The polygraph, the lie detector test, is premised on the idea that lying produces measurable physiological changes that identify deception. However, subjects frequently fool the polygraph using tricks and techniques to manipulate their reactions. Why does this occur? The psychology and neurobiology of deception explain how people conceal lies from so-called lie detectors.

To beat the polygraph, it helps measures. The polygraph records indicators like blood pressure, pulse, respiration, and skin conductivity. The assumption is that the anxiety of lying causes observable bodily responses. However, these reactions stem from many sources besides lying. The polygraph captures ambiguous stress signals requiring interpretation about cause and meaning.

Non-linear thinking

One reason people fool the polygraph is that lying involves complex non-linear thinking. Unlike truth-telling, deceit requires contemplating multiple scenarios, projections of how a lie will be received, moral rationalization, and suppression of guilt. This dynamic way of reasoning activates different neurological pathways. The multidimensional thought process alters normal reactions.

Emotional control

Skilled liars also exhibit greater emotional control and regulation. MRI studies show reduced activity in brain regions like the amygdala when habitual liars are deceiving. They deliberately calm anxiety and fear. Liars also suppress outward displays such as awkward smiles. This ability to minimize emotional cues helps evade polygraph detection.


There are many conscious techniques people use to alter reactions and “beat” the polygraph. Physical countermeasures include biting the tongue, pressing toes to the floor, or placing tacks in shoes to cause pain that disguises anxiety. Mental countermeasures include calming visualization or silently repeating a mantra. Taking drugs is another common countermeasure.

Blunted responses

Studies also show that people with certain personality traits like narcissism, duplicity, and manipulativeness exhibit blunted neurological and physiological responses when lying. A lack of remorse or empathy may diminish typical reactions. Some brains work so that deceit barely registers a stress response.

Contextual factors

Polygraphs contribute to deceptions by contextual factors surrounding the deception. Rehearsed lies provoke less anxiety. High-stakes lies generate responses due to fear of consequences rather than lying itself. Familiarity with the examiner and lie detector test florida environments also alters reactions. Context shapes the psychology of each instance of deception.

Perceived accuracy

The common belief that polygraphs are highly accurate lie detectors also aids liars. This perception provides confidence that using countermeasures will go undetected since examiners presume the machine is working. Ironically, the myth of infallibility enables deceit. Liars manipulate the test with less apprehension and anxiety. Their faith in countermeasures works against detection.

Misdirected scrutiny

Polygraph examiners concentrate on physiological measurements rather than the subject’s behavior and testimony. Cues like evasive eyes, inconsistent facts, and implausible claims often signal deception better than readings. However, examiners miss these tangible behavioral clues while concentrating on the psychometric exam. Scrutiny in the wrong place abets lying.