A polygraph was invented by American jurist and psychologist William Marston in the period of the First World War. The instrument became so popular, that rare police department ignored it in the 1940s.
In the meantime, Soviet Union scientists were working on the project of its own polygraph. Their first sketches appeared in the 1920s. Nowadays, polygraph testing is commonly used in criminal investigation, security, various business areas and some other fields. The main reason of its popularity is the high level of accuracy shown by this appliance – 98%.