Saturday, 22 September 2012 08:22

Voice Stress Lie Detectors-Hype or Not

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Voice-stress analysis has long been considered as a practical alternative to the much more strenuous polygraph interrogation that is used in insurance fraud and police investigations.


Technologies based on voice analysis lie detection have been developed to potentially screen terrorists in airports and to catch philandering spouses in marital disputes. In fact, handheld versions are rampantly sold online as “portable voice analyzers” or “handheld lie detectors.”

But do voice-stress analyzers really work?

When inconclusive polygraph test results showed their weakness in evaluating skilled liars, the field of voice-stress analysis became suddenly promising as a new lie-detecting method. Unfortunately, a lie detector machine based on voice-stress analysis also presents grossly unreliable results.

Voice-stress analysis is based on a premise that the perceived tremors in a person’s voice can indicate whether he is lying or not. However, after careful scrutiny, voice-stress analysis is shown to be useful only for detecting a person’s level of stress. It cannot reliably predict deceit because a nervous demeanor does not necessarily mean dishonesty.

Mitchell S. Sommers, an associate professor of psychology in the Arts and Sciences Department at Washington University in St. Louis, studied the effectiveness of the Vericator. The study was supported by the Department of Defense Polygraph Institute or DODPI in Fort Jackson, SC. The Vericator is a computer-based program which looks at credibility using slight variations in inflection, speech, and tone of voice. In order to detect deception, several different scenarios were used. The test subjects were questioned using various interrogation techniques. Interrogation was done under conditions which induced varying levels of stress. Consequently, stress was successfully detected by the Vericator but not everyone who had showed stress levels were lying.

The gray area in voice-stress analysis and polygraph testing occurs where lie detection is performed on two social extremes: introverts and extroverts. Introverts almost always look nervous when they are questioned even when they are telling the truth. Their voice will reflect that level of nervousness and will show up as glaring tell-tale signs of lying. Extroverts, on the other hand, are socially adept and can appear extremely confident even when they are lying. Their voice will show the inflection of someone who is telling the truth.

So, when it comes to buying that too-good-to-be-true portable voice analyzer that you see online, you might want to think hard: is it really worth your money?

Read 9027 times Last modified on Thursday, 18 April 2013 11:48
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