Yep. It has been used on humans... At least as far as we know they are humans. For what it's worth, I'm almost down for all of the employees being hosts and not knowing it.
Ditto. I think they're all hosts in Ford's elaborate scheme to create his own version of humanity. Notice how he always has this "knowing" look on his face when he's talking to or interacting with anyone on the show? It's like that halfway proud and halfway curious look a parent gives their child as they watch them mature.