Stephen. Bennettgreer, age 13, of Fisherville, Ky., for his question:
How does a lie detector work?
A detective tracks down hard to find facts. A detector is a sensitive device that reveals secrets beyond the probing powers of a human detective. The lie detector was invented to test whether a person is lying, and most of the time it its inventors claim it can do.
A certain smartie' thinks he can tell a lie and get away with it,, He may indeed fool you and me with his smooth words and steady eye, but he does not fool himself.
When a person tells a deliberate lie, hidden changes occur in his body, and so far as we know none of them are good for the System. Smartie has to be told that it is wrong to lie, but if he learned just how he cheats himself maybe he would think twice before cheating his friends and relatives.
The lie detector records the hidden changes that occur when a person tells a deliberate lie. The machine works only if the person knows or believes he is not truthful. If you report a false statement that you believe is true, no changes occur in your body or on the charts. The machine records reveal different body processes, some of them automatic and beyond a person's control.
Different indicators are fixed where they can record these processes. Each indicator is connected to a metal finger that writes a graph on a revolving drum. Each written record from a sensitive indicator is a continuous graph of a normal process and the changes that occur in it when a person lies. The person tested sits in a special chair and an expert asks tricky questions.
When a person lies, his heart bats a trifle faster. His pulse speeds up and his blood pressure rises a little. These automatic reactions are recorded by a detector in an arm band. A pheumograph tube is placed around the chest of a person being questioned. It records subtle changes in respiration. If he lies, he may breathe faster or hold his breath.
Changes also occur in the skin and muscles. A galvanograph is fixed to the palm of a hand and the chair is fitted with other detectors. Slight changes in the perspiration and skin temperature of the hand are recorded. Slight muscular twitches and tensions are recorded in the arms and legs. As a rule, a careful reading of all these interrelated graphs tells an expert whether the suspect did or did not lie.
The lie detector actually is a multiple inatrument for probing subtle Emotions. WE react with Emotion to what WE do and to what others do,and these reactions cause bodily changes. However, SOME of our Emotions are confused or unsound. The lie detector is likely to fail on a person who is upset or dazed by inner emotional conflicts.