Confirmation Bias and Other Systemic Causes of Wrongful Convictions

Confirmation Bias and Other Systemic Causes of Wrongful Convictions: A Sentinel Events Perspective,
By D. Kim Rossmo and Joycelyn M. Pollock.

Their study suggests that 37% of wrongful convictions result from confirmation bias.

Table 1: Causal Factors (≥ 10)
Causal Factor

Confirmation bias 37
Tunnel vision 24
High-profile crime/media attention 23
Management/supervision issues 22
Careless/incompetent investigation 20
Improper interrogations 20
Rush to judgment 19
Flawed forensics 15
Problematic witness/informant 14
Evidence analysis/logic failure 12
Interagency conflict/DA interference 10

Welcome to military sexual assault investigations and prosecutions.

confirmation bias, in particular, held a pivotal position in the causal structure of wrongful convictions. Faulty assumptions, probability errors, and groupthink often played supporting roles. Cognitive bias affects not just investigators, but also prosecutors, defense lawyers, scientists, military leaders, politicians-indeed, everyone.

“Believe the victim” and victim-centric interviews and investigations require the application of cognitive/ confirmation bias–IMHO deliberately. A presumption of guilt follows which reinforces CB.

Confirmation bias is a type of selective thinking. Once a hypothesis has been formed, our inclination is to confirm rather than refute it. We tend to look for supporting information, interpret ambiguous information as consistent with our beliefs, and minimize any inconsistent evidence. Types of confirmation bias include: (1) the biased search for evidence; (2) the biased interpretation of information; and (3) a biased memory (selective recall).

Confirmation bias can cause a detective to interpret information in a biased manner-evidence that supports the investigative theory is taken at face value, while contradicting evidence is skeptically
scrutinized. Other manifestations of confirmation bias include the failure to search for evidence that might prove a suspect’s alibi, not utilizing such evidence if found, and refusing to consider alternative


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