When Confidence Becomes a Liability: Confirmation Bias and Science-Based Interviewing

I recently watched a news segment announcing new leads in a long-standing cold case. It was national news, you probably saw it. The investigator being interviewed confidently explained why they believed the investigation had finally be broken open. But having followed the case closely, sitting in on the meetings, and being familiar with the underlying facts, it was immediately clear that something was missing from the narrative, substantial exculpatory information that pointed away from the so-called “sexy” leads being highlighted.

Those facts did not disappear with a news story. They were simply ignored. The narrative being presented favored a single desired outcome, one that would come with notoriety (Netflix producers were following this person, seriously), and that outcome was the very reason the investigator was on the news. When investigators discount or sideline exculpatory information to sustain a preferred theory, the case does not become stronger, it becomes dangerous. Those overlooked facts linger, resurface, and eventually expose the investigation to failure, public scrutiny, and organizational and reputational embarrassment. This is a real-world example of confirmation bias being mistaken for sound investigative progress.

Those missing facts mattered. They suggested an alternative explanation, one that challenged the certainty being presented. Facts like these never disappear. They linger quietly in case files, reports, and memories. When ignored, they resurface later as investigative failure, organizational embarrassment, or worse, wrongful justice outcomes.

This is a real-world example of confirmation bias masquerading as sound investigation.

Confirmation bias skews the truth in cases. Science-Based Interviewing uses red teaming to combat confirmation bias and other biases.

What Is Confirmation Bias?

Confirmation bias is the tendency to seek, interpret, favor, and recall information that confirms an existing belief, case theory, or hypothesis. In investigations, it often appears after an initial theory takes hold, sometimes early, sometimes subtly, and sometimes reinforced by peers or supervisors.

This bias is not a character flaw. It is a human cognitive shortcut, well documented in psychological research. The danger lies not in having hypotheses, but in treating them as conclusions.

In investigative interviews, confirmation bias can shape:

• The questions asked and not asked

• The evidence emphasized and ignored

• The information dismissed or minimized

The first and most important step is acknowledging that confirmation bias affects everyone, including experienced investigators, supervisors, and commanders. Awareness is not weakness, it is professional investigative discipline.

How Confirmation Bias Skews the Truth

I. Tunnel Vision in Investigations

Once investigators commit to a theory, they may unintentionally seek only information that supports it. Contradictory or exculpatory evidence becomes background noise. Occasionally this evidence is explained away as trivial or disregarded altogether. This tunnel vision can waste time, drain resources, and push investigations in the wrong direction.

II. Risk of Unjust Outcomes

History and DNA exonerations show that confirmation bias plays a role in wrongful convictions. Individuals targeted early may face prolonged scrutiny or interrogation, while alternative suspects or explanations are overlooked or not even sought out. In many of these cases, the true offender remained free.

III. Organizational and Reputational Damage

Biased investigations do not stop at the case level. When errors surface, accountability spreads upward in organizations, including the larger criminal justice system. Agencies, corporations, and organizations lose credibility, sometimes permanently.

IV. Erosion of Public Trust

Public confidence in the criminal justice system and agencies erodes when investigations turn out to be biased or incomplete. Trust, once lost, is difficult to rebuild.

Countering Confirmation Bias with Science-Based Interviewing

Science-Based Interviewing (SBI) is designed to reduce, not amplify, cognitive bias. SBI emphasizes information gathering over theory confirmation through pseudoscience and relies on research-backed communication and decision-making principles.

A critical component of SBI is structured critical thinking, supported by red teaming techniques.

Red Teaming for Investigators

Red teaming deliberately challenges assumptions and case theories before they harden into conclusions. Two particularly effective techniques are:

1. On the Contrary (Devil’s Advocacy)

This method forces investigators to actively consider competing explanations by asking questions such as:

• Is the opposite also plausible?

• Is this the only explanation?

• What is the strongest argument against this theory?

Often, a single well-placed question is enough to reopen objective thinking.

2. Key Assumptions Check

Assumptions are not inherently wrong, but they are untested. A Key Assumptions Check asks:

• Is this logical?

• Is this accurate?

• Is this rooted in bias or experience?

• How confident are others that this will occur?

• If this is wrong, how does it change the investigation?

This process does not slow investigations—it protects them.

Simply challenging yourself and your original case hypotheses (including subsequent ones) is enough to show less bias in an investigation. By adopting a mindset that questions assumptions and/or plays the devil's advocate, you will only help your interviews and investigations. Your evidence, assumptions, and theories can be evaluated more objectively by activating critical thinking through red teaming.

Conclusion

Confirmation bias is a predictable human tendency—but predictable does not mean unavoidable. Left unchecked, it distorts interviews, weakens investigations, and places outcomes, credibility, and justice at risk.

Science-Based Interviewing (SBI)—supported by red teaming and disciplined critical thinking—offers a practical, defensible way forward. By deliberately challenging assumptions, testing hypotheses, and prioritizing information over outcomes, investigators can remain open, ethical, and evidence-driven.

This is the foundation of the work taught through Insight & Integrity (IXI) and advanced in agencies through Project Aletheia’s Train-the-Trainer program, which equips agencies and organizations to institutionalize SBI, reduce bias, and build sustainable investigative excellence.

Successful investigations are not built on certainty. They are built on curiosity, better information gathering, and disciplined thinking.

Science-Based Interviewing and Red Teaming Resources

Ask, K., & Granhag, P. A. (2007). Motivational sources of confirmation bias in criminal investigations: The need for cognitive closure. Journal of Investigative Psychology and Offender Profiling, 4(1), 43-63.

Garrett, B. L. (2011). Convicting the Innocent: Where Criminal Prosecutions Go Wrong. Harvard University Press.

Hoffman, B. G. (2017). Red teaming: How your business can conquer the competition by challenging everything. Random House Audio Publishing Group.

Nickerson, R. S. (1998). Confirmation bias: A ubiquitous phenomenon in many guises. Review of General Psychology, 2(2), 175-220.

O’Brien, Barbara Prime Suspect: An Examination of Factors that Aggravate and Counteract Confirmation Bias in Criminal Investigations, Psychology, Public Policy, and Law, Vol. 15(4) 315 (2009).