The impact on juror verdicts of judicial instruction to disregard inadmissible evidence: A meta-analysis
ABSTRACT The effect on juror verdicts of judicial instructions to disregard inadmissible evidence was evaluated using meta-analysis. One hundred seventy-five hypothesis tests from 48 studies with a combined 8,474 participants were examined. Results revealed that inadmissible evidence (IE) has a reliable effect on verdicts consistent with the content of the IE. Judicial instruction to ignore the inadmissible evidence does not effectively eliminate IE impact. However, if judges provide a rationale for a ruling of inadmissibility, juror compliance may be increased. Contested evidence ruled admissible accentuates that information, resulting in a significant impact on verdicts. Suggestions for how the courts may mitigate the impact of inadmissible evidence more effectively are discussed.
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- "We began this paper by considering what happens when a lawyer violates the rules of evidence by pointing out a witness's previous bad character. Consistent with the results on disregarding inadmissible evidence (Steblay et al., 2006), we suggested that even if the violation is pointed out by the judge, people will nonetheless tend to discount the testimony and so lower their degree of belief in the conclusion it is intended to support. This intuition runs counter to procedural approaches, which suggest that dialogical rules like the rules of evidence are part of our cognitive resources for evaluating everyday arguments. "
ABSTRACT: When directed to ignore evidence of a witness's previous bad character because of a violation of the rules of evidence, are jurors' beliefs still affected? The intuition is that they will be because in everyday argumentation, fallacies, like the ad hominem, are effective argumentative strategies. An ad hominem argument (against the person) undermines a conclusion by questioning the character of the proposer. This intuition divides current theories of argumentation. According to pragmadialectical theory (e.g., Van Eemeren & Grootendorst, 2004), procedural rules exactly like the rules of evidence are part of our cognitive resources for evaluating arguments. If 1 of these rules is violated, an argument should be treated as a fallacy and so it should not alter someone's belief in the conclusion. Some recent experiments investigating how reasonable these arguments are perceived to be seem to support this account (van Eemeren, Garssen, & Meuffels, 2009). These experiments are critiqued from the perspective of the relevance (Walton, 2009, 2010) and epistemic (Hahn & Oaksford, 2006, 2007; Oaksford & Hahn, 2004) approaches to argumentation. An experiment investigates the predictions of these approaches for a graded belief change version of van Eemeren et al.'s (2009) experiment, and the results are modeled using a Bayesian congruent prior model. These results cannot be explained by the pragmadialectical approach and show that in everyday argument people are extremely sensitive to the epistemic relevance of evidence. Moreover, it seems highly unlikely that this can be switched off in more formal contexts such as the courtroom. (PsycINFO Database Record (c) 2015 APA, all rights reserved).Journal of Experimental Psychology Learning Memory and Cognition 07/2015; DOI:10.1037/xlm0000151 · 3.10 Impact Factor
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- "Juries are more likely to acquit if the defendant has no criminal record (Givelber and Farrell 2008). They are not sufficiently sensitive to selection bias in the presentation of evidence (Koehler and Thompson 2006) and not sufficiently likely to disregard inadmissible evidence (Steblay, Hosch et al. 2006). While rigorous proof would of course require experimental tests, it seems plausible that these differences can be put down to a property of intuitive decision-making. "
ABSTRACT: Jury members do not normally have the privilege of a complete, unbiased picture of the case. To make the best of patently incomplete evidence, they cannot but at least partially rely on their intuition. We provide evidence for this claim based on self-report data as well as more subtle measures of unconscious modifications of the evidence in order to fit the favoured interpretation (coherence shifts). In three experiments we investigated whether members of a mock jury apply standards of proof in a normatively appropriate way, how well they take into account explicitly stated probability information, and which factors influence the size of coherence shifts. We found a mixed pattern of results: manipulation of the standard of proof influences conviction rates in the intended direction, but there are fewer convictions in both standard of proof conditions than normatively expected. When asked to indicate the minimum probability of guilt necessary for conviction, subjects do not sufficiently discriminate between “beyond a reasonable doubt” and “preponderance of the evidence”. Even substantial manipulations of the posterior probability of guilt had very little effect on conviction rates. Reliance on intuitive processes seems to reduce the influence of explicitly stated probabilities. We furthermore found effects of verdict and of the probability manipulation on the size of coherence shifts. We argue that the performance of jury members could be improved by providing them with supplementary information on context, such that they are able to put explicit information on probabilities in perspective.
- "One study in particular however, revealed interesting and relevant findings to the present study. A meta-analysis of 49 studies examining inadmissible evidence, found that judicial admonition did not completely cure the impression made by this type of evidence (Steblay, et al., 2006). However, improvements in effects were observed when instructions included a justification for inadmissibility, namely when the judge explained the unreliability associated with the evidence, that it was considered hearsay evidence, or that it was immaterial to the case. "