EFFECT OF LIE DETECTOR EVIDENCE ON JURY DELIBERATIONS AN EMPIRICAL STUDY

• NCJ Number: 46365
• Journal: Journal of Police Science and Administration Volume: 5 Issue: 2 Dated: (1977) Pages: 148-154
• Author(s): S C CARLSON; M S PASANO; J A JANNUZZO
• Date Published: 1977
• Length: 8 pages
• Corporate Author: International Assoc of Chiefs of Police
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

A STUDY WAS UNDERTAKEN TO FURTHER EXPLORE THE FINDINGS OF TWO PREVIOUS STUDIES WHICH INDICATED THAT JURORS TEND TO UNCRITICALLY ACCEPT LIE DETECTOR EVIDENCE AND TO BASE THEIR VERDICTS SOLELY ON SUCH EVIDENCE.

Abstract

USABLE RESPONSES WERE COLLECTED FROM 55 TO 100 JURORS SITTING ON MOOT TRIALS WHICH WERE PART OF A TRAINING PROGRAM IN TRIAL ADVOCACY AT YALE LAW SCHOOL. DURING THE TRIAL, JURORS HEARD CASES AND REACHED THEIR VERDICTS. AFTERWARDS, THEY WERE PRESENTED WITH ADDITIONAL LIE DETECTOR EVIDENCE PERTAINING TO CENTRAL ISSUES IN THE CASE. DIFFERENT JURORS WERE TOLD THAT POLYGRAPH EVIDENCE HAD EITHER A 70 PERCENT OR A 95 PERCENT ACCURACY RATE. THEY WERE ALSO GIVEN A QUESTIONNAIRE CONCERNING LIE DETECTOR TESTIMONY AND ITS EFFECTS ON THEIR VERDICTS. OF THE 31 JURORS WHO FACED A CONFLICT BETWEEN THEIR VERDICTS AT THE TRIAL AND AFTER SEEING THE ADDITIONAL EVIDENCE, ONLY SIX (19.3 PERCENT) INDICATED THEY WOULD CHANGE THEIR VERDICTS ON THE BASIS OF THE POLYGRAPH EVIDENCE, AND FOUR OF THESE HAD BEEN TOLD THAT SUCH EVIDENCE WAS 95 PERCENT ACCURATE. AN ADDITIONAL SEVEN JURORS (22.6 PERCENT) STATED THEY WERE UNCERTAIN ABOUT CHANGING THEIR VOTE; OF THESE, FIVE HAD BEEN TOLD THE EVIDENCE WAS 95 PERCENT ACCURATE. OVERALL, THE JURORS WERE STRIKINGLY UNSWAYED BY POLYGRAPH EVIDENCE, AND THE LOWER THE ACCURACY OF THE LIE DETECTOR, THE LESS LIKELY THE JUROR TO CHANGE HIS VOTE. EXPLANATIONS GIVEN BY JURORS FOR CHANGING OR NOT CHANGING THEIR VOTES INDICATED THAT THEY TOOK SERIOUSLY THEIR SWORN DUTIES AND CONSIDERED THE POLYGRAPH EVIDENCE IN ACCORD WITH RELEVANT ISSUES IN THE CASE AND THE CHARGE ON BURDEN OF PROOF. IN THE ENTIRE STUDY, ONLY 14.5 PERCENT OF THE JURORS LABELLED POLYGRAPHIC EVIDENCE AS MORE SIGNIFICANT THAN OTHER EVIDENCE, AND ALL OF THESE HAD BEEN TOLD THE LIE DETECTOR WAS 95 PERCENT ACCURATE. DISTRUST OF POLYGRAPHIC EVIDENCE WAS SPONTANEOUSLY EXPRESSED BY 10 OF THE 55 JURORS (18.1 PERCENT), AND THIS DISTRUST WAS APPARENTLY NOT AFFECTED BY THE DEGREE OF ACCURACY ATTRIBUTED TO THE EVIDENCE IN THE JURY INSTRUCTIONS. IN GENERAL, THE FINDINGS DO NOT SUPPORT THOSE IN THE EARLIER STUDIES. POSSIBLE METHODOLOGICAL PROBLEMS ARE EXAMINED. RECOMMENDATIONS ARE MADE FOR FURTHER RESEARCH. (JAP)