PSLE: Dear students, Do not STRESS; Do your BEST; Forget the REST. "You may never know what results come of your action, but if you do nothing there will be no result.” ~ Mahatma Gandhi.

Lie Detector

In 1921, John A. Larson, a medical student from California University developed a lie detector as "Polygraph" that detects lies with a fair degree of accuracy. In 1972, the American inventor Alan Bell developed another improved model of it which was able to detect slight tremblings in the voice which often occur when a person tells a lie

Today many models have been invented and is widely used in crime detection. Some of them are figured here as:

Concept use to detect lies in lie detector: When someone tells a lie, there occur certain physiocological changes in the body. The victims heart beat increases leading to rapid respiration. His blood pressure increases and breathing pattern changes. Various parts of the machine are attached to human body and the report is produced. It is assumed to be 80% accurate