Context effect and confirmation bias in criminal fact finding

Eric Rassin

doi:10.1111/lcrp.12172

Abstract

PurposeFact finding is an important part of the job of criminal trial judges and juries. In the literature, several potential pitfalls hindering fact finding have been identified, such as context effects (i.e. an unintended effect of non‐probative information on conviction) and confirmation bias (i.e. a skewed selection of and overreliance on guilt‐confirming evidence and neglect of exonerating information). In the present study, the effect of irrelevant contextual information on conviction and subsequent confirmation bias was tested.MethodA sample of Dutch professional criminal trial judges (N = 105) studied a case file and decided on their conviction of the suspect’s guilt, and subsequent investigation endeavours. There were two versions of the file, differing in non‐probative details that might affect conviction, such as crime severity and facial appearance of the suspect.ResultsFindings suggest that context information indeed affected conviction, and the subsequent preference for guilt‐confirming investigation endeavours.ConclusionProfessional judges may be susceptible to bias threatening the objectivity of legal decision‐making.

Highlights

One of the crucial questions to be answered by criminal trial judges, and in some instances by the jury, is whether or not the suspect committed the crime of which he/she is suspected
Its unstructured nature makes criminal fact finding a process in which psychological pitfalls may well hinder objectivity
The purpose of the present study was to test to what extent context effects and confirmation bias occur in the decisionmaking of professional criminal trial judges

Summary

Introduction

One of the crucial questions to be answered by criminal trial judges, and in some instances by the jury, is whether or not the suspect committed the crime of which he/she is suspected. Its unstructured nature makes criminal fact finding a process in which psychological pitfalls may well hinder objectivity One such pitfall is the context effect (see Dror, Charlton, & Peron, 2006), that is, the unintended influencing of conviction by. Another pitfall that has been argued to hinder criminal fact finding is confirmation bias or tunnel vision The context effect and confirmation bias discussed above are generally likely to be disadvantageous to the suspect, in that they tend to increase (rather than decrease) perceived strength of the evidence and conviction. It was hypothesized that professional judges, like lays, are susceptible to context effects and confirmation bias

Objectives

Methods

Results

Conclusion