If you want children ages 4 to 8 to tell the truth, it's best not to threaten to punish them if they lie.
An experiment involving 372 children, led by Prof. Victoria Talwar of McGill's Dept. of Educational and Counselling Psychology, left each child alone in a room for 1 minute with a toy behind them on a table, having told the child not to peek during their absence.
While they were out of the room, a hidden video camera filmed what went on.
When the researchers returned, they asked the child, a simple question: "When I was gone, did you turn around and peak at the toy?"
What the researchers discovered was that: