I get a weekly list of notable TED talks. This week, one of the featured talks was by the researcher Dr. Kang Lee who is a student of child development and specializes in children telling lies. You can look him up on the TED web site or use this recent post on my blog of the email I received today. Dr. Kang begins with the story of an elementary school principal who received a phone call explaining that Johnny is sick and won't be coming to school today. The principal asked who was speaking and was told "I am my father."
Kang explains that many adults assume that kids are poor liars and that telling a lie is a morally reprehensible act that children should avoid. However, he has found that children tend to develop the language and mental abilities around age 2 or 3 needed to successfully lie. He has checked out many different types of adults for their ability to detect the sorts of lies his procedure produces. They only do as well as chance at detecting kids' lies.
Dr. Kang describes his procedure in his talk. Much like the work done with an experimental version of self-control, a game of guessing for a prize is interrupted and the experimenter leaves the room. Kang says the excuse is accompanied by a warning not to cheat by looking at the card while alone. Video cameras record what the child does while alone. The experimenter asks the children if they cheated. Kang reports that more than 90% of the kids take a look at the cards while alone but that lying about their behavior is related to the age of the child. The older the child, the more likely to look and the more likely to lie.
Kang ends by saying that all the types of adults he has tested do no better at detecting lies than chance. (He evidently always presents the adults with a video of a child telling the truth and one of a child lying and asks the subject to say which is the liar.)
He ends by showing a new technology for detecting lies that has promise and may be superior to today's lie detectors. He recommends that we celebrate when our child tells the first lie because it is an important milestone in development.