The document discusses the psychology and theory behind polygraph examinations. It states that polygraph techniques use physiological changes accompanying deception that can be recorded and interpreted. When lying, the body's functions are influenced by the mental state of fear or anxiety, causing fluctuations in things like pulse rate, blood pressure, breathing and perspiration. The polygraph aims to measure this fear of detection rather than deception itself by comparing physiological responses to different types of questions. However, other personal factors can also influence responses. More research is needed to improve the theoretical basis for polygraph applications.