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Psychological Stress Evaluator (PSE)

The PSE instrument detects, measures and graphically displays the degree of presence or absence of inaudible body tremors that are superimposed on the human voice (at all ages) and on all warm blooded animals. These tremors disappear according to the amount of stress that is present at the moment of utterance. The interview and test are recorded by the computer or cell phone.

To do a test, the PSE examiner asks the subject various questions. The PSE technology filters the vocal answers, creates patterns and displays those patterns on the screen. The PSE examiner evaluates the patterns for truth or deception. PSE does not use painful attached wires that polygraphs must have. PSE only needs a recording of the subject's vocal responses. PSE can be used overtly or covertly, in any language, over the phone, from any audio or video tape and entire sentences can be analyzed for lies. PSE has many advantages over the old polygraph. Only Dektor's system of Voice Stress Analysis has been independently proven to be completely reliable, effective and valid for truth verification.

PSE History

In 1969, two former U. S Army Colonels of Counter-Intelligence saw a need for a new lie detection system that did not have limitations, inconclusive, counter-measures and unreliable accuracy that affected polygraph. They called their new technology Voice Stress Analysis. They called the instrument using it PSE. The company was called Dektor. The PSE is used worldwide for all types of criminal cases, civil cases, employment screening and psychological evaluations. Accurate truth verification solves cases, saves investigative man-hours and that saves money.

PSE-Touch and PSE-LEEP

The new PSE-Touch and PSE-LEEP are the most advanced systems ever invented for lie detection. The PSE-Touch is the new PSE 7010 analog/digital technology in the Asus Prime touch tablet. The PSE-LEEP (law enforcement evaluation program) is the 7010 technology in a high performance Android cell phone. No mouse is needed. All functions are controlled by touching the screens. The investigator now has two extremely portable systems for lie detection and investigations. The cell phone and tablet can still be used for their other functions. The Asus tablet was proven superior in quality and performance over the Apple IPad 3. The PSE-Touch and LEEP have built in audio and video abilities to record information for unlimited hours.

They are used to record witness statements and videotaping crime scenes. Lie Detection tests can also be given in the field. Recorded information can be analyzed later for lies. Audio and Skype calls can be made. Our web site has much more information about the PSE-Touch and LEEP. Dektor also offers the PSE 7010 Pro and the standard PSE 7010 software systems that can be loaded into any PC, laptop or desktop. The Pro version gives the examiner many features and benefits that are not in the PSE standard version. The PSE software does not affect the computer at all. The new PSE 7010 technology has a far greater range of sensitivity to vocal stress changes than previous PSE instruments. The PSE 7010 will produce patterns with much more information than ever for superior evaluation and analysis by the examiner. With much more information being displayed, test conclusions are much easier for the PSE examiner. The PSE systems are now even more advanced for lie detection than any computer polygraph or imitation "voice lie detector" sold today. The PSE program is password protected from outsiders.

The PSE is the "easy to learn, easy to use" truth verification system.

PSE Chart Patterns and Evaluation

The PSE uses individual patterns that are easy to understand to determine truth or deception for complete accuracy. Basically, if a pattern with the most stress is on a relevant question, the subject is attempting deception.

The PSE is Superior over polygraph and computer polygraph.

In summary:

The PSE can analyze yes or no answers and phrases or entire sentences. Polygraphs only do yes or no answers.

The PSE only needs the voice and does not use attached wires. Polygraphs need those painful attached wires.

The PSE tests can be done in person (overtly or covertly), in any language, over the telephone, television, radio, from any previously made tape recording or videotape. Polygraphs can only be done with subject present and knows they are being tested.

The PSE is not affected by drugs, alcohol, or any type of countermeasures. Polygraphs are fooled by drugs, alcohol and manual manipulations.

The PSE never has "inconclusive." Polygraphs and computer polygraphs have "inconclusive."

The PSE always uses a recorder to preserve confessions for court and protect people from false accusations during the interview with the subject. Polygraphs never use tape recorder and suffer from those problems.

The PSE only needs 10 days for training. Polygraphs require 8-10 weeks for training and the costs are far more for living expenses and lost time away from company and family.

Validation Studies

From 1978-1979, the Chanute Police Department in Kansas used a federally funded field study of the PSE (LEAA Grant #77-A-3412-2-8). 159 tests were done by the request of 24 separate police departments in the 9 county area around Chanute. After the study, the Chanute Police Department stated "this (PSE) instrument is one of the best investigative tools available at any price. We base this judgment on the PSE's versatility, ease of operation, simplicity, accuracy, and relatively short training period. We have not found anyone that the PSE would not work on." The 70 investigators stated that the crimes would not have been solved without the PSE.

On December 17, 1979, the PSE and the polygraph had a face-off in the U. S. District Court for the Western District of North Carolina. A defendant had been convicted in State Court and had been given a life sentence, based largely on an unfavorable polygraph examination. A favorable PSE examination had not been admitted. An American Polygraph Association expert witness appeared for the prosecution and PSE expert witness for the defendant. Most of the testimony at this hearing involved the presentation of the study done on the PSE and polygraph.

Because of the data presented, the Federal Court found: "This court is satisfied from the evidence that both polygraph and Psychological Stress Evaluator provide substantially reliable methods of evaluating psychological stress, and the Psychological Stress Evaluator is at least as reliable as the polygraph, and possibly more reliable."

