NCJ Number
84297
Date Published
1981
Length
8 pages
Annotation
The practical uses of the polygraph, its advantages and limitations, and guidelines on how best to use it as an investigative tool are discussed.
Abstract
The basic polygraph measures breathing patterns, cardio patterns (heart rate, pulse rate), and sensitivity patterns (galvanic skin response) as expressions of emotional reactions that indicate whether or not a person is lying about the material covered in the test. The steps of a typical structured polygraph examination are (1) the determination of what is being sought and whether or not the polygraph can be of assistance, (2) a pretest interview, (3) preparation of test questions, (4) testing of the subject, and (5) preparation of findings and conclusions. Types of testing are specific testing that focuses on one or more issues, preemployment screening to determine if an applicant meets the employer's minimum requirements, and periodic testing to determine whether an employee is involved in thefts or rule violations during employment. Advantages of the polygraph test are that it can eliminate persons under suspicion and suggest further investigation of persons who appear to be lying. Limitations of the polygraph are that it requires a suitable subject and the structure of the test and the qualifications of the examiner determine the value of the results. As a rule, polygraph evidence is not admissible in court, so the polygraph cannot yield direct evidence in a case; however, it can be used to suggest areas where admissible evidence may be sought.