Evidence for Anchoring Bias During Physician Decision-Making

Ly, D. P., Shekelle, P. G., & Song, Z. (2023).

JAMA Internal Medicine, 183(8), 818.

https://doi.org/10.1001/jamainternmed.2023.2366

Abstract

Introduction

Cognitive biases are hypothesized to influence physician decision-making, but large-scale evidence consistent with their influence is limited. One such bias is anchoring bias, or the focus on a single—often initial—piece of information when making clinical decisions without sufficiently adjusting to later information.

Objective

To examine whether physicians were less likely to test patients with congestive heart failure (CHF) presenting to the emergency department (ED) with shortness of breath (SOB) for pulmonary embolism (PE) when the patient visit reason section, documented in triage before physicians see the patient, mentioned CHF.

Design, Setting, and Participants

In this cross-sectional study of 2011 to 2018 national Veterans Affairs data, patients with CHF presenting with SOB in Veterans Affairs EDs were included in the analysis. Analyses were performed from July 2019 to January 2023.

Conclusions and Relevance

In this cross-sectional study among patients with CHF presenting with SOB, physicians were less likely to test for PE when the patient visit reason that was documented before they saw the patient mentioned CHF. Physicians may anchor on such initial information in decision-making, which in this case was associated with delayed workup and diagnosis of PE.

Here is the conclusion of the paper:

In conclusion, among patients with CHF presenting to the ED with SOB, we find that ED physicians were less likely to test for PE when the initial reason for visit, documented before the physician's evaluation, specifically mentioned CHF. These results are consistent with physicians anchoring on initial information. Presenting physicians with the patient’s general signs and symptoms, rather than specific diagnoses, may mitigate this anchoring. Other interventions include refining knowledge of findings that distinguish between alternative diagnoses for a particular clinical presentation.

Quick snapshot:

Anchoring bias is a cognitive bias that causes us to rely too heavily on the first piece of information we receive when making a decision. This can lead us to make inaccurate or suboptimal decisions, especially when the initial information is not accurate or relevant.

The findings of this study suggest that anchoring bias may be a significant factor in physician decision-making. This could lead to delayed or missed diagnoses, which could have serious consequences for patients.

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.