Nothing but the truth: Mock jurors' use of stricken evidence in decision-making.

Abstract

The potential effects of stricken evidence on jurors' decisions is a problem for legal proceedings, and also for theories of information processing and decision making. Understanding the factors affecting individual reasoning in this context may lead to more general models of how memory and reasoning processes deal with change in information status over time. Prior studies of juror decision making have presented case information, followed by instructions to disregard target information in later judgments. Results indicate that, in some cases, the information is used in verdict decisions while in others, it is not. Three studies were conducted to resolve the issue of when individual jurors successfully disregard stricken evidence. The studies examine the impact of the truth of target evidence on its use in later decision making. In these studies, mock jurors were presented with materials describing a criminal trial. In three experimental conditions, materials contained additional pro-prosecution target evidence, for example, a wiretapped phone call, in which the defendant allegedly confessed to the crime. In one condition, the evidence was admissible; in another condition it was ruled inadmissible because it had been illegally obtained; and in the third condition, it was stricken because it was not true; for example, it was determined that the voice on the tape was not that of the defendant. A control condition, in which no additional evidence was presented, was also included. Dependent variables measured were verdict decisions, confidence in verdicts, participants' perceptions of the evidence, their opinions about the defendant's personality, and their interpretations of hypothetical situations in which the defendants' actions were ambiguous. The results show that stricken evidence will be used in individual jurors' interpretations of other evidence, inferences, and verdict decisions, if that evidence is true. If the evidence is presented but stricken because it is found to be untrue, participants will not use the information in verdict decisions; however, its presentation will still have indirect effects on their interpretations of related information. These findings suggest that future research on cognitive processes in knowledge correction should examine beliefs about the perceived truth of information in addition to its legal status.