Our gadgets around us are changing and I think that it will continue for a while. I really wonder if there is a nice example about usability and overall experience testing methods for Personal area network gadgets, especially head positioned visual ones,glasses.
For instance, eye-tracking was a method for usability testing before but now eye movements are changing pages or even an action for the device itself. Ergonomics are another perspective that we can rely on but could not find any study about the comfortable eye movements while there are many studies about tracking cursor and movements.
Edit:
What kind of methodologies can it be used while transferring an existing solution to another device level (PAN) and also protecting the overall user experience? Ergonomically, do they have constraints and if yes, what are they?