The polygraph is an instrument that detects, monitors, and records physiological responses that are allegedly of psychological origin and attributed to deception. Hence the human mind and its complex psychology are the core of the detected physical responses. However, the polygraph industry has almost entirely overlooked psychological issues in its training and publishing. Th e industry focuses its attention and interest on various technical aspects of the test such as e.g. scoring, rather than concentrating on what is most important, i.e. the examinee’s psychology, as it is responsible for almost the entire test result. Th e paper extensively explains the importance of examinee psychology and its infl uence on test outcome, points to the shortfalls in training and publication activity of the industry, and discusses the result and impact of the industry’s approach.