What is guilty knowledge test?

The Guilty Knowledge Test (GKT) is a psychological assessment designed to detect deception by measuring a person's physiological responses to information that only a guilty individual would recognize. During the test, subjects are presented with details related to a crime, and their reactions—such as changes in heart rate, skin conductance, or respiration—are monitored. If a subject shows a significant response to specific crime-related information, it suggests that they possess knowledge associated with the crime, indicating potential guilt. The GKT is often used in criminal investigations and polygraph testing.