Who knew that George Costanza could be so right?
According to Michael Shermer citing Robert Trivers’s “The Folly of Fools”, liars need to practice keeping their voices in a lower register, maintaining eye contact, and controlling their gestures so that they don’t appear nervous. And liars need to think harder than truthful people to keep their story both plausible and consistent. But all of that hard work isn’t necessary if you believe the lie.
As a fiction writer I’ve seen first-hand how my memories can be replaced by fictionalized versions as I write draft after draft of a story.