Dimensions of Evidence Evaluation in Legal Judgment: Application of Multidimensional Scaling and Unfolding

The purpose of this study was to explore the dimensions that laypersons use to evaluate evidence presented in criminal cases and to determine whether the dimensions differ according to legal decision using rankings of the importance of evidence. Multidimensional scaling was performed using the proximity matrix generated from the entire data set, and it was found that laypeople are likely to evaluate evidence according to the legal party from which it was presented (Dimension 1), while Dimension 2 may reflect the sequence of events or the objectivity of the evidence itself. The multidimensional scaling configurations for the guilty and not guilty decision were similar to the configuration of the total data, but the clustering of the evidence and the meaning of the dimensions tended to be clearer in the guilty decision configuration. When comparing vector model configurations of multidimensional unfolding using ranking data, no evidence or dimension was observed to be particularly important to those who were pro-defendant, but a majority of those who were pro-prosecution people valued the defense's evidence. Although this study is exploratory and has limited generalizability to laypersons' evidence evaluation dimensions, it is expected to provide essential knowledge for systemic understanding of the jury decision-making process.