On the Many Impacts of Inadmissible Testimony: Selective Compliance, Need for Cognition, and the Overcorrection Bias

A mock juror study tested three hypotheses: (a) Jurors comply selectively with instructions to disregard inadmissible testimony, (b) this effect is greater among jurors who are high rather than low in the need for cognition (NC), and (c) high-NC decision makers sometimes overcorrect against the perceived biasing agent of inadmissible testimony. Participants read a trial summary in which the admissibility of an incriminating wiretap and the basis for this ruling were manipulated. Consistent with the prediction that jurors would be motivated to reach a “just” verdict, participants disregarded an inadmissible wiretap when it was deemed unreliable but not when it violated due process. This pattern of selective compliance was found only among high-NC jurors. High-NC participants also exhibited signs of bias overcorrection, estimating the probability of the defendant’s guilt to be lower in the inadmissible-unreliable condition than in the no-wiretap control. The theoretical and practical implications of these results are discussed.