5 Key Factors That Affect Lie Detector Accuracy
A lie detector, more accurately known as a polygraph, is the modern bogeyman used by law enforcement and intelligence agencies to exact confessions from crime suspects. True to its name, the instrument is designed to establish whether a test subject is telling the truth or not by analyzing a series of physiological changes associated with lying.
However, lie detectors are no longer deployed exclusively by the FBI. These devices have since permeated our social spaces, too.
In late 2023, acclaimed singer and actress Ariana Grande took a lie detector test to dispel widespread plastic surgery rumors. Grande admitted to being reserved about taking a polygraph test despite mounting pressure from her fans and critics, citing her long-term battle with various anxiety disorders. Although she reportedly passed the test, many were left questioning the accuracy and authenticity of polygraph tests.
The reality is that lie detector tests aren’t foolproof. That explains why polygraph results are inadmissible in criminal and civil cases in about half of all U.S. states.
Here are the top five reasons you may fail a lie detector test.
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- Unprofessional Examiners
Not everyone should perform a polygraph evaluation. Polygraph examiners are typically required to possess a bachelor’s degree in behavioral sciences as a minimum, with a major in criminology, criminal justice, forensic science, or police science.
Even outside the law enforcement and intelligence community, the person administering a lie detector test must have completed specialized training in an accredited polygraph institute. The examiner must also be independent, objective, and impartial.
Lacking the relevant skills and qualifications is the surest way to contaminate lie detector tests.
One study examining the role of experience in performing polygraph tests involved seven experienced and three inexperienced examiners. At the end of the experiment, data obtained from the experienced cohort had a remarkably higher accuracy of 91.4% compared to 77.5% for the less experienced group.
- Wrong Focus Subject and Chosen Setting
A battle-hardened soldier may casually narrate a gruesome murder they committed or witnessed without batting an eyelid. After all, they’ve probably encountered hundreds of similar scenarios. That’s in sharp contrast to, say, a teenager or religious figure.
The authenticity of polygraph tests is highly predicated on the topic of the examination. If it’s a theme the examinee feels strongly about, their physiological responses may be highly unreliable.
Besides, the setting a polygraph examiner chooses for the screening can impact the test results. Many lie detector tests are administered in confined rooms, which may increase anxiety and reduce the accuracy score.
The examinee should share any concerns with the examiner prior to taking a polygraph test. Whether it’s an uncomfortable chair, foul smell, or crowded space, such issues should be addressed before proceeding with the test.
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- Feelings of Guilt
Guilt ranks among the top reasons people fail polygraph tests.
And no, we’re not referring to the overwhelming feelings of guilt weighing down an actual perpetrator of a heinous crime. If anything, many serial killers like Gary Ridgway aced polygraph tests and went on to commit multiple murders before the law finally caught up with them.
Instead, we’re talking about the guilty feelings a polygraph test subject may harbor in relation to the subject matter.
Say you witnessed a public altercation between strangers, which resulted in the stabbing of one of the parties. While the victim is completely unknown, you’re convinced you could have de-escalated the situation if you had stepped in earlier. In such cases, guilty feelings can severely falsify the outcome of a polygraph test.
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- Familiarity with Polygraphs and Intelligence Levels
Certain professions require taking or administering polygraph tests from time to time. Noteworthy examples include criminal justice and law enforcement.
A jailbird who has taken lie detector tests multiple times in their criminal career is likelier to beat the test even if they’re guilty of their accusations.
The same goes for a detective who has administered polygraph exams for years and suddenly finds themselves on the receiving end. Their mere similarity with the instrument improves their chances of lying undetected.
Research on the role of intelligence in polygraph tests is ongoing. However, most findings indicate that intellectual and emotional intelligence can contaminate lie detector tests.
- Exposure to Certain Drugs and Medications
Polygraph results can have far-reaching implications on the test subject’s criminal culpability and general reputation. Therefore, it’s imperative to have all lie detector tests administered only upon establishing that the examinee isn’t under any drugs (both prescription and recreational).
While anti-anxiety drugs can calm your nerves and improve your focus during lie detector exams, these medications may alter your emotional state, lower your blood pressure, and reduce your heart rate.
Altering these key variables can impact the accuracy of polygraph tests.
Again, a polygraph participant must disclose any medications they’re currently using. That includes banned or restricted substances. The examiner can then determine whether to proceed with the test.
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Wrap Up
Lie detector tests were meant to enable law enforcement and intelligent officers to establish criminal culpability by analyzing physiological reactions to certain questions. However, mounting reports indicate that polygraph evaluations aren’t foolproof.
You can improve the accuracy of lie detector tests by having them administered by professional examiners and in the right environments. Moreover, it’s best to ensure the test subject is mentally, emotionally, and psychologically disposed to undergo the screening.