A polygraph, often referred to as a psychophysiological detection of deception (PDD) instrument, measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while a subject is asked and answers a series of questions. The underlying theory is that deceptive answers will produce physiological responses that can be differentiated from those associated with truthful answers. For example, a sudden increase in perspiration might be interpreted as a sign of anxiety related to deception.
The use of physiological responses to assess truthfulness has a long and controversial history. While proponents claim it can be a valuable tool in investigations and security screenings, its accuracy remains debated. Despite its limitations, the technique continues to be employed in various contexts, including criminal investigations, pre-employment screenings, and national security matters. Understanding the scientific basis and limitations of this technology is crucial for its appropriate application.
