Eagerness.. you let them work through a endless labyrinth of forms. While the human drops out after the 2nd form- the ai is willing to go all the way always.
I'm not familiar with the specific example, but as a first hunch, if I had to implement such a system, it'd be part of the flow after the successful signup, not during.
You could also pretend to pass-through and watch the behavior of the "user" after success.