Instruments that Detect Deception

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Instruments that detect deception

Instruments that Detect Deception

There are several different types of instruments that detect deception. If you are interested in finding out which one is the best, please keep reading on.

Detecting deception has been around for years. In fact, an instrument was invented in 1921 by John Larson. This was the polygraph instrument and its commonly called the “lie detector machine”. There is also voice stress, but which one is the better?

Now I know what you are thinking. The best instrument has to be the polygraph instrument because this blog is written by a polygraph examiner. Before we answer this question, lets discuss both and review the data.

Computer Voice Stress Analyzer

Computer Voice Stress Analyzer (CVSA) are designed to measure voice patterns. So how does it work?

A person speaks into a microphone and their voice is analyzed by computer because it’s detects “micro-tremors”. These “micro-tremors” are vibrations in the persons throat, but disappear when under stress. The patterns are then analyzed for deception.

Voice stress has been around for years. The scientific community shows it to be highly unreliable. Most noteworthy, research lists voice stress as “no better than chance“. Therefore, flip a coin because you have a 50/50 chance on passing.

Overall, this research and the few controlled tests conducted over the past decade offer little or no scientific basis for the use of the computer voice stress analyzer or similar voice measurement instruments as an alternative to the polygraph for the detection of deception. The practical performance of voice stress analysis for detecting deception has not been impressive.

US National Academy of Sciences (2003)


A polygraph instrument measures the physiological responses of the examinee. There are several steps within the examination. In addition, the examiners uses several components during data collection. Afterwards, the examiner reviews the data and renders an opinion.

Nervousness is a common thought by an examinee. None of the polygraph components measure nervousness; therefore, all you have to do is tell the truth. The CBP video is a good reference regarding nervousness.

There are four polygraph manufactures in North America. Motor City Polygraph, LLC uses the LX6 by Lafayette Instrument, but all manufactures can effectively record the physiological data.

According to the American Polygraph Association, polygraph testing is one of the most accurate means available to determine truth and deception. So how accurate is the polygraph?

The data shows that specific-issue testing is around 92% accurate. But, it can go as high as 97%. Each testing format, including scoring method, is different. Call Motor City Polygraph, LLC for details.

Michigan Law has minimum standards for instruments that detect deception. Voice stress instruments don’t meet the requirements because it’s only recording the voice.


There are a variety of instruments available today that detect deception. If fact, the newest instrument looks at the eyes and it’s called EyeDetect. This new technology is showing good reviews. More noteworthy, several articles suggest good results when in conjunction with polygraph.

In conclusion, polygraph is know to be the best instrument in detecting deception. The data shows it and it’s in compliance with Michigan law. But, everyone has remember that it’s not perfect. In fact, nothing is 100% accurate. This includes fingerprints, DNA and eye witness statements.

Contact Us at Motor City Polygraph, LLC if you have any polygraph questions. Let us be your trusted source for polygraph services.