Interviewer Assumptions, Contamination & Reliability Degradation
by Stan B. Walters
ORCID 0009-0002-1063-0519
Archival edition DOI: https://doi.org/10.5281/zenodo.21416103
False confessions are rarely the result of a single tactic.
More often, they emerge from a chain of interviewer decisions:
premature assumptions, confirmation bias, contamination, unreliable deception assessments, and the failure to preserve statement reliability.
Long before today’s growing scrutiny surrounding false confessions, courtroom-defensible interviewing, and unreliable deception cues, this article challenged a controversial but critical question:
Who bears responsibility when investigative methods compromise reliability?
Originally published in 2007, this archive article reflects early concepts that contributed to the development of the Cognitive Reliability Framework™— a structured, evidence-based approach focused on preserving and assessing statement reliability in investigative interviews.
False Confessions Rarely Begin With a Single Decision
Interview failures rarely begin at the moment of confession.
They often begin much earlier — during assessment, interpretation, and premature cognitive commitment.
Once an interviewer becomes committed to an assumption, information may begin to be filtered through confirmation rather than clarification. Contradictory information may receive less attention, uncertainty may be interpreted as deception, and interviews may gradually shift from information development to confession confirmation.
Over time, that process can contaminate reliability itself.
The issue is not simply whether a confession was obtained.
The issue is whether the methods used preserved the integrity and reliability of the information being produced.
The Danger of Unreliable Deception Assessments
One of the most overlooked risks in investigative interviewing is reliance on unsupported deception indicators.
For decades, investigators have been taught to interpret selected verbal and nonverbal behaviors as signs of deception. Yet many commonly taught indicators have failed to demonstrate reliable scientific validity under modern research scrutiny.
That concern becomes especially important in false confession discussions.
If unreliable behavioral assumptions shape the direction of an interview, they may also shape:
- what questions are pursued,
- how ambiguity is interpreted,
- what evidence is emphasized,
- and how aggressively an interviewer seeks confirmation.
The result may not simply be a poor interview.
It may be a progressively contaminated one.
Reliability Can Be Degraded Long Before the Confession
Once an investigator becomes psychologically committed to a theory, the interview process itself may begin reinforcing that commitment.
Over time, contamination can emerge through:
- selective attention,
- omission blindness,
- fact feeding,
- repeated reinforcement,
- minimization,
- and narrowing alternative explanations.
As reliability degrades, the distinction between “information obtained” and “information influenced” becomes increasingly important.
That distinction matters operationally, ethically, and legally.
Because when reliability deteriorates inside the interview room, the consequences may extend far beyond the interview itself.
The Goal Is Reliability — Not Simply Confession
Modern investigative interviewing increasingly recognizes that the objective of an interview is not simply obtaining a confession.
The objective is preserving and assessing reliability.
That requires interviewers to:
- avoid premature assumptions,
- minimize contamination,
- ethically test information,
- and remain aware of how interviewer choices influence interview outcomes.
A confession alone does not establish reliability.
Reliability must be demonstrated through the quality, integrity, and independence of the information obtained.
Because a false confession does not serve justice.
Archive Article
False Confession: Who’s Responsible?
By Stan B. Walters
Originally published February 2007 in The Interview Room newsletter
Recently I was comparing “notes” with a social psychologist who is conducting research on cues to deception. She has been collecting data about the lie cues taught by the numerous interview and interrogation courses and attempting to validate the reliability of those cues. She shared with me a comment made by an instructor in one of these courses that not only did she find disturbing by that I find at least professionally if not ethically appalling. A question was raised in class about the issue of false confessions and how they should be handled. The instructor informed the participants that the interviewer should blame the subject for the false confession.
With the country’s legal system current focus on wrongful convictions and false confessions, how irresponsible could a professional investigator be to blame a false confession on the suspect? The objective of the investigative interviewer should be finding the truth by accurately spotting deception and ultimately obtaining a legal and ethical admission or confession. Such professionals should also be keenly aware of what methods and techniques could induce a highly suggestible subject to make a false confession.
One issue that immediately concerns me about the instructor’s statement is there must be some problem with the human behavior cues that are being taught in this course. We are expected to spot a subject’s apparent deception regarding their involvement in some inappropriate or criminal act by observing and identifying specific verbal and nonverbal cues of deception.
If the cues being taught are reliable discriminators of deception, then why would the interviewer not be able to spot the very same signs that would undoubtedly be generated by a subject who is falsely confessing? The objective of any investigation is to uncover the real story.
Doesn’t the fact that there has been a false confession run completely counter to that objective? The fact that the investigator has become focused on this subject as being the person that there may in fact have been a faulty or inadequate investigative effort which would include the identification, collection and preservation of evidence and more importantly the interviews of other sources, victims and witnesses. Once again, how has the interviewer missed the cues of omission and embellishment by the victims, witnesses or informants that I assume have already been interviewed during the investigation.
A couple of months ago I wrote an article for this newsletter that was entitled ‘Pre-Conception: An Interrogation Assassin’. My premise in that article was one of if not the most insidious states of mind that an interviewer could have any pre-conception about a person’s credibility and honesty about an issue. With an inaccurate assessment of the subject’s honesty and relying on signs of deception that have been proven to be unreliable and then proceeding without considering that their technique may increase the chances of a false confession is the path to disaster.
If the investigator is prepared to take the credit for solving a case and wants the credit for getting a confession from a subject then he or she is also are responsible for a false confession. Blaming the subject for their false confessions is an absolutely unacceptable excuse.
Our job is to find the truth. A false confession does not serve justice.
Additional Resources
- The Cognitive Reliability Framework™ (CRF)
- From First Contact to Final Question: An Introduction to Evidence-Based Interview and Interrogation
- Evidence-Based Interview & Interrogation Articles by Stan B. Walters
