ACCURACY AND RELIABILITY OF POLICE POLYGRAPHIC ('LIE DETECTOR') EXAMINERS', JUDGMENTS OF TRUTH AND DECEPTION THE EFFECT OF SELECTED VARIABLES

• NCJ Number: 19956
• Author(s): F S HORVATH
• Date Published: 1973
• Length: 219 pages
• Grant Number(s): 73-NI-99-1014
• Publication Format: Document
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America
• Note: GRADUATE RESEARCH FELLOWSHIP GRANT

Annotation

TEN POLYGRAPHIC EXAMINERS WITH VARYING YEARS OF EXPERIENCE RATED THE POLYGRAPHIC RECORDINGS OF 112 SUBJECTS AND INDICATED IF THE SUBJECT WAS BEING TRUTHFUL, HIS DEGREE OF SURENESS, AND THE EASE OF INTERPRETABILITY.

Abstract

THE RECORDINGS WERE CROSS CATEGORIZED AS VERIFIED OR UNVERIFIED, AS PERTAINING TO SUBJECTS CONSIDERED TRUTHFUL OR DECEPTIVE, AND AS INVOLVING CRIMES AGAINST A PERSON OR PROPERTY CRIMES. THE THREE PHYSIOLOGICAL INDICES USED WERE RESPIRATORY, ELECTRODERMAL (GSR) AND CARDIOVASCULAR. IT WAS FOUND THAT THE EVALUATORS MADE 63.1 PERCENT CORRECT JUDGMENTS. CONTRARY TO EXPECTATIONS, HIGH-EXPERIENCE EVALUATORS WERE NEITHER MORE ACCURATE, NOR CONFIDENT, NOR DID THEY CONSIDER RECORDINGS EASIER TO INTERPRET THAN DID LOW EXPERIENCE EVALUATORS. THE RESULTS OF A NUMERICAL SCORING-SCHEME, AS CARRIED OUT BY EVALUATORS ON A SUB-SAMPLE OF RECORDINGS, INDICATED THAT GSR SCORES WERE MORE ACCURATE THAN WERE THOSE OF THE OTHER TWO INDICES IF INCONCLUSIVE SCORES WERE ELIMINATED, AND THAT GSR WAS SCORED MORE CONSISTENTLY THAN EITHER RESPIRATORY OR CARDIOVASCULAR ACTIVITY.