Effect of Eye-Witness Testimony Confidence on Juror Decisions

Slane, C. R., & Dodson, C. S. (2022). Eye-witness confidence and Mock juror decisions of guilt: A meta-analytic review. Law and Human Behavior, 46(1), 45-66. https://doi.org/10.1037/lhb0000481

In this journal article, Slane and Dodson (2022) investigate the impact of eye-witness confidence on different dependent variables, including (i) jurors’ perception of accuracy, (ii) judgment of guilt, and (iii) guilt or non-guilt verdict. The primary hypothesis (hypothesis) was that highly confident eye-witnesses are more persuasive to jurors than those with lower confidence. The second hypothesis was that eye-witness confidence at trial is more persuasive to the mock juror than the identification. Finally, the third hypothesis (hypothesis 3) is the numerical expression of confidence is more persuasive than verbal confidence.

To test the hypothesis, Slane and Dodson (2022) adopted a meta-analysis of 35 studies (20 published papers, seven theses or seven dissertations) to investigate the effect of confidence on juror judgment and the influence of the primary moderator variables. The latter included the format of the confidence expression and the time of the confidence. The researcher adopted the comprehensive metanalysis software (CMA) to run four primary analyses. The primary moderating variables include the confidence timing and the confidence expression type. The secondary moderating variables in the study included the level of confidence and the safeguards. The most significant safeguards include the expert testimony or the juror instructions.

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The meta-analysis shows eye-witness confidence influences juror decisions. When the eye witness was highly confident, reaching the guilty verdict was much easier than when the eye witness was less confident. However, the eyewitness is unlikely to express low confidence before the juror. The moderator analysis reveals that the timing of the confidence statement is not a significant factor for the juror’s decisions of guilt or accuracy. The results of the moderator analysis show that numerical or verbal expressions do not moderate the influence of eye-witness confidence. Moreover, the result shows including the safeguards does not influence the effect of eye-witness confidence across the studies.

Slane and Dodson (2022) explain that eye-witness confidence persuades the jurors, although the impact is modest. Thus, increased confidence affects the juror’s decision for guilt and the suspect’s identification. In addition, the persuasive effect of the verbal and numerical expression of confidence is similar. Finally, the study results show the jurors are not sensitive to the differences in the eye-witness confidence at trial from the initial identification.

Quigley-McBride, A., Crozier, W., Dodson, C., Teitcher, J., & Garrett, B. L. (2021). Face value? How jurors evaluate eye-witness face recognition ability. SSRN Electronic Journal. https://doi.org/10.2139/ssrn.4032866

In this study, Quigley-McBride et al. (2021) examine the significance of face memory ability tests in determining eye-witness accuracy. Post-identification confidence is a common determinant of eye-witness accuracy, but it is not often reliable. Despite this shortcoming, the jurors rely on the eye-witness confidence to measure accuracy. When an eye-witness testifies, the jury examines information such as how well the perpetrator and the police administration of the lineup. This study emphasises the significance of face memory ability tests to access objective information about an individual ability to recognise a face as a key determinant for accuracy.

Quigley-McBride et al. (2021) ran three online studies ((N₁ = 3,143, N₂ = 1,156, N₃ = 3,180) to determine how the jury and lay persons evaluate the face memory ability. Scientific tools such as the Cambridge Face Memory Test (CFMT) are significant in measuring face recognition ability. In experiment 1, the participant read a mock court transcript of an eyewitness in specific versions to determine how this information was interpreted.

The study results indicate that jury-eligible participants can interpret the information as objectively good or poor facial memory. The eye-witness face memory ability and post-identification confidence significantly influenced the verdict decisions. The classic effect in the jury decision-making literature is that a high confidence eye-witness influences high rates of guilty verdicts. In addition, the jury-eligible participants can integrate the face memory information into the results of post-identification confidence. The incidences of good