A Harvard professor says that you can spot liars, because they have certain speech and behavioral patterns:
In terms of strategic cues, the researchers discovered the following:
Bald-faced liars tended to use many more words during the ultimatum game than did truth tellers, presumably in an attempt to win over suspicious receivers. Van Swol dubbed this “the Pinocchio effect.” “Just like Pinocchio’s nose, the number of words grew along with the lie,” she says.
Allocators who engaged in deception by omission, on the other hand, used fewer words and shorter sentences than truth tellers.
Among the findings related to nonstrategic cues:
On average, liars used more swear words than did truth tellers—especially in cases where the recipients voiced suspicion about the true amount of the endowment. “We think this may be due to the fact that it takes a lot of cognitive energy to lie,” Van Swol says. “Using so much of your brain to lie may make it hard to monitor yourself in other areas.”
Liars used far more third-person pronouns than truth tellers or omitters. “This is a way of distancing themselves from and avoiding ownership of the lie,” Van Swol explains.
Liars spoke in more complex sentences than either omitters or truth tellers.
In sum, liars overuse words, swear a lot, and use third person pronouns. Or in other words, Jon Stewart.