Lori Ann Mehollic, age 14, of Burgettstown, Pa., for her question:

WHO INVENTED THE LIE DETECTOR?

Normal people have certain physical reactions when they act or feel guilty. In 1885 an Italian criminologist suggested a machine to reveal changes in the blood pressure of a suspect. Several other experts had similar ideas. But the first workable lie detector, or polygraph, was not developed until 1921. Several improvements were added to later models.

The first model was developed by John A. Larson, an American psychologist. It recorded changes in breathing and blood pressure. In 1926 Leonarde Keeler, an American criminologist, built a better polygraph. In 1945 John Reid assembled all the known tests plus some new features. This super polygraph registers blood pressure and heartbeat, also subtle changes in the breathing, skin and muscles.