Expert testimony on the polygraph test: Issues surrounding admissibility and examination of jurors’ critical evaluation of evidence. -- Advances in Psychological Research
Chapter
Overview
Overview
Abstract
Researchers remain divided on the validity of polygraph testing. In light of changes in the admissibility of expert scientific testimony in Daubert v. Merrell Dow Pharmaceuticals (1993), testimony by a polygraph examiner in court may become more prevalent, despite the fact that the test has not yet gained "general acceptance" within the scientific community. We describe the controversy surrounding the admissibility of the polygraph test with respect to Daubert. An additional issue surrounding admissibility with respect to polygraph test results concerns the potential impact on jurors. The belief that the test carries special dangers because it is likely accorded “excessive weight” by jurors has been articulated by such decisions as U.S., v. Alexander (1975), and U.S. v. Scheffer (1998). We examine the research on how jurors are likely to react to polygraph test results, and whether they can critically evaluate this testimony. The present study examines the impact of expert testimony concerning the polygraph test. A total of 190 participants were randomly assigned a mock trial transcript concerning child sexual abuse that varied expert testimony: (1) no-polygraph control, (2) polygraph examiner, (3) polygraph examiner and pro-polygraph expert, (4) polygraph examiner and anti-polygraph expert, (5) polygraph examiner and both pro- and anti-polygraph experts. Across all conditions, jurors were skeptical of polygraph evidence, indicating the accuracy was approximately 65%. Only the anti-polygraph expert condition produced guilt judgments that differed significantly from the no-polygraph control group. The present findings suggest that are most persuaded by expert testimony which is critical of the polygraph test. Implications for admissibility and the concern that polygraph test results are given “excessive weight” are discussed.
