Testing Acts vs. Feelings: Why Credibility Assessment Cannot Measure Emotions

Howdy, folks — Jerry Thomas here. Today I want to talk about something that comes up more often than you might expect: the idea of using a credibility assessment test to find out how someone feels. It is a reasonable thing to wonder about, and the answer is worth understanding — because it gets to the heart of what these tools actually do, and what they simply cannot.

The Nature of Emotional Feelings

Emotions are deeply personal, complex, and profoundly individual. One person feels joy in a situation that leaves another unmoved. Feelings are shaped by our experiences, our history, our biology, and the moment we are living in. Smart people have been studying human emotion ever since, as I like to say, Keith Richards changed Methuselah's diapers — and we are still working on it.

Here is the thing about emotions that makes them fundamentally different from physical acts: they move. They are not fixed in history. They change, sometimes slowly and sometimes overnight, and there is nothing we can do to pin them down permanently.

Physical Acts vs. Emotional Feelings

A credibility assessment test — whether polygraph or EyeDetect — works by detecting physiological responses associated with deception about a specific, concrete event. Did you take the money? Did you say those words? Were you at that location? These are physical acts — things that occurred or did not occur, rooted in a fixed moment in time.

Emotions are not actions — they are internal experiences. There is no physical proof of a feeling the way there is physical proof of an act. A person can feel one thing and show another. They can be completely sincere about what they feel today and feel something entirely different tomorrow — not because they lied, but because that is how emotions work.

Why We Cannot Test Emotional Truth

Credibility assessment tests detect deception by measuring the body's involuntary response to a known truth versus a known lie. For that to work, there must be an objective fact — something the subject either knows is true or knows is false. This is precisely what Handler, Shaw & Gougler (2010)^[1] illuminate in their foundational APA paper on emotion and polygraph: polygraph subjects appraise or evaluate test questions against some type of goal that is at stake, and those appraisals mediate the physiological response. When feelings rather than facts are at issue, there is no fixed goal against which to appraise — and therefore no reliable physiological signal to measure.

With emotions, that foundation does not exist. If someone says "I love you," there is no objective fact to measure against. They may genuinely believe it in the moment. Their feelings may have changed since they last examined them. They may not fully understand what they feel at all. Handler, Shaw & Gougler note that the specific emotion triggered during a polygraph examination can vary widely among individuals based on prior experiences, values, goals, and expectations — and that physiological reactions must be interpreted with caution because it is not always clear which emotion has evoked which pattern of response.^[1] None of those scenarios involves deception in any measurable physiological sense.

Handler, Shaw & Gougler also address the infidelity scenario directly — and their finding is important. They note that a subject could, in theory, suppress a memory of previous infidelity or disconnect from a former deception by diverting attention to another goal entirely, such as the need to preserve a relationship or pass a screening. In doing so, they could redirect their physiological salience and produce responses that appear truthful — not because they are lying about their feelings, but because feelings are inherently fluid and context-dependent.^[1] This is precisely why no responsible examiner should claim that a polygraph test measures love, loyalty, or any other emotional state.

What that means practically: if you are asking "Did my partner have a physical relationship with someone else?" — that is a question credibility assessment can address. If you are asking "Does my partner still love me?" — no test in existence can answer that, and any examiner who tells you otherwise is not being straight with you.

What Does Work

If you are in a situation where trust has been broken — or where you simply need clarity about what actually happened — single-issue credibility assessment testing focused on specific physical acts is the right tool. It is precise, it is focused, and it provides the clearest answer the science can produce about a concrete event.

For everything else — the question of how someone feels, whether they have genuinely changed, whether trust can be rebuilt — those answers come through communication, counseling, and time. No instrument measures those things. No examiner should claim otherwise.