People who want to deceive you, I explain to Kelly, will often use a simple technique which has a simple name: too many details. The man’s use of the story about the cat he left unfed in a friend’s apartment: too many details. His reference to leaving the door open, “like ladies do in old movies”: too many details. His volunteering that he is always late (“broken watch, not my fault”): too many details.

When people are telling the truth, they don’t feel doubted, so they don’t feel the need for additional support in the form of details. When people lie, however, even if what they say sounds credible to you, it doesn’t sound credible to them, so they keep talking.