Last night, I was conducting a usability test with a participant who was very uncertain of his actions. Before the test, I said all of the usual stuff about it being a test of the software and not him, asked him to imagine I wasn't there, that we were hoping he could help us find the software's weaknesses, and so on. The task he was given had also been successfully used with other participants already.
But it still went badly.
The participant became unsure of how to proceed, lost confidence in himself, and he clearly started feeling like it was more of a test of HIM rather than the software. The test dragged on and, despite yielding a good amount of useful feedback, it clearly hadn't been a pleasant experience for him.
How should I rescue such situations in the future? Is there anything I can do to get such sessions back on track, or should I just call an early end to tests where the user gets 'stuck' and stops enjoying it?
I'd welcome any advice...