anchor Books. http://courses.arch.ntua.gr/fsr/137555/Hall-The-Hidden-Dimension.pdf
 Greenberg, S., Marquardt, N., Ballendat, T., Diaz-Marino, R., & Wang, M. (2011). Proxemic interactions: the new ubicomp?. interactions, 18(1), 42-50. http://grouplab.cpsc.ucalgary.ca/grouplab/uploads/Publications/Publications/2011-ProxemicInteraction.Interactions.pdf
 Ballendat, T., Marquardt, N., & Greenberg, S. (2010, November). Proxemic interaction: designing for a proximity and orientation-aware environment. In ACM International Conference on Interactive Tabletops and Surfaces (pp. 121-130). ACM. http://www.cs.ucf.edu/courses/cap6121/spr11/readings/proxemic.pdf
 Marquardt, N., Diaz-Marino, R., Boring, S., & Greenberg, S. (2011, October). The proximity toolkit: prototyping proxemic interactions in ubiquitous computing ecologies. In Proceedings of the 24th annual ACM symposium on User interface software and technology (pp. 315-326). ACM. http://curis.ku.dk/ws/files/44312111/marquardt.UIST_2011.proximity_toolkit.pdf