Having done a bunch of user studies in the past, one of the big issues I've seen is the Hawthorne Effect ( http://en.wikipedia.org/wiki/Hawthorne_effect http://

Having done a bunch of user studies in the past, one of the big issues I've seen is the Hawthorne Effect ( http://en.wikipedia.org/wiki/Hawthorne_effect http://en.wikipedia.org/wiki/Hawthorne_effect ) -- just the fact that the user knows they are being watched, they change their behavior so much that the study is irrelevant. I think GazeHawk has the chance to push usability closer to being unbiased -- very promising!