Electronic and Electromechanical Tester of Physiological Sensors
Polygraph equipment has been used by law enforcement and security forces since the 1920s. At this time, polygraph testimonies are admissible in court in 19 states in the United States of America and polygraphs are actively used as an investigative tool in Canada. Due to a long standing debate and controversy surrounding the scientific basis of polygraph testing, polygraphs and polygraph evidence are less commonly used and typically not admissible in court in many
other countries. Nevertheless, polygraphs are still commonly used as a screening tool for hiring new employees into security-sensitive positions. The polygraph monitors several physiological indicators (such as skin conductivity, breathing, pulse and blood pressure) during an interview in which the subject is asked a series of questions. The expectation is that deceptive answers will register different physiological responses from those corresponding to truthful answers. Modern polygraphs are computerized and create digital recordings of all physiological signals captured during an interview.
Since polygraph testimony is still in wide usage, it is important to understand how different instruments respond to identical excitations and to be able to validate and calibrate physiological sensors and thus ensure reliability of obtained readings. The goal of this project is to develop an Electronic and
Electromechanical Tester (EET) that simulates three physiological channels used in polygraph equipment (two channels of respiration and electrodermal response) by providing a direct mechanical or electrical response equivalent to that of a human attached to the respective sensors. In this sense, the EET provides a simulation of the real physiological processes and provides an accurate and repeatable way of testing polygraph equipment. In addition, the EET can be used to test and validate other physiological measurement systems that capture respiration and GSR, such as equipment used in sleep laboratories.