The race to create a perfect lie detector – and the dangers of succeeding

We learn to lie as children, between the ages of two and five. By adulthood, we are prolific. We lie to our employers, our partners and, most of all, one study has found, to our mothers. The average person hears up to 200 lies a day, according to research by Jerry Jellison, a psychologist at the University of Southern California. The majority of the lies we tell are "white", the inconsequential niceties – "I love your dress!" – that grease the wheels of human interaction. But most people tell one or two "big" lies a day, says Richard Wiseman, a psychologist at the University of Hertfordshire. We lie to promote ourselves, protect ourselves and to hurt or avoid hurting others. The mystery is how we keep getting away with it. Our bodies expose us in every way. We stutter, stall and make Freudian slips. "No mortal can keep a secret," wrote the psychoanalyst in 1905.