In the laboratory experiment, 20 students responded verbally to the presentation of low-stress (Card Test) and high-stress (Horror Picture Test) stimuli. In the field experiment, 56 criminal suspects similarly responded to low-stress (Card Test) and high-stress (Polygraph Test) stimuli. Subjects' responses were processed by the Psychological Stress Evaluator, and they were judged blindly by three trained judges. The results showed low reliability and validity scores. However, some aspects of data consistency indicate the need for further study before a final conclusion concerning the applicability of the instrument for lie detection is reached. About 45 references are included. (Author abstract modified)