The Court of Public Opinion: Lay Perceptions of Polygraph Testing

We sampled a total of 411 participants and randomly assigned them one of three brief trial vignettes that contained either no-polygraph evidence, evidence of a passed polygraph test, or evidence of a failed polygraph test. Participants rendered guilt judgments and answered a series of questions concerning the trial in particular, and polygraph tests in general. Similar to previous studies on the impact of polygraph evidence on jurors' guilt judgments, this sample of jury-eligible adults indicated that they did not find polygraph test evidence to be persuasive. Moreover, it mattered little to participants whether the results indicated the defendant passed a polygraph test, or that he failed a polygraph test. However, when our findings are compared to those of previous surveys involving experts in the field of psychophysiology, they differ in a number of important respects. The implications for decisions regarding admissibility (e.g., U.S. v. Alexander, 1975 and U.S. v. Scheffer, 1998) are discussed.