[Psychophysiological research by the East German State Security and the use of so-called lie detectors in the GDR].

This study is the first to describe research conducted by the GDR State Security on polygraphs and voice analyzers and their conspiratorial use. Stasi files are used to show that the so-called lie detector was also used in the GDR. Up until the late 1960s, MfS superiors considered psychophysiological tests with the polygraph to be questionable and "ethically and morally reprehensible". This did not prevent a few experts from conducting extensive research. In addition, own spies were trained to pass polygraph tests in the West without being recognized. With the development of voice analyzers in the early 1970s, the MfS expanded its psychophysiological research. Voice analyses were carried out in hundreds of cases - to identify informers and in criminal investigations. All of the equipment came from the West and was procured despite embargo regulations. Shortly before the end of the GDR, use and research were to be expanded. The public knew nothing about this. There were only indications in the analyzed files that the psychophysiological devices were being used for civilian purposes. The Stasi files on this subject have not yet been fully indexed.