I was thinking they may be looking at how long it takes for a user to click the "I'm not a robot" link. A robot would probably load the page and quickly, witho

I was thinking they may be looking at how long it takes for a user to click the "I'm not a robot" link. A robot would probably load the page and quickly, without delay, send the HTTP POST but I have to imagine they thought of this already and bots writers would quickly add a sleep() call in there at some point... Yea, I wonder about their internal logic too.