Physiological Detection of Deception: Measurement of Responses to Questions and Answers During Countermeasure Maneuvers

Physiological detection of deception (“lie detection”) procedures were evaluated with 24 actors, half of whom were “guilty” of a mock-crime and half were “innocent.” All subjects were trained in the Stanislavsky method of acting and were instructed to use this method to appear innocent on the polygraph test. Two versions of the control question detection of deception test were employed: one in which subjects verbally answered immediately following each question and the other in which they delayed their verbal answer for 8 sec following each question. The delayed answer technique allowed the separate measurement of physiological responses to the questions and the answers. Skin resistance responses, cardiovascular changes, and respiration were recorded and analyzed. Excluding inconclusive results, the overall accuracy of the decisions varied between 78% and 91% depending on the test employed. The principal results were: 1) attempts by guilty subjects to appear innocent were totally ineffective, 2) physiological responses elicited by the questions were more valid indicators of deception and nondeception than were the responses elicited by the verbal answers, and 3) errors occurred more frequently with innocent subjects (between 17% and 25% depending on the measure used) than with guilty subjects (0% with each measure). Variables which may affect the generalizability of these results to the field situation are discussed and suggestions for increasing the generalizability of laboratory findings are made.