How presumptive thinking shapes investigative interviews before the first question is ever asked
by Stan B. Walters
Confirmation bias is often described as an interviewer problem.
In reality, it frequently begins long before the interview itself.
Investigators are trained to recognize patterns, interpret behaviors, and make rapid assessments under pressure. The danger emerges when those assessments become presumptive—when early interpretations begin shaping how information is heard, filtered, and pursued.
Once an interview becomes presumptive, the interviewer may unknowingly begin:
- seeking confirmation instead of clarification,
- interpreting uncertainty as deception,
- overlooking contradictory information,
- and feeding details that contaminate reliability.
The result is not simply a poor interview.
It is an interview shaped by premature cognitive commitment.
And once that occurs, reliability begins to erode long before the courtroom ever enters the picture.
The Problem with Presumptive Interviewing
Most investigators do not intentionally enter an interview seeking to contaminate information or narrow the investigative lens. The problem is more subtle.
Presumptive thinking often develops from:
- prior reports,
- witness statements,
- emotional case details,
- investigative pressure,
- organizational culture,
- or training that encourages premature behavioral interpretation.
Once a presumption forms, the interview itself can slowly shift from information-gathering to confirmation-seeking.
Questions become narrower.
Interruptions increase.
Contradictory information receives less attention.
The interviewer begins listening through the filter of expectation rather than through the pursuit of reliability.
This is where interviews begin to deteriorate—not because the interviewer lacks experience, but because the diagnostic process has already been compromised.
Presumption Changes What Investigators Notice
Research in cognitive psychology consistently demonstrates that expectation influences perception and interpretation.
In investigative interviews, presumptive thinking can cause interviewers to:
- overvalue information supporting their theory,
- minimize information contradicting it,
- misinterpret emotional reactions,
- and mistake uncertainty or cognitive strain for deception.
This becomes particularly dangerous when investigators rely heavily on generalized behavioral assumptions or so-called “deception cues” that lack scientific reliability.
Once an interviewer begins interpreting behaviors through a presumptive lens, almost any reaction can appear suspicious.
The interview no longer becomes an assessment of reliability.
It becomes an exercise in reinforcing an existing belief.
Reliability Requires Diagnostic Discipline
Reliable interviews require something more difficult than confidence.
They require restraint.
The interviewer must resist the urge to prematurely explain behaviors, fill gaps, or force meaning onto incomplete information. Instead, investigators must focus on facilitating accurate, uncontaminated narratives that can later be tested for reliability through evidence and structured analysis.
Evidence confirms reliability.
It does not create it.
That distinction matters.
Because once contamination occurs—through leading questions, evidence feeding, selective listening, or presumptive interpretation—the reliability of the interview begins to weaken regardless of the final outcome.
The Courtroom Eventually Sees the Process
The courtroom does not merely evaluate conclusions.
It increasingly evaluates how those conclusions were reached.
Jurors, attorneys, judges, and experts are paying closer attention to:
- confirmation bias,
- contamination,
- coercive influence,
- unreliable behavioral interpretations,
- and the overall integrity of investigative interviewing practices.
The issue is no longer whether investigators intended to act improperly.
The issue is whether the process itself supports reliability.
And that begins with recognizing how presumptive thinking can quietly shape an interview before the first question is ever asked.
Stan B. Walters is an internationally recognized expert specializing in evidence-based investigative interviewing, statement reliability, cognitive interviewing strategies, and courtroom-defensible interview practices. He is the developer of the Cognitive Reliability Framework™ (CRF), a structured diagnostic approach to assessing statement reliability in investigative interviews.
Learn more at:
https://TheLieGuy.com
Free eBook:”From First Contact to Final Question. An Introduction to Evidence-Based Interview & Interrogation.“
