Anchoring Effect in Legal Decision-Making: A Meta-Analysis

Bystranowski, P., Janik, B., Próchnicki, M., 

& Skórska, P. 

(2021). Law and Human Behavior, 45(1), 1-23. 

http://dx.doi.org/10.1037/lhb0000438

Objective

We conducted a meta-analysis to examine whether numeric decision-making in law is susceptible to the effect of (possibly arbitrary) values present in the decision contexts (anchoring effect) and to investigate which factors might moderate this effect. 

Hypotheses

We predicted that the presence of numeric anchors would bias legal decision-makers’ judgment in the direction of the anchor value. We hypothesized that the effect size of anchoring would be moderated by several variables, which we grouped into three categories: methodological (type of stimuli; type of sample), psychological (standard vs. basic paradigm; anchor value; type of scale on which the participants assessed the target value), and legal (relevance of the anchor; type of the anchor; area of law to which the presented case belonged; presence of any salient numeric values other than the main anchor). 

Method

Twenty-nine studies (93 effect sizes; N = 8,549) met the inclusion criteria. We divided them into two groups, depending on whether they included a control group, and calculated the overall effect size using a random-effects Model with robust variance estimation. We assessed the influence of moderators using random effects metaregression. 

Results

The overall effect sizes of anchoring for studies with a control group (z = .27, 95% CI [.21, .33], d = .58, 95% CI [.44, .73]) and without a control group (z = .39, 95% CI [.31, .47], d = .91, 95% CI [.69, 1.12]) were both significant, although we provide some evidence of possible publication bias. We found preliminary evidence of a potential moderating effect of some legally relevant factors, such as legal expertise or the anchor relevance. 

Conclusions

Existing research indicates anchoring effects exist in legal contexts. The influence of anchors seems to depend on some situational factors, which paves the way for future research on countering the problematic effect in legal settings.

The research is here.

Is justice blind or myopic? An examination of the effects of meta-cognitive myopia and truth bias on mock jurors and judges

M. Pantazi, O. Klein, & M. Kissine

Judgment and Decision Making, 
Vol. 15, No. 2, March 2020, pp. 214-229

Abstract

Previous studies have shown that people are truth-biased in that they tend to believe the information they receive, even if it is clearly flagged as false. The truth bias has been recently proposed to be an instance of meta-cognitive myopia, that is, of a generalized human insensitivity towards the quality and correctness of the information available in the environment. In two studies we tested whether meta-cognitive myopia and the ensuing truth bias may operate in a courtroom setting. Based on a well-established paradigm in the truth-bias literature, we asked mock jurors (Study 1) and professional judges (Study 2) to read two crime reports containing aggravating or mitigating information that was explicitly flagged as false. Our findings suggest that jurors and judges are truth-biased, as their decisions and memory about the cases were affected by the false information. We discuss the implications of the potential operation of the truth bias in the courtroom, in the light of the literature on inadmissible and discredible evidence, and make some policy suggestions.

From the Discussion:

Fortunately, the judiciary system is to some extent shielded by intrusions of illegitimate evidence, since objections are most often raised before a witness’s answer or piece of evidence is presented in court. Therefore, most of the time, inadmissible or false evidence is prevented from entering the fact-finders’ mental representations of a case in the first place. Nevertheless, objections can also be raised after a witnesses’ response has been given. Such objections may not actually protect the fact-finders from the information that has already been presented. An important question that remains open from a policy perspective is therefore how we are to safeguard the rules of evidence, given the fact-finders’ inability to take such meta-information into account.

The research is here.