Introduction: The Myth of the Human Lie Detector
We are fascinated by the idea of knowing who is telling the truth. From popular TV shows to our own daily interactions, there’s a deep-seated desire to “read” people, to spot the lie, and to get to the bottom of a story. This has created a persistent myth: that some people are human lie detectors, able to uncover deception through a single nervous glance, a fidgeting hand, or a subtle change in tone.
In the world of professional workplace investigations, however, this myth has no place. When tasked with making sense of conflicting reports about harassment, discrimination, or other misconduct, trained investigators don’t rely on a “gut feeling” or a supposed superpower. Instead, they use a deliberate, systematic process to piece together the most likely version of events. This article shares five key factors that professionals use to move beyond body language and build a credible, defensible conclusion.
1. It’s About the Process, Not a Superpower
The first and most crucial principle of assessing credibility is that it is a methodical practice, not an innate talent. Investigators are not tasked with achieving absolute certainty or declaring someone a “liar” in a definitive, cinematic way. Their primary function is to serve as an impartial fact-finder, tasked with providing a fair process for all parties and reaching reasoned findings based on the evidence.
The standard used in workplace investigations is the “preponderance of the evidence.” This legal term has a simple meaning: determining what is “more likely than not” to have occurred based on all the available information. The goal is to reach a “reasoned conclusion” that is fair, objective, and defensible, not to prove a case beyond a reasonable doubt, as in a criminal trial. This structured approach ensures that findings are based on a holistic review of the facts, not on a single, often misleading, personal impression.
2. Plausibility Is Harmony with the Probable
One of the foundational factors an investigator considers is “inherent plausibility.” In simple terms, does a person’s account make logical sense on its face? Does it align with how things generally work in that specific workplace and under the circumstances described?
This concept was powerfully articulated by the British Columbia Court of Appeal in a decision that has become a guiding principle for investigators:
“the real test of the truth of the story of the witness in such a case must be its harmony with the preponderance of the probabilities which a practical and informed person would readily recognize as reasonable in that place and in those conditions.”, Faryna v Chorny, [1952] 2 D.L.R. 354 (B.C.C.A.)
This principle grounds the investigation in logic and reason. It moves the assessment away from subjective belief and toward an objective question: What would a practical, informed person find believable under these specific circumstances? An account that aligns with the probable course of events in that context is considered more plausible.
3. Corroboration Is the Gold Standard
Corroboration is independent evidence that supports or confirms a person’s story. While a plausible narrative is a strong start, evidence that backs it up is even stronger. This is why corroboration is often called the “gold standard” in workplace investigations.
Corroborating evidence can take many forms, including:
- Other witness testimony: Do other individuals have firsthand knowledge that supports a key part of the account?
- Digital communications: Do emails, text messages, or internal chat logs confirm timelines, interactions, or statements?
- Company documents: Do phone records, time sheets, work schedules, or other official records align with a person’s narrative?
Corroboration provides objective support for an account, allowing an investigator to move beyond a “he said, she said” scenario and base findings on verifiable facts.
4. Beware the Demeanor Deception
The most common misconception about assessing credibility is that body language is a reliable indicator of truthfulness. Investigators are trained to be extremely cautious about relying on a person’s demeanor, such as their eye contact, tone of voice, or whether they fidget, to determine if they are lying. In criminal law, the Courts routinely caution Judges about not using the body language or demeanour of a witness as evidence of truthfulness. These warnings are equally applicable in the workplace investigation context.
Behaviors often associated with dishonesty can just as easily be caused by other factors, including the stress and anxiety of the interview process itself, cultural differences in communication styles, or an individual’s personality. As one investigative text puts it: body language indicates emotions, not deception.
Because relying on demeanor is so problematic and prone to bias, the Association of Workplace Investigators (AWI) advises extreme caution and does not endorse its use as a primary credibility factor. Relying on demeanor can lead to serious errors in judgment. It risks allowing unconscious bias to influence the outcome, leading to incorrect assessments based on stereotypes or personal intuition rather than on the evidence. A good investigator focuses on what is said and how it fits with other evidence, not on how it is said. This same caution applies to assessing a witness’s memory, where inconsistencies are often misread as deception rather than understood as a natural response to stress or trauma.
5. Memory Is a Reconstruction, Not a Recording
Scientific research has definitively shown that human memory does not work like a video camera. It is not a perfect, unchangeable recording of past events that can be replayed with total accuracy. Instead, memory is a “reconstructive” and “malleable” process.
This means that every time a memory is recalled, it is actively reconstructed, and is vulnerable to being altered by “post-event information”, details, ideas, or suggestions encountered after the event, which can become integrated into the original memory. For example:
- Social Contagion: Discussing an incident with other witnesses can cause people’s memories to blend, incorporating details they didn’t personally observe.
- Leading Questions: The way a question is framed can influence how an event is remembered.
- Trauma: Experiencing a traumatic event can have a significant neurobiological impact on memory, sometimes resulting in fragmented recall, gaps, or inconsistencies. These are often normal neurological responses, not indicators of deceit.
Furthermore, a witness’s confidence in their memory is not a reliable indicator of its accuracy. People can be highly confident about a memory that is factually incorrect. Investigators understand these limitations and assess inconsistencies in memory within this scientific context, recognizing that a perfect, linear recall of a stressful event is the exception, not the rule.
Conclusion: Assembling the Puzzle
Assessing credibility is not about finding a single “tell” that reveals the truth. It is like assembling a complex puzzle. An investigator carefully gathers each piece, plausibility, corroboration, consistency, and a scientific understanding of human memory, and methodically fits them together. The final picture emerges not from one clue, but from the combined weight and coherence of all the available evidence. The next time you’re faced with conflicting stories, which pieces of the puzzle will you look for first?
