THE POLYGRAPH MEASURES AND RECORDS PHYSIOLOGICAL CHANGES OF SWEAT GLAND ACTIVITY, PLUS AND BLOOD PRESSURE, AND BREATHING. IT IS THE MOST WIDELY ACCEPTED OF THE TRUTH-SEEKING INSTRUMENTS. RESEARCH ON THE POLYGRAPH HAS YIELDED MORE IMPRESSIVE RESULTS FOR CRIMINAL CASE EXAMINATIONS THAN FOR LABORATORY EXPERIMENTS, HOWEVER, BECAUSE IT IS DIFFICULT TO DUPLICATE THE EMOTION OF A LYING CRIMINAL SUSPECT. IN ASSESSING THE RELIABILITY AND VALIDITY OF AN EXAMINATION, RECENT STUDIES CONCLUDE THAT A WELL-DESIGNED EXAMINATION ADMINISTERED BY A SKILLED POLYGRAPHIST IS HIGHLY VALID. THE POLGRAPH HAS BEEN USED IN BOTH PUBLIC AND PRIVATE PREEMPLOYMENT TESTING, IN COURTROOM USE UNDER LIMITED CIRCUMSTANCES, AND IN CRIMINAL INVESTIGATIONS. IT IS NOT, HOWEVER, A SUBSTITUTE FOR COMPREHENSIVE FIELD INVESTIGATION. POLICE AND POLYGRAPHISTS MUST WORK TOGETHER AND THE POLYGRAPHIST MUST BE GIVEN AS MUCH INFORMATION ABOUT THE CRIME AS POSSIBLE. TO GAIN THE SUSPECT'S COOPERATION IN TAKING THE TEST, OFFICERS SHOULD EMPHASIZE THAT THE EXAMINATION IS INTENDED TO DETERMINE THE SUSPECT'S TRUTHFULNESS. ONLY ONE CRIME SHOULD BE INVESTIGATED AT A A TIME AND THE POLYGRAPHIST SHOULD HAVE TOTAL RESPONSIBILITY FOR ALL ISSUES COVERED AND ALL TEST QUESTIONS. WHEN RESULTS SHOW A SUSPECT HAS BEEN TRUTHFUL, ATTENTION CAN BE FOCUSED ON OTHERS WHO MAY BE GUILTY. RESULTS INDICATING LYING SHOULD BE FOLLOWED BY INTENSIFIED INVESTIGATION AND RESUMPTION OF THE INTERROGATION. A PHOTOGRAPH STUDY QUESTIONS, A RESOURCE TEXT, AND CHARTS SHOWING PEAK-OF-TENSION TEST RESPONSE PATTERN AND POLYGRAM TRACINGS ARE ATTACHED. (AOP)