“All of this gives us a model of how a human behaves,” says Shet. “It’s a whole bag of cues that make this hard to spoof for a bot.” He adds that Google also will use other variables that it is keeping secret—revealing them, he says, would help botmasters improve their software and undermine Google’s filters.
Like keeping such "secrets" ever worked for anyone. I call this broken.
Biting the hand that feeds IT
