In the design process of an AR application, a series of questions related to human-computer interaction (HCI) call for attention: Who are the users and what are their needs? How can a system be designed to work effectively and efficiently for these users? How is effectiveness and efficiency measured in AR applications? Do users prefer an AR system or an alternative tool to go about their work? And finally, with what kind of tasks and what kind of alternative tools should the usability of AR applications be tested?
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The need for studies evaluating the effect of computerized tools on human cooperation and communication is well justified and documented in the first paper, prepared by Billinghurst, Belcher, Gupta, and Kiyokawa [that’s indeed a good paper that shows an evaluation of an AR table]

I think the same goes for studying locative media from an usability and collaborative point of view. My only concern here is that the evaluation they propose is a bit limitated. They just take into account frequency of events and differences among different conditions. There are plenty of other methods ranging from quantitative (as proposed in the evaluations described in this paper or with different types of statistical techniques like multilevel modeling or sequential analysis) to qualitative (ethnography, cognitive anthropology à la Hutchins, french ergonomics…).