• Korean Journal of Forensic Psychology
• /
• v.13 no.1
• /
• pp.1-22
• /
• 2022

This study tested the effect of the verdict category of lay-participation trial in Korea on the legal decision of layperson and the role of representation of 'innocent' in the process. Representation of 'innocent' refers to a psychological threshold for deciding someone's innocence (no fault or sin) in a general sense. The functions as a threshold for a legal decision of 'beyond a reasonable doubt (BRD)' and the individual threshold (IT), regarded as a standard for judgment of guilt established by law and an estimate of an individual's threshold, respectively, were compared. This study used a 2×2 complete factorial design in which the verdict category (guilty/innocent vs. guilty/not guilty) and the defendant's likelihood of guilt (low vs. high) were manipulated. Data from 137 lay-people who voluntarily participated in the online experiment was analyzed. The experiment's procedure was in the order of measuring 'representation of innocent' and the likelihood of guilt of an accused, presenting one of four trial vignettes, and obtaining legal decisions (verdict confidence and estimation of the likelihood of guilt for the defendant). As a result, it was found that the verdict category did not significantly affect the legal decision of layperson. However, the guilty verdict rate of the 'guilty/innocent' condition tended to be higher than those of the 'guilty/not guilty' condition. The layperson's representation of 'innocent' and the verdict category had an interaction effect on the difference between BRD and IT (threshold change) at the significance level of .1. In the 'guilty/innocent' condition, the threshold change varying with layperson's representation of 'innocent' was larger than in the 'guilty/not guilty' condition. In comparing the function of BRD and IT, IT significantly predicted the lay person's legal decision at the significance level of .1 by interacting with the likelihood of guilt for the defendant. Therefore, it could be said that IT was a better threshold estimator than BRD. The implication of this study is that it provided experimental evidence for the effect of the verdict category of lay-participation trial in Korea, which is a problem often raised among lawyers, and suggested logical reasoning and empirical grounds for the psychological mechanism of the possible effect.

• Korean Journal of Culture and Social Issue
• /
• v.21 no.3
• /
• pp.497-510
• /
• 2015

The jury instruction consists of a set of legal rules and provides a guide for jurors to interpret evidence and the legal standard of a proof beyond reasonable doubt. Jury instructions are usually given after the closing arguments (at the end of the trial). But some research has shown that jury instruction provided before the evidence may have an impact on verdict. The present study was to determine the cognitive process caused by early instruction: (1) Early instruction may influence the verdict by upwardly adjusting the threshold for the decision to convict; (2) early instruction may influence the verdict through evaluations of the probative values of evidence; (3) Or both. 187 people older than 20 years of age participated in the on-line survey. With a trial scenario, one independent variable, Instruction Procedure, was manipulated in three levels: before-and-after the evidence procedure, after-only evidence procedure, and no-instruction procedure. The instruction procedure conditions did not show any difference in the evaluation of the probative values of evidence. On the other hand, before-and-after condition showed the lowest rate of guilty verdict and the highest probability of guilt for the defendant in the scenario. This latter result clearly suggested that the instruction procedure affects the decision threshold. Specifically, instruction provided twice, once before and again after the evidence, may upwardly shift the threshold for the decision to convict.