Myers, B., & Arbuthnot, J. (1997). Polygraph testimony and juror judgments: A comparison of the guilty knowledge test and the control question test. Journal of Applied Social Psychology, 27, 1421-1437.
The present experiment investigated the impact of the Control Question Test (CQT) and the Guilty Knowledge Test (GKT) on the verdicts of mock jurors. Although studies have indicated that polygraph evidence has little influence on jurors’ verdicts (Cavoukian & Heselgrave, 1980; Spanos, Myers, Dubreuil, & Pawlak, 1992–1993), no research has previously distinguished between the different types of polygraph tests and their impact on juror verdicts. In the present study, jurors were shown a videotape of a simulated rape-murder trial that contained either CQT polygraph evidence, GKT polygraph evidence, or no polygraph evidence. No differences were found among the 3 conditions for either jury verdicts or individual juror verdicts, and jurors tended to rate both forms of polygraph testimony below other forms of equally suspect evidence, such as eyewitness testimony, in its influence on their decision-making process.
No impact of polygraph evidence on jury verdicts; very little discussion of polygraph evidence or eyewitness testimony. Rated importance of polygraph data strongly correlated with verdict preference before deliberation but not after.