We’re bad at accurately interpreting behavior and speech patterns, said James Alcock, professor of psychology at Canada’s York University. Learning is based on getting regular feedback, he told me. Try to add 2 + 2 and someone will tell you whether you got it right or wrong. Over time, that feedback allows you to know when you’re right. But there’s no systematic un-blinding to tell you when you correctly guessed whether you were being lied to. The feedback we get on this is spotty. Often there is none. Sometimes the feedback itself is incorrect. There’s never a chance to really learn and get better, Alcock said. “So why should we be good at it?”
Take people whose job it is to professionally detect lies — judges, police officers, customs agents. Studies show they believe themselves to be better than chance at spotting liars. But the same studies show they aren’t, Alcock said. And that makes sense, he told me, because the feedback they get misleads them. Customs agents, for instance, correctly pull aside smugglers for searches just often enough to reinforce their sense of their own accuracy. But “they have no idea about the ones they didn’t search who got away,” Alcock said.
Maggie Koerth-baker, writing in fivethirtyeight