Over the last 2 years I have been heavily involved in working with tabletop software, specifically software for Microsoft Surface. Having content displayed directly on the table top can radically change the interaction that occurs between the users sitting around the table. How we present the information on the table top will greatly impact on this interaction.
A number of researchers have spent considerable time and effort working on this challenge and recently at the ACM International Conference on Interactive Tabletops and Surfaces 2010 (http://www.its2010.org/) some of this research was presented. One of the more interesting (and arguably problematic) papers was presented by Tang, Pahud, Carpendale and Buxton; entitled VisTACO: Visualizing Tabletop Collaboration. The paper presents a way that researchers can scientifically understand the interactions of the users at a table. One of goals being to validate the design of a multi-user tabletop computer.
I say this can be problematic because while it is easy to track the user interaction on the table top, with software, this project (as described in the paper) attempts to solve a couple of other challenges; 1. does the interaction change if the people are not all physically sitting at the same table, 2. does the spatial position (configuration) of the users impact on the interaction models. The results are certainly useful but do they tell the whole story about the success of an interaction model?
From the work we have been doing in the real world with tabletop multi user deployments at nsquared there are other factors at play that are less easy to measure. The emotional connections that are made between people at a table during an interaction is often (maybe always?) more important than the actual physical interactions that have occurred. Creating an environment that encourages a rich and deep social engagement has been one of our goals at nsquared.
Our other goal at nsquared, which might be even harder to evaluate, is to enhance the intelligence of the people using the technology. More on this topic another day.