Test of the analysis of competing hypotheses in legal decision-making

Enide Maegherman*, Karl Ask, Robert Horselenberg, Peter J. van Koppen

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


The analysis of competing hypotheses (ACH) has been suggested to be a method that can protect against confirmation bias in the context of intelligence analysis. In the current study, we aimed to determine whether ACH could counter confirmation bias in the reasoning with evidence in the context of criminal law proceedings. Law students (N = 191) received information about the ACH method or general information about biases. They were given a case vignette with a main suspect and a list of 24 questions, 6 of which they could ask about the case. Half of the questions related to incriminating information, whereas the other half related to exonerating information. Contrary to our expectations, participants in both conditions favoured questions relating to exonerating information and rated the exonerating evidence as being more important for their decision. Despite the lack of bias observed, it seems participants failed to properly apply the ACH method.

Original languageEnglish
Pages (from-to)62-70
Number of pages9
JournalApplied Cognitive Psychology
Issue number1
Early online date24 Aug 2020
Publication statusPublished - Jan 2021


This research is supported by a fellowship awarded from the Erasmus Mundus Joint Doctorate Program The House of Legal Psychology (EMJD‐LP) with Framework Partnership Agreement (FPA) 2013‐0036 and Specific Grant Agreement (SGA) 532473‐EM‐5‐2017‐1‐NL‐ERA MUNDUS‐EPJD. We would like to thank Imke Jacobs for her help with data collection and Stephanie Blom for her help with creating the material.

FundersFunder number
Forecast Public Art2013‐0036


    • ACH
    • confirmation bias
    • evidence
    • legal decision-making


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