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45 Law & Hum. Behav. 1 (2021)

handle is hein.journals/lwhmbv45 and id is 1 raw text is: AMERICAN                   American
PSYCHOLOGICAL             Psychology-Law

= = ASSOCIATION  ~  Society                                    Law and Human Behavior

© 2021 American Psychological Association
ISSN: 0147-7307

2021, Vol. 45, No. 1, 1-23

Anchoring Effect in Legal Decision-Making: A Meta-Analysis
Piotr Bystranowskil, Bartosz Janik2, Maciej Pr6chnicki3, and Paulina Sk6rska4
1 Interdisciplinary Centre for Ethics, Jagiellonian University
2 Faculty of Law and Administration, University of Silesia in Katowice
3 Faculty of Law and Administration, Jagiellonian University
4 Centre for Evaluation and Analysis of Public Policies, Jagiellonian University
Objective: We conducted a meta-analysis to examine whether numeric decision-making in law is sus-
ceptible 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 pub-
lication 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 situa-
tional factors, which paves the way for future research on countering the problematic effect in legal
Public Significance Statement
Our review corroborates the thesis that numeric decisions in law (such as damages or prison terms)
are susceptible to the effect of salient numbers present in the decision context. Such anchoring
effects might have undesirable consequences, possibly making court rulings biased or erratic. Our
results, however, suggest that the effect might be moderated by a number of factors, which might be
used by lawmakers to limit the influence of undesirable anchors or by attorneys to calibrate their
Keywords: anchoring effect, meta-analysis, legal decision-making, judges and juries

Bradley D. McAuliff served as Action Editor.
Piotr Bystranowski  https://orcid.org/0000-0001-5539-1342
Bartosz Janik  https://orcid.org/0000-0002-7471-6402
Maciej Pr6chnicki  https://orcid.org/0000-0002-2151-9915
PaulinaSk6rska   https://orcid.org/0000-0001-9037-3190
We presented earlier drafts of this article at the 35th Annual Conference
of the European Association of Law and Economics, Milan, Italy, and at
the conference Law and Mind 2, Krakow, Poland. This research has
received funding from the European Research Council (ERC) under the
H2020 European Research Council research and innovation program
(Grant agreement 805498) as well as from the Priority Research Area
Society of the Future under the program Excellence Initiative - Research

University at the Jagiellonian University in Krakow. Maciej Pr6chnicki
was supported by the National Science Centre, Poland (Grant 2017/25/N/
HS5/00944) and Bartosz Janik was supported by the National Science
Centre, Poland (Grants 2016/23/N/HS5/00952 and 2020/36/C/HS5/00111
supported literature search and analysis of the results of the study,
respectively). We are indebted to Krzysztof Kasparek for indispensable
assistance with the meta-analytic techniques employed in this article, to
Jeffrey Rachlinski and Michael Saks for helpful comments on earlier drafts,
as well as to many scholars who provided us with unreported data from their
experimental studies.
Correspondence concerning this article should be addressed to Maciej
Pr6chnicki, Faculty of Law and Administration, Jagiellonian University,
Bracka 12, 31-005 Krakow, Poland. Email: maciej.prochnicki@uj.edu.pl

Law and Human Behavior

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