The court ruled: "Based upon that evidence and upon review of the lengthy trial record, I am of the opinion that petitioner was unconstitutionally denied a fair trial when the court admitted evidence of an unfavorable lie detection report but excluded evidence of a favorable lie detection report, and that he should have a new trial."

In 1972 a study was conducted for the Howard County, Maryland Police Department in which 43 criminal suspects took lie detection examinations that were instrumented simultaneously with a polygraph and a PSE. The test of validity was provided by a comparison of the examiner's conclusions for which complete and concrete corroboration was, or later became available, the PSE proved 100 percent accurate. The polygraph, in the same examinations, produced two cases of "un-testable subjects" and two cases of "inconclusive results." Comparison with the conclusions of a second, independent examiner produced agreement for 100 percent of the PSE findings and 93 percent for the polygraph.

In 1979, Dr. Israel Nachshon, Bar Ilan University, Israel, and Tuyva Amsel conducted a study entitled PSE-Polygraph Study, a PSE Validation Study. They conducted the PSE study using tapes made during polygraph examinations of criminal suspects by Israeli Police. Independent corroboration was not used in this case; rather the polygraph findings were assumed to be true. Agreement between the PSE and polygraph occurred in 94 percent of the cases.

The Nachshon and Amsel study was carried two steps further. In the first step, blind chart reading was employed. The Polygraph examiners read their charts and the PSE examiner read his without being able to identify the subject or make use of global impressions available with the original polygraph calls. In the second step, the PSE and polygraph charts were similarly dissected to remove the control-test patterns of responses so calls could be made simply on stress determination. In both cases, the PSE bettered the polygraph in agreeing with original polygraph findings. As a result, Dr. Nachshon stated, "I was convinced that the PSE is as good as the polygraph as an instrument to detect lies."

Psychology and Medicine

Along with truth verification, PSE is used for many types of psychological evaluations. The PSE test called Word Emotion Test (WET) determines exactly what area or area's is causing stress and to what degree each area is causing stress. Stress acts as wear and tear on the body. Untreated stress can cause physical, emotional, or behavior problems. Stress can also cause abuse of drugs, alcohol, smoking or food. The WET test determines the problems much faster and is completely accurate than only talking to a patient about their problems. The faster a diagnosis is made, the faster and more accurate the treatment will be. The WET test can also determine the effectiveness of the treatment that is being used by the therapist. PSE has no attached wires and is far more effective than the slow reactions of biofeedback devices. The WET test can be used on adults or children. Companies have used the PSE to evaluate various types of drugs. PSE can be used to determine spousal infidelity. PSE has been used in studies to analyze the stress in vocal utterances of various warm blooded animals, such as dogs and cats. Market research firms use PSE to analyze people's answers in their various surveys. PSE is used by probation and parole departments to decide is a convict should be released. PSE is used to test sex offenders during treatment to get accurate details about what the offender did and how well he is doing in treatment.


After the PSE had been sold for about 10 years, imitation "voice lie detectors" began to be sold. The sellers of those devices claimed they used Voice Stress Analysis. But, ONLY Dektor in 1969 invented the Voice Stress Analysis technology, the proven training methods and the validated chart analysis techniques. The prices of imitations range from $50 to $25,000. Most imitations today use software that is only basic audio software that reacts to sounds. Some may use fancy graphics on the computer screen. Some devices have patterns that look only like PSE patterns or have lights, numbers or words to show "lies." Imitations use instructors that were no qualified by Dektor to train lie detection. Imitations use terms to suggest they do Voice Stress Analysis, such as digital voice stress, computer voice stress, etc.

Imitations have fancy websites and use inflated sales numbers and "techno babble" to make people think their devices is real. One gadget uses a "patent" claim that so far is based on unproven ideas. Other unreliable "lie detector" methods sold are 3 or 4 day courses that teach body language, written or verbal statement analysis, facial expressions, etc. Law Enforcement has proven imitations have only about a "flip of a coin" accuracy in real crimes. Some imitations insist on yearly "recertification fees" only to make extra money. Several devices have software that turns off unless a very large fee is paid each year by the buyer to the seller of the gadget. Each examiner must pay a fee. If the gadget is turned off, the buyer loses all of the money he has paid to that point and the gadget is completely useless. Those recertification fees can be increased at any time and must be paid for life.


The Dektor website for additional details is here you can find many articles and studies on the PSE and Voice Stress Analysis. Here you can instantly read the famous 200 page book written in 1969 by Mr. Michael Kradz. Mr. Kradz was Chief of Investigations for the State of Maryland during the 1960's. His book proved the complete reliability, effectiveness and validity of the PSE system. The website has an 8 minute video explaining the PSE-7010 system, including screenshots. The website proves why the PSE is vastly superior in truth verification over polygraph, imitation "voice lie detectors" and other methods of lie detection.

Only PSE has validation by the U. S. government for 40 years. Only PSE qualifies to EEOC validation standards for employment screening or law enforcement and government personnel.

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Michael P. Gervais is an experienced Private Investigator with 30 years of experience in Law Enforcement. He has a strong educational background which includes an A.S. in Criminal Justice and numerous certificates in law enforcement science and criminal justice. His background also includes four years in the US Marine Corps as a Military Policeman, Scout, and White House Honor Guard. His company, Silent Warrior, is located in Southern California and provides state and nationwide services.

